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Generalize the setcc -> PHI and Select folding optimizations to work with

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any constant RHS, not just a constant integer RHS.  This implements
select.ll:test17


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21470 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-04-23 15:31:55 +00:00
parent 17ce8d22c3
commit 6970b661cb
1 changed files with 37 additions and 30 deletions
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67
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -2450,10 +2450,6 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
switch (LHSI->getOpcode()) {
case Instruction::PHI:
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
break;
case Instruction::And:
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
LHSI->getOperand(0)->hasOneUse()) {
@ -2705,32 +2701,6 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
}
}
break;
case Instruction::Select:
// If either operand of the select is a constant, we can fold the
// comparison into the select arms, which will cause one to be
// constant folded and the select turned into a bitwise or.
Value *Op1 = 0, *Op2 = 0;
if (LHSI->hasOneUse()) {
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
// Fold the known value into the constant operand.
Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
// Insert a new SetCC of the other select operand.
Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
LHSI->getOperand(2), CI,
I.getName()), I);
} else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
// Fold the known value into the constant operand.
Op2 = ConstantExpr::get(I.getOpcode(), C, CI);
// Insert a new SetCC of the other select operand.
Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
LHSI->getOperand(1), CI,
I.getName()), I);
}
}
if (Op1)
return new SelectInst(LHSI->getOperand(0), Op1, Op2);
break;
}
// Simplify seteq and setne instructions...
@ -2896,6 +2866,43 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
}
}
// Handle setcc with constant RHS's that can be integer, FP or pointer.
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
switch (LHSI->getOpcode()) {
case Instruction::PHI:
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
break;
case Instruction::Select:
// If either operand of the select is a constant, we can fold the
// comparison into the select arms, which will cause one to be
// constant folded and the select turned into a bitwise or.
Value *Op1 = 0, *Op2 = 0;
if (LHSI->hasOneUse()) {
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
// Fold the known value into the constant operand.
Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
// Insert a new SetCC of the other select operand.
Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
LHSI->getOperand(2), RHSC,
I.getName()), I);
} else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
// Fold the known value into the constant operand.
Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
// Insert a new SetCC of the other select operand.
Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
LHSI->getOperand(1), RHSC,
I.getName()), I);
}
}
if (Op1)
return new SelectInst(LHSI->getOperand(0), Op1, Op2);
break;
}
}
// If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
if (User *GEP = dyn_castGetElementPtr(Op0))
if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))