mesa update 11 july 2011

4 files changed, 2018 insertions, 1578 deletions

diff --git a/mesalib/src/glsl/ir_optimization.h b/mesalib/src/glsl/ir_optimization.h
index dd265673c..59a040751 100644
--- a/mesalib/src/glsl/ir_optimization.h
+++ b/mesalib/src/glsl/ir_optimization.h
@@ -56,10 +56,8 @@ bool do_if_simplification(exec_list *instructions);
 bool do_discard_simplification(exec_list *instructions);
 bool lower_if_to_cond_assign(exec_list *instructions, unsigned max_depth = 0);
 bool do_mat_op_to_vec(exec_list *instructions);
-bool do_mod_to_fract(exec_list *instructions);
 bool do_noop_swizzle(exec_list *instructions);
 bool do_structure_splitting(exec_list *instructions);
-bool do_sub_to_add_neg(exec_list *instructions);
 bool do_swizzle_swizzle(exec_list *instructions);
 bool do_tree_grafting(exec_list *instructions);
 bool do_vec_index_to_cond_assign(exec_list *instructions);
diff --git a/mesalib/src/glsl/ir_reader.cpp b/mesalib/src/glsl/ir_reader.cpp
index 201e436be..f3a621734 100644
--- a/mesalib/src/glsl/ir_reader.cpp
+++ b/mesalib/src/glsl/ir_reader.cpp
@@ -1,1005 +1,1007 @@
-/*

- * Copyright © 2010 Intel Corporation

- *

- * Permission is hereby granted, free of charge, to any person obtaining a

- * copy of this software and associated documentation files (the "Software"),

- * to deal in the Software without restriction, including without limitation

- * the rights to use, copy, modify, merge, publish, distribute, sublicense,

- * and/or sell copies of the Software, and to permit persons to whom the

- * Software is furnished to do so, subject to the following conditions:

- *

- * The above copyright notice and this permission notice (including the next

- * paragraph) shall be included in all copies or substantial portions of the

- * Software.

- *

- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

- * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

- * DEALINGS IN THE SOFTWARE.

- */

-

-#include "ir_reader.h"

-#include "glsl_parser_extras.h"

-#include "glsl_types.h"

-#include "s_expression.h"

-

-const static bool debug = false;

-

-class ir_reader {

-public:

-   ir_reader(_mesa_glsl_parse_state *);

-

-   void read(exec_list *instructions, const char *src, bool scan_for_protos);

-

-private:

-   void *mem_ctx;

-   _mesa_glsl_parse_state *state;

-

-   void ir_read_error(s_expression *, const char *fmt, ...);

-

-   const glsl_type *read_type(s_expression *);

-

-   void scan_for_prototypes(exec_list *, s_expression *);

-   ir_function *read_function(s_expression *, bool skip_body);

-   void read_function_sig(ir_function *, s_expression *, bool skip_body);

-

-   void read_instructions(exec_list *, s_expression *, ir_loop *);

-   ir_instruction *read_instruction(s_expression *, ir_loop *);

-   ir_variable *read_declaration(s_expression *);

-   ir_if *read_if(s_expression *, ir_loop *);

-   ir_loop *read_loop(s_expression *);

-   ir_return *read_return(s_expression *);

-   ir_rvalue *read_rvalue(s_expression *);

-   ir_assignment *read_assignment(s_expression *);

-   ir_expression *read_expression(s_expression *);

-   ir_call *read_call(s_expression *);

-   ir_swizzle *read_swizzle(s_expression *);

-   ir_constant *read_constant(s_expression *);

-   ir_texture *read_texture(s_expression *);

-

-   ir_dereference *read_dereference(s_expression *);

-};

-

-ir_reader::ir_reader(_mesa_glsl_parse_state *state) : state(state)

-{

-   this->mem_ctx = state;

-}

-

-void

-_mesa_glsl_read_ir(_mesa_glsl_parse_state *state, exec_list *instructions,

-		   const char *src, bool scan_for_protos)

-{

-   ir_reader r(state);

-   r.read(instructions, src, scan_for_protos);

-}

-

-void

-ir_reader::read(exec_list *instructions, const char *src, bool scan_for_protos)

-{

-   s_expression *expr = s_expression::read_expression(mem_ctx, src);

-   if (expr == NULL) {

-      ir_read_error(NULL, "couldn't parse S-Expression.");

-      return;

-   }

-   

-   if (scan_for_protos) {

-      scan_for_prototypes(instructions, expr);

-      if (state->error)

-	 return;

-   }

-

-   read_instructions(instructions, expr, NULL);

-   ralloc_free(expr);

-

-   if (debug)

-      validate_ir_tree(instructions);

-}

-

-void

-ir_reader::ir_read_error(s_expression *expr, const char *fmt, ...)

-{

-   va_list ap;

-

-   state->error = true;

-

-   if (state->current_function != NULL)

-      ralloc_asprintf_append(&state->info_log, "In function %s:\n",

-			     state->current_function->function_name());

-   ralloc_strcat(&state->info_log, "error: ");

-

-   va_start(ap, fmt);

-   ralloc_vasprintf_append(&state->info_log, fmt, ap);

-   va_end(ap);

-   ralloc_strcat(&state->info_log, "\n");

-

-   if (expr != NULL) {

-      ralloc_strcat(&state->info_log, "...in this context:\n   ");

-      expr->print();

-      ralloc_strcat(&state->info_log, "\n\n");

-   }

-}

-

-const glsl_type *

-ir_reader::read_type(s_expression *expr)

-{

-   s_expression *s_base_type;

-   s_int *s_size;

-

-   s_pattern pat[] = { "array", s_base_type, s_size };

-   if (MATCH(expr, pat)) {

-      const glsl_type *base_type = read_type(s_base_type);

-      if (base_type == NULL) {

-	 ir_read_error(NULL, "when reading base type of array type");

-	 return NULL;

-      }

-

-      return glsl_type::get_array_instance(base_type, s_size->value());

-   }

-   

-   s_symbol *type_sym = SX_AS_SYMBOL(expr);

-   if (type_sym == NULL) {

-      ir_read_error(expr, "expected <type>");

-      return NULL;

-   }

-

-   const glsl_type *type = state->symbols->get_type(type_sym->value());

-   if (type == NULL)

-      ir_read_error(expr, "invalid type: %s", type_sym->value());

-

-   return type;

-}

-

-

-void

-ir_reader::scan_for_prototypes(exec_list *instructions, s_expression *expr)

-{

-   s_list *list = SX_AS_LIST(expr);

-   if (list == NULL) {

-      ir_read_error(expr, "Expected (<instruction> ...); found an atom.");

-      return;

-   }

-

-   foreach_iter(exec_list_iterator, it, list->subexpressions) {

-      s_list *sub = SX_AS_LIST(it.get());

-      if (sub == NULL)

-	 continue; // not a (function ...); ignore it.

-

-      s_symbol *tag = SX_AS_SYMBOL(sub->subexpressions.get_head());

-      if (tag == NULL || strcmp(tag->value(), "function") != 0)

-	 continue; // not a (function ...); ignore it.

-

-      ir_function *f = read_function(sub, true);

-      if (f == NULL)

-	 return;

-      instructions->push_tail(f);

-   }

-}

-

-ir_function *

-ir_reader::read_function(s_expression *expr, bool skip_body)

-{

-   bool added = false;

-   s_symbol *name;

-

-   s_pattern pat[] = { "function", name };

-   if (!PARTIAL_MATCH(expr, pat)) {

-      ir_read_error(expr, "Expected (function <name> (signature ...) ...)");

-      return NULL;

-   }

-

-   ir_function *f = state->symbols->get_function(name->value());

-   if (f == NULL) {

-      f = new(mem_ctx) ir_function(name->value());

-      added = state->symbols->add_function(f);

-      assert(added);

-   }

-

-   exec_list_iterator it = ((s_list *) expr)->subexpressions.iterator();

-   it.next(); // skip "function" tag

-   it.next(); // skip function name

-   for (/* nothing */; it.has_next(); it.next()) {

-      s_expression *s_sig = (s_expression *) it.get();

-      read_function_sig(f, s_sig, skip_body);

-   }

-   return added ? f : NULL;

-}

-

-void

-ir_reader::read_function_sig(ir_function *f, s_expression *expr, bool skip_body)

-{

-   s_expression *type_expr;

-   s_list *paramlist;

-   s_list *body_list;

-

-   s_pattern pat[] = { "signature", type_expr, paramlist, body_list };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "Expected (signature <type> (parameters ...) "

-			  "(<instruction> ...))");

-      return;

-   }

-

-   const glsl_type *return_type = read_type(type_expr);

-   if (return_type == NULL)

-      return;

-

-   s_symbol *paramtag = SX_AS_SYMBOL(paramlist->subexpressions.get_head());

-   if (paramtag == NULL || strcmp(paramtag->value(), "parameters") != 0) {

-      ir_read_error(paramlist, "Expected (parameters ...)");

-      return;

-   }

-

-   // Read the parameters list into a temporary place.

-   exec_list hir_parameters;

-   state->symbols->push_scope();

-

-   exec_list_iterator it = paramlist->subexpressions.iterator();

-   for (it.next() /* skip "parameters" */; it.has_next(); it.next()) {

-      ir_variable *var = read_declaration((s_expression *) it.get());

-      if (var == NULL)

-	 return;

-

-      hir_parameters.push_tail(var);

-   }

-

-   ir_function_signature *sig = f->exact_matching_signature(&hir_parameters);

-   if (sig == NULL && skip_body) {

-      /* If scanning for prototypes, generate a new signature. */

-      sig = new(mem_ctx) ir_function_signature(return_type);

-      sig->is_builtin = true;

-      f->add_signature(sig);

-   } else if (sig != NULL) {

-      const char *badvar = sig->qualifiers_match(&hir_parameters);

-      if (badvar != NULL) {

-	 ir_read_error(expr, "function `%s' parameter `%s' qualifiers "

-		       "don't match prototype", f->name, badvar);

-	 return;

-      }

-

-      if (sig->return_type != return_type) {

-	 ir_read_error(expr, "function `%s' return type doesn't "

-		       "match prototype", f->name);

-	 return;

-      }

-   } else {

-      /* No prototype for this body exists - skip it. */

-      state->symbols->pop_scope();

-      return;

-   }

-   assert(sig != NULL);

-

-   sig->replace_parameters(&hir_parameters);

-

-   if (!skip_body && !body_list->subexpressions.is_empty()) {

-      if (sig->is_defined) {

-	 ir_read_error(expr, "function %s redefined", f->name);

-	 return;

-      }

-      state->current_function = sig;

-      read_instructions(&sig->body, body_list, NULL);

-      state->current_function = NULL;

-      sig->is_defined = true;

-   }

-

-   state->symbols->pop_scope();

-}

-

-void

-ir_reader::read_instructions(exec_list *instructions, s_expression *expr,

-			     ir_loop *loop_ctx)

-{

-   // Read in a list of instructions

-   s_list *list = SX_AS_LIST(expr);

-   if (list == NULL) {

-      ir_read_error(expr, "Expected (<instruction> ...); found an atom.");

-      return;

-   }

-

-   foreach_iter(exec_list_iterator, it, list->subexpressions) {

-      s_expression *sub = (s_expression*) it.get();

-      ir_instruction *ir = read_instruction(sub, loop_ctx);

-      if (ir != NULL) {

-	 /* Global variable declarations should be moved to the top, before

-	  * any functions that might use them.  Functions are added to the

-	  * instruction stream when scanning for prototypes, so without this

-	  * hack, they always appear before variable declarations.

-	  */

-	 if (state->current_function == NULL && ir->as_variable() != NULL)

-	    instructions->push_head(ir);

-	 else

-	    instructions->push_tail(ir);

-      }

-   }

-}

-

-

-ir_instruction *

-ir_reader::read_instruction(s_expression *expr, ir_loop *loop_ctx)

-{

-   s_symbol *symbol = SX_AS_SYMBOL(expr);

-   if (symbol != NULL) {

-      if (strcmp(symbol->value(), "break") == 0 && loop_ctx != NULL)

-	 return new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_break);

-      if (strcmp(symbol->value(), "continue") == 0 && loop_ctx != NULL)

-	 return new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue);

-   }

-

-   s_list *list = SX_AS_LIST(expr);

-   if (list == NULL || list->subexpressions.is_empty()) {

-      ir_read_error(expr, "Invalid instruction.\n");

-      return NULL;

-   }

-

-   s_symbol *tag = SX_AS_SYMBOL(list->subexpressions.get_head());

-   if (tag == NULL) {

-      ir_read_error(expr, "expected instruction tag");

-      return NULL;

-   }

-

-   ir_instruction *inst = NULL;

-   if (strcmp(tag->value(), "declare") == 0) {

-      inst = read_declaration(list);

-   } else if (strcmp(tag->value(), "assign") == 0) {

-      inst = read_assignment(list);

-   } else if (strcmp(tag->value(), "if") == 0) {

-      inst = read_if(list, loop_ctx);

-   } else if (strcmp(tag->value(), "loop") == 0) {

-      inst = read_loop(list);

-   } else if (strcmp(tag->value(), "return") == 0) {

-      inst = read_return(list);

-   } else if (strcmp(tag->value(), "function") == 0) {

-      inst = read_function(list, false);

-   } else {

-      inst = read_rvalue(list);

-      if (inst == NULL)

-	 ir_read_error(NULL, "when reading instruction");

-   }

-   return inst;

-}

-

-ir_variable *

-ir_reader::read_declaration(s_expression *expr)

-{

-   s_list *s_quals;

-   s_expression *s_type;

-   s_symbol *s_name;

-

-   s_pattern pat[] = { "declare", s_quals, s_type, s_name };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (declare (<qualifiers>) <type> <name>)");

-      return NULL;

-   }

-

-   const glsl_type *type = read_type(s_type);

-   if (type == NULL)

-      return NULL;

-

-   ir_variable *var = new(mem_ctx) ir_variable(type, s_name->value(),

-					       ir_var_auto);

-

-   foreach_iter(exec_list_iterator, it, s_quals->subexpressions) {

-      s_symbol *qualifier = SX_AS_SYMBOL(it.get());

-      if (qualifier == NULL) {

-	 ir_read_error(expr, "qualifier list must contain only symbols");

-	 return NULL;

-      }

-

-      // FINISHME: Check for duplicate/conflicting qualifiers.

-      if (strcmp(qualifier->value(), "centroid") == 0) {

-	 var->centroid = 1;

-      } else if (strcmp(qualifier->value(), "invariant") == 0) {

-	 var->invariant = 1;

-      } else if (strcmp(qualifier->value(), "uniform") == 0) {

-	 var->mode = ir_var_uniform;

-      } else if (strcmp(qualifier->value(), "auto") == 0) {

-	 var->mode = ir_var_auto;

-      } else if (strcmp(qualifier->value(), "in") == 0) {

-	 var->mode = ir_var_in;

-      } else if (strcmp(qualifier->value(), "const_in") == 0) {

-	 var->mode = ir_var_const_in;

-      } else if (strcmp(qualifier->value(), "out") == 0) {

-	 var->mode = ir_var_out;

-      } else if (strcmp(qualifier->value(), "inout") == 0) {

-	 var->mode = ir_var_inout;

-      } else if (strcmp(qualifier->value(), "smooth") == 0) {

-	 var->interpolation = ir_var_smooth;

-      } else if (strcmp(qualifier->value(), "flat") == 0) {

-	 var->interpolation = ir_var_flat;

-      } else if (strcmp(qualifier->value(), "noperspective") == 0) {

-	 var->interpolation = ir_var_noperspective;

-      } else {

-	 ir_read_error(expr, "unknown qualifier: %s", qualifier->value());

-	 return NULL;

-      }

-   }

-

-   // Add the variable to the symbol table

-   state->symbols->add_variable(var);

-

-   return var;

-}

-

-

-ir_if *

-ir_reader::read_if(s_expression *expr, ir_loop *loop_ctx)

-{

-   s_expression *s_cond;

-   s_expression *s_then;

-   s_expression *s_else;

-

-   s_pattern pat[] = { "if", s_cond, s_then, s_else };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (if <condition> (<then>...) (<else>...))");

-      return NULL;

-   }

-

-   ir_rvalue *condition = read_rvalue(s_cond);

-   if (condition == NULL) {

-      ir_read_error(NULL, "when reading condition of (if ...)");

-      return NULL;

-   }

-

-   ir_if *iff = new(mem_ctx) ir_if(condition);

-

-   read_instructions(&iff->then_instructions, s_then, loop_ctx);

-   read_instructions(&iff->else_instructions, s_else, loop_ctx);

-   if (state->error) {

-      delete iff;

-      iff = NULL;

-   }

-   return iff;

-}

-

-

-ir_loop *

-ir_reader::read_loop(s_expression *expr)

-{

-   s_expression *s_counter, *s_from, *s_to, *s_inc, *s_body;

-

-   s_pattern pat[] = { "loop", s_counter, s_from, s_to, s_inc, s_body };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (loop <counter> <from> <to> "

-			  "<increment> <body>)");

-      return NULL;

-   }

-

-   // FINISHME: actually read the count/from/to fields.

-

-   ir_loop *loop = new(mem_ctx) ir_loop;

-   read_instructions(&loop->body_instructions, s_body, loop);

-   if (state->error) {

-      delete loop;

-      loop = NULL;

-   }

-   return loop;

-}

-

-

-ir_return *

-ir_reader::read_return(s_expression *expr)

-{

-   s_expression *s_retval;

-

-   s_pattern pat[] = { "return", s_retval};

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (return <rvalue>)");

-      return NULL;

-   }

-

-   ir_rvalue *retval = read_rvalue(s_retval);

-   if (retval == NULL) {

-      ir_read_error(NULL, "when reading return value");

-      return NULL;

-   }

-

-   return new(mem_ctx) ir_return(retval);

-}

-

-

-ir_rvalue *

-ir_reader::read_rvalue(s_expression *expr)

-{

-   s_list *list = SX_AS_LIST(expr);

-   if (list == NULL || list->subexpressions.is_empty())

-      return NULL;

-

-   s_symbol *tag = SX_AS_SYMBOL(list->subexpressions.get_head());

-   if (tag == NULL) {

-      ir_read_error(expr, "expected rvalue tag");

-      return NULL;

-   }

-

-   ir_rvalue *rvalue = read_dereference(list);

-   if (rvalue != NULL || state->error)

-      return rvalue;

-   else if (strcmp(tag->value(), "swiz") == 0) {

-      rvalue = read_swizzle(list);

-   } else if (strcmp(tag->value(), "expression") == 0) {

-      rvalue = read_expression(list);

-   } else if (strcmp(tag->value(), "call") == 0) {

-      rvalue = read_call(list);

-   } else if (strcmp(tag->value(), "constant") == 0) {

-      rvalue = read_constant(list);

-   } else {

-      rvalue = read_texture(list);

-      if (rvalue == NULL && !state->error)

-	 ir_read_error(expr, "unrecognized rvalue tag: %s", tag->value());

-   }

-

-   return rvalue;

-}

-

-ir_assignment *

-ir_reader::read_assignment(s_expression *expr)

-{

-   s_expression *cond_expr = NULL;

-   s_expression *lhs_expr, *rhs_expr;

-   s_list       *mask_list;

-

-   s_pattern pat4[] = { "assign",            mask_list, lhs_expr, rhs_expr };

-   s_pattern pat5[] = { "assign", cond_expr, mask_list, lhs_expr, rhs_expr };

-   if (!MATCH(expr, pat4) && !MATCH(expr, pat5)) {

-      ir_read_error(expr, "expected (assign [<condition>] (<write mask>) "

-			  "<lhs> <rhs>)");

-      return NULL;

-   }

-

-   ir_rvalue *condition = NULL;

-   if (cond_expr != NULL) {

-      condition = read_rvalue(cond_expr);

-      if (condition == NULL) {

-	 ir_read_error(NULL, "when reading condition of assignment");

-	 return NULL;

-      }

-   }

-

-   unsigned mask = 0;

-

-   s_symbol *mask_symbol;

-   s_pattern mask_pat[] = { mask_symbol };

-   if (MATCH(mask_list, mask_pat)) {

-      const char *mask_str = mask_symbol->value();

-      unsigned mask_length = strlen(mask_str);

-      if (mask_length > 4) {

-	 ir_read_error(expr, "invalid write mask: %s", mask_str);

-	 return NULL;

-      }

-

-      const unsigned idx_map[] = { 3, 0, 1, 2 }; /* w=bit 3, x=0, y=1, z=2 */

-

-      for (unsigned i = 0; i < mask_length; i++) {

-	 if (mask_str[i] < 'w' || mask_str[i] > 'z') {

-	    ir_read_error(expr, "write mask contains invalid character: %c",

-			  mask_str[i]);

-	    return NULL;

-	 }

-	 mask |= 1 << idx_map[mask_str[i] - 'w'];

-      }

-   } else if (!mask_list->subexpressions.is_empty()) {

-      ir_read_error(mask_list, "expected () or (<write mask>)");

-      return NULL;

-   }

-

-   ir_dereference *lhs = read_dereference(lhs_expr);

-   if (lhs == NULL) {

-      ir_read_error(NULL, "when reading left-hand side of assignment");

-      return NULL;

-   }

-

-   ir_rvalue *rhs = read_rvalue(rhs_expr);

-   if (rhs == NULL) {

-      ir_read_error(NULL, "when reading right-hand side of assignment");

-      return NULL;

-   }

-

-   if (mask == 0 && (lhs->type->is_vector() || lhs->type->is_scalar())) {

-      ir_read_error(expr, "non-zero write mask required.");

-      return NULL;

-   }

-

-   return new(mem_ctx) ir_assignment(lhs, rhs, condition, mask);

-}

-

-ir_call *

-ir_reader::read_call(s_expression *expr)

-{

-   s_symbol *name;

-   s_list *params;

-

-   s_pattern pat[] = { "call", name, params };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (call <name> (<param> ...))");

-      return NULL;

-   }

-

-   exec_list parameters;

-

-   foreach_iter(exec_list_iterator, it, params->subexpressions) {

-      s_expression *expr = (s_expression*) it.get();

-      ir_rvalue *param = read_rvalue(expr);

-      if (param == NULL) {

-	 ir_read_error(expr, "when reading parameter to function call");

-	 return NULL;

-      }

-      parameters.push_tail(param);

-   }

-

-   ir_function *f = state->symbols->get_function(name->value());

-   if (f == NULL) {

-      ir_read_error(expr, "found call to undefined function %s",

-		    name->value());

-      return NULL;

-   }

-

-   ir_function_signature *callee = f->matching_signature(&parameters);

-   if (callee == NULL) {

-      ir_read_error(expr, "couldn't find matching signature for function "

-                    "%s", name->value());

-      return NULL;

-   }

-

-   return new(mem_ctx) ir_call(callee, &parameters);

-}

-

-ir_expression *

-ir_reader::read_expression(s_expression *expr)

-{

-   s_expression *s_type;

-   s_symbol *s_op;

-   s_expression *s_arg1;

-

-   s_pattern pat[] = { "expression", s_type, s_op, s_arg1 };

-   if (!PARTIAL_MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (expression <type> <operator> "

-			  "<operand> [<operand>])");

-      return NULL;

-   }

-   s_expression *s_arg2 = (s_expression *) s_arg1->next; // may be tail sentinel

-

-   const glsl_type *type = read_type(s_type);

-   if (type == NULL)

-      return NULL;

-

-   /* Read the operator */

-   ir_expression_operation op = ir_expression::get_operator(s_op->value());

-   if (op == (ir_expression_operation) -1) {

-      ir_read_error(expr, "invalid operator: %s", s_op->value());

-      return NULL;

-   }

-    

-   unsigned num_operands = ir_expression::get_num_operands(op);

-   if (num_operands == 1 && !s_arg1->next->is_tail_sentinel()) {

-      ir_read_error(expr, "expected (expression <type> %s <operand>)",

-		    s_op->value());

-      return NULL;

-   }

-

-   ir_rvalue *arg1 = read_rvalue(s_arg1);

-   ir_rvalue *arg2 = NULL;

-   if (arg1 == NULL) {

-      ir_read_error(NULL, "when reading first operand of %s", s_op->value());

-      return NULL;

-   }

-

-   if (num_operands == 2) {

-      if (s_arg2->is_tail_sentinel() || !s_arg2->next->is_tail_sentinel()) {

-	 ir_read_error(expr, "expected (expression <type> %s <operand> "

-			     "<operand>)", s_op->value());

-	 return NULL;

-      }

-      arg2 = read_rvalue(s_arg2);

-      if (arg2 == NULL) {

-	 ir_read_error(NULL, "when reading second operand of %s",

-		       s_op->value());

-	 return NULL;

-      }

-   }

-

-   return new(mem_ctx) ir_expression(op, type, arg1, arg2);

-}

-

-ir_swizzle *

-ir_reader::read_swizzle(s_expression *expr)

-{

-   s_symbol *swiz;

-   s_expression *sub;

-

-   s_pattern pat[] = { "swiz", swiz, sub };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (swiz <swizzle> <rvalue>)");

-      return NULL;

-   }

-

-   if (strlen(swiz->value()) > 4) {

-      ir_read_error(expr, "expected a valid swizzle; found %s", swiz->value());

-      return NULL;

-   }

-

-   ir_rvalue *rvalue = read_rvalue(sub);

-   if (rvalue == NULL)

-      return NULL;

-

-   ir_swizzle *ir = ir_swizzle::create(rvalue, swiz->value(),

-				       rvalue->type->vector_elements);

-   if (ir == NULL)

-      ir_read_error(expr, "invalid swizzle");

-

-   return ir;

-}

-

-ir_constant *

-ir_reader::read_constant(s_expression *expr)

-{

-   s_expression *type_expr;

-   s_list *values;

-

-   s_pattern pat[] = { "constant", type_expr, values };

-   if (!MATCH(expr, pat)) {

-      ir_read_error(expr, "expected (constant <type> (...))");

-      return NULL;

-   }

-

-   const glsl_type *type = read_type(type_expr);

-   if (type == NULL)

-      return NULL;

-

-   if (values == NULL) {

-      ir_read_error(expr, "expected (constant <type> (...))");

-      return NULL;

-   }

-

-   if (type->is_array()) {

-      unsigned elements_supplied = 0;

-      exec_list elements;

-      foreach_iter(exec_list_iterator, it, values->subexpressions) {

-	 s_expression *elt = (s_expression *) it.get();

-	 ir_constant *ir_elt = read_constant(elt);

-	 if (ir_elt == NULL)

-	    return NULL;

-	 elements.push_tail(ir_elt);

-	 elements_supplied++;

-      }

-

-      if (elements_supplied != type->length) {

-	 ir_read_error(values, "expected exactly %u array elements, "

-		       "given %u", type->length, elements_supplied);

-	 return NULL;

-      }

-      return new(mem_ctx) ir_constant(type, &elements);

-   }

-

-   const glsl_type *const base_type = type->get_base_type();

-

-   ir_constant_data data = { { 0 } };

-

-   // Read in list of values (at most 16).

-   int k = 0;

-   foreach_iter(exec_list_iterator, it, values->subexpressions) {

-      if (k >= 16) {

-	 ir_read_error(values, "expected at most 16 numbers");

-	 return NULL;

-      }

-

-      s_expression *expr = (s_expression*) it.get();

-

-      if (base_type->base_type == GLSL_TYPE_FLOAT) {

-	 s_number *value = SX_AS_NUMBER(expr);

-	 if (value == NULL) {

-	    ir_read_error(values, "expected numbers");

-	    return NULL;

-	 }

-	 data.f[k] = value->fvalue();

-      } else {

-	 s_int *value = SX_AS_INT(expr);

-	 if (value == NULL) {

-	    ir_read_error(values, "expected integers");

-	    return NULL;

-	 }

-

-	 switch (base_type->base_type) {

-	 case GLSL_TYPE_UINT: {

-	    data.u[k] = value->value();

-	    break;

-	 }

-	 case GLSL_TYPE_INT: {

-	    data.i[k] = value->value();

-	    break;

-	 }

-	 case GLSL_TYPE_BOOL: {

-	    data.b[k] = value->value();

-	    break;

-	 }

-	 default:

-	    ir_read_error(values, "unsupported constant type");

-	    return NULL;

-	 }

-      }

-      ++k;

-   }

-

-   return new(mem_ctx) ir_constant(type, &data);

-}

-

-ir_dereference *

-ir_reader::read_dereference(s_expression *expr)

-{

-   s_symbol *s_var;

-   s_expression *s_subject;

-   s_expression *s_index;

-   s_symbol *s_field;

-

-   s_pattern var_pat[] = { "var_ref", s_var };

-   s_pattern array_pat[] = { "array_ref", s_subject, s_index };

-   s_pattern record_pat[] = { "record_ref", s_subject, s_field };

-

-   if (MATCH(expr, var_pat)) {

-      ir_variable *var = state->symbols->get_variable(s_var->value());

-      if (var == NULL) {

-	 ir_read_error(expr, "undeclared variable: %s", s_var->value());

-	 return NULL;

-      }

-      return new(mem_ctx) ir_dereference_variable(var);

-   } else if (MATCH(expr, array_pat)) {

-      ir_rvalue *subject = read_rvalue(s_subject);

-      if (subject == NULL) {

-	 ir_read_error(NULL, "when reading the subject of an array_ref");

-	 return NULL;

-      }

-

-      ir_rvalue *idx = read_rvalue(s_index);

-      if (subject == NULL) {

-	 ir_read_error(NULL, "when reading the index of an array_ref");

-	 return NULL;

-      }

-      return new(mem_ctx) ir_dereference_array(subject, idx);

-   } else if (MATCH(expr, record_pat)) {

-      ir_rvalue *subject = read_rvalue(s_subject);

-      if (subject == NULL) {

-	 ir_read_error(NULL, "when reading the subject of a record_ref");

-	 return NULL;

-      }

-      return new(mem_ctx) ir_dereference_record(subject, s_field->value());

-   }

-   return NULL;

-}

-

-ir_texture *

-ir_reader::read_texture(s_expression *expr)

-{

-   s_symbol *tag = NULL;

-   s_expression *s_type = NULL;

-   s_expression *s_sampler = NULL;

-   s_expression *s_coord = NULL;

-   s_expression *s_offset = NULL;

-   s_expression *s_proj = NULL;

-   s_list *s_shadow = NULL;

-   s_expression *s_lod = NULL;

-

-   ir_texture_opcode op = ir_tex; /* silence warning */

-

-   s_pattern tex_pattern[] =

-      { "tex", s_type, s_sampler, s_coord, s_offset, s_proj, s_shadow };

-   s_pattern txf_pattern[] =

-      { "txf", s_type, s_sampler, s_coord, s_offset, s_lod };

-   s_pattern other_pattern[] =

-      { tag, s_type, s_sampler, s_coord, s_offset, s_proj, s_shadow, s_lod };

-

-   if (MATCH(expr, tex_pattern)) {

-      op = ir_tex;

-   } else if (MATCH(expr, txf_pattern)) {

-      op = ir_txf;

-   } else if (MATCH(expr, other_pattern)) {

-      op = ir_texture::get_opcode(tag->value());

-      if (op == -1)

-	 return NULL;

-   } else {

-      ir_read_error(NULL, "unexpected texture pattern");

-      return NULL;

-   }

-

-   ir_texture *tex = new(mem_ctx) ir_texture(op);

-

-   // Read return type

-   const glsl_type *type = read_type(s_type);

-   if (type == NULL) {

-      ir_read_error(NULL, "when reading type in (%s ...)",

-		    tex->opcode_string());

-      return NULL;

-   }

-

-   // Read sampler (must be a deref)

-   ir_dereference *sampler = read_dereference(s_sampler);

-   if (sampler == NULL) {

-      ir_read_error(NULL, "when reading sampler in (%s ...)",

-		    tex->opcode_string());

-      return NULL;

-   }

-   tex->set_sampler(sampler, type);

-

-   // Read coordinate (any rvalue)

-   tex->coordinate = read_rvalue(s_coord);

-   if (tex->coordinate == NULL) {

-      ir_read_error(NULL, "when reading coordinate in (%s ...)",

-		    tex->opcode_string());

-      return NULL;

-   }

-

-   // Read texel offset - either 0 or an rvalue.

-   s_int *si_offset = SX_AS_INT(s_offset);

-   if (si_offset == NULL || si_offset->value() != 0) {

-      tex->offset = read_rvalue(s_offset);

-      if (tex->offset == NULL) {

-	 ir_read_error(s_offset, "expected 0 or an expression");

-	 return NULL;

-      }

-   }

-

-   if (op != ir_txf) {

-      s_int *proj_as_int = SX_AS_INT(s_proj);

-      if (proj_as_int && proj_as_int->value() == 1) {

-	 tex->projector = NULL;

-      } else {

-	 tex->projector = read_rvalue(s_proj);

-	 if (tex->projector == NULL) {

-	    ir_read_error(NULL, "when reading projective divide in (%s ..)",

-	                  tex->opcode_string());

-	    return NULL;

-	 }

-      }

-

-      if (s_shadow->subexpressions.is_empty()) {

-	 tex->shadow_comparitor = NULL;

-      } else {

-	 tex->shadow_comparitor = read_rvalue(s_shadow);

-	 if (tex->shadow_comparitor == NULL) {

-	    ir_read_error(NULL, "when reading shadow comparitor in (%s ..)",

-			  tex->opcode_string());

-	    return NULL;

-	 }

-      }

-   }

-

-   switch (op) {

-   case ir_txb:

-      tex->lod_info.bias = read_rvalue(s_lod);

-      if (tex->lod_info.bias == NULL) {

-	 ir_read_error(NULL, "when reading LOD bias in (txb ...)");

-	 return NULL;

-      }

-      break;

-   case ir_txl:

-   case ir_txf:

-      tex->lod_info.lod = read_rvalue(s_lod);

-      if (tex->lod_info.lod == NULL) {

-	 ir_read_error(NULL, "when reading LOD in (%s ...)",

-		       tex->opcode_string());

-	 return NULL;

-      }

-      break;

-   case ir_txd: {

-      s_expression *s_dx, *s_dy;

-      s_pattern dxdy_pat[] = { s_dx, s_dy };

-      if (!MATCH(s_lod, dxdy_pat)) {

-	 ir_read_error(s_lod, "expected (dPdx dPdy) in (txd ...)");

-	 return NULL;

-      }

-      tex->lod_info.grad.dPdx = read_rvalue(s_dx);

-      if (tex->lod_info.grad.dPdx == NULL) {

-	 ir_read_error(NULL, "when reading dPdx in (txd ...)");

-	 return NULL;

-      }

-      tex->lod_info.grad.dPdy = read_rvalue(s_dy);

-      if (tex->lod_info.grad.dPdy == NULL) {

-	 ir_read_error(NULL, "when reading dPdy in (txd ...)");

-	 return NULL;

-      }

-      break;

-   }

-   default:

-      // tex doesn't have any extra parameters.

-      break;

-   };

-   return tex;

-}

+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "ir_reader.h"
+#include "glsl_parser_extras.h"
+#include "glsl_types.h"
+#include "s_expression.h"
+
+const static bool debug = false;
+
+class ir_reader {
+public:
+   ir_reader(_mesa_glsl_parse_state *);
+
+   void read(exec_list *instructions, const char *src, bool scan_for_protos);
+
+private:
+   void *mem_ctx;
+   _mesa_glsl_parse_state *state;
+
+   void ir_read_error(s_expression *, const char *fmt, ...);
+
+   const glsl_type *read_type(s_expression *);
+
+   void scan_for_prototypes(exec_list *, s_expression *);
+   ir_function *read_function(s_expression *, bool skip_body);
+   void read_function_sig(ir_function *, s_expression *, bool skip_body);
+
+   void read_instructions(exec_list *, s_expression *, ir_loop *);
+   ir_instruction *read_instruction(s_expression *, ir_loop *);
+   ir_variable *read_declaration(s_expression *);
+   ir_if *read_if(s_expression *, ir_loop *);
+   ir_loop *read_loop(s_expression *);
+   ir_return *read_return(s_expression *);
+   ir_rvalue *read_rvalue(s_expression *);
+   ir_assignment *read_assignment(s_expression *);
+   ir_expression *read_expression(s_expression *);
+   ir_call *read_call(s_expression *);
+   ir_swizzle *read_swizzle(s_expression *);
+   ir_constant *read_constant(s_expression *);
+   ir_texture *read_texture(s_expression *);
+
+   ir_dereference *read_dereference(s_expression *);
+};
+
+ir_reader::ir_reader(_mesa_glsl_parse_state *state) : state(state)
+{
+   this->mem_ctx = state;
+}
+
+void
+_mesa_glsl_read_ir(_mesa_glsl_parse_state *state, exec_list *instructions,
+		   const char *src, bool scan_for_protos)
+{
+   ir_reader r(state);
+   r.read(instructions, src, scan_for_protos);
+}
+
+void
+ir_reader::read(exec_list *instructions, const char *src, bool scan_for_protos)
+{
+   s_expression *expr = s_expression::read_expression(mem_ctx, src);
+   if (expr == NULL) {
+      ir_read_error(NULL, "couldn't parse S-Expression.");
+      return;
+   }
+   
+   if (scan_for_protos) {
+      scan_for_prototypes(instructions, expr);
+      if (state->error)
+	 return;
+   }
+
+   read_instructions(instructions, expr, NULL);
+   ralloc_free(expr);
+
+   if (debug)
+      validate_ir_tree(instructions);
+}
+
+void
+ir_reader::ir_read_error(s_expression *expr, const char *fmt, ...)
+{
+   va_list ap;
+
+   state->error = true;
+
+   if (state->current_function != NULL)
+      ralloc_asprintf_append(&state->info_log, "In function %s:\n",
+			     state->current_function->function_name());
+   ralloc_strcat(&state->info_log, "error: ");
+
+   va_start(ap, fmt);
+   ralloc_vasprintf_append(&state->info_log, fmt, ap);
+   va_end(ap);
+   ralloc_strcat(&state->info_log, "\n");
+
+   if (expr != NULL) {
+      ralloc_strcat(&state->info_log, "...in this context:\n   ");
+      expr->print();
+      ralloc_strcat(&state->info_log, "\n\n");
+   }
+}
+
+const glsl_type *
+ir_reader::read_type(s_expression *expr)
+{
+   s_expression *s_base_type;
+   s_int *s_size;
+
+   s_pattern pat[] = { "array", s_base_type, s_size };
+   if (MATCH(expr, pat)) {
+      const glsl_type *base_type = read_type(s_base_type);
+      if (base_type == NULL) {
+	 ir_read_error(NULL, "when reading base type of array type");
+	 return NULL;
+      }
+
+      return glsl_type::get_array_instance(base_type, s_size->value());
+   }
+   
+   s_symbol *type_sym = SX_AS_SYMBOL(expr);
+   if (type_sym == NULL) {
+      ir_read_error(expr, "expected <type>");
+      return NULL;
+   }
+
+   const glsl_type *type = state->symbols->get_type(type_sym->value());
+   if (type == NULL)
+      ir_read_error(expr, "invalid type: %s", type_sym->value());
+
+   return type;
+}
+
+
+void
+ir_reader::scan_for_prototypes(exec_list *instructions, s_expression *expr)
+{
+   s_list *list = SX_AS_LIST(expr);
+   if (list == NULL) {
+      ir_read_error(expr, "Expected (<instruction> ...); found an atom.");
+      return;
+   }
+
+   foreach_iter(exec_list_iterator, it, list->subexpressions) {
+      s_list *sub = SX_AS_LIST(it.get());
+      if (sub == NULL)
+	 continue; // not a (function ...); ignore it.
+
+      s_symbol *tag = SX_AS_SYMBOL(sub->subexpressions.get_head());
+      if (tag == NULL || strcmp(tag->value(), "function") != 0)
+	 continue; // not a (function ...); ignore it.
+
+      ir_function *f = read_function(sub, true);
+      if (f == NULL)
+	 return;
+      instructions->push_tail(f);
+   }
+}
+
+ir_function *
+ir_reader::read_function(s_expression *expr, bool skip_body)
+{
+   bool added = false;
+   s_symbol *name;
+
+   s_pattern pat[] = { "function", name };
+   if (!PARTIAL_MATCH(expr, pat)) {
+      ir_read_error(expr, "Expected (function <name> (signature ...) ...)");
+      return NULL;
+   }
+
+   ir_function *f = state->symbols->get_function(name->value());
+   if (f == NULL) {
+      f = new(mem_ctx) ir_function(name->value());
+      added = state->symbols->add_function(f);
+      assert(added);
+   }
+
+   exec_list_iterator it = ((s_list *) expr)->subexpressions.iterator();
+   it.next(); // skip "function" tag
+   it.next(); // skip function name
+   for (/* nothing */; it.has_next(); it.next()) {
+      s_expression *s_sig = (s_expression *) it.get();
+      read_function_sig(f, s_sig, skip_body);
+   }
+   return added ? f : NULL;
+}
+
+void
+ir_reader::read_function_sig(ir_function *f, s_expression *expr, bool skip_body)
+{
+   s_expression *type_expr;
+   s_list *paramlist;
+   s_list *body_list;
+
+   s_pattern pat[] = { "signature", type_expr, paramlist, body_list };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "Expected (signature <type> (parameters ...) "
+			  "(<instruction> ...))");
+      return;
+   }
+
+   const glsl_type *return_type = read_type(type_expr);
+   if (return_type == NULL)
+      return;
+
+   s_symbol *paramtag = SX_AS_SYMBOL(paramlist->subexpressions.get_head());
+   if (paramtag == NULL || strcmp(paramtag->value(), "parameters") != 0) {
+      ir_read_error(paramlist, "Expected (parameters ...)");
+      return;
+   }
+
+   // Read the parameters list into a temporary place.
+   exec_list hir_parameters;
+   state->symbols->push_scope();
+
+   exec_list_iterator it = paramlist->subexpressions.iterator();
+   for (it.next() /* skip "parameters" */; it.has_next(); it.next()) {
+      ir_variable *var = read_declaration((s_expression *) it.get());
+      if (var == NULL)
+	 return;
+
+      hir_parameters.push_tail(var);
+   }
+
+   ir_function_signature *sig = f->exact_matching_signature(&hir_parameters);
+   if (sig == NULL && skip_body) {
+      /* If scanning for prototypes, generate a new signature. */
+      sig = new(mem_ctx) ir_function_signature(return_type);
+      sig->is_builtin = true;
+      f->add_signature(sig);
+   } else if (sig != NULL) {
+      const char *badvar = sig->qualifiers_match(&hir_parameters);
+      if (badvar != NULL) {
+	 ir_read_error(expr, "function `%s' parameter `%s' qualifiers "
+		       "don't match prototype", f->name, badvar);
+	 return;
+      }
+
+      if (sig->return_type != return_type) {
+	 ir_read_error(expr, "function `%s' return type doesn't "
+		       "match prototype", f->name);
+	 return;
+      }
+   } else {
+      /* No prototype for this body exists - skip it. */
+      state->symbols->pop_scope();
+      return;
+   }
+   assert(sig != NULL);
+
+   sig->replace_parameters(&hir_parameters);
+
+   if (!skip_body && !body_list->subexpressions.is_empty()) {
+      if (sig->is_defined) {
+	 ir_read_error(expr, "function %s redefined", f->name);
+	 return;
+      }
+      state->current_function = sig;
+      read_instructions(&sig->body, body_list, NULL);
+      state->current_function = NULL;
+      sig->is_defined = true;
+   }
+
+   state->symbols->pop_scope();
+}
+
+void
+ir_reader::read_instructions(exec_list *instructions, s_expression *expr,
+			     ir_loop *loop_ctx)
+{
+   // Read in a list of instructions
+   s_list *list = SX_AS_LIST(expr);
+   if (list == NULL) {
+      ir_read_error(expr, "Expected (<instruction> ...); found an atom.");
+      return;
+   }
+
+   foreach_iter(exec_list_iterator, it, list->subexpressions) {
+      s_expression *sub = (s_expression*) it.get();
+      ir_instruction *ir = read_instruction(sub, loop_ctx);
+      if (ir != NULL) {
+	 /* Global variable declarations should be moved to the top, before
+	  * any functions that might use them.  Functions are added to the
+	  * instruction stream when scanning for prototypes, so without this
+	  * hack, they always appear before variable declarations.
+	  */
+	 if (state->current_function == NULL && ir->as_variable() != NULL)
+	    instructions->push_head(ir);
+	 else
+	    instructions->push_tail(ir);
+      }
+   }
+}
+
+
+ir_instruction *
+ir_reader::read_instruction(s_expression *expr, ir_loop *loop_ctx)
+{
+   s_symbol *symbol = SX_AS_SYMBOL(expr);
+   if (symbol != NULL) {
+      if (strcmp(symbol->value(), "break") == 0 && loop_ctx != NULL)
+	 return new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_break);
+      if (strcmp(symbol->value(), "continue") == 0 && loop_ctx != NULL)
+	 return new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue);
+   }
+
+   s_list *list = SX_AS_LIST(expr);
+   if (list == NULL || list->subexpressions.is_empty()) {
+      ir_read_error(expr, "Invalid instruction.\n");
+      return NULL;
+   }
+
+   s_symbol *tag = SX_AS_SYMBOL(list->subexpressions.get_head());
+   if (tag == NULL) {
+      ir_read_error(expr, "expected instruction tag");
+      return NULL;
+   }
+
+   ir_instruction *inst = NULL;
+   if (strcmp(tag->value(), "declare") == 0) {
+      inst = read_declaration(list);
+   } else if (strcmp(tag->value(), "assign") == 0) {
+      inst = read_assignment(list);
+   } else if (strcmp(tag->value(), "if") == 0) {
+      inst = read_if(list, loop_ctx);
+   } else if (strcmp(tag->value(), "loop") == 0) {
+      inst = read_loop(list);
+   } else if (strcmp(tag->value(), "return") == 0) {
+      inst = read_return(list);
+   } else if (strcmp(tag->value(), "function") == 0) {
+      inst = read_function(list, false);
+   } else {
+      inst = read_rvalue(list);
+      if (inst == NULL)
+	 ir_read_error(NULL, "when reading instruction");
+   }
+   return inst;
+}
+
+ir_variable *
+ir_reader::read_declaration(s_expression *expr)
+{
+   s_list *s_quals;
+   s_expression *s_type;
+   s_symbol *s_name;
+
+   s_pattern pat[] = { "declare", s_quals, s_type, s_name };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (declare (<qualifiers>) <type> <name>)");
+      return NULL;
+   }
+
+   const glsl_type *type = read_type(s_type);
+   if (type == NULL)
+      return NULL;
+
+   ir_variable *var = new(mem_ctx) ir_variable(type, s_name->value(),
+					       ir_var_auto);
+
+   foreach_iter(exec_list_iterator, it, s_quals->subexpressions) {
+      s_symbol *qualifier = SX_AS_SYMBOL(it.get());
+      if (qualifier == NULL) {
+	 ir_read_error(expr, "qualifier list must contain only symbols");
+	 return NULL;
+      }
+
+      // FINISHME: Check for duplicate/conflicting qualifiers.
+      if (strcmp(qualifier->value(), "centroid") == 0) {
+	 var->centroid = 1;
+      } else if (strcmp(qualifier->value(), "invariant") == 0) {
+	 var->invariant = 1;
+      } else if (strcmp(qualifier->value(), "uniform") == 0) {
+	 var->mode = ir_var_uniform;
+      } else if (strcmp(qualifier->value(), "auto") == 0) {
+	 var->mode = ir_var_auto;
+      } else if (strcmp(qualifier->value(), "in") == 0) {
+	 var->mode = ir_var_in;
+      } else if (strcmp(qualifier->value(), "const_in") == 0) {
+	 var->mode = ir_var_const_in;
+      } else if (strcmp(qualifier->value(), "out") == 0) {
+	 var->mode = ir_var_out;
+      } else if (strcmp(qualifier->value(), "inout") == 0) {
+	 var->mode = ir_var_inout;
+      } else if (strcmp(qualifier->value(), "smooth") == 0) {
+	 var->interpolation = ir_var_smooth;
+      } else if (strcmp(qualifier->value(), "flat") == 0) {
+	 var->interpolation = ir_var_flat;
+      } else if (strcmp(qualifier->value(), "noperspective") == 0) {
+	 var->interpolation = ir_var_noperspective;
+      } else {
+	 ir_read_error(expr, "unknown qualifier: %s", qualifier->value());
+	 return NULL;
+      }
+   }
+
+   // Add the variable to the symbol table
+   state->symbols->add_variable(var);
+
+   return var;
+}
+
+
+ir_if *
+ir_reader::read_if(s_expression *expr, ir_loop *loop_ctx)
+{
+   s_expression *s_cond;
+   s_expression *s_then;
+   s_expression *s_else;
+
+   s_pattern pat[] = { "if", s_cond, s_then, s_else };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (if <condition> (<then>...) (<else>...))");
+      return NULL;
+   }
+
+   ir_rvalue *condition = read_rvalue(s_cond);
+   if (condition == NULL) {
+      ir_read_error(NULL, "when reading condition of (if ...)");
+      return NULL;
+   }
+
+   ir_if *iff = new(mem_ctx) ir_if(condition);
+
+   read_instructions(&iff->then_instructions, s_then, loop_ctx);
+   read_instructions(&iff->else_instructions, s_else, loop_ctx);
+   if (state->error) {
+      delete iff;
+      iff = NULL;
+   }
+   return iff;
+}
+
+
+ir_loop *
+ir_reader::read_loop(s_expression *expr)
+{
+   s_expression *s_counter, *s_from, *s_to, *s_inc, *s_body;
+
+   s_pattern pat[] = { "loop", s_counter, s_from, s_to, s_inc, s_body };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (loop <counter> <from> <to> "
+			  "<increment> <body>)");
+      return NULL;
+   }
+
+   // FINISHME: actually read the count/from/to fields.
+
+   ir_loop *loop = new(mem_ctx) ir_loop;
+   read_instructions(&loop->body_instructions, s_body, loop);
+   if (state->error) {
+      delete loop;
+      loop = NULL;
+   }
+   return loop;
+}
+
+
+ir_return *
+ir_reader::read_return(s_expression *expr)
+{
+   s_expression *s_retval;
+
+   s_pattern return_value_pat[] = { "return", s_retval};
+   s_pattern return_void_pat[] = { "return" };
+   if (MATCH(expr, return_value_pat)) {
+      ir_rvalue *retval = read_rvalue(s_retval);
+      if (retval == NULL) {
+         ir_read_error(NULL, "when reading return value");
+         return NULL;
+      }
+      return new(mem_ctx) ir_return(retval);
+   } else if (MATCH(expr, return_void_pat)) {
+      return new(mem_ctx) ir_return;
+   } else {
+      ir_read_error(expr, "expected (return <rvalue>) or (return)");
+      return NULL;
+   }
+}
+
+
+ir_rvalue *
+ir_reader::read_rvalue(s_expression *expr)
+{
+   s_list *list = SX_AS_LIST(expr);
+   if (list == NULL || list->subexpressions.is_empty())
+      return NULL;
+
+   s_symbol *tag = SX_AS_SYMBOL(list->subexpressions.get_head());
+   if (tag == NULL) {
+      ir_read_error(expr, "expected rvalue tag");
+      return NULL;
+   }
+
+   ir_rvalue *rvalue = read_dereference(list);
+   if (rvalue != NULL || state->error)
+      return rvalue;
+   else if (strcmp(tag->value(), "swiz") == 0) {
+      rvalue = read_swizzle(list);
+   } else if (strcmp(tag->value(), "expression") == 0) {
+      rvalue = read_expression(list);
+   } else if (strcmp(tag->value(), "call") == 0) {
+      rvalue = read_call(list);
+   } else if (strcmp(tag->value(), "constant") == 0) {
+      rvalue = read_constant(list);
+   } else {
+      rvalue = read_texture(list);
+      if (rvalue == NULL && !state->error)
+	 ir_read_error(expr, "unrecognized rvalue tag: %s", tag->value());
+   }
+
+   return rvalue;
+}
+
+ir_assignment *
+ir_reader::read_assignment(s_expression *expr)
+{
+   s_expression *cond_expr = NULL;
+   s_expression *lhs_expr, *rhs_expr;
+   s_list       *mask_list;
+
+   s_pattern pat4[] = { "assign",            mask_list, lhs_expr, rhs_expr };
+   s_pattern pat5[] = { "assign", cond_expr, mask_list, lhs_expr, rhs_expr };
+   if (!MATCH(expr, pat4) && !MATCH(expr, pat5)) {
+      ir_read_error(expr, "expected (assign [<condition>] (<write mask>) "
+			  "<lhs> <rhs>)");
+      return NULL;
+   }
+
+   ir_rvalue *condition = NULL;
+   if (cond_expr != NULL) {
+      condition = read_rvalue(cond_expr);
+      if (condition == NULL) {
+	 ir_read_error(NULL, "when reading condition of assignment");
+	 return NULL;
+      }
+   }
+
+   unsigned mask = 0;
+
+   s_symbol *mask_symbol;
+   s_pattern mask_pat[] = { mask_symbol };
+   if (MATCH(mask_list, mask_pat)) {
+      const char *mask_str = mask_symbol->value();
+      unsigned mask_length = strlen(mask_str);
+      if (mask_length > 4) {
+	 ir_read_error(expr, "invalid write mask: %s", mask_str);
+	 return NULL;
+      }
+
+      const unsigned idx_map[] = { 3, 0, 1, 2 }; /* w=bit 3, x=0, y=1, z=2 */
+
+      for (unsigned i = 0; i < mask_length; i++) {
+	 if (mask_str[i] < 'w' || mask_str[i] > 'z') {
+	    ir_read_error(expr, "write mask contains invalid character: %c",
+			  mask_str[i]);
+	    return NULL;
+	 }
+	 mask |= 1 << idx_map[mask_str[i] - 'w'];
+      }
+   } else if (!mask_list->subexpressions.is_empty()) {
+      ir_read_error(mask_list, "expected () or (<write mask>)");
+      return NULL;
+   }
+
+   ir_dereference *lhs = read_dereference(lhs_expr);
+   if (lhs == NULL) {
+      ir_read_error(NULL, "when reading left-hand side of assignment");
+      return NULL;
+   }
+
+   ir_rvalue *rhs = read_rvalue(rhs_expr);
+   if (rhs == NULL) {
+      ir_read_error(NULL, "when reading right-hand side of assignment");
+      return NULL;
+   }
+
+   if (mask == 0 && (lhs->type->is_vector() || lhs->type->is_scalar())) {
+      ir_read_error(expr, "non-zero write mask required.");
+      return NULL;
+   }
+
+   return new(mem_ctx) ir_assignment(lhs, rhs, condition, mask);
+}
+
+ir_call *
+ir_reader::read_call(s_expression *expr)
+{
+   s_symbol *name;
+   s_list *params;
+
+   s_pattern pat[] = { "call", name, params };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (call <name> (<param> ...))");
+      return NULL;
+   }
+
+   exec_list parameters;
+
+   foreach_iter(exec_list_iterator, it, params->subexpressions) {
+      s_expression *expr = (s_expression*) it.get();
+      ir_rvalue *param = read_rvalue(expr);
+      if (param == NULL) {
+	 ir_read_error(expr, "when reading parameter to function call");
+	 return NULL;
+      }
+      parameters.push_tail(param);
+   }
+
+   ir_function *f = state->symbols->get_function(name->value());
+   if (f == NULL) {
+      ir_read_error(expr, "found call to undefined function %s",
+		    name->value());
+      return NULL;
+   }
+
+   ir_function_signature *callee = f->matching_signature(&parameters);
+   if (callee == NULL) {
+      ir_read_error(expr, "couldn't find matching signature for function "
+                    "%s", name->value());
+      return NULL;
+   }
+
+   return new(mem_ctx) ir_call(callee, &parameters);
+}
+
+ir_expression *
+ir_reader::read_expression(s_expression *expr)
+{
+   s_expression *s_type;
+   s_symbol *s_op;
+   s_expression *s_arg1;
+
+   s_pattern pat[] = { "expression", s_type, s_op, s_arg1 };
+   if (!PARTIAL_MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (expression <type> <operator> "
+			  "<operand> [<operand>])");
+      return NULL;
+   }
+   s_expression *s_arg2 = (s_expression *) s_arg1->next; // may be tail sentinel
+
+   const glsl_type *type = read_type(s_type);
+   if (type == NULL)
+      return NULL;
+
+   /* Read the operator */
+   ir_expression_operation op = ir_expression::get_operator(s_op->value());
+   if (op == (ir_expression_operation) -1) {
+      ir_read_error(expr, "invalid operator: %s", s_op->value());
+      return NULL;
+   }
+    
+   unsigned num_operands = ir_expression::get_num_operands(op);
+   if (num_operands == 1 && !s_arg1->next->is_tail_sentinel()) {
+      ir_read_error(expr, "expected (expression <type> %s <operand>)",
+		    s_op->value());
+      return NULL;
+   }
+
+   ir_rvalue *arg1 = read_rvalue(s_arg1);
+   ir_rvalue *arg2 = NULL;
+   if (arg1 == NULL) {
+      ir_read_error(NULL, "when reading first operand of %s", s_op->value());
+      return NULL;
+   }
+
+   if (num_operands == 2) {
+      if (s_arg2->is_tail_sentinel() || !s_arg2->next->is_tail_sentinel()) {
+	 ir_read_error(expr, "expected (expression <type> %s <operand> "
+			     "<operand>)", s_op->value());
+	 return NULL;
+      }
+      arg2 = read_rvalue(s_arg2);
+      if (arg2 == NULL) {
+	 ir_read_error(NULL, "when reading second operand of %s",
+		       s_op->value());
+	 return NULL;
+      }
+   }
+
+   return new(mem_ctx) ir_expression(op, type, arg1, arg2);
+}
+
+ir_swizzle *
+ir_reader::read_swizzle(s_expression *expr)
+{
+   s_symbol *swiz;
+   s_expression *sub;
+
+   s_pattern pat[] = { "swiz", swiz, sub };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (swiz <swizzle> <rvalue>)");
+      return NULL;
+   }
+
+   if (strlen(swiz->value()) > 4) {
+      ir_read_error(expr, "expected a valid swizzle; found %s", swiz->value());
+      return NULL;
+   }
+
+   ir_rvalue *rvalue = read_rvalue(sub);
+   if (rvalue == NULL)
+      return NULL;
+
+   ir_swizzle *ir = ir_swizzle::create(rvalue, swiz->value(),
+				       rvalue->type->vector_elements);
+   if (ir == NULL)
+      ir_read_error(expr, "invalid swizzle");
+
+   return ir;
+}
+
+ir_constant *
+ir_reader::read_constant(s_expression *expr)
+{
+   s_expression *type_expr;
+   s_list *values;
+
+   s_pattern pat[] = { "constant", type_expr, values };
+   if (!MATCH(expr, pat)) {
+      ir_read_error(expr, "expected (constant <type> (...))");
+      return NULL;
+   }
+
+   const glsl_type *type = read_type(type_expr);
+   if (type == NULL)
+      return NULL;
+
+   if (values == NULL) {
+      ir_read_error(expr, "expected (constant <type> (...))");
+      return NULL;
+   }
+
+   if (type->is_array()) {
+      unsigned elements_supplied = 0;
+      exec_list elements;
+      foreach_iter(exec_list_iterator, it, values->subexpressions) {
+	 s_expression *elt = (s_expression *) it.get();
+	 ir_constant *ir_elt = read_constant(elt);
+	 if (ir_elt == NULL)
+	    return NULL;
+	 elements.push_tail(ir_elt);
+	 elements_supplied++;
+      }
+
+      if (elements_supplied != type->length) {
+	 ir_read_error(values, "expected exactly %u array elements, "
+		       "given %u", type->length, elements_supplied);
+	 return NULL;
+      }
+      return new(mem_ctx) ir_constant(type, &elements);
+   }
+
+   const glsl_type *const base_type = type->get_base_type();
+
+   ir_constant_data data = { { 0 } };
+
+   // Read in list of values (at most 16).
+   int k = 0;
+   foreach_iter(exec_list_iterator, it, values->subexpressions) {
+      if (k >= 16) {
+	 ir_read_error(values, "expected at most 16 numbers");
+	 return NULL;
+      }
+
+      s_expression *expr = (s_expression*) it.get();
+
+      if (base_type->base_type == GLSL_TYPE_FLOAT) {
+	 s_number *value = SX_AS_NUMBER(expr);
+	 if (value == NULL) {
+	    ir_read_error(values, "expected numbers");
+	    return NULL;
+	 }
+	 data.f[k] = value->fvalue();
+      } else {
+	 s_int *value = SX_AS_INT(expr);
+	 if (value == NULL) {
+	    ir_read_error(values, "expected integers");
+	    return NULL;
+	 }
+
+	 switch (base_type->base_type) {
+	 case GLSL_TYPE_UINT: {
+	    data.u[k] = value->value();
+	    break;
+	 }
+	 case GLSL_TYPE_INT: {
+	    data.i[k] = value->value();
+	    break;
+	 }
+	 case GLSL_TYPE_BOOL: {
+	    data.b[k] = value->value();
+	    break;
+	 }
+	 default:
+	    ir_read_error(values, "unsupported constant type");
+	    return NULL;
+	 }
+      }
+      ++k;
+   }
+
+   return new(mem_ctx) ir_constant(type, &data);
+}
+
+ir_dereference *
+ir_reader::read_dereference(s_expression *expr)
+{
+   s_symbol *s_var;
+   s_expression *s_subject;
+   s_expression *s_index;
+   s_symbol *s_field;
+
+   s_pattern var_pat[] = { "var_ref", s_var };
+   s_pattern array_pat[] = { "array_ref", s_subject, s_index };
+   s_pattern record_pat[] = { "record_ref", s_subject, s_field };
+
+   if (MATCH(expr, var_pat)) {
+      ir_variable *var = state->symbols->get_variable(s_var->value());
+      if (var == NULL) {
+	 ir_read_error(expr, "undeclared variable: %s", s_var->value());
+	 return NULL;
+      }
+      return new(mem_ctx) ir_dereference_variable(var);
+   } else if (MATCH(expr, array_pat)) {
+      ir_rvalue *subject = read_rvalue(s_subject);
+      if (subject == NULL) {
+	 ir_read_error(NULL, "when reading the subject of an array_ref");
+	 return NULL;
+      }
+
+      ir_rvalue *idx = read_rvalue(s_index);
+      if (subject == NULL) {
+	 ir_read_error(NULL, "when reading the index of an array_ref");
+	 return NULL;
+      }
+      return new(mem_ctx) ir_dereference_array(subject, idx);
+   } else if (MATCH(expr, record_pat)) {
+      ir_rvalue *subject = read_rvalue(s_subject);
+      if (subject == NULL) {
+	 ir_read_error(NULL, "when reading the subject of a record_ref");
+	 return NULL;
+      }
+      return new(mem_ctx) ir_dereference_record(subject, s_field->value());
+   }
+   return NULL;
+}
+
+ir_texture *
+ir_reader::read_texture(s_expression *expr)
+{
+   s_symbol *tag = NULL;
+   s_expression *s_type = NULL;
+   s_expression *s_sampler = NULL;
+   s_expression *s_coord = NULL;
+   s_expression *s_offset = NULL;
+   s_expression *s_proj = NULL;
+   s_list *s_shadow = NULL;
+   s_expression *s_lod = NULL;
+
+   ir_texture_opcode op = ir_tex; /* silence warning */
+
+   s_pattern tex_pattern[] =
+      { "tex", s_type, s_sampler, s_coord, s_offset, s_proj, s_shadow };
+   s_pattern txf_pattern[] =
+      { "txf", s_type, s_sampler, s_coord, s_offset, s_lod };
+   s_pattern other_pattern[] =
+      { tag, s_type, s_sampler, s_coord, s_offset, s_proj, s_shadow, s_lod };
+
+   if (MATCH(expr, tex_pattern)) {
+      op = ir_tex;
+   } else if (MATCH(expr, txf_pattern)) {
+      op = ir_txf;
+   } else if (MATCH(expr, other_pattern)) {
+      op = ir_texture::get_opcode(tag->value());
+      if (op == -1)
+	 return NULL;
+   } else {
+      ir_read_error(NULL, "unexpected texture pattern");
+      return NULL;
+   }
+
+   ir_texture *tex = new(mem_ctx) ir_texture(op);
+
+   // Read return type
+   const glsl_type *type = read_type(s_type);
+   if (type == NULL) {
+      ir_read_error(NULL, "when reading type in (%s ...)",
+		    tex->opcode_string());
+      return NULL;
+   }
+
+   // Read sampler (must be a deref)
+   ir_dereference *sampler = read_dereference(s_sampler);
+   if (sampler == NULL) {
+      ir_read_error(NULL, "when reading sampler in (%s ...)",
+		    tex->opcode_string());
+      return NULL;
+   }
+   tex->set_sampler(sampler, type);
+
+   // Read coordinate (any rvalue)
+   tex->coordinate = read_rvalue(s_coord);
+   if (tex->coordinate == NULL) {
+      ir_read_error(NULL, "when reading coordinate in (%s ...)",
+		    tex->opcode_string());
+      return NULL;
+   }
+
+   // Read texel offset - either 0 or an rvalue.
+   s_int *si_offset = SX_AS_INT(s_offset);
+   if (si_offset == NULL || si_offset->value() != 0) {
+      tex->offset = read_rvalue(s_offset);
+      if (tex->offset == NULL) {
+	 ir_read_error(s_offset, "expected 0 or an expression");
+	 return NULL;
+      }
+   }
+
+   if (op != ir_txf) {
+      s_int *proj_as_int = SX_AS_INT(s_proj);
+      if (proj_as_int && proj_as_int->value() == 1) {
+	 tex->projector = NULL;
+      } else {
+	 tex->projector = read_rvalue(s_proj);
+	 if (tex->projector == NULL) {
+	    ir_read_error(NULL, "when reading projective divide in (%s ..)",
+	                  tex->opcode_string());
+	    return NULL;
+	 }
+      }
+
+      if (s_shadow->subexpressions.is_empty()) {
+	 tex->shadow_comparitor = NULL;
+      } else {
+	 tex->shadow_comparitor = read_rvalue(s_shadow);
+	 if (tex->shadow_comparitor == NULL) {
+	    ir_read_error(NULL, "when reading shadow comparitor in (%s ..)",
+			  tex->opcode_string());
+	    return NULL;
+	 }
+      }
+   }
+
+   switch (op) {
+   case ir_txb:
+      tex->lod_info.bias = read_rvalue(s_lod);
+      if (tex->lod_info.bias == NULL) {
+	 ir_read_error(NULL, "when reading LOD bias in (txb ...)");
+	 return NULL;
+      }
+      break;
+   case ir_txl:
+   case ir_txf:
+      tex->lod_info.lod = read_rvalue(s_lod);
+      if (tex->lod_info.lod == NULL) {
+	 ir_read_error(NULL, "when reading LOD in (%s ...)",
+		       tex->opcode_string());
+	 return NULL;
+      }
+      break;
+   case ir_txd: {
+      s_expression *s_dx, *s_dy;
+      s_pattern dxdy_pat[] = { s_dx, s_dy };
+      if (!MATCH(s_lod, dxdy_pat)) {
+	 ir_read_error(s_lod, "expected (dPdx dPdy) in (txd ...)");
+	 return NULL;
+      }
+      tex->lod_info.grad.dPdx = read_rvalue(s_dx);
+      if (tex->lod_info.grad.dPdx == NULL) {
+	 ir_read_error(NULL, "when reading dPdx in (txd ...)");
+	 return NULL;
+      }
+      tex->lod_info.grad.dPdy = read_rvalue(s_dy);
+      if (tex->lod_info.grad.dPdy == NULL) {
+	 ir_read_error(NULL, "when reading dPdy in (txd ...)");
+	 return NULL;
+      }
+      break;
+   }
+   default:
+      // tex doesn't have any extra parameters.
+      break;
+   };
+   return tex;
+}
diff --git a/mesalib/src/glsl/linker.cpp b/mesalib/src/glsl/linker.cpp
index 265da84e5..34b64837a 100644
--- a/mesalib/src/glsl/linker.cpp
+++ b/mesalib/src/glsl/linker.cpp
@@ -1248,7 +1248,7 @@ assign_attribute_or_color_locations(gl_shader_program *prog,
     */
 
    const int generic_base = (target_index == MESA_SHADER_VERTEX)
-     ? VERT_ATTRIB_GENERIC0 : FRAG_RESULT_DATA0;
+      ? (int) VERT_ATTRIB_GENERIC0 : (int) FRAG_RESULT_DATA0;
 
    const enum ir_variable_mode direction =
       (target_index == MESA_SHADER_VERTEX) ? ir_var_in : ir_var_out;
diff --git a/mesalib/src/glsl/lower_jumps.cpp b/mesalib/src/glsl/lower_jumps.cpp
index 17be39f5b..61874990a 100644
--- a/mesalib/src/glsl/lower_jumps.cpp
+++ b/mesalib/src/glsl/lower_jumps.cpp
@@ -1,570 +1,1010 @@
-/*

- * Copyright © 2010 Luca Barbieri

- *

- * Permission is hereby granted, free of charge, to any person obtaining a

- * copy of this software and associated documentation files (the "Software"),

- * to deal in the Software without restriction, including without limitation

- * the rights to use, copy, modify, merge, publish, distribute, sublicense,

- * and/or sell copies of the Software, and to permit persons to whom the

- * Software is furnished to do so, subject to the following conditions:

- *

- * The above copyright notice and this permission notice (including the next

- * paragraph) shall be included in all copies or substantial portions of the

- * Software.

- *

- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

- * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

- * DEALINGS IN THE SOFTWARE.

- */

-

-/**

- * \file lower_jumps.cpp

- *

- * This pass lowers jumps (break, continue, and return) to if/else structures.

- *

- * It can be asked to:

- * 1. Pull jumps out of ifs where possible

- * 2. Remove all "continue"s, replacing them with an "execute flag"

- * 3. Replace all "break" with a single conditional one at the end of the loop

- * 4. Replace all "return"s with a single return at the end of the function,

- *    for the main function and/or other functions

- *

- * Applying this pass gives several benefits:

- * 1. All functions can be inlined.

- * 2. nv40 and other pre-DX10 chips without "continue" can be supported

- * 3. nv30 and other pre-DX10 chips with no control flow at all are better

- *    supported

- *

- * Continues are lowered by adding a per-loop "execute flag", initialized to

- * true, that when cleared inhibits all execution until the end of the loop.

- *

- * Breaks are lowered to continues, plus setting a "break flag" that is checked

- * at the end of the loop, and trigger the unique "break".

- *

- * Returns are lowered to breaks/continues, plus adding a "return flag" that

- * causes loops to break again out of their enclosing loops until all the

- * loops are exited: then the "execute flag" logic will ignore everything

- * until the end of the function.

- *

- * Note that "continue" and "return" can also be implemented by adding

- * a dummy loop and using break.

- * However, this is bad for hardware with limited nesting depth, and

- * prevents further optimization, and thus is not currently performed.

- */

-

-#include "glsl_types.h"

-#include <string.h>

-#include "ir.h"

-

-enum jump_strength

-{

-   strength_none,

-   strength_always_clears_execute_flag,

-   strength_continue,

-   strength_break,

-   strength_return

-};

-

-struct block_record

-{

-   /* minimum jump strength (of lowered IR, not pre-lowering IR)

-    *

-    * If the block ends with a jump, must be the strength of the jump.

-    * Otherwise, the jump would be dead and have been deleted before)

-    *

-    * If the block doesn't end with a jump, it can be different than strength_none if all paths before it lead to some jump

-    * (e.g. an if with a return in one branch, and a break in the other, while not lowering them)

-    * Note that identical jumps are usually unified though.

-    */

-   jump_strength min_strength;

-

-   /* can anything clear the execute flag? */

-   bool may_clear_execute_flag;

-

-   block_record()

-   {

-      this->min_strength = strength_none;

-      this->may_clear_execute_flag = false;

-   }

-};

-

-struct loop_record

-{

-   ir_function_signature* signature;

-   ir_loop* loop;

-

-   /* used to avoid lowering the break used to represent lowered breaks */

-   unsigned nesting_depth;

-   bool in_if_at_the_end_of_the_loop;

-

-   bool may_set_return_flag;

-

-   ir_variable* break_flag;

-   ir_variable* execute_flag; /* cleared to emulate continue */

-

-   loop_record(ir_function_signature* p_signature = 0, ir_loop* p_loop = 0)

-   {

-      this->signature = p_signature;

-      this->loop = p_loop;

-      this->nesting_depth = 0;

-      this->in_if_at_the_end_of_the_loop = false;

-      this->may_set_return_flag = false;

-      this->break_flag = 0;

-      this->execute_flag = 0;

-   }

-

-   ir_variable* get_execute_flag()

-   {

-      /* also supported for the "function loop" */

-      if(!this->execute_flag) {

-         exec_list& list = this->loop ? this->loop->body_instructions : signature->body;

-         this->execute_flag = new(this->signature) ir_variable(glsl_type::bool_type, "execute_flag", ir_var_temporary);

-         list.push_head(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(execute_flag), new(this->signature) ir_constant(true), 0));

-         list.push_head(this->execute_flag);

-      }

-      return this->execute_flag;

-   }

-

-   ir_variable* get_break_flag()

-   {

-      assert(this->loop);

-      if(!this->break_flag) {

-         this->break_flag = new(this->signature) ir_variable(glsl_type::bool_type, "break_flag", ir_var_temporary);

-         this->loop->insert_before(this->break_flag);

-         this->loop->insert_before(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(break_flag), new(this->signature) ir_constant(false), 0));

-      }

-      return this->break_flag;

-   }

-};

-

-struct function_record

-{

-   ir_function_signature* signature;

-   ir_variable* return_flag; /* used to break out of all loops and then jump to the return instruction */

-   ir_variable* return_value;

-   bool is_main;

-   unsigned nesting_depth;

-

-   function_record(ir_function_signature* p_signature = 0)

-   {

-      this->signature = p_signature;

-      this->return_flag = 0;

-      this->return_value = 0;

-      this->nesting_depth = 0;

-      this->is_main = this->signature && (strcmp(this->signature->function_name(), "main") == 0);

-   }

-

-   ir_variable* get_return_flag()

-   {

-      if(!this->return_flag) {

-         this->return_flag = new(this->signature) ir_variable(glsl_type::bool_type, "return_flag", ir_var_temporary);

-         this->signature->body.push_head(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(return_flag), new(this->signature) ir_constant(false), 0));

-         this->signature->body.push_head(this->return_flag);

-      }

-      return this->return_flag;

-   }

-

-   ir_variable* get_return_value()

-   {

-      if(!this->return_value) {

-         assert(!this->signature->return_type->is_void());

-         return_value = new(this->signature) ir_variable(this->signature->return_type, "return_value", ir_var_temporary);

-         this->signature->body.push_head(this->return_value);

-      }

-      return this->return_value;

-   }

-};

-

-struct ir_lower_jumps_visitor : public ir_control_flow_visitor {

-   bool progress;

-

-   struct function_record function;

-   struct loop_record loop;

-   struct block_record block;

-

-   bool pull_out_jumps;

-   bool lower_continue;

-   bool lower_break;

-   bool lower_sub_return;

-   bool lower_main_return;

-

-   ir_lower_jumps_visitor()

-   {

-      this->progress = false;

-   }

-

-   void truncate_after_instruction(exec_node *ir)

-   {

-      if (!ir)

-         return;

-

-      while (!ir->get_next()->is_tail_sentinel()) {

-         ((ir_instruction *)ir->get_next())->remove();

-         this->progress = true;

-      }

-   }

-

-   void move_outer_block_inside(ir_instruction *ir, exec_list *inner_block)

-   {

-      while (!ir->get_next()->is_tail_sentinel()) {

-         ir_instruction *move_ir = (ir_instruction *)ir->get_next();

-

-         move_ir->remove();

-         inner_block->push_tail(move_ir);

-      }

-   }

-

-   virtual void visit(class ir_loop_jump * ir)

-   {

-      truncate_after_instruction(ir);

-      this->block.min_strength = ir->is_break() ? strength_break : strength_continue;

-   }

-

-   virtual void visit(class ir_return * ir)

-   {

-      truncate_after_instruction(ir);

-      this->block.min_strength = strength_return;

-   }

-

-   virtual void visit(class ir_discard * ir)

-   {

-   }

-

-   enum jump_strength get_jump_strength(ir_instruction* ir)

-   {

-      if(!ir)

-         return strength_none;

-      else if(ir->ir_type == ir_type_loop_jump) {

-         if(((ir_loop_jump*)ir)->is_break())

-            return strength_break;

-         else

-            return strength_continue;

-      } else if(ir->ir_type == ir_type_return)

-         return strength_return;

-      else

-         return strength_none;

-   }

-

-   bool should_lower_jump(ir_jump* ir)

-   {

-      unsigned strength = get_jump_strength(ir);

-      bool lower;

-      switch(strength)

-      {

-      case strength_none:

-         lower = false; /* don't change this, code relies on it */

-         break;

-      case strength_continue:

-         lower = lower_continue;

-         break;

-      case strength_break:

-         assert(this->loop.loop);

-         /* never lower "canonical break" */

-         if(ir->get_next()->is_tail_sentinel() && (this->loop.nesting_depth == 0

-               || (this->loop.nesting_depth == 1 && this->loop.in_if_at_the_end_of_the_loop)))

-            lower = false;

-         else

-            lower = lower_break;

-         break;

-      case strength_return:

-         /* never lower return at the end of a this->function */

-         if(this->function.nesting_depth == 0 && ir->get_next()->is_tail_sentinel())

-            lower = false;

-         else if (this->function.is_main)

-            lower = lower_main_return;

-         else

-            lower = lower_sub_return;

-         break;

-      }

-      return lower;

-   }

-

-   block_record visit_block(exec_list* list)

-   {

-      block_record saved_block = this->block;

-      this->block = block_record();

-      visit_exec_list(list, this);

-      block_record ret = this->block;

-      this->block = saved_block;

-      return ret;

-   }

-

-   virtual void visit(ir_if *ir)

-   {

-      if(this->loop.nesting_depth == 0 && ir->get_next()->is_tail_sentinel())

-         this->loop.in_if_at_the_end_of_the_loop = true;

-

-      ++this->function.nesting_depth;

-      ++this->loop.nesting_depth;

-

-      block_record block_records[2];

-      ir_jump* jumps[2];

-

-      block_records[0] = visit_block(&ir->then_instructions);

-      block_records[1] = visit_block(&ir->else_instructions);

-

-retry: /* we get here if we put code after the if inside a branch */

-   for(unsigned i = 0; i < 2; ++i) {

-      exec_list& list = i ? ir->else_instructions : ir->then_instructions;

-      jumps[i] = 0;

-      if(!list.is_empty() && get_jump_strength((ir_instruction*)list.get_tail()))

-         jumps[i] = (ir_jump*)list.get_tail();

-   }

-

-      for(;;) {

-         jump_strength jump_strengths[2];

-

-         for(unsigned i = 0; i < 2; ++i) {

-            if(jumps[i]) {

-               jump_strengths[i] = block_records[i].min_strength;

-               assert(jump_strengths[i] == get_jump_strength(jumps[i]));

-            } else

-               jump_strengths[i] = strength_none;

-         }

-

-         /* move both jumps out if possible */

-         if(pull_out_jumps && jump_strengths[0] == jump_strengths[1]) {

-            bool unify = true;

-            if(jump_strengths[0] == strength_continue)

-               ir->insert_after(new(ir) ir_loop_jump(ir_loop_jump::jump_continue));

-            else if(jump_strengths[0] == strength_break)

-               ir->insert_after(new(ir) ir_loop_jump(ir_loop_jump::jump_break));

-            /* FINISHME: unify returns with identical expressions */

-            else if(jump_strengths[0] == strength_return && this->function.signature->return_type->is_void())

-               ir->insert_after(new(ir) ir_return(NULL));

-	    else

-	       unify = false;

-

-            if(unify) {

-               jumps[0]->remove();

-               jumps[1]->remove();

-               this->progress = true;

-

-               jumps[0] = 0;

-               jumps[1] = 0;

-               block_records[0].min_strength = strength_none;

-               block_records[1].min_strength = strength_none;

-               break;

-            }

-         }

-

-         /* lower a jump: if both need to lowered, start with the strongest one, so that

-          * we might later unify the lowered version with the other one

-          */

-         bool should_lower[2];

-         for(unsigned i = 0; i < 2; ++i)

-            should_lower[i] = should_lower_jump(jumps[i]);

-

-         int lower;

-         if(should_lower[1] && should_lower[0])

-            lower = jump_strengths[1] > jump_strengths[0];

-         else if(should_lower[0])

-            lower = 0;

-         else if(should_lower[1])

-            lower = 1;

-         else

-            break;

-

-         if(jump_strengths[lower] == strength_return) {

-            ir_variable* return_flag = this->function.get_return_flag();

-            if(!this->function.signature->return_type->is_void()) {

-               ir_variable* return_value = this->function.get_return_value();

-               jumps[lower]->insert_before(new(ir) ir_assignment(new (ir) ir_dereference_variable(return_value), ((ir_return*)jumps[lower])->value, NULL));

-            }

-            jumps[lower]->insert_before(new(ir) ir_assignment(new (ir) ir_dereference_variable(return_flag), new (ir) ir_constant(true), NULL));

-            this->loop.may_set_return_flag = true;

-            if(this->loop.loop) {

-               ir_loop_jump* lowered = 0;

-               lowered = new(ir) ir_loop_jump(ir_loop_jump::jump_break);

-               block_records[lower].min_strength = strength_break;

-               jumps[lower]->replace_with(lowered);

-               jumps[lower] = lowered;

-            } else

-               goto lower_continue;

-            this->progress = true;

-         } else if(jump_strengths[lower] == strength_break) {

-            /* We can't lower to an actual continue because that would execute the increment.

-             *

-             * In the lowered code, we instead put the break check between the this->loop body and the increment,

-             * which is impossible with a real continue as defined by the GLSL IR currently.

-             *

-             * Smarter options (such as undoing the increment) are possible but it's not worth implementing them,

-             * because if break is lowered, continue is almost surely lowered too.

-             */

-            jumps[lower]->insert_before(new(ir) ir_assignment(new (ir) ir_dereference_variable(this->loop.get_break_flag()), new (ir) ir_constant(true), 0));

-            goto lower_continue;

-         } else if(jump_strengths[lower] == strength_continue) {

-lower_continue:

-            ir_variable* execute_flag = this->loop.get_execute_flag();

-            jumps[lower]->replace_with(new(ir) ir_assignment(new (ir) ir_dereference_variable(execute_flag), new (ir) ir_constant(false), 0));

-            jumps[lower] = 0;

-            block_records[lower].min_strength = strength_always_clears_execute_flag;

-            block_records[lower].may_clear_execute_flag = true;

-            this->progress = true;

-            break;

-         }

-      }

-

-      /* move out a jump out if possible */

-      if(pull_out_jumps) {

-         int move_out = -1;

-         if(jumps[0] && block_records[1].min_strength >= strength_continue)

-            move_out = 0;

-         else if(jumps[1] && block_records[0].min_strength >= strength_continue)

-            move_out = 1;

-

-         if(move_out >= 0)

-         {

-            jumps[move_out]->remove();

-            ir->insert_after(jumps[move_out]);

-            jumps[move_out] = 0;

-            block_records[move_out].min_strength = strength_none;

-            this->progress = true;

-         }

-      }

-

-      if(block_records[0].min_strength < block_records[1].min_strength)

-         this->block.min_strength = block_records[0].min_strength;

-      else

-         this->block.min_strength = block_records[1].min_strength;

-      this->block.may_clear_execute_flag = this->block.may_clear_execute_flag || block_records[0].may_clear_execute_flag || block_records[1].may_clear_execute_flag;

-

-      if(this->block.min_strength)

-         truncate_after_instruction(ir);

-      else if(this->block.may_clear_execute_flag)

-      {

-         int move_into = -1;

-         if(block_records[0].min_strength && !block_records[1].may_clear_execute_flag)

-            move_into = 1;

-         else if(block_records[1].min_strength && !block_records[0].may_clear_execute_flag)

-            move_into = 0;

-

-         if(move_into >= 0) {

-            assert(!block_records[move_into].min_strength && !block_records[move_into].may_clear_execute_flag); /* otherwise, we just truncated */

-

-            exec_list* list = move_into ? &ir->else_instructions : &ir->then_instructions;

-            exec_node* next = ir->get_next();

-            if(!next->is_tail_sentinel()) {

-               move_outer_block_inside(ir, list);

-

-               exec_list list;

-               list.head = next;

-               block_records[move_into] = visit_block(&list);

-

-               this->progress = true;

-               goto retry;

-            }

-         } else {

-            ir_instruction* ir_after;

-            for(ir_after = (ir_instruction*)ir->get_next(); !ir_after->is_tail_sentinel();)

-            {

-               ir_if* ir_if = ir_after->as_if();

-               if(ir_if && ir_if->else_instructions.is_empty()) {

-                  ir_dereference_variable* ir_if_cond_deref = ir_if->condition->as_dereference_variable();

-                  if(ir_if_cond_deref && ir_if_cond_deref->var == this->loop.execute_flag) {

-                     ir_instruction* ir_next = (ir_instruction*)ir_after->get_next();

-                     ir_after->insert_before(&ir_if->then_instructions);

-                     ir_after->remove();

-                     ir_after = ir_next;

-                     continue;

-                  }

-               }

-               ir_after = (ir_instruction*)ir_after->get_next();

-

-               /* only set this if we find any unprotected instruction */

-               this->progress = true;

-            }

-

-            if(!ir->get_next()->is_tail_sentinel()) {

-               assert(this->loop.execute_flag);

-               ir_if* if_execute = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.execute_flag));

-               move_outer_block_inside(ir, &if_execute->then_instructions);

-               ir->insert_after(if_execute);

-            }

-         }

-      }

-      --this->loop.nesting_depth;

-      --this->function.nesting_depth;

-   }

-

-   virtual void visit(ir_loop *ir)

-   {

-      ++this->function.nesting_depth;

-      loop_record saved_loop = this->loop;

-      this->loop = loop_record(this->function.signature, ir);

-

-      block_record body = visit_block(&ir->body_instructions);

-

-      if(body.min_strength >= strength_break) {

-         /* FINISHME: turn the this->loop into an if, or replace it with its body */

-      }

-

-      if(this->loop.break_flag) {

-         ir_if* break_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.break_flag));

-         break_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));

-         ir->body_instructions.push_tail(break_if);

-      }

-

-      if(this->loop.may_set_return_flag) {

-         assert(this->function.return_flag);

-         ir_if* return_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->function.return_flag));

-         saved_loop.may_set_return_flag = true;

-         if(saved_loop.loop)

-            return_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));

-         else

-            move_outer_block_inside(ir, &return_if->else_instructions);

-         ir->insert_after(return_if);

-      }

-

-      this->loop = saved_loop;

-      --this->function.nesting_depth;

-   }

-

-   virtual void visit(ir_function_signature *ir)

-   {

-      /* these are not strictly necessary */

-      assert(!this->function.signature);

-      assert(!this->loop.loop);

-

-      function_record saved_function = this->function;

-      loop_record saved_loop = this->loop;

-      this->function = function_record(ir);

-      this->loop = loop_record(ir);

-

-      assert(!this->loop.loop);

-      visit_block(&ir->body);

-

-      if(this->function.return_value)

-         ir->body.push_tail(new(ir) ir_return(new (ir) ir_dereference_variable(this->function.return_value)));

-

-      this->loop = saved_loop;

-      this->function = saved_function;

-   }

-

-   virtual void visit(class ir_function * ir)

-   {

-      visit_block(&ir->signatures);

-   }

-};

-

-bool

-do_lower_jumps(exec_list *instructions, bool pull_out_jumps, bool lower_sub_return, bool lower_main_return, bool lower_continue, bool lower_break)

-{

-   ir_lower_jumps_visitor v;

-   v.pull_out_jumps = pull_out_jumps;

-   v.lower_continue = lower_continue;

-   v.lower_break = lower_break;

-   v.lower_sub_return = lower_sub_return;

-   v.lower_main_return = lower_main_return;

-

-   do {

-      v.progress = false;

-      visit_exec_list(instructions, &v);

-   } while (v.progress);

-

-   return v.progress;

-}

+/*
+ * Copyright © 2010 Luca Barbieri
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file lower_jumps.cpp
+ *
+ * This pass lowers jumps (break, continue, and return) to if/else structures.
+ *
+ * It can be asked to:
+ * 1. Pull jumps out of ifs where possible
+ * 2. Remove all "continue"s, replacing them with an "execute flag"
+ * 3. Replace all "break" with a single conditional one at the end of the loop
+ * 4. Replace all "return"s with a single return at the end of the function,
+ *    for the main function and/or other functions
+ *
+ * Applying this pass gives several benefits:
+ * 1. All functions can be inlined.
+ * 2. nv40 and other pre-DX10 chips without "continue" can be supported
+ * 3. nv30 and other pre-DX10 chips with no control flow at all are better
+ *    supported
+ *
+ * Continues are lowered by adding a per-loop "execute flag", initialized to
+ * true, that when cleared inhibits all execution until the end of the loop.
+ *
+ * Breaks are lowered to continues, plus setting a "break flag" that is checked
+ * at the end of the loop, and trigger the unique "break".
+ *
+ * Returns are lowered to breaks/continues, plus adding a "return flag" that
+ * causes loops to break again out of their enclosing loops until all the
+ * loops are exited: then the "execute flag" logic will ignore everything
+ * until the end of the function.
+ *
+ * Note that "continue" and "return" can also be implemented by adding
+ * a dummy loop and using break.
+ * However, this is bad for hardware with limited nesting depth, and
+ * prevents further optimization, and thus is not currently performed.
+ */
+
+#include "glsl_types.h"
+#include <string.h>
+#include "ir.h"
+
+/**
+ * Enum recording the result of analyzing how control flow might exit
+ * an IR node.
+ *
+ * Each possible value of jump_strength indicates a strictly stronger
+ * guarantee on control flow than the previous value.
+ *
+ * The ordering of strengths roughly reflects the way jumps are
+ * lowered: jumps with higher strength tend to be lowered to jumps of
+ * lower strength.  Accordingly, strength is used as a heuristic to
+ * determine which lowering to perform first.
+ *
+ * This enum is also used by get_jump_strength() to categorize
+ * instructions as either break, continue, return, or other.  When
+ * used in this fashion, strength_always_clears_execute_flag is not
+ * used.
+ *
+ * The control flow analysis made by this optimization pass makes two
+ * simplifying assumptions:
+ *
+ * - It ignores discard instructions, since they are lowered by a
+ *   separate pass (lower_discard.cpp).
+ *
+ * - It assumes it is always possible for control to flow from a loop
+ *   to the instruction immediately following it.  Technically, this
+ *   is not true (since all execution paths through the loop might
+ *   jump back to the top, or return from the function).
+ *
+ * Both of these simplifying assumtions are safe, since they can never
+ * cause reachable code to be incorrectly classified as unreachable;
+ * they can only do the opposite.
+ */
+enum jump_strength
+{
+   /**
+    * Analysis has produced no guarantee on how control flow might
+    * exit this IR node.  It might fall out the bottom (with or
+    * without clearing the execute flag, if present), or it might
+    * continue to the top of the innermost enclosing loop, break out
+    * of it, or return from the function.
+    */
+   strength_none,
+
+   /**
+    * The only way control can fall out the bottom of this node is
+    * through a code path that clears the execute flag.  It might also
+    * continue to the top of the innermost enclosing loop, break out
+    * of it, or return from the function.
+    */
+   strength_always_clears_execute_flag,
+
+   /**
+    * Control cannot fall out the bottom of this node.  It might
+    * continue to the top of the innermost enclosing loop, break out
+    * of it, or return from the function.
+    */
+   strength_continue,
+
+   /**
+    * Control cannot fall out the bottom of this node, or continue the
+    * top of the innermost enclosing loop.  It can only break out of
+    * it or return from the function.
+    */
+   strength_break,
+
+   /**
+    * Control cannot fall out the bottom of this node, continue to the
+    * top of the innermost enclosing loop, or break out of it.  It can
+    * only return from the function.
+    */
+   strength_return
+};
+
+struct block_record
+{
+   /* minimum jump strength (of lowered IR, not pre-lowering IR)
+    *
+    * If the block ends with a jump, must be the strength of the jump.
+    * Otherwise, the jump would be dead and have been deleted before)
+    *
+    * If the block doesn't end with a jump, it can be different than strength_none if all paths before it lead to some jump
+    * (e.g. an if with a return in one branch, and a break in the other, while not lowering them)
+    * Note that identical jumps are usually unified though.
+    */
+   jump_strength min_strength;
+
+   /* can anything clear the execute flag? */
+   bool may_clear_execute_flag;
+
+   block_record()
+   {
+      this->min_strength = strength_none;
+      this->may_clear_execute_flag = false;
+   }
+};
+
+struct loop_record
+{
+   ir_function_signature* signature;
+   ir_loop* loop;
+
+   /* used to avoid lowering the break used to represent lowered breaks */
+   unsigned nesting_depth;
+   bool in_if_at_the_end_of_the_loop;
+
+   bool may_set_return_flag;
+
+   ir_variable* break_flag;
+   ir_variable* execute_flag; /* cleared to emulate continue */
+
+   loop_record(ir_function_signature* p_signature = 0, ir_loop* p_loop = 0)
+   {
+      this->signature = p_signature;
+      this->loop = p_loop;
+      this->nesting_depth = 0;
+      this->in_if_at_the_end_of_the_loop = false;
+      this->may_set_return_flag = false;
+      this->break_flag = 0;
+      this->execute_flag = 0;
+   }
+
+   ir_variable* get_execute_flag()
+   {
+      /* also supported for the "function loop" */
+      if(!this->execute_flag) {
+         exec_list& list = this->loop ? this->loop->body_instructions : signature->body;
+         this->execute_flag = new(this->signature) ir_variable(glsl_type::bool_type, "execute_flag", ir_var_temporary);
+         list.push_head(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(execute_flag), new(this->signature) ir_constant(true), 0));
+         list.push_head(this->execute_flag);
+      }
+      return this->execute_flag;
+   }
+
+   ir_variable* get_break_flag()
+   {
+      assert(this->loop);
+      if(!this->break_flag) {
+         this->break_flag = new(this->signature) ir_variable(glsl_type::bool_type, "break_flag", ir_var_temporary);
+         this->loop->insert_before(this->break_flag);
+         this->loop->insert_before(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(break_flag), new(this->signature) ir_constant(false), 0));
+      }
+      return this->break_flag;
+   }
+};
+
+struct function_record
+{
+   ir_function_signature* signature;
+   ir_variable* return_flag; /* used to break out of all loops and then jump to the return instruction */
+   ir_variable* return_value;
+   bool lower_return;
+   unsigned nesting_depth;
+
+   function_record(ir_function_signature* p_signature = 0,
+                   bool lower_return = false)
+   {
+      this->signature = p_signature;
+      this->return_flag = 0;
+      this->return_value = 0;
+      this->nesting_depth = 0;
+      this->lower_return = lower_return;
+   }
+
+   ir_variable* get_return_flag()
+   {
+      if(!this->return_flag) {
+         this->return_flag = new(this->signature) ir_variable(glsl_type::bool_type, "return_flag", ir_var_temporary);
+         this->signature->body.push_head(new(this->signature) ir_assignment(new(this->signature) ir_dereference_variable(return_flag), new(this->signature) ir_constant(false), 0));
+         this->signature->body.push_head(this->return_flag);
+      }
+      return this->return_flag;
+   }
+
+   ir_variable* get_return_value()
+   {
+      if(!this->return_value) {
+         assert(!this->signature->return_type->is_void());
+         return_value = new(this->signature) ir_variable(this->signature->return_type, "return_value", ir_var_temporary);
+         this->signature->body.push_head(this->return_value);
+      }
+      return this->return_value;
+   }
+};
+
+struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
+   /* Postconditions: on exit of any visit() function:
+    *
+    * ANALYSIS: this->block.min_strength,
+    * this->block.may_clear_execute_flag, and
+    * this->loop.may_set_return_flag are updated to reflect the
+    * characteristics of the visited statement.
+    *
+    * DEAD_CODE_ELIMINATION: If this->block.min_strength is not
+    * strength_none, the visited node is at the end of its exec_list.
+    * In other words, any unreachable statements that follow the
+    * visited statement in its exec_list have been removed.
+    *
+    * CONTAINED_JUMPS_LOWERED: If the visited statement contains other
+    * statements, then should_lower_jump() is false for all of the
+    * return, break, or continue statements it contains.
+    *
+    * Note that visiting a jump does not lower it.  That is the
+    * responsibility of the statement (or function signature) that
+    * contains the jump.
+    */
+
+   bool progress;
+
+   struct function_record function;
+   struct loop_record loop;
+   struct block_record block;
+
+   bool pull_out_jumps;
+   bool lower_continue;
+   bool lower_break;
+   bool lower_sub_return;
+   bool lower_main_return;
+
+   ir_lower_jumps_visitor()
+   {
+      this->progress = false;
+   }
+
+   void truncate_after_instruction(exec_node *ir)
+   {
+      if (!ir)
+         return;
+
+      while (!ir->get_next()->is_tail_sentinel()) {
+         ((ir_instruction *)ir->get_next())->remove();
+         this->progress = true;
+      }
+   }
+
+   void move_outer_block_inside(ir_instruction *ir, exec_list *inner_block)
+   {
+      while (!ir->get_next()->is_tail_sentinel()) {
+         ir_instruction *move_ir = (ir_instruction *)ir->get_next();
+
+         move_ir->remove();
+         inner_block->push_tail(move_ir);
+      }
+   }
+
+   /**
+    * Insert the instructions necessary to lower a return statement,
+    * before the given return instruction.
+    */
+   void insert_lowered_return(ir_return *ir)
+   {
+      ir_variable* return_flag = this->function.get_return_flag();
+      if(!this->function.signature->return_type->is_void()) {
+         ir_variable* return_value = this->function.get_return_value();
+         ir->insert_before(
+            new(ir) ir_assignment(
+               new (ir) ir_dereference_variable(return_value),
+               ir->value));
+      }
+      ir->insert_before(
+         new(ir) ir_assignment(
+            new (ir) ir_dereference_variable(return_flag),
+            new (ir) ir_constant(true)));
+      this->loop.may_set_return_flag = true;
+   }
+
+   /**
+    * If the given instruction is a return, lower it to instructions
+    * that store the return value (if there is one), set the return
+    * flag, and then break.
+    *
+    * It is safe to pass NULL to this function.
+    */
+   void lower_return_unconditionally(ir_instruction *ir)
+   {
+      if (get_jump_strength(ir) != strength_return) {
+         return;
+      }
+      insert_lowered_return((ir_return*)ir);
+      ir->replace_with(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
+   }
+
+   /**
+    * Create the necessary instruction to replace a break instruction.
+    */
+   ir_instruction *create_lowered_break()
+   {
+      void *ctx = this->function.signature;
+      return new(ctx) ir_assignment(
+          new(ctx) ir_dereference_variable(this->loop.get_break_flag()),
+          new(ctx) ir_constant(true),
+          0);
+   }
+
+   /**
+    * If the given instruction is a break, lower it to an instruction
+    * that sets the break flag, without consulting
+    * should_lower_jump().
+    *
+    * It is safe to pass NULL to this function.
+    */
+   void lower_break_unconditionally(ir_instruction *ir)
+   {
+      if (get_jump_strength(ir) != strength_break) {
+         return;
+      }
+      ir->replace_with(create_lowered_break());
+   }
+
+   /**
+    * If the block ends in a conditional or unconditional break, lower
+    * it, even though should_lower_jump() says it needn't be lowered.
+    */
+   void lower_final_breaks(exec_list *block)
+   {
+      ir_instruction *ir = (ir_instruction *) block->get_tail();
+      lower_break_unconditionally(ir);
+      ir_if *ir_if = ir->as_if();
+      if (ir_if) {
+          lower_break_unconditionally(
+              (ir_instruction *) ir_if->then_instructions.get_tail());
+          lower_break_unconditionally(
+              (ir_instruction *) ir_if->else_instructions.get_tail());
+      }
+   }
+
+   virtual void visit(class ir_loop_jump * ir)
+   {
+      /* Eliminate all instructions after each one, since they are
+       * unreachable.  This satisfies the DEAD_CODE_ELIMINATION
+       * postcondition.
+       */
+      truncate_after_instruction(ir);
+
+      /* Set this->block.min_strength based on this instruction.  This
+       * satisfies the ANALYSIS postcondition.  It is not necessary to
+       * update this->block.may_clear_execute_flag or
+       * this->loop.may_set_return_flag, because an unlowered jump
+       * instruction can't change any flags.
+       */
+      this->block.min_strength = ir->is_break() ? strength_break : strength_continue;
+
+      /* The CONTAINED_JUMPS_LOWERED postcondition is already
+       * satisfied, because jump statements can't contain other
+       * statements.
+       */
+   }
+
+   virtual void visit(class ir_return * ir)
+   {
+      /* Eliminate all instructions after each one, since they are
+       * unreachable.  This satisfies the DEAD_CODE_ELIMINATION
+       * postcondition.
+       */
+      truncate_after_instruction(ir);
+
+      /* Set this->block.min_strength based on this instruction.  This
+       * satisfies the ANALYSIS postcondition.  It is not necessary to
+       * update this->block.may_clear_execute_flag or
+       * this->loop.may_set_return_flag, because an unlowered return
+       * instruction can't change any flags.
+       */
+      this->block.min_strength = strength_return;
+
+      /* The CONTAINED_JUMPS_LOWERED postcondition is already
+       * satisfied, because jump statements can't contain other
+       * statements.
+       */
+   }
+
+   virtual void visit(class ir_discard * ir)
+   {
+      /* Nothing needs to be done.  The ANALYSIS and
+       * DEAD_CODE_ELIMINATION postconditions are already satisfied,
+       * because discard statements are ignored by this optimization
+       * pass.  The CONTAINED_JUMPS_LOWERED postcondition is already
+       * satisfied, because discard statements can't contain other
+       * statements.
+       */
+   }
+
+   enum jump_strength get_jump_strength(ir_instruction* ir)
+   {
+      if(!ir)
+         return strength_none;
+      else if(ir->ir_type == ir_type_loop_jump) {
+         if(((ir_loop_jump*)ir)->is_break())
+            return strength_break;
+         else
+            return strength_continue;
+      } else if(ir->ir_type == ir_type_return)
+         return strength_return;
+      else
+         return strength_none;
+   }
+
+   bool should_lower_jump(ir_jump* ir)
+   {
+      unsigned strength = get_jump_strength(ir);
+      bool lower;
+      switch(strength)
+      {
+      case strength_none:
+         lower = false; /* don't change this, code relies on it */
+         break;
+      case strength_continue:
+         lower = lower_continue;
+         break;
+      case strength_break:
+         assert(this->loop.loop);
+         /* never lower "canonical break" */
+         if(ir->get_next()->is_tail_sentinel() && (this->loop.nesting_depth == 0
+               || (this->loop.nesting_depth == 1 && this->loop.in_if_at_the_end_of_the_loop)))
+            lower = false;
+         else
+            lower = lower_break;
+         break;
+      case strength_return:
+         /* never lower return at the end of a this->function */
+         if(this->function.nesting_depth == 0 && ir->get_next()->is_tail_sentinel())
+            lower = false;
+         else
+            lower = this->function.lower_return;
+         break;
+      }
+      return lower;
+   }
+
+   block_record visit_block(exec_list* list)
+   {
+      /* Note: since visiting a node may change that node's next
+       * pointer, we can't use visit_exec_list(), because
+       * visit_exec_list() caches the node's next pointer before
+       * visiting it.  So we use foreach_list() instead.
+       *
+       * foreach_list() isn't safe if the node being visited gets
+       * removed, but fortunately this visitor doesn't do that.
+       */
+
+      block_record saved_block = this->block;
+      this->block = block_record();
+      foreach_list(node, list) {
+         ((ir_instruction *) node)->accept(this);
+      }
+      block_record ret = this->block;
+      this->block = saved_block;
+      return ret;
+   }
+
+   virtual void visit(ir_if *ir)
+   {
+      if(this->loop.nesting_depth == 0 && ir->get_next()->is_tail_sentinel())
+         this->loop.in_if_at_the_end_of_the_loop = true;
+
+      ++this->function.nesting_depth;
+      ++this->loop.nesting_depth;
+
+      block_record block_records[2];
+      ir_jump* jumps[2];
+
+      /* Recursively lower nested jumps.  This satisfies the
+       * CONTAINED_JUMPS_LOWERED postcondition, except in the case of
+       * unconditional jumps at the end of ir->then_instructions and
+       * ir->else_instructions, which are handled below.
+       */
+      block_records[0] = visit_block(&ir->then_instructions);
+      block_records[1] = visit_block(&ir->else_instructions);
+
+retry: /* we get here if we put code after the if inside a branch */
+
+      /* Determine which of ir->then_instructions and
+       * ir->else_instructions end with an unconditional jump.
+       */
+      for(unsigned i = 0; i < 2; ++i) {
+         exec_list& list = i ? ir->else_instructions : ir->then_instructions;
+         jumps[i] = 0;
+         if(!list.is_empty() && get_jump_strength((ir_instruction*)list.get_tail()))
+            jumps[i] = (ir_jump*)list.get_tail();
+      }
+
+      /* Loop until we have satisfied the CONTAINED_JUMPS_LOWERED
+       * postcondition by lowering jumps in both then_instructions and
+       * else_instructions.
+       */
+      for(;;) {
+         /* Determine the types of the jumps that terminate
+          * ir->then_instructions and ir->else_instructions.
+          */
+         jump_strength jump_strengths[2];
+
+         for(unsigned i = 0; i < 2; ++i) {
+            if(jumps[i]) {
+               jump_strengths[i] = block_records[i].min_strength;
+               assert(jump_strengths[i] == get_jump_strength(jumps[i]));
+            } else
+               jump_strengths[i] = strength_none;
+         }
+
+         /* If both code paths end in a jump, and the jumps are the
+          * same, and we are pulling out jumps, replace them with a
+          * single jump that comes after the if instruction.  The new
+          * jump will be visited next, and it will be lowered if
+          * necessary by the loop or conditional that encloses it.
+          */
+         if(pull_out_jumps && jump_strengths[0] == jump_strengths[1]) {
+            bool unify = true;
+            if(jump_strengths[0] == strength_continue)
+               ir->insert_after(new(ir) ir_loop_jump(ir_loop_jump::jump_continue));
+            else if(jump_strengths[0] == strength_break)
+               ir->insert_after(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
+            /* FINISHME: unify returns with identical expressions */
+            else if(jump_strengths[0] == strength_return && this->function.signature->return_type->is_void())
+               ir->insert_after(new(ir) ir_return(NULL));
+	    else
+	       unify = false;
+
+            if(unify) {
+               jumps[0]->remove();
+               jumps[1]->remove();
+               this->progress = true;
+
+               /* Update jumps[] to reflect the fact that the jumps
+                * are gone, and update block_records[] to reflect the
+                * fact that control can now flow to the next
+                * instruction.
+                */
+               jumps[0] = 0;
+               jumps[1] = 0;
+               block_records[0].min_strength = strength_none;
+               block_records[1].min_strength = strength_none;
+
+               /* The CONTAINED_JUMPS_LOWERED postcondition is now
+                * satisfied, so we can break out of the loop.
+                */
+               break;
+            }
+         }
+
+         /* lower a jump: if both need to lowered, start with the strongest one, so that
+          * we might later unify the lowered version with the other one
+          */
+         bool should_lower[2];
+         for(unsigned i = 0; i < 2; ++i)
+            should_lower[i] = should_lower_jump(jumps[i]);
+
+         int lower;
+         if(should_lower[1] && should_lower[0])
+            lower = jump_strengths[1] > jump_strengths[0];
+         else if(should_lower[0])
+            lower = 0;
+         else if(should_lower[1])
+            lower = 1;
+         else
+            /* Neither code path ends in a jump that needs to be
+             * lowered, so the CONTAINED_JUMPS_LOWERED postcondition
+             * is satisfied and we can break out of the loop.
+             */
+            break;
+
+         if(jump_strengths[lower] == strength_return) {
+            /* To lower a return, we create a return flag (if the
+             * function doesn't have one already) and add instructions
+             * that: 1. store the return value (if this function has a
+             * non-void return) and 2. set the return flag
+             */
+            insert_lowered_return((ir_return*)jumps[lower]);
+            if(this->loop.loop) {
+               /* If we are in a loop, replace the return instruction
+                * with a break instruction, and then loop so that the
+                * break instruction can be lowered if necessary.
+                */
+               ir_loop_jump* lowered = 0;
+               lowered = new(ir) ir_loop_jump(ir_loop_jump::jump_break);
+               /* Note: we must update block_records and jumps to
+                * reflect the fact that the control path has been
+                * altered from a return to a break.
+                */
+               block_records[lower].min_strength = strength_break;
+               jumps[lower]->replace_with(lowered);
+               jumps[lower] = lowered;
+            } else {
+               /* If we are not in a loop, we then proceed as we would
+                * for a continue statement (set the execute flag to
+                * false to prevent the rest of the function from
+                * executing).
+                */
+               goto lower_continue;
+            }
+            this->progress = true;
+         } else if(jump_strengths[lower] == strength_break) {
+            /* To lower a break, we create a break flag (if the loop
+             * doesn't have one already) and add an instruction that
+             * sets it.
+             *
+             * Then we proceed as we would for a continue statement
+             * (set the execute flag to false to prevent the rest of
+             * the loop body from executing).
+             *
+             * The visit() function for the loop will ensure that the
+             * break flag is checked after executing the loop body.
+             */
+            jumps[lower]->insert_before(create_lowered_break());
+            goto lower_continue;
+         } else if(jump_strengths[lower] == strength_continue) {
+lower_continue:
+            /* To lower a continue, we create an execute flag (if the
+             * loop doesn't have one already) and replace the continue
+             * with an instruction that clears it.
+             *
+             * Note that this code path gets exercised when lowering
+             * return statements that are not inside a loop, so
+             * this->loop must be initialized even outside of loops.
+             */
+            ir_variable* execute_flag = this->loop.get_execute_flag();
+            jumps[lower]->replace_with(new(ir) ir_assignment(new (ir) ir_dereference_variable(execute_flag), new (ir) ir_constant(false), 0));
+            /* Note: we must update block_records and jumps to reflect
+             * the fact that the control path has been altered to an
+             * instruction that clears the execute flag.
+             */
+            jumps[lower] = 0;
+            block_records[lower].min_strength = strength_always_clears_execute_flag;
+            block_records[lower].may_clear_execute_flag = true;
+            this->progress = true;
+
+            /* Let the loop run again, in case the other branch of the
+             * if needs to be lowered too.
+             */
+         }
+      }
+
+      /* move out a jump out if possible */
+      if(pull_out_jumps) {
+         /* If one of the branches ends in a jump, and control cannot
+          * fall out the bottom of the other branch, then we can move
+          * the jump after the if.
+          *
+          * Set move_out to the branch we are moving a jump out of.
+          */
+         int move_out = -1;
+         if(jumps[0] && block_records[1].min_strength >= strength_continue)
+            move_out = 0;
+         else if(jumps[1] && block_records[0].min_strength >= strength_continue)
+            move_out = 1;
+
+         if(move_out >= 0)
+         {
+            jumps[move_out]->remove();
+            ir->insert_after(jumps[move_out]);
+            /* Note: we must update block_records and jumps to reflect
+             * the fact that the jump has been moved out of the if.
+             */
+            jumps[move_out] = 0;
+            block_records[move_out].min_strength = strength_none;
+            this->progress = true;
+         }
+      }
+
+      /* Now satisfy the ANALYSIS postcondition by setting
+       * this->block.min_strength and
+       * this->block.may_clear_execute_flag based on the
+       * characteristics of the two branches.
+       */
+      if(block_records[0].min_strength < block_records[1].min_strength)
+         this->block.min_strength = block_records[0].min_strength;
+      else
+         this->block.min_strength = block_records[1].min_strength;
+      this->block.may_clear_execute_flag = this->block.may_clear_execute_flag || block_records[0].may_clear_execute_flag || block_records[1].may_clear_execute_flag;
+
+      /* Now we need to clean up the instructions that follow the
+       * if.
+       *
+       * If those instructions are unreachable, then satisfy the
+       * DEAD_CODE_ELIMINATION postcondition by eliminating them.
+       * Otherwise that postcondition is already satisfied.
+       */
+      if(this->block.min_strength)
+         truncate_after_instruction(ir);
+      else if(this->block.may_clear_execute_flag)
+      {
+         /* If the "if" instruction might clear the execute flag, then
+          * we need to guard any instructions that follow so that they
+          * are only executed if the execute flag is set.
+          *
+          * If one of the branches of the "if" always clears the
+          * execute flag, and the other branch never clears it, then
+          * this is easy: just move all the instructions following the
+          * "if" into the branch that never clears it.
+          */
+         int move_into = -1;
+         if(block_records[0].min_strength && !block_records[1].may_clear_execute_flag)
+            move_into = 1;
+         else if(block_records[1].min_strength && !block_records[0].may_clear_execute_flag)
+            move_into = 0;
+
+         if(move_into >= 0) {
+            assert(!block_records[move_into].min_strength && !block_records[move_into].may_clear_execute_flag); /* otherwise, we just truncated */
+
+            exec_list* list = move_into ? &ir->else_instructions : &ir->then_instructions;
+            exec_node* next = ir->get_next();
+            if(!next->is_tail_sentinel()) {
+               move_outer_block_inside(ir, list);
+
+               /* If any instructions moved, then we need to visit
+                * them (since they are now inside the "if").  Since
+                * block_records[move_into] is in its default state
+                * (see assertion above), we can safely replace
+                * block_records[move_into] with the result of this
+                * analysis.
+                */
+               exec_list list;
+               list.head = next;
+               block_records[move_into] = visit_block(&list);
+
+               /*
+                * Then we need to re-start our jump lowering, since one
+                * of the instructions we moved might be a jump that
+                * needs to be lowered.
+                */
+               this->progress = true;
+               goto retry;
+            }
+         } else {
+            /* If we get here, then the simple case didn't apply; we
+             * need to actually guard the instructions that follow.
+             *
+             * To avoid creating unnecessarily-deep nesting, first
+             * look through the instructions that follow and unwrap
+             * any instructions that that are already wrapped in the
+             * appropriate guard.
+             */
+            ir_instruction* ir_after;
+            for(ir_after = (ir_instruction*)ir->get_next(); !ir_after->is_tail_sentinel();)
+            {
+               ir_if* ir_if = ir_after->as_if();
+               if(ir_if && ir_if->else_instructions.is_empty()) {
+                  ir_dereference_variable* ir_if_cond_deref = ir_if->condition->as_dereference_variable();
+                  if(ir_if_cond_deref && ir_if_cond_deref->var == this->loop.execute_flag) {
+                     ir_instruction* ir_next = (ir_instruction*)ir_after->get_next();
+                     ir_after->insert_before(&ir_if->then_instructions);
+                     ir_after->remove();
+                     ir_after = ir_next;
+                     continue;
+                  }
+               }
+               ir_after = (ir_instruction*)ir_after->get_next();
+
+               /* only set this if we find any unprotected instruction */
+               this->progress = true;
+            }
+
+            /* Then, wrap all the instructions that follow in a single
+             * guard.
+             */
+            if(!ir->get_next()->is_tail_sentinel()) {
+               assert(this->loop.execute_flag);
+               ir_if* if_execute = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.execute_flag));
+               move_outer_block_inside(ir, &if_execute->then_instructions);
+               ir->insert_after(if_execute);
+            }
+         }
+      }
+      --this->loop.nesting_depth;
+      --this->function.nesting_depth;
+   }
+
+   virtual void visit(ir_loop *ir)
+   {
+      /* Visit the body of the loop, with a fresh data structure in
+       * this->loop so that the analysis we do here won't bleed into
+       * enclosing loops.
+       *
+       * We assume that all code after a loop is reachable from the
+       * loop (see comments on enum jump_strength), so the
+       * DEAD_CODE_ELIMINATION postcondition is automatically
+       * satisfied, as is the block.min_strength portion of the
+       * ANALYSIS postcondition.
+       *
+       * The block.may_clear_execute_flag portion of the ANALYSIS
+       * postcondition is automatically satisfied because execute
+       * flags do not propagate outside of loops.
+       *
+       * The loop.may_set_return_flag portion of the ANALYSIS
+       * postcondition is handled below.
+       */
+      ++this->function.nesting_depth;
+      loop_record saved_loop = this->loop;
+      this->loop = loop_record(this->function.signature, ir);
+
+      /* Recursively lower nested jumps.  This satisfies the
+       * CONTAINED_JUMPS_LOWERED postcondition, except in the case of
+       * an unconditional continue or return at the bottom of the
+       * loop, which are handled below.
+       */
+      block_record body = visit_block(&ir->body_instructions);
+
+      /* If the loop ends in an unconditional continue, eliminate it
+       * because it is redundant.
+       */
+      ir_instruction *ir_last
+         = (ir_instruction *) ir->body_instructions.get_tail();
+      if (get_jump_strength(ir_last) == strength_continue) {
+         ir_last->remove();
+      }
+
+      /* If the loop ends in an unconditional return, and we are
+       * lowering returns, lower it.
+       */
+      if (this->function.lower_return)
+         lower_return_unconditionally(ir_last);
+
+      if(body.min_strength >= strength_break) {
+         /* FINISHME: If the min_strength of the loop body is
+          * strength_break or strength_return, that means that it
+          * isn't a loop at all, since control flow always leaves the
+          * body of the loop via break or return.  In principle the
+          * loop could be eliminated in this case.  This optimization
+          * is not implemented yet.
+          */
+      }
+
+      if(this->loop.break_flag) {
+         /* We only get here if we are lowering breaks */
+         assert (lower_break);
+
+         /* If a break flag was generated while visiting the body of
+          * the loop, then at least one break was lowered, so we need
+          * to generate an if statement at the end of the loop that
+          * does a "break" if the break flag is set.  The break we
+          * generate won't violate the CONTAINED_JUMPS_LOWERED
+          * postcondition, because should_lower_jump() always returns
+          * false for a break that happens at the end of a loop.
+          *
+          * However, if the loop already ends in a conditional or
+          * unconditional break, then we need to lower that break,
+          * because it won't be at the end of the loop anymore.
+          */
+         lower_final_breaks(&ir->body_instructions);
+
+         ir_if* break_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.break_flag));
+         break_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
+         ir->body_instructions.push_tail(break_if);
+      }
+
+      /* If the body of the loop may set the return flag, then at
+       * least one return was lowered to a break, so we need to ensure
+       * that the return flag is checked after the body of the loop is
+       * executed.
+       */
+      if(this->loop.may_set_return_flag) {
+         assert(this->function.return_flag);
+         /* Generate the if statement to check the return flag */
+         ir_if* return_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->function.return_flag));
+         /* Note: we also need to propagate the knowledge that the
+          * return flag may get set to the outer context.  This
+          * satisfies the loop.may_set_return_flag part of the
+          * ANALYSIS postcondition.
+          */
+         saved_loop.may_set_return_flag = true;
+         if(saved_loop.loop)
+            /* If this loop is nested inside another one, then the if
+             * statement that we generated should break out of that
+             * loop if the return flag is set.  Caller will lower that
+             * break statement if necessary.
+             */
+            return_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
+         else
+            /* Otherwise, all we need to do is ensure that the
+             * instructions that follow are only executed if the
+             * return flag is clear.  We can do that by moving those
+             * instructions into the else clause of the generated if
+             * statement.
+             */
+            move_outer_block_inside(ir, &return_if->else_instructions);
+         ir->insert_after(return_if);
+      }
+
+      this->loop = saved_loop;
+      --this->function.nesting_depth;
+   }
+
+   virtual void visit(ir_function_signature *ir)
+   {
+      /* these are not strictly necessary */
+      assert(!this->function.signature);
+      assert(!this->loop.loop);
+
+      bool lower_return;
+      if (strcmp(ir->function_name(), "main") == 0)
+         lower_return = lower_main_return;
+      else
+         lower_return = lower_sub_return;
+
+      function_record saved_function = this->function;
+      loop_record saved_loop = this->loop;
+      this->function = function_record(ir, lower_return);
+      this->loop = loop_record(ir);
+
+      assert(!this->loop.loop);
+
+      /* Visit the body of the function to lower any jumps that occur
+       * in it, except possibly an unconditional return statement at
+       * the end of it.
+       */
+      visit_block(&ir->body);
+
+      /* If the body ended in an unconditional return of non-void,
+       * then we don't need to lower it because it's the one canonical
+       * return.
+       *
+       * If the body ended in a return of void, eliminate it because
+       * it is redundant.
+       */
+      if (ir->return_type->is_void() &&
+          get_jump_strength((ir_instruction *) ir->body.get_tail())) {
+         ir_jump *jump = (ir_jump *) ir->body.get_tail();
+         assert (jump->ir_type == ir_type_return);
+         jump->remove();
+      }
+
+      if(this->function.return_value)
+         ir->body.push_tail(new(ir) ir_return(new (ir) ir_dereference_variable(this->function.return_value)));
+
+      this->loop = saved_loop;
+      this->function = saved_function;
+   }
+
+   virtual void visit(class ir_function * ir)
+   {
+      visit_block(&ir->signatures);
+   }
+};
+
+bool
+do_lower_jumps(exec_list *instructions, bool pull_out_jumps, bool lower_sub_return, bool lower_main_return, bool lower_continue, bool lower_break)
+{
+   ir_lower_jumps_visitor v;
+   v.pull_out_jumps = pull_out_jumps;
+   v.lower_continue = lower_continue;
+   v.lower_break = lower_break;
+   v.lower_sub_return = lower_sub_return;
+   v.lower_main_return = lower_main_return;
+
+   do {
+      v.progress = false;
+      visit_exec_list(instructions, &v);
+   } while (v.progress);
+
+   return v.progress;
+}