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Turn off critical edge splitting for landing pads. The introduction of a

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non-landing pad basic block as the successor to a block that ends in an
unconditional jump will cause block folding to remove the added block as a
successor. Thus eventually removing it AND the landing pad entirely. Critical
edge splitting is an optimization, so we can safely turn it off when dealing
with landing pads.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91634 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2009-12-17 23:42:32 +00:00
parent 08ce53996e
commit 3de8249078
2 changed files with 5 additions and 4 deletions
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7
lib/CodeGen/PHIElimination.cpp
View File

@ -71,7 +71,7 @@ bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
Changed |= EliminatePHINodes(Fn, *I);
// Remove dead IMPLICIT_DEF instructions.
for (SmallPtrSet<MachineInstr*,4>::iterator I = ImpDefs.begin(),
for (SmallPtrSet<MachineInstr*, 4>::iterator I = ImpDefs.begin(),
E = ImpDefs.end(); I != E; ++I) {
MachineInstr *DefMI = *I;
unsigned DefReg = DefMI->getOperand(0).getReg();
@ -83,8 +83,8 @@ bool llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
for (LoweredPHIMap::iterator I = LoweredPHIs.begin(), E = LoweredPHIs.end();
I != E; ++I)
Fn.DeleteMachineInstr(I->first);
LoweredPHIs.clear();
LoweredPHIs.clear();
ImpDefs.clear();
VRegPHIUseCount.clear();
return Changed;
@ -384,7 +384,8 @@ void llvm::PHIElimination::analyzePHINodes(const MachineFunction& Fn) {
bool llvm::PHIElimination::SplitPHIEdges(MachineFunction &MF,
MachineBasicBlock &MBB,
LiveVariables &LV) {
if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI)
if (MBB.empty() || MBB.front().getOpcode() != TargetInstrInfo::PHI ||
MBB.isLandingPad())
return false; // Quick exit for basic blocks without PHIs.
for (MachineBasicBlock::const_iterator BBI = MBB.begin(), BBE = MBB.end();

2
lib/CodeGen/StrongPHIElimination.cpp
View File

@ -907,7 +907,7 @@ bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
// Determine which phi node operands need copies
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
if (!I->empty() &&
if (!I->empty() && !I->isLandingPad() &&
I->begin()->getOpcode() == TargetInstrInfo::PHI)
processBlock(I);