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Exposed PHIElimination pass within CodeGen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76688 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -14,6 +14,7 @@
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "phielim"
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#include "PHIElimination.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/Instructions.h"
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#include "llvm/CodeGen/LiveVariables.h"
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@ -22,7 +23,6 @@
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/STLExtras.h"
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@ -34,76 +34,20 @@ using namespace llvm;
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STATISTIC(NumAtomic, "Number of atomic phis lowered");
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namespace {
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class VISIBILITY_HIDDEN PNE : public MachineFunctionPass {
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MachineRegisterInfo *MRI; // Machine register information
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public:
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static char ID; // Pass identification, replacement for typeid
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PNE() : MachineFunctionPass(&ID) {}
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virtual bool runOnMachineFunction(MachineFunction &Fn);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addPreserved<LiveVariables>();
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AU.addPreservedID(MachineLoopInfoID);
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AU.addPreservedID(MachineDominatorsID);
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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private:
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/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
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/// in predecessor basic blocks.
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///
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bool EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB);
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void LowerAtomicPHINode(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator AfterPHIsIt);
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/// analyzePHINodes - Gather information about the PHI nodes in
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/// here. In particular, we want to map the number of uses of a virtual
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/// register which is used in a PHI node. We map that to the BB the
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/// vreg is coming from. This is used later to determine when the vreg
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/// is killed in the BB.
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///
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void analyzePHINodes(const MachineFunction& Fn);
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// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
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// SrcReg. This needs to be after any def or uses of SrcReg, but before
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// any subsequent point where control flow might jump out of the basic
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// block.
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MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
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unsigned SrcReg);
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// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
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// also after any exception handling labels: in landing pads execution
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// starts at the label, so any copies placed before it won't be executed!
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MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) {
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// Rather than assuming that EH labels come before other kinds of labels,
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// just skip all labels.
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while (I != MBB.end() &&
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(I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
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++I;
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return I;
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}
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typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
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typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
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VRegPHIUse VRegPHIUseCount;
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// Defs of PHI sources which are implicit_def.
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SmallPtrSet<MachineInstr*, 4> ImpDefs;
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};
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}
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char PNE::ID = 0;
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static RegisterPass<PNE>
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char PHIElimination::ID = 0;
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static RegisterPass<PHIElimination>
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X("phi-node-elimination", "Eliminate PHI nodes for register allocation");
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const PassInfo *const llvm::PHIEliminationID = &X;
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bool PNE::runOnMachineFunction(MachineFunction &Fn) {
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void llvm::PHIElimination::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addPreserved<LiveVariables>();
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AU.addPreservedID(MachineLoopInfoID);
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AU.addPreservedID(MachineDominatorsID);
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
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MRI = &Fn.getRegInfo();
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analyzePHINodes(Fn);
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@ -132,7 +76,8 @@ bool PNE::runOnMachineFunction(MachineFunction &Fn) {
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/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions in
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/// predecessor basic blocks.
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///
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bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) {
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bool llvm::PHIElimination::EliminatePHINodes(MachineFunction &MF,
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MachineBasicBlock &MBB) {
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if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI)
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return false; // Quick exit for basic blocks without PHIs.
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@ -162,8 +107,9 @@ static bool isSourceDefinedByImplicitDef(const MachineInstr *MPhi,
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// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg.
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// This needs to be after any def or uses of SrcReg, but before any subsequent
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// point where control flow might jump out of the basic block.
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MachineBasicBlock::iterator PNE::FindCopyInsertPoint(MachineBasicBlock &MBB,
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unsigned SrcReg) {
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MachineBasicBlock::iterator
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llvm::PHIElimination::FindCopyInsertPoint(MachineBasicBlock &MBB,
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unsigned SrcReg) {
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// Handle the trivial case trivially.
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if (MBB.empty())
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return MBB.begin();
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@ -206,9 +152,10 @@ MachineBasicBlock::iterator PNE::FindCopyInsertPoint(MachineBasicBlock &MBB,
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/// under the assuption that it needs to be lowered in a way that supports
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/// atomic execution of PHIs. This lowering method is always correct all of the
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/// time.
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///
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void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator AfterPHIsIt) {
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///
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void llvm::PHIElimination::LowerAtomicPHINode(
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator AfterPHIsIt) {
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// Unlink the PHI node from the basic block, but don't delete the PHI yet.
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MachineInstr *MPhi = MBB.remove(MBB.begin());
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@ -420,7 +367,7 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
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/// used in a PHI node. We map that to the BB the vreg is coming from. This is
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/// used later to determine when the vreg is killed in the BB.
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///
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void PNE::analyzePHINodes(const MachineFunction& Fn) {
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void llvm::PHIElimination::analyzePHINodes(const MachineFunction& Fn) {
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for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
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I != E; ++I)
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for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
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80
lib/CodeGen/PHIElimination.h
Normal file
80
lib/CodeGen/PHIElimination.h
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@ -0,0 +1,80 @@
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//===-- lib/CodeGen/PHIElimination.h ----------------------------*- C++ -*-===//
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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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#ifndef LLVM_CODEGEN_PHIELIMINATION_HPP
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#define LLVM_CODEGEN_PHIELIMINATION_HPP
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include <map>
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namespace llvm {
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/// Lower PHI instructions to copies.
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class PHIElimination : public MachineFunctionPass {
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MachineRegisterInfo *MRI; // Machine register information
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public:
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static char ID; // Pass identification, replacement for typeid
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PHIElimination() : MachineFunctionPass(&ID) {}
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virtual bool runOnMachineFunction(MachineFunction &Fn);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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private:
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/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
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/// in predecessor basic blocks.
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///
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bool EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB);
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void LowerAtomicPHINode(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator AfterPHIsIt);
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/// analyzePHINodes - Gather information about the PHI nodes in
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/// here. In particular, we want to map the number of uses of a virtual
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/// register which is used in a PHI node. We map that to the BB the
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/// vreg is coming from. This is used later to determine when the vreg
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/// is killed in the BB.
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///
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void analyzePHINodes(const MachineFunction& Fn);
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// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
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// SrcReg. This needs to be after any def or uses of SrcReg, but before
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// any subsequent point where control flow might jump out of the basic
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// block.
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MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
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unsigned SrcReg);
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// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
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// also after any exception handling labels: in landing pads execution
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// starts at the label, so any copies placed before it won't be executed!
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MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) {
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// Rather than assuming that EH labels come before other kinds of labels,
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// just skip all labels.
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while (I != MBB.end() &&
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(I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
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++I;
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return I;
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}
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typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
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typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
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VRegPHIUse VRegPHIUseCount;
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// Defs of PHI sources which are implicit_def.
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SmallPtrSet<MachineInstr*, 4> ImpDefs;
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};
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}
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#endif /* PHIELIMINATION_H */
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