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Diffstat (limited to 'src/compiler/glsl/opt_constant_folding.cpp')
| -rw-r--r-- | src/compiler/glsl/opt_constant_folding.cpp | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/src/compiler/glsl/opt_constant_folding.cpp b/src/compiler/glsl/opt_constant_folding.cpp new file mode 100644 index 00000000000..150a17b2af6 --- /dev/null +++ b/src/compiler/glsl/opt_constant_folding.cpp @@ -0,0 +1,190 @@ +/* + * 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 opt_constant_folding.cpp + * Replace constant-valued expressions with references to constant values. + */ + +#include "ir.h" +#include "ir_visitor.h" +#include "ir_rvalue_visitor.h" +#include "ir_optimization.h" +#include "compiler/glsl_types.h" + +namespace { + +/** + * Visitor class for replacing expressions with ir_constant values. + */ + +class ir_constant_folding_visitor : public ir_rvalue_visitor { +public: + ir_constant_folding_visitor() + { + this->progress = false; + } + + virtual ~ir_constant_folding_visitor() + { + /* empty */ + } + + virtual ir_visitor_status visit_enter(ir_discard *ir); + virtual ir_visitor_status visit_enter(ir_assignment *ir); + virtual ir_visitor_status visit_enter(ir_call *ir); + + virtual void handle_rvalue(ir_rvalue **rvalue); + + bool progress; +}; + +} /* unnamed namespace */ + +void +ir_constant_folding_visitor::handle_rvalue(ir_rvalue **rvalue) +{ + if (*rvalue == NULL || (*rvalue)->ir_type == ir_type_constant) + return; + + /* Note that we do rvalue visitoring on leaving. So if an + * expression has a non-constant operand, no need to go looking + * down it to find if it's constant. This cuts the time of this + * pass down drastically. + */ + ir_expression *expr = (*rvalue)->as_expression(); + if (expr) { + for (unsigned int i = 0; i < expr->get_num_operands(); i++) { + if (!expr->operands[i]->as_constant()) + return; + } + } + + /* Ditto for swizzles. */ + ir_swizzle *swiz = (*rvalue)->as_swizzle(); + if (swiz && !swiz->val->as_constant()) + return; + + ir_constant *constant = (*rvalue)->constant_expression_value(); + if (constant) { + *rvalue = constant; + this->progress = true; + } else { + (*rvalue)->accept(this); + } +} + +ir_visitor_status +ir_constant_folding_visitor::visit_enter(ir_discard *ir) +{ + if (ir->condition) { + ir->condition->accept(this); + handle_rvalue(&ir->condition); + + ir_constant *const_val = ir->condition->as_constant(); + /* If the condition is constant, either remove the condition or + * remove the never-executed assignment. + */ + if (const_val) { + if (const_val->value.b[0]) + ir->condition = NULL; + else + ir->remove(); + this->progress = true; + } + } + + return visit_continue_with_parent; +} + +ir_visitor_status +ir_constant_folding_visitor::visit_enter(ir_assignment *ir) +{ + ir->rhs->accept(this); + handle_rvalue(&ir->rhs); + + if (ir->condition) { + ir->condition->accept(this); + handle_rvalue(&ir->condition); + + ir_constant *const_val = ir->condition->as_constant(); + /* If the condition is constant, either remove the condition or + * remove the never-executed assignment. + */ + if (const_val) { + if (const_val->value.b[0]) + ir->condition = NULL; + else + ir->remove(); + this->progress = true; + } + } + + /* Don't descend into the LHS because we want it to stay as a + * variable dereference. FINISHME: We probably should to get array + * indices though. + */ + return visit_continue_with_parent; +} + +ir_visitor_status +ir_constant_folding_visitor::visit_enter(ir_call *ir) +{ + /* Attempt to constant fold parameters */ + foreach_two_lists(formal_node, &ir->callee->parameters, + actual_node, &ir->actual_parameters) { + ir_rvalue *param_rval = (ir_rvalue *) actual_node; + ir_variable *sig_param = (ir_variable *) formal_node; + + if (sig_param->data.mode == ir_var_function_in + || sig_param->data.mode == ir_var_const_in) { + ir_rvalue *new_param = param_rval; + + handle_rvalue(&new_param); + if (new_param != param_rval) { + param_rval->replace_with(new_param); + } + } + } + + /* Next, see if the call can be replaced with an assignment of a constant */ + ir_constant *const_val = ir->constant_expression_value(); + + if (const_val != NULL) { + ir_assignment *assignment = + new(ralloc_parent(ir)) ir_assignment(ir->return_deref, const_val); + ir->replace_with(assignment); + } + + return visit_continue_with_parent; +} + +bool +do_constant_folding(exec_list *instructions) +{ + ir_constant_folding_visitor constant_folding; + + visit_list_elements(&constant_folding, instructions); + + return constant_folding.progress; +} |