| //===- bolt/Passes/LoopInversionPass.h --------------------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef BOLT_PASSES_LOOPINVERSION_H |
| #define BOLT_PASSES_LOOPINVERSION_H |
| |
| #include "bolt/Passes/BinaryPasses.h" |
| |
| // This pass founds cases when BBs have layout: |
| // #BB0: |
| // .... |
| // #BB1: |
| // cmp |
| // cond_jmp #BB3 |
| // #BB2: |
| // <loop body> |
| // jmp #BB1 |
| // #BB3: |
| // <loop exit> |
| // |
| // And swaps BB1 and BB2: |
| // #BB0: |
| // .... |
| // jmp #BB1 |
| // #BB2: |
| // <loop body> |
| // #BB1: |
| // cmp |
| // cond_njmp #BB2 |
| // #BB3: |
| // <loop exit> |
| // |
| // And vice versa depending on the profile information. |
| // The advantage is that the loop uses only one conditional jump, |
| // the unconditional jump is only used once on the loop start. |
| |
| namespace llvm { |
| namespace bolt { |
| |
| class LoopInversionPass : public BinaryFunctionPass { |
| public: |
| explicit LoopInversionPass() : BinaryFunctionPass(false) {} |
| |
| const char *getName() const override { return "loop-inversion-opt"; } |
| |
| /// Pass entry point |
| void runOnFunctions(BinaryContext &BC) override; |
| bool runOnFunction(BinaryFunction &Function); |
| }; |
| |
| } // namespace bolt |
| } // namespace llvm |
| |
| #endif |