6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-04 02:24:29 +00:00
Code Issues Projects Releases Wiki Activity

This optimization makes MANY phi nodes that all have the same incoming value.

Browse Source 
If this happens, detect it early instead of relying on instcombine to notice
it later.  This can be a big speedup, because PHI nodes can have many
incoming values.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17741 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-11-14 19:29:34 +00:00
parent bac32866a7
commit b58934484b
1 changed files with 23 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -3456,21 +3456,37 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(), PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
PN.getName()+".in"); PN.getName()+".in");
NewPN->op_reserve(PN.getNumOperands()); NewPN->op_reserve(PN.getNumOperands());
InsertNewInstBefore(NewPN, PN);
Value *InVal = FirstInst->getOperand(0);
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
// Add all operands to the new PHI. // Add all operands to the new PHI.
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
NewPN->addIncoming(cast<Instruction>(PN.getIncomingValue(i))->getOperand(0), Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
PN.getIncomingBlock(i)); if (NewInVal != InVal)
InVal = 0;
NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
}
Value *PhiVal;
if (InVal) {
// The new PHI unions all of the same values together. This is really
// common, so we handle it intelligently here for compile-time speed.
PhiVal = InVal;
delete NewPN;
} else {
InsertNewInstBefore(NewPN, PN);
PhiVal = NewPN;
}
// Insert and return the new operation. // Insert and return the new operation.
if (isa<CastInst>(FirstInst)) if (isa<CastInst>(FirstInst))
return new CastInst(NewPN, PN.getType()); return new CastInst(PhiVal, PN.getType());
else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
return BinaryOperator::create(BinOp->getOpcode(), NewPN, ConstantOp); return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
else else
return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(), return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
NewPN, ConstantOp); PhiVal, ConstantOp);
} }
// PHINode simplification // PHINode simplification