forked from OSchip/llvm-project
73 lines
2.1 KiB
C++
73 lines
2.1 KiB
C++
//===- TailDuplication.cpp - Duplicate blocks into predecessors' tails ----===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass duplicates basic blocks ending in unconditional branches into
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// the tails of their predecessors, using the TailDuplicator utility class.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/TailDuplicator.h"
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#include "llvm/Pass.h"
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using namespace llvm;
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#define DEBUG_TYPE "tailduplication"
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namespace {
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/// Perform tail duplication. Delegates to TailDuplicator
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class TailDuplicatePass : public MachineFunctionPass {
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TailDuplicator Duplicator;
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public:
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static char ID;
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explicit TailDuplicatePass() : MachineFunctionPass(ID) {}
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bool runOnMachineFunction(MachineFunction &MF) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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};
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} // end anonymous namespace
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char TailDuplicatePass::ID = 0;
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char &llvm::TailDuplicateID = TailDuplicatePass::ID;
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INITIALIZE_PASS(TailDuplicatePass, DEBUG_TYPE, "Tail Duplication", false, false)
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bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
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if (skipFunction(MF.getFunction()))
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return false;
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auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
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// TODO: Querying isSSA() to determine pre-/post-regalloc is fragile, better
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// split this into two passes instead.
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bool PreRegAlloc = MF.getRegInfo().isSSA();
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Duplicator.initMF(MF, PreRegAlloc, MBPI, /* LayoutMode */ false);
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bool MadeChange = false;
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while (Duplicator.tailDuplicateBlocks())
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MadeChange = true;
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return MadeChange;
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}
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void TailDuplicatePass::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<MachineBranchProbabilityInfo>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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