xserver and mesa git update 28-12-2010

1 files changed, 497 insertions, 496 deletions

diff --git a/mesalib/src/glsl/loop_analysis.cpp b/mesalib/src/glsl/loop_analysis.cpp
index 91e34da0e..f32b91ce8 100644
--- a/mesalib/src/glsl/loop_analysis.cpp
+++ b/mesalib/src/glsl/loop_analysis.cpp
@@ -1,496 +1,497 @@
-/*
- * 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 "glsl_types.h"
-#include "loop_analysis.h"
-#include "ir_hierarchical_visitor.h"
-
-static bool is_loop_terminator(ir_if *ir);
-
-static bool all_expression_operands_are_loop_constant(ir_rvalue *,
-						      hash_table *);
-
-static ir_rvalue *get_basic_induction_increment(ir_assignment *, hash_table *);
-
-
-loop_state::loop_state()
-{
-   this->ht = hash_table_ctor(0, hash_table_pointer_hash,
-			      hash_table_pointer_compare);
-   this->mem_ctx = talloc_init("loop state");
-}
-
-
-loop_state::~loop_state()
-{
-   hash_table_dtor(this->ht);
-}
-
-
-loop_variable_state *
-loop_state::insert(ir_loop *ir)
-{
-   loop_variable_state *ls = new(this->mem_ctx) loop_variable_state;
-   hash_table_insert(this->ht, ls, ir);
-
-   return ls;
-}
-
-
-loop_variable_state *
-loop_state::get(const ir_loop *ir)
-{
-   return (loop_variable_state *) hash_table_find(this->ht, ir);
-}
-
-
-loop_variable *
-loop_variable_state::get(const ir_variable *ir)
-{
-   return (loop_variable *) hash_table_find(this->var_hash, ir);
-}
-
-
-loop_variable *
-loop_variable_state::insert(ir_variable *var)
-{
-   void *mem_ctx = talloc_parent(this);
-   loop_variable *lv = talloc_zero(mem_ctx, loop_variable);
-
-   lv->var = var;
-
-   hash_table_insert(this->var_hash, lv, lv->var);
-   this->variables.push_tail(lv);
-
-   return lv;
-}
-
-
-loop_terminator *
-loop_variable_state::insert(ir_if *if_stmt)
-{
-   void *mem_ctx = talloc_parent(this);
-   loop_terminator *t = talloc_zero(mem_ctx, loop_terminator);
-
-   t->ir = if_stmt;
-   this->terminators.push_tail(t);
-
-   return t;
-}
-
-
-class loop_analysis : public ir_hierarchical_visitor {
-public:
-   loop_analysis();
-
-   virtual ir_visitor_status visit(ir_loop_jump *);
-   virtual ir_visitor_status visit(ir_dereference_variable *);
-
-   virtual ir_visitor_status visit_enter(ir_loop *);
-   virtual ir_visitor_status visit_leave(ir_loop *);
-   virtual ir_visitor_status visit_enter(ir_assignment *);
-   virtual ir_visitor_status visit_leave(ir_assignment *);
-   virtual ir_visitor_status visit_enter(ir_if *);
-   virtual ir_visitor_status visit_leave(ir_if *);
-
-   loop_state *loops;
-
-   int if_statement_depth;
-
-   ir_assignment *current_assignment;
-
-   exec_list state;
-};
-
-
-loop_analysis::loop_analysis()
-{
-   this->loops = new loop_state;
-
-   this->if_statement_depth = 0;
-   this->current_assignment = NULL;
-}
-
-
-ir_visitor_status
-loop_analysis::visit(ir_loop_jump *ir)
-{
-   (void) ir;
-
-   assert(!this->state.is_empty());
-
-   loop_variable_state *const ls =
-      (loop_variable_state *) this->state.get_head();
-
-   ls->num_loop_jumps++;
-
-   return visit_continue;
-}
-
-
-ir_visitor_status
-loop_analysis::visit(ir_dereference_variable *ir)
-{
-   /* If we're not somewhere inside a loop, there's nothing to do.
-    */
-   if (this->state.is_empty())
-      return visit_continue;
-
-   loop_variable_state *const ls =
-      (loop_variable_state *) this->state.get_head();
-
-   ir_variable *var = ir->variable_referenced();
-   loop_variable *lv = ls->get(var);
-
-   if (lv == NULL) {
-      lv = ls->insert(var);
-      lv->read_before_write = !this->in_assignee;
-   }
-
-   if (this->in_assignee) {
-      assert(this->current_assignment != NULL);
-
-      lv->conditional_assignment = (this->if_statement_depth > 0)
-	 || (this->current_assignment->condition != NULL);
-
-      if (lv->first_assignment == NULL) {
-	 assert(lv->num_assignments == 0);
-
-	 lv->first_assignment = this->current_assignment;
-      }
-
-      lv->num_assignments++;
-   } else if (lv->first_assignment == this->current_assignment) {
-      /* This catches the case where the variable is used in the RHS of an
-       * assignment where it is also in the LHS.
-       */
-      lv->read_before_write = true;
-   }
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_enter(ir_loop *ir)
-{
-   loop_variable_state *ls = this->loops->insert(ir);
-   this->state.push_head(ls);
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_leave(ir_loop *ir)
-{
-   loop_variable_state *const ls =
-      (loop_variable_state *) this->state.pop_head();
-
-
-   foreach_list(node, &ir->body_instructions) {
-      /* Skip over declarations at the start of a loop.
-       */
-      if (((ir_instruction *) node)->as_variable())
-	 continue;
-
-      ir_if *if_stmt = ((ir_instruction *) node)->as_if();
-
-      if ((if_stmt != NULL) && is_loop_terminator(if_stmt))
-	 ls->insert(if_stmt);
-      else
-	 break;
-   }
-
-
-   foreach_list_safe(node, &ls->variables) {
-      loop_variable *lv = (loop_variable *) node;
-
-      /* Move variables that are already marked as being loop constant to
-       * a separate list.  These trivially don't need to be tested.
-       */
-      if (lv->is_loop_constant()) {
-	 lv->remove();
-	 ls->constants.push_tail(lv);
-      }
-   }
-
-   /* Each variable assigned in the loop that isn't already marked as being loop
-    * constant might still be loop constant.  The requirements at this point
-    * are:
-    *
-    *    - Variable is written before it is read.
-    *
-    *    - Only one assignment to the variable.
-    *
-    *    - All operands on the RHS of the assignment are also loop constants.
-    *
-    * The last requirement is the reason for the progress loop.  A variable
-    * marked as a loop constant on one pass may allow other variables to be
-    * marked as loop constant on following passes.
-    */
-   bool progress;
-   do {
-      progress = false;
-
-      foreach_list_safe(node, &ls->variables) {
-	 loop_variable *lv = (loop_variable *) node;
-
-	 if (lv->conditional_assignment || (lv->num_assignments > 1))
-	    continue;
-
-	 /* Process the RHS of the assignment.  If all of the variables
-	  * accessed there are loop constants, then add this
-	  */
-	 ir_rvalue *const rhs = lv->first_assignment->rhs;
-	 if (all_expression_operands_are_loop_constant(rhs, ls->var_hash)) {
-	    lv->rhs_clean = true;
-
-	    if (lv->is_loop_constant()) {
-	       progress = true;
-
-	       lv->remove();
-	       ls->constants.push_tail(lv);
-	    }
-	 }
-      }
-   } while (progress);
-
-   /* The remaining variables that are not loop invariant might be loop
-    * induction variables.
-    */
-   foreach_list_safe(node, &ls->variables) {
-      loop_variable *lv = (loop_variable *) node;
-
-      /* If there is more than one assignment to a variable, it cannot be a
-       * loop induction variable.  This isn't strictly true, but this is a
-       * very simple induction variable detector, and it can't handle more
-       * complex cases.
-       */
-      if (lv->num_assignments > 1)
-	 continue;
-
-      /* All of the variables with zero assignments in the loop are loop
-       * invariant, and they should have already been filtered out.
-       */
-      assert(lv->num_assignments == 1);
-      assert(lv->first_assignment != NULL);
-
-      /* The assignmnet to the variable in the loop must be unconditional.
-       */
-      if (lv->conditional_assignment)
-	 continue;
-
-      /* Basic loop induction variables have a single assignment in the loop
-       * that has the form 'VAR = VAR + i' or 'VAR = VAR - i' where i is a
-       * loop invariant.
-       */
-      ir_rvalue *const inc =
-	 get_basic_induction_increment(lv->first_assignment, ls->var_hash);
-      if (inc != NULL) {
-	 lv->iv_scale = NULL;
-	 lv->biv = lv->var;
-	 lv->increment = inc;
-
-	 lv->remove();
-	 ls->induction_variables.push_tail(lv);
-      }
-   }
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_enter(ir_if *ir)
-{
-   (void) ir;
-
-   if (!this->state.is_empty())
-      this->if_statement_depth++;
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_leave(ir_if *ir)
-{
-   (void) ir;
-
-   if (!this->state.is_empty())
-      this->if_statement_depth--;
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_enter(ir_assignment *ir)
-{
-   /* If we're not somewhere inside a loop, there's nothing to do.
-    */
-   if (this->state.is_empty())
-      return visit_continue_with_parent;
-
-   this->current_assignment = ir;
-
-   return visit_continue;
-}
-
-ir_visitor_status
-loop_analysis::visit_leave(ir_assignment *ir)
-{
-   /* Since the visit_enter exits with visit_continue_with_parent for this
-    * case, the loop state stack should never be empty here.
-    */
-   assert(!this->state.is_empty());
-
-   assert(this->current_assignment == ir);
-   this->current_assignment = NULL;
-
-   return visit_continue;
-}
-
-
-class examine_rhs : public ir_hierarchical_visitor {
-public:
-   examine_rhs(hash_table *loop_variables)
-   {
-      this->only_uses_loop_constants = true;
-      this->loop_variables = loop_variables;
-   }
-
-   virtual ir_visitor_status visit(ir_dereference_variable *ir)
-   {
-      loop_variable *lv =
-	 (loop_variable *) hash_table_find(this->loop_variables, ir->var);
-
-      assert(lv != NULL);
-
-      if (lv->is_loop_constant()) {
-	 return visit_continue;
-      } else {
-	 this->only_uses_loop_constants = false;
-	 return visit_stop;
-      }
-   }
-
-   hash_table *loop_variables;
-   bool only_uses_loop_constants;
-};
-
-
-bool
-all_expression_operands_are_loop_constant(ir_rvalue *ir, hash_table *variables)
-{
-   examine_rhs v(variables);
-
-   ir->accept(&v);
-
-   return v.only_uses_loop_constants;
-}
-
-
-ir_rvalue *
-get_basic_induction_increment(ir_assignment *ir, hash_table *var_hash)
-{
-   /* The RHS must be a binary expression.
-    */
-   ir_expression *const rhs = ir->rhs->as_expression();
-   if ((rhs == NULL)
-       || ((rhs->operation != ir_binop_add)
-	   && (rhs->operation != ir_binop_sub)))
-      return NULL;
-
-   /* One of the of operands of the expression must be the variable assigned.
-    * If the operation is subtraction, the variable in question must be the
-    * "left" operand.
-    */
-   ir_variable *const var = ir->lhs->variable_referenced();
-
-   ir_variable *const op0 = rhs->operands[0]->variable_referenced();
-   ir_variable *const op1 = rhs->operands[1]->variable_referenced();
-
-   if (((op0 != var) && (op1 != var))
-       || ((op1 == var) && (rhs->operation == ir_binop_sub)))
-      return NULL;
-
-   ir_rvalue *inc = (op0 == var) ? rhs->operands[1] : rhs->operands[0];
-
-   if (inc->as_constant() == NULL) {
-      ir_variable *const inc_var = inc->variable_referenced();
-      if (inc_var != NULL) {
-	 loop_variable *lv =
-	    (loop_variable *) hash_table_find(var_hash, inc_var);
-
-	 if (!lv->is_loop_constant())
-	    inc = NULL;
-      } else
-	 inc = NULL;
-   }
-
-   if ((inc != NULL) && (rhs->operation == ir_binop_sub)) {
-      void *mem_ctx = talloc_parent(ir);
-
-      inc = new(mem_ctx) ir_expression(ir_unop_neg,
-				       inc->type,
-				       inc->clone(mem_ctx, NULL),
-				       NULL);
-   }
-
-   return inc;
-}
-
-
-/**
- * Detect whether an if-statement is a loop terminating condition
- *
- * Detects if-statements of the form
- *
- *  (if (expression bool ...) (break))
- */
-bool
-is_loop_terminator(ir_if *ir)
-{
-   if (!ir->else_instructions.is_empty())
-      return false;
-
-   ir_instruction *const inst =
-      (ir_instruction *) ir->then_instructions.get_head();
-   assert(inst != NULL);
-
-   if (inst->ir_type != ir_type_loop_jump)
-      return false;
-
-   ir_loop_jump *const jump = (ir_loop_jump *) inst;
-   if (jump->mode != ir_loop_jump::jump_break)
-      return false;
-
-   return true;
-}
-
-
-loop_state *
-analyze_loop_variables(exec_list *instructions)
-{
-   loop_analysis v;
-
-   v.run(instructions);
-   return v.loops;
-}
+/*

+ * 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 "glsl_types.h"

+#include "loop_analysis.h"

+#include "ir_hierarchical_visitor.h"

+

+static bool is_loop_terminator(ir_if *ir);

+

+static bool all_expression_operands_are_loop_constant(ir_rvalue *,

+						      hash_table *);

+

+static ir_rvalue *get_basic_induction_increment(ir_assignment *, hash_table *);

+

+

+loop_state::loop_state()

+{

+   this->ht = hash_table_ctor(0, hash_table_pointer_hash,

+			      hash_table_pointer_compare);

+   this->mem_ctx = talloc_init("loop state");

+}

+

+

+loop_state::~loop_state()

+{

+   hash_table_dtor(this->ht);

+   talloc_free(this->mem_ctx);

+}

+

+

+loop_variable_state *

+loop_state::insert(ir_loop *ir)

+{

+   loop_variable_state *ls = new(this->mem_ctx) loop_variable_state;

+   hash_table_insert(this->ht, ls, ir);

+

+   return ls;

+}

+

+

+loop_variable_state *

+loop_state::get(const ir_loop *ir)

+{

+   return (loop_variable_state *) hash_table_find(this->ht, ir);

+}

+

+

+loop_variable *

+loop_variable_state::get(const ir_variable *ir)

+{

+   return (loop_variable *) hash_table_find(this->var_hash, ir);

+}

+

+

+loop_variable *

+loop_variable_state::insert(ir_variable *var)

+{

+   void *mem_ctx = talloc_parent(this);

+   loop_variable *lv = talloc_zero(mem_ctx, loop_variable);

+

+   lv->var = var;

+

+   hash_table_insert(this->var_hash, lv, lv->var);

+   this->variables.push_tail(lv);

+

+   return lv;

+}

+

+

+loop_terminator *

+loop_variable_state::insert(ir_if *if_stmt)

+{

+   void *mem_ctx = talloc_parent(this);

+   loop_terminator *t = talloc_zero(mem_ctx, loop_terminator);

+

+   t->ir = if_stmt;

+   this->terminators.push_tail(t);

+

+   return t;

+}

+

+

+class loop_analysis : public ir_hierarchical_visitor {

+public:

+   loop_analysis();

+

+   virtual ir_visitor_status visit(ir_loop_jump *);

+   virtual ir_visitor_status visit(ir_dereference_variable *);

+

+   virtual ir_visitor_status visit_enter(ir_loop *);

+   virtual ir_visitor_status visit_leave(ir_loop *);

+   virtual ir_visitor_status visit_enter(ir_assignment *);

+   virtual ir_visitor_status visit_leave(ir_assignment *);

+   virtual ir_visitor_status visit_enter(ir_if *);

+   virtual ir_visitor_status visit_leave(ir_if *);

+

+   loop_state *loops;

+

+   int if_statement_depth;

+

+   ir_assignment *current_assignment;

+

+   exec_list state;

+};

+

+

+loop_analysis::loop_analysis()

+{

+   this->loops = new loop_state;

+

+   this->if_statement_depth = 0;

+   this->current_assignment = NULL;

+}

+

+

+ir_visitor_status

+loop_analysis::visit(ir_loop_jump *ir)

+{

+   (void) ir;

+

+   assert(!this->state.is_empty());

+

+   loop_variable_state *const ls =

+      (loop_variable_state *) this->state.get_head();

+

+   ls->num_loop_jumps++;

+

+   return visit_continue;

+}

+

+

+ir_visitor_status

+loop_analysis::visit(ir_dereference_variable *ir)

+{

+   /* If we're not somewhere inside a loop, there's nothing to do.

+    */

+   if (this->state.is_empty())

+      return visit_continue;

+

+   loop_variable_state *const ls =

+      (loop_variable_state *) this->state.get_head();

+

+   ir_variable *var = ir->variable_referenced();

+   loop_variable *lv = ls->get(var);

+

+   if (lv == NULL) {

+      lv = ls->insert(var);

+      lv->read_before_write = !this->in_assignee;

+   }

+

+   if (this->in_assignee) {

+      assert(this->current_assignment != NULL);

+

+      lv->conditional_assignment = (this->if_statement_depth > 0)

+	 || (this->current_assignment->condition != NULL);

+

+      if (lv->first_assignment == NULL) {

+	 assert(lv->num_assignments == 0);

+

+	 lv->first_assignment = this->current_assignment;

+      }

+

+      lv->num_assignments++;

+   } else if (lv->first_assignment == this->current_assignment) {

+      /* This catches the case where the variable is used in the RHS of an

+       * assignment where it is also in the LHS.

+       */

+      lv->read_before_write = true;

+   }

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_enter(ir_loop *ir)

+{

+   loop_variable_state *ls = this->loops->insert(ir);

+   this->state.push_head(ls);

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_leave(ir_loop *ir)

+{

+   loop_variable_state *const ls =

+      (loop_variable_state *) this->state.pop_head();

+

+

+   foreach_list(node, &ir->body_instructions) {

+      /* Skip over declarations at the start of a loop.

+       */

+      if (((ir_instruction *) node)->as_variable())

+	 continue;

+

+      ir_if *if_stmt = ((ir_instruction *) node)->as_if();

+

+      if ((if_stmt != NULL) && is_loop_terminator(if_stmt))

+	 ls->insert(if_stmt);

+      else

+	 break;

+   }

+

+

+   foreach_list_safe(node, &ls->variables) {

+      loop_variable *lv = (loop_variable *) node;

+

+      /* Move variables that are already marked as being loop constant to

+       * a separate list.  These trivially don't need to be tested.

+       */

+      if (lv->is_loop_constant()) {

+	 lv->remove();

+	 ls->constants.push_tail(lv);

+      }

+   }

+

+   /* Each variable assigned in the loop that isn't already marked as being loop

+    * constant might still be loop constant.  The requirements at this point

+    * are:

+    *

+    *    - Variable is written before it is read.

+    *

+    *    - Only one assignment to the variable.

+    *

+    *    - All operands on the RHS of the assignment are also loop constants.

+    *

+    * The last requirement is the reason for the progress loop.  A variable

+    * marked as a loop constant on one pass may allow other variables to be

+    * marked as loop constant on following passes.

+    */

+   bool progress;

+   do {

+      progress = false;

+

+      foreach_list_safe(node, &ls->variables) {

+	 loop_variable *lv = (loop_variable *) node;

+

+	 if (lv->conditional_assignment || (lv->num_assignments > 1))

+	    continue;

+

+	 /* Process the RHS of the assignment.  If all of the variables

+	  * accessed there are loop constants, then add this

+	  */

+	 ir_rvalue *const rhs = lv->first_assignment->rhs;

+	 if (all_expression_operands_are_loop_constant(rhs, ls->var_hash)) {

+	    lv->rhs_clean = true;

+

+	    if (lv->is_loop_constant()) {

+	       progress = true;

+

+	       lv->remove();

+	       ls->constants.push_tail(lv);

+	    }

+	 }

+      }

+   } while (progress);

+

+   /* The remaining variables that are not loop invariant might be loop

+    * induction variables.

+    */

+   foreach_list_safe(node, &ls->variables) {

+      loop_variable *lv = (loop_variable *) node;

+

+      /* If there is more than one assignment to a variable, it cannot be a

+       * loop induction variable.  This isn't strictly true, but this is a

+       * very simple induction variable detector, and it can't handle more

+       * complex cases.

+       */

+      if (lv->num_assignments > 1)

+	 continue;

+

+      /* All of the variables with zero assignments in the loop are loop

+       * invariant, and they should have already been filtered out.

+       */

+      assert(lv->num_assignments == 1);

+      assert(lv->first_assignment != NULL);

+

+      /* The assignmnet to the variable in the loop must be unconditional.

+       */

+      if (lv->conditional_assignment)

+	 continue;

+

+      /* Basic loop induction variables have a single assignment in the loop

+       * that has the form 'VAR = VAR + i' or 'VAR = VAR - i' where i is a

+       * loop invariant.

+       */

+      ir_rvalue *const inc =

+	 get_basic_induction_increment(lv->first_assignment, ls->var_hash);

+      if (inc != NULL) {

+	 lv->iv_scale = NULL;

+	 lv->biv = lv->var;

+	 lv->increment = inc;

+

+	 lv->remove();

+	 ls->induction_variables.push_tail(lv);

+      }

+   }

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_enter(ir_if *ir)

+{

+   (void) ir;

+

+   if (!this->state.is_empty())

+      this->if_statement_depth++;

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_leave(ir_if *ir)

+{

+   (void) ir;

+

+   if (!this->state.is_empty())

+      this->if_statement_depth--;

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_enter(ir_assignment *ir)

+{

+   /* If we're not somewhere inside a loop, there's nothing to do.

+    */

+   if (this->state.is_empty())

+      return visit_continue_with_parent;

+

+   this->current_assignment = ir;

+

+   return visit_continue;

+}

+

+ir_visitor_status

+loop_analysis::visit_leave(ir_assignment *ir)

+{

+   /* Since the visit_enter exits with visit_continue_with_parent for this

+    * case, the loop state stack should never be empty here.

+    */

+   assert(!this->state.is_empty());

+

+   assert(this->current_assignment == ir);

+   this->current_assignment = NULL;

+

+   return visit_continue;

+}

+

+

+class examine_rhs : public ir_hierarchical_visitor {

+public:

+   examine_rhs(hash_table *loop_variables)

+   {

+      this->only_uses_loop_constants = true;

+      this->loop_variables = loop_variables;

+   }

+

+   virtual ir_visitor_status visit(ir_dereference_variable *ir)

+   {

+      loop_variable *lv =

+	 (loop_variable *) hash_table_find(this->loop_variables, ir->var);

+

+      assert(lv != NULL);

+

+      if (lv->is_loop_constant()) {

+	 return visit_continue;

+      } else {

+	 this->only_uses_loop_constants = false;

+	 return visit_stop;

+      }

+   }

+

+   hash_table *loop_variables;

+   bool only_uses_loop_constants;

+};

+

+

+bool

+all_expression_operands_are_loop_constant(ir_rvalue *ir, hash_table *variables)

+{

+   examine_rhs v(variables);

+

+   ir->accept(&v);

+

+   return v.only_uses_loop_constants;

+}

+

+

+ir_rvalue *

+get_basic_induction_increment(ir_assignment *ir, hash_table *var_hash)

+{

+   /* The RHS must be a binary expression.

+    */

+   ir_expression *const rhs = ir->rhs->as_expression();

+   if ((rhs == NULL)

+       || ((rhs->operation != ir_binop_add)

+	   && (rhs->operation != ir_binop_sub)))

+      return NULL;

+

+   /* One of the of operands of the expression must be the variable assigned.

+    * If the operation is subtraction, the variable in question must be the

+    * "left" operand.

+    */

+   ir_variable *const var = ir->lhs->variable_referenced();

+

+   ir_variable *const op0 = rhs->operands[0]->variable_referenced();

+   ir_variable *const op1 = rhs->operands[1]->variable_referenced();

+

+   if (((op0 != var) && (op1 != var))

+       || ((op1 == var) && (rhs->operation == ir_binop_sub)))

+      return NULL;

+

+   ir_rvalue *inc = (op0 == var) ? rhs->operands[1] : rhs->operands[0];

+

+   if (inc->as_constant() == NULL) {

+      ir_variable *const inc_var = inc->variable_referenced();

+      if (inc_var != NULL) {

+	 loop_variable *lv =

+	    (loop_variable *) hash_table_find(var_hash, inc_var);

+

+	 if (!lv->is_loop_constant())

+	    inc = NULL;

+      } else

+	 inc = NULL;

+   }

+

+   if ((inc != NULL) && (rhs->operation == ir_binop_sub)) {

+      void *mem_ctx = talloc_parent(ir);

+

+      inc = new(mem_ctx) ir_expression(ir_unop_neg,

+				       inc->type,

+				       inc->clone(mem_ctx, NULL),

+				       NULL);

+   }

+

+   return inc;

+}

+

+

+/**

+ * Detect whether an if-statement is a loop terminating condition

+ *

+ * Detects if-statements of the form

+ *

+ *  (if (expression bool ...) (break))

+ */

+bool

+is_loop_terminator(ir_if *ir)

+{

+   if (!ir->else_instructions.is_empty())

+      return false;

+

+   ir_instruction *const inst =

+      (ir_instruction *) ir->then_instructions.get_head();

+   assert(inst != NULL);

+

+   if (inst->ir_type != ir_type_loop_jump)

+      return false;

+

+   ir_loop_jump *const jump = (ir_loop_jump *) inst;

+   if (jump->mode != ir_loop_jump::jump_break)

+      return false;

+

+   return true;

+}

+

+

+loop_state *

+analyze_loop_variables(exec_list *instructions)

+{

+   loop_analysis v;

+

+   v.run(instructions);

+   return v.loops;

+}