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Exposed PHIElimination pass within CodeGen.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76688 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames 2009-07-21 23:47:33 +00:00
parent 97d2cae44b
commit fae02a2ab1
2 changed files with 101 additions and 74 deletions
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95
lib/CodeGen/PHIElimination.cpp
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@ -14,6 +14,7 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "phielim"
#include "PHIElimination.h"
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/CodeGen/LiveVariables.h"
@ -22,7 +23,6 @@
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/STLExtras.h"
@ -34,76 +34,20 @@ using namespace llvm;
STATISTIC(NumAtomic, "Number of atomic phis lowered");
namespace {
class VISIBILITY_HIDDEN PNE : public MachineFunctionPass {
MachineRegisterInfo *MRI; // Machine register information
public:
static char ID; // Pass identification, replacement for typeid
PNE() : MachineFunctionPass(&ID) {}
virtual bool runOnMachineFunction(MachineFunction &Fn);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
private:
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
/// in predecessor basic blocks.
///
bool EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB);
void LowerAtomicPHINode(MachineBasicBlock &MBB,
MachineBasicBlock::iterator AfterPHIsIt);
/// analyzePHINodes - Gather information about the PHI nodes in
/// here. In particular, we want to map the number of uses of a virtual
/// register which is used in a PHI node. We map that to the BB the
/// vreg is coming from. This is used later to determine when the vreg
/// is killed in the BB.
///
void analyzePHINodes(const MachineFunction& Fn);
// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
// SrcReg. This needs to be after any def or uses of SrcReg, but before
// any subsequent point where control flow might jump out of the basic
// block.
MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
unsigned SrcReg);
// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
// also after any exception handling labels: in landing pads execution
// starts at the label, so any copies placed before it won't be executed!
MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) {
// Rather than assuming that EH labels come before other kinds of labels,
// just skip all labels.
while (I != MBB.end() &&
(I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
++I;
return I;
}
typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
VRegPHIUse VRegPHIUseCount;
// Defs of PHI sources which are implicit_def.
SmallPtrSet<MachineInstr*, 4> ImpDefs;
};
}
char PNE::ID = 0;
static RegisterPass<PNE>
char PHIElimination::ID = 0;
static RegisterPass<PHIElimination>
X("phi-node-elimination", "Eliminate PHI nodes for register allocation");
const PassInfo *const llvm::PHIEliminationID = &X;
bool PNE::runOnMachineFunction(MachineFunction &Fn) {
void llvm::PHIElimination::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
MRI = &Fn.getRegInfo();
analyzePHINodes(Fn);
@ -132,7 +76,8 @@ bool PNE::runOnMachineFunction(MachineFunction &Fn) {
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions in
/// predecessor basic blocks.
///
bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) {
bool llvm::PHIElimination::EliminatePHINodes(MachineFunction &MF,
MachineBasicBlock &MBB) {
if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI)
return false; // Quick exit for basic blocks without PHIs.
@ -162,8 +107,9 @@ static bool isSourceDefinedByImplicitDef(const MachineInstr *MPhi,
// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg.
// This needs to be after any def or uses of SrcReg, but before any subsequent
// point where control flow might jump out of the basic block.
MachineBasicBlock::iterator PNE::FindCopyInsertPoint(MachineBasicBlock &MBB,
unsigned SrcReg) {
MachineBasicBlock::iterator
llvm::PHIElimination::FindCopyInsertPoint(MachineBasicBlock &MBB,
unsigned SrcReg) {
// Handle the trivial case trivially.
if (MBB.empty())
return MBB.begin();
@ -206,9 +152,10 @@ MachineBasicBlock::iterator PNE::FindCopyInsertPoint(MachineBasicBlock &MBB,
/// under the assuption that it needs to be lowered in a way that supports
/// atomic execution of PHIs. This lowering method is always correct all of the
/// time.
///
void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
MachineBasicBlock::iterator AfterPHIsIt) {
///
void llvm::PHIElimination::LowerAtomicPHINode(
MachineBasicBlock &MBB,
MachineBasicBlock::iterator AfterPHIsIt) {
// Unlink the PHI node from the basic block, but don't delete the PHI yet.
MachineInstr *MPhi = MBB.remove(MBB.begin());
@ -420,7 +367,7 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
/// used in a PHI node. We map that to the BB the vreg is coming from. This is
/// used later to determine when the vreg is killed in the BB.
///
void PNE::analyzePHINodes(const MachineFunction& Fn) {
void llvm::PHIElimination::analyzePHINodes(const MachineFunction& Fn) {
for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
I != E; ++I)
for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();

80
lib/CodeGen/PHIElimination.h Normal file
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@ -0,0 +1,80 @@
//===-- lib/CodeGen/PHIElimination.h ----------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_PHIELIMINATION_HPP
#define LLVM_CODEGEN_PHIELIMINATION_HPP
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Target/TargetInstrInfo.h"
#include <map>
namespace llvm {
/// Lower PHI instructions to copies.
class PHIElimination : public MachineFunctionPass {
MachineRegisterInfo *MRI; // Machine register information
public:
static char ID; // Pass identification, replacement for typeid
PHIElimination() : MachineFunctionPass(&ID) {}
virtual bool runOnMachineFunction(MachineFunction &Fn);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
private:
/// EliminatePHINodes - Eliminate phi nodes by inserting copy instructions
/// in predecessor basic blocks.
///
bool EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB);
void LowerAtomicPHINode(MachineBasicBlock &MBB,
MachineBasicBlock::iterator AfterPHIsIt);
/// analyzePHINodes - Gather information about the PHI nodes in
/// here. In particular, we want to map the number of uses of a virtual
/// register which is used in a PHI node. We map that to the BB the
/// vreg is coming from. This is used later to determine when the vreg
/// is killed in the BB.
///
void analyzePHINodes(const MachineFunction& Fn);
// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
// SrcReg. This needs to be after any def or uses of SrcReg, but before
// any subsequent point where control flow might jump out of the basic
// block.
MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
unsigned SrcReg);
// SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
// also after any exception handling labels: in landing pads execution
// starts at the label, so any copies placed before it won't be executed!
MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) {
// Rather than assuming that EH labels come before other kinds of labels,
// just skip all labels.
while (I != MBB.end() &&
(I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
++I;
return I;
}
typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
VRegPHIUse VRegPHIUseCount;
// Defs of PHI sources which are implicit_def.
SmallPtrSet<MachineInstr*, 4> ImpDefs;
};
}
#endif /* PHIELIMINATION_H */