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Anti-dependency breaking needs to be careful regarding instructions with

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multiple register definitions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92864 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach 2010-01-06 22:21:25 +00:00
parent 130063207d
commit 80c2b0d9ef
2 changed files with 9 additions and 3 deletions
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9
lib/CodeGen/CriticalAntiDepBreaker.cpp
View File

@ -288,7 +288,8 @@ void CriticalAntiDepBreaker::ScanInstruction(MachineInstr *MI,
}
unsigned
CriticalAntiDepBreaker::findSuitableFreeRegister(unsigned AntiDepReg,
CriticalAntiDepBreaker::findSuitableFreeRegister(MachineInstr *MI,
unsigned AntiDepReg,
unsigned LastNewReg,
const TargetRegisterClass *RC)
{
@ -301,6 +302,10 @@ CriticalAntiDepBreaker::findSuitableFreeRegister(unsigned AntiDepReg,
// an anti-dependence with this AntiDepReg, because that would
// re-introduce that anti-dependence.
if (NewReg == LastNewReg) continue;
// If the instruction already has a def of the NewReg, it's not suitable.
// For example, Instruction with multiple definitions can result in this
// condition.
if (MI->modifiesRegister(NewReg, TRI)) continue;
// If NewReg is dead and NewReg's most recent def is not before
// AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg.
assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u))
@ -496,7 +501,7 @@ BreakAntiDependencies(std::vector<SUnit>& SUnits,
// TODO: Instead of picking the first free register, consider which might
// be the best.
if (AntiDepReg != 0) {
if (unsigned NewReg = findSuitableFreeRegister(AntiDepReg,
if (unsigned NewReg = findSuitableFreeRegister(MI, AntiDepReg,
LastNewReg[AntiDepReg],
RC)) {
DEBUG(dbgs() << "Breaking anti-dependence edge on "

3
lib/CodeGen/CriticalAntiDepBreaker.h
View File

@ -88,7 +88,8 @@ namespace llvm {
private:
void PrescanInstruction(MachineInstr *MI);
void ScanInstruction(MachineInstr *MI, unsigned Count);
unsigned findSuitableFreeRegister(unsigned AntiDepReg,
unsigned findSuitableFreeRegister(MachineInstr *MI,
unsigned AntiDepReg,
unsigned LastNewReg,
const TargetRegisterClass *);
};