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authorStephen Hines <srhines@google.com>2019-07-02 16:25:20 -0700
committerAli B <abittin@gmail.com>2019-07-05 19:33:16 +0300
commit9afee4e65dc5f9f5eb371683729ff67b8df81d03 (patch)
tree4cf241d6c9044f91ee8c06e6920174d06f8de0b6 /clang-r353983e/include/llvm/Transforms/Utils/LCSSA.h
parent2f19bd722c4c825320d1511c1ed83161b7f95d51 (diff)
Update prebuilt Clang to r353983e.HEADq10.0
clang 9.0.5 (based on r353983e) from build 5696680. Bug: http://b/135931688 Bug: http://b/136008926 Test: N/A Change-Id: I922d17410047d2e2df4625615352c588ee71b203
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+//===- 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