svn merge ^/branches/released .

1 files changed, 288 insertions, 0 deletions

diff --git a/mesalib/src/glsl/lower_instructions.cpp b/mesalib/src/glsl/lower_instructions.cpp
new file mode 100644
index 000000000..6e44d1319
--- /dev/null
+++ b/mesalib/src/glsl/lower_instructions.cpp
@@ -0,0 +1,288 @@
+/*

+ * 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.

+ */

+

+/**

+ * \file lower_instructions.cpp

+ *

+ * Many GPUs lack native instructions for certain expression operations, and

+ * must replace them with some other expression tree.  This pass lowers some

+ * of the most common cases, allowing the lowering code to be implemented once

+ * rather than in each driver backend.

+ *

+ * Currently supported transformations:

+ * - SUB_TO_ADD_NEG

+ * - DIV_TO_MUL_RCP

+ * - EXP_TO_EXP2

+ * - POW_TO_EXP2

+ * - LOG_TO_LOG2

+ * - MOD_TO_FRACT

+ *

+ * SUB_TO_ADD_NEG:

+ * ---------------

+ * Breaks an ir_binop_sub expression down to add(op0, neg(op1))

+ *

+ * This simplifies expression reassociation, and for many backends

+ * there is no subtract operation separate from adding the negation.

+ * For backends with native subtract operations, they will probably

+ * want to recognize add(op0, neg(op1)) or the other way around to

+ * produce a subtract anyway.

+ *

+ * DIV_TO_MUL_RCP:

+ * ---------------

+ * Breaks an ir_unop_div expression down to op0 * (rcp(op1)).

+ *

+ * Many GPUs don't have a divide instruction (945 and 965 included),

+ * but they do have an RCP instruction to compute an approximate

+ * reciprocal.  By breaking the operation down, constant reciprocals

+ * can get constant folded.

+ *

+ * EXP_TO_EXP2 and LOG_TO_LOG2:

+ * ----------------------------

+ * Many GPUs don't have a base e log or exponent instruction, but they

+ * do have base 2 versions, so this pass converts exp and log to exp2

+ * and log2 operations.

+ *

+ * POW_TO_EXP2:

+ * -----------

+ * Many older GPUs don't have an x**y instruction.  For these GPUs, convert

+ * x**y to 2**(y * log2(x)).

+ *

+ * MOD_TO_FRACT:

+ * -------------

+ * Breaks an ir_unop_mod expression down to (op1 * fract(op0 / op1))

+ *

+ * Many GPUs don't have a MOD instruction (945 and 965 included), and

+ * if we have to break it down like this anyway, it gives an

+ * opportunity to do things like constant fold the (1.0 / op1) easily.

+ */

+

+#include "main/core.h" /* for M_LOG2E */

+#include "glsl_types.h"

+#include "ir.h"

+#include "ir_optimization.h"

+

+class lower_instructions_visitor : public ir_hierarchical_visitor {

+public:

+   lower_instructions_visitor(unsigned lower)

+      : progress(false), lower(lower) { }

+

+   ir_visitor_status visit_leave(ir_expression *);

+

+   bool progress;

+

+private:

+   unsigned lower; /** Bitfield of which operations to lower */

+

+   void sub_to_add_neg(ir_expression *);

+   void div_to_mul_rcp(ir_expression *);

+   void mod_to_fract(ir_expression *);

+   void exp_to_exp2(ir_expression *);

+   void pow_to_exp2(ir_expression *);

+   void log_to_log2(ir_expression *);

+};

+

+/**

+ * Determine if a particular type of lowering should occur

+ */

+#define lowering(x) (this->lower & x)

+

+bool

+lower_instructions(exec_list *instructions, unsigned what_to_lower)

+{

+   lower_instructions_visitor v(what_to_lower);

+

+   visit_list_elements(&v, instructions);

+   return v.progress;

+}

+

+void

+lower_instructions_visitor::sub_to_add_neg(ir_expression *ir)

+{

+   ir->operation = ir_binop_add;

+   ir->operands[1] = new(ir) ir_expression(ir_unop_neg, ir->operands[1]->type,

+					   ir->operands[1], NULL);

+   this->progress = true;

+}

+

+void

+lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir)

+{

+   if (!ir->operands[1]->type->is_integer()) {

+      /* New expression for the 1.0 / op1 */

+      ir_rvalue *expr;

+      expr = new(ir) ir_expression(ir_unop_rcp,

+				   ir->operands[1]->type,

+				   ir->operands[1],

+				   NULL);

+

+      /* op0 / op1 -> op0 * (1.0 / op1) */

+      ir->operation = ir_binop_mul;

+      ir->operands[1] = expr;

+   } else {

+      /* Be careful with integer division -- we need to do it as a

+       * float and re-truncate, since rcp(n > 1) of an integer would

+       * just be 0.

+       */

+      ir_rvalue *op0, *op1;

+      const struct glsl_type *vec_type;

+

+      vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,

+					 ir->operands[1]->type->vector_elements,

+					 ir->operands[1]->type->matrix_columns);

+

+      if (ir->operands[1]->type->base_type == GLSL_TYPE_INT)

+	 op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL);

+      else

+	 op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL);

+

+      op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL);

+

+      vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,

+					 ir->operands[0]->type->vector_elements,

+					 ir->operands[0]->type->matrix_columns);

+

+      if (ir->operands[0]->type->base_type == GLSL_TYPE_INT)

+	 op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL);

+      else

+	 op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL);

+

+      op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1);

+

+      ir->operation = ir_unop_f2i;

+      ir->operands[0] = op0;

+      ir->operands[1] = NULL;

+   }

+

+   this->progress = true;

+}

+

+void

+lower_instructions_visitor::exp_to_exp2(ir_expression *ir)

+{

+   ir_constant *log2_e = new(ir) ir_constant(float(M_LOG2E));

+

+   ir->operation = ir_unop_exp2;

+   ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[0]->type,

+					   ir->operands[0], log2_e);

+   this->progress = true;

+}

+

+void

+lower_instructions_visitor::pow_to_exp2(ir_expression *ir)

+{

+   ir_expression *const log2_x =

+      new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,

+			    ir->operands[0]);

+

+   ir->operation = ir_unop_exp2;

+   ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[1]->type,

+					   ir->operands[1], log2_x);

+   ir->operands[1] = NULL;

+   this->progress = true;

+}

+

+void

+lower_instructions_visitor::log_to_log2(ir_expression *ir)

+{

+   ir->operation = ir_binop_mul;

+   ir->operands[0] = new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,

+					   ir->operands[0], NULL);

+   ir->operands[1] = new(ir) ir_constant(float(1.0 / M_LOG2E));

+   this->progress = true;

+}

+

+void

+lower_instructions_visitor::mod_to_fract(ir_expression *ir)

+{

+   ir_variable *temp = new(ir) ir_variable(ir->operands[1]->type, "mod_b",

+					   ir_var_temporary);

+   this->base_ir->insert_before(temp);

+

+   ir_assignment *const assign =

+      new(ir) ir_assignment(new(ir) ir_dereference_variable(temp),

+			    ir->operands[1], NULL);

+

+   this->base_ir->insert_before(assign);

+

+   ir_expression *const div_expr =

+      new(ir) ir_expression(ir_binop_div, ir->operands[0]->type,

+			    ir->operands[0],

+			    new(ir) ir_dereference_variable(temp));

+

+   /* Don't generate new IR that would need to be lowered in an additional

+    * pass.

+    */

+   if (lowering(DIV_TO_MUL_RCP))

+      div_to_mul_rcp(div_expr);

+

+   ir_rvalue *expr = new(ir) ir_expression(ir_unop_fract,

+					   ir->operands[0]->type,

+					   div_expr,

+					   NULL);

+

+   ir->operation = ir_binop_mul;

+   ir->operands[0] = new(ir) ir_dereference_variable(temp);

+   ir->operands[1] = expr;

+   this->progress = true;

+}

+

+ir_visitor_status

+lower_instructions_visitor::visit_leave(ir_expression *ir)

+{

+   switch (ir->operation) {

+   case ir_binop_sub:

+      if (lowering(SUB_TO_ADD_NEG))

+	 sub_to_add_neg(ir);

+      break;

+

+   case ir_binop_div:

+      if (lowering(DIV_TO_MUL_RCP))

+	 div_to_mul_rcp(ir);

+      break;

+

+   case ir_unop_exp:

+      if (lowering(EXP_TO_EXP2))

+	 exp_to_exp2(ir);

+      break;

+

+   case ir_unop_log:

+      if (lowering(LOG_TO_LOG2))

+	 log_to_log2(ir);

+      break;

+

+   case ir_binop_mod:

+      if (lowering(MOD_TO_FRACT))

+	 mod_to_fract(ir);

+      break;

+

+   case ir_binop_pow:

+      if (lowering(POW_TO_EXP2))

+	 pow_to_exp2(ir);

+      break;

+

+   default:

+      return visit_continue;

+   }

+

+   return visit_continue;

+}