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0b3ecba332
proven safe.
Summary:
Currently LoopFusion give up when the second loop nest preheader is
not empty. For example:
for (int i = 0; i < 100; ++i) {}
x+=1;
for (int i = 0; i < 100; ++i) {}
The above example should be safe to fuse.
This PR moves instructions in FC1 preheader (e.g. x+=1; ) to
FC0 preheader, which then LoopFusion is able to fuse them.
Reviewer: kbarton, Meinersbur, jdoerfert, dmgreen, fhahn, hfinkel,
bmahjour, etiotto
Reviewed By: jdoerfert
Subscribers: hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D71821
66 lines
2.8 KiB
C++
66 lines
2.8 KiB
C++
//===- Transform/Utils/CodeMoverUtils.h - CodeMover Utils -------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This family of functions determine movements are safe on basic blocks, and
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// instructions contained within a function.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
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#define LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
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namespace llvm {
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class BasicBlock;
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class DependenceInfo;
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class DominatorTree;
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class Instruction;
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class PostDominatorTree;
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/// Return true if \p I0 and \p I1 are control flow equivalent.
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/// Two instructions are control flow equivalent if their basic blocks are
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/// control flow equivalent.
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bool isControlFlowEquivalent(const Instruction &I0, const Instruction &I1,
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const DominatorTree &DT,
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const PostDominatorTree &PDT);
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/// Return true if \p BB0 and \p BB1 are control flow equivalent.
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/// Two basic blocks are control flow equivalent if when one executes, the other
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/// is guaranteed to execute.
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bool isControlFlowEquivalent(const BasicBlock &BB0, const BasicBlock &BB1,
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const DominatorTree &DT,
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const PostDominatorTree &PDT);
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/// Return true if \p I can be safely moved before \p InsertPoint.
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bool isSafeToMoveBefore(Instruction &I, Instruction &InsertPoint,
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DominatorTree &DT, const PostDominatorTree &PDT,
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DependenceInfo &DI);
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/// Return true if all instructions (except the terminator) in \p BB can be
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/// safely moved before \p InsertPoint.
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bool isSafeToMoveBefore(BasicBlock &BB, Instruction &InsertPoint,
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DominatorTree &DT, const PostDominatorTree &PDT,
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DependenceInfo &DI);
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/// Move instructions, in an order-preserving manner, from \p FromBB to the
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/// beginning of \p ToBB when proven safe.
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void moveInstructionsToTheBeginning(BasicBlock &FromBB, BasicBlock &ToBB,
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DominatorTree &DT,
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const PostDominatorTree &PDT,
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DependenceInfo &DI);
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/// Move instructions, in an order-preserving manner, from \p FromBB to the end
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/// of \p ToBB when proven safe.
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void moveInstructionsToTheEnd(BasicBlock &FromBB, BasicBlock &ToBB,
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DominatorTree &DT, const PostDominatorTree &PDT,
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DependenceInfo &DI);
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
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