| // Copyright (c) 2019 Google LLC |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "source/reduce/conditional_branch_to_simple_conditional_branch_reduction_opportunity.h" |
| |
| #include "source/reduce/reduction_util.h" |
| |
| namespace spvtools { |
| namespace reduce { |
| |
| ConditionalBranchToSimpleConditionalBranchReductionOpportunity:: |
| ConditionalBranchToSimpleConditionalBranchReductionOpportunity( |
| opt::IRContext* context, |
| opt::Instruction* conditional_branch_instruction, bool redirect_to_true) |
| : context_(context), |
| conditional_branch_instruction_(conditional_branch_instruction), |
| redirect_to_true_(redirect_to_true) {} |
| |
| bool ConditionalBranchToSimpleConditionalBranchReductionOpportunity:: |
| PreconditionHolds() { |
| // Another opportunity may have already simplified this conditional branch, |
| // which should disable this opportunity. |
| return conditional_branch_instruction_->GetSingleWordInOperand( |
| kTrueBranchOperandIndex) != |
| conditional_branch_instruction_->GetSingleWordInOperand( |
| kFalseBranchOperandIndex); |
| } |
| |
| void ConditionalBranchToSimpleConditionalBranchReductionOpportunity::Apply() { |
| uint32_t operand_to_modify = |
| redirect_to_true_ ? kFalseBranchOperandIndex : kTrueBranchOperandIndex; |
| uint32_t operand_to_copy = |
| redirect_to_true_ ? kTrueBranchOperandIndex : kFalseBranchOperandIndex; |
| |
| auto old_successor_block_id = |
| conditional_branch_instruction_->GetSingleWordInOperand( |
| operand_to_modify); |
| |
| // Do the branch redirection. |
| conditional_branch_instruction_->SetInOperand( |
| operand_to_modify, |
| {conditional_branch_instruction_->GetSingleWordInOperand( |
| operand_to_copy)}); |
| |
| // The old successor block may have phi instructions; these will need to |
| // respect the change in edges. |
| AdaptPhiInstructionsForRemovedEdge( |
| context_->get_instr_block(conditional_branch_instruction_)->id(), |
| context_->cfg()->block(old_successor_block_id)); |
| |
| // We have changed the CFG. |
| context_->InvalidateAnalysesExceptFor( |
| opt::IRContext::Analysis::kAnalysisNone); |
| } |
| |
| } // namespace reduce |
| } // namespace spvtools |
