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[InstCombine] Don't create extra ConstantInt objects in foldSelectICmpAnd. NFCI

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Instead just use APInt objects and only create a ConstantInt at the end if we need it for the Offset.

llvm-svn: 307270
This commit is contained in:
Craig Topper 2017-07-06 15:58:54 +00:00
parent 279c30993a
commit 963d55cb1b
1 changed files with 17 additions and 19 deletions
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36
lib/Transforms/InstCombine/InstCombineSelect.cpp
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@ -868,8 +868,8 @@ Instruction *InstCombiner::foldSPFofSPF(Instruction *Inner,
/// icmp instruction with zero, and we have an 'and' with the non-constant value
/// and a power of two we can turn the select into a shift on the result of the
/// 'and'.
static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
ConstantInt *FalseVal,
static Value *foldSelectICmpAnd(const SelectInst &SI, APInt TrueVal,
APInt FalseVal,
InstCombiner::BuilderTy *Builder) {
const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
if (!IC || !IC->isEquality() || !SI.getType()->isIntegerTy())
@ -886,38 +886,35 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
// If both select arms are non-zero see if we have a select of the form
// 'x ? 2^n + C : C'. Then we can offset both arms by C, use the logic
// for 'x ? 2^n : 0' and fix the thing up at the end.
ConstantInt *Offset = nullptr;
if (!TrueVal->isZero() && !FalseVal->isZero()) {
if ((TrueVal->getValue() - FalseVal->getValue()).isPowerOf2())
APInt Offset(TrueVal.getBitWidth(), 0);
if (!TrueVal.isNullValue() && !FalseVal.isNullValue()) {
if ((TrueVal - FalseVal).isPowerOf2())
Offset = FalseVal;
else if ((FalseVal->getValue() - TrueVal->getValue()).isPowerOf2())
else if ((FalseVal - TrueVal).isPowerOf2())
Offset = TrueVal;
else
return nullptr;
// Adjust TrueVal and FalseVal to the offset.
TrueVal = ConstantInt::get(Builder->getContext(),
TrueVal->getValue() - Offset->getValue());
FalseVal = ConstantInt::get(Builder->getContext(),
FalseVal->getValue() - Offset->getValue());
TrueVal -= Offset;
FalseVal -= Offset;
}
// Make sure the mask in the 'and' and one of the select arms is a power of 2.
if (!AndRHS->getValue().isPowerOf2() ||
(!TrueVal->getValue().isPowerOf2() &&
!FalseVal->getValue().isPowerOf2()))
(!TrueVal.isPowerOf2() && !FalseVal.isPowerOf2()))
return nullptr;
// Determine which shift is needed to transform result of the 'and' into the
// desired result.
ConstantInt *ValC = !TrueVal->isZero() ? TrueVal : FalseVal;
unsigned ValZeros = ValC->getValue().logBase2();
const APInt &ValC = !TrueVal.isNullValue() ? TrueVal : FalseVal;
unsigned ValZeros = ValC.logBase2();
unsigned AndZeros = AndRHS->getValue().logBase2();
// If types don't match we can still convert the select by introducing a zext
// or a trunc of the 'and'. The trunc case requires that all of the truncated
// bits are zero, we can figure that out by looking at the 'and' mask.
if (AndZeros >= ValC->getBitWidth())
if (AndZeros >= ValC.getBitWidth())
return nullptr;
Value *V = Builder->CreateZExtOrTrunc(LHS, SI.getType());
@ -928,14 +925,14 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
// Okay, now we know that everything is set up, we just don't know whether we
// have a icmp_ne or icmp_eq and whether the true or false val is the zero.
bool ShouldNotVal = !TrueVal->isZero();
bool ShouldNotVal = !TrueVal.isNullValue();
ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
if (ShouldNotVal)
V = Builder->CreateXor(V, ValC);
// Apply an offset if needed.
if (Offset)
V = Builder->CreateAdd(V, Offset);
if (!Offset.isNullValue())
V = Builder->CreateAdd(V, ConstantInt::get(V->getType(), Offset));
return V;
}
@ -1250,7 +1247,8 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal))
if (Value *V = foldSelectICmpAnd(SI, TrueValC, FalseValC, Builder))
if (Value *V = foldSelectICmpAnd(SI, TrueValC->getValue(),
FalseValC->getValue(), Builder))
return replaceInstUsesWith(SI, V);
// See if we are selecting two values based on a comparison of the two values.