diff options
| author | Stephen Hines <srhines@google.com> | 2019-07-02 16:25:20 -0700 |
|---|---|---|
| committer | Ali B <abittin@gmail.com> | 2019-07-05 19:33:16 +0300 |
| commit | 9afee4e65dc5f9f5eb371683729ff67b8df81d03 (patch) | |
| tree | 4cf241d6c9044f91ee8c06e6920174d06f8de0b6 /clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h | |
| parent | 2f19bd722c4c825320d1511c1ed83161b7f95d51 (diff) | |
clang 9.0.5 (based on r353983e) from build 5696680.
Bug: http://b/135931688
Bug: http://b/136008926
Test: N/A
Change-Id: I922d17410047d2e2df4625615352c588ee71b203
Diffstat (limited to 'clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h')
| -rw-r--r-- | clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h b/clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h new file mode 100644 index 00000000..b01c8022 --- /dev/null +++ b/clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h @@ -0,0 +1,43 @@ +//===- LCSSA.h - Loop-closed SSA transform Pass -----------------*- 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 +// +//===----------------------------------------------------------------------===// +// +// This pass transforms loops by placing phi nodes at the end of the loops for +// all values that are live across the loop boundary. For example, it turns +// the left into the right code: +// +// for (...) for (...) +// if (c) if (c) +// X1 = ... X1 = ... +// else else +// X2 = ... X2 = ... +// X3 = phi(X1, X2) X3 = phi(X1, X2) +// ... = X3 + 4 X4 = phi(X3) +// ... = X4 + 4 +// +// This is still valid LLVM; the extra phi nodes are purely redundant, and will +// be trivially eliminated by InstCombine. The major benefit of this +// transformation is that it makes many other loop optimizations, such as +// LoopUnswitching, simpler. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_TRANSFORMS_UTILS_LCSSA_H +#define LLVM_TRANSFORMS_UTILS_LCSSA_H + +#include "llvm/IR/PassManager.h" + +namespace llvm { + +/// Converts loops into loop-closed SSA form. +class LCSSAPass : public PassInfoMixin<LCSSAPass> { +public: + PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM); +}; +} // end namespace llvm + +#endif // LLVM_TRANSFORMS_UTILS_LCSSA_H |
