diff options
Diffstat (limited to 'src/glsl/ir_div_to_mul_rcp.cpp')
| -rw-r--r-- | src/glsl/ir_div_to_mul_rcp.cpp | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/src/glsl/ir_div_to_mul_rcp.cpp b/src/glsl/ir_div_to_mul_rcp.cpp new file mode 100644 index 00000000000..640d5d64f98 --- /dev/null +++ b/src/glsl/ir_div_to_mul_rcp.cpp @@ -0,0 +1,115 @@ +/* + * 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 ir_div_to_mul_rcp.cpp + * + * 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. + */ + +#include "ir.h" +#include "glsl_types.h" + +class ir_div_to_mul_rcp_visitor : public ir_hierarchical_visitor { +public: + ir_div_to_mul_rcp_visitor() + { + this->made_progress = false; + } + + ir_visitor_status visit_leave(ir_expression *); + + bool made_progress; +}; + +bool +do_div_to_mul_rcp(exec_list *instructions) +{ + ir_div_to_mul_rcp_visitor v; + + visit_list_elements(&v, instructions); + return v.made_progress; +} + +ir_visitor_status +ir_div_to_mul_rcp_visitor::visit_leave(ir_expression *ir) +{ + if (ir->operation != ir_binop_div) + return visit_continue; + + if (ir->operands[1]->type->base_type != GLSL_TYPE_INT && + ir->operands[1]->type->base_type != GLSL_TYPE_UINT) { + /* 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->made_progress = true; + + return visit_continue; +} |