//
//===----------------------------------------------------------------------===//
-#include "InstCombine.h"
+#include "InstCombineInternal.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/PatternMatch.h"
static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
const DataLayout *TD,
const TargetLibraryInfo *TLI,
- DominatorTree *DT,
- AssumptionTracker *AT) {
+ DominatorTree *DT, AssumptionCache *AC) {
// Trivial replacement.
if (V == Op)
return RepOp;
if (CmpInst *C = dyn_cast<CmpInst>(I)) {
if (C->getOperand(0) == Op)
return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), TD,
- TLI, DT, AT);
+ TLI, DT, AC);
if (C->getOperand(1) == Op)
return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, TD,
- TLI, DT, AT);
+ TLI, DT, AC);
}
// TODO: We could hand off more cases to instsimplify here.
return Builder->CreateOr(V, Y);
}
+/// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
+/// call to cttz/ctlz with flag 'is_zero_undef' cleared.
+///
+/// For example, we can fold the following code sequence:
+/// \code
+/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
+/// %1 = icmp ne i32 %x, 0
+/// %2 = select i1 %1, i32 %0, i32 32
+/// \code
+///
+/// into:
+/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
+static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
+ InstCombiner::BuilderTy *Builder) {
+ ICmpInst::Predicate Pred = ICI->getPredicate();
+ Value *CmpLHS = ICI->getOperand(0);
+ Value *CmpRHS = ICI->getOperand(1);
+
+ // Check if the condition value compares a value for equality against zero.
+ if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
+ return nullptr;
+
+ Value *Count = FalseVal;
+ Value *ValueOnZero = TrueVal;
+ if (Pred == ICmpInst::ICMP_NE)
+ std::swap(Count, ValueOnZero);
+
+ // Skip zero extend/truncate.
+ Value *V = nullptr;
+ if (match(Count, m_ZExt(m_Value(V))) ||
+ match(Count, m_Trunc(m_Value(V))))
+ Count = V;
+
+ // Check if the value propagated on zero is a constant number equal to the
+ // sizeof in bits of 'Count'.
+ unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
+ if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
+ return nullptr;
+
+ // Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
+ // input to the cttz/ctlz is used as LHS for the compare instruction.
+ if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
+ match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
+ IntrinsicInst *II = cast<IntrinsicInst>(Count);
+ IRBuilder<> Builder(II);
+ if (cast<ConstantInt>(II->getArgOperand(1))->isOne()) {
+ // Explicitly clear the 'undef_on_zero' flag.
+ IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
+ Type *Ty = NewI->getArgOperand(1)->getType();
+ NewI->setArgOperand(1, Constant::getNullValue(Ty));
+ Builder.Insert(NewI);
+ Count = NewI;
+ }
+
+ return Builder.CreateZExtOrTrunc(Count, ValueOnZero->getType());
+ }
+
+ return nullptr;
+}
+
/// visitSelectInstWithICmp - Visit a SelectInst that has an
/// ICmpInst as its first operand.
///
// arms of the select. See if substituting this value into the arm and
// simplifying the result yields the same value as the other arm.
if (Pred == ICmpInst::ICMP_EQ) {
- if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, DL, TLI,
- DT, AT) == TrueVal ||
- SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, DL, TLI,
- DT, AT) == TrueVal)
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, DL, TLI, DT, AC) ==
+ TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, DL, TLI, DT, AC) ==
+ TrueVal)
return ReplaceInstUsesWith(SI, FalseVal);
- if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, DL, TLI,
- DT, AT) == FalseVal ||
- SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, DL, TLI,
- DT, AT) == FalseVal)
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, DL, TLI, DT, AC) ==
+ FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, DL, TLI, DT, AC) ==
+ FalseVal)
return ReplaceInstUsesWith(SI, FalseVal);
} else if (Pred == ICmpInst::ICMP_NE) {
- if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, DL, TLI,
- DT, AT) == FalseVal ||
- SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, DL, TLI,
- DT, AT) == FalseVal)
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, DL, TLI, DT, AC) ==
+ FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, DL, TLI, DT, AC) ==
+ FalseVal)
return ReplaceInstUsesWith(SI, TrueVal);
- if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, DL, TLI,
- DT, AT) == TrueVal ||
- SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, DL, TLI,
- DT, AT) == TrueVal)
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, DL, TLI, DT, AC) ==
+ TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, DL, TLI, DT, AC) ==
+ TrueVal)
return ReplaceInstUsesWith(SI, TrueVal);
}
}
}
- {
+ if (unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits()) {
+ APInt MinSignedValue = APInt::getSignBit(BitWidth);
Value *X;
const APInt *Y, *C;
- if (match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
+ bool TrueWhenUnset;
+ bool IsBitTest = false;
+ if (ICmpInst::isEquality(Pred) &&
+ match(CmpLHS, m_And(m_Value(X), m_Power2(Y))) &&
match(CmpRHS, m_Zero())) {
+ IsBitTest = true;
+ TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
+ } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
+ X = CmpLHS;
+ Y = &MinSignedValue;
+ IsBitTest = true;
+ TrueWhenUnset = false;
+ } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
+ X = CmpLHS;
+ Y = &MinSignedValue;
+ IsBitTest = true;
+ TrueWhenUnset = true;
+ }
+ if (IsBitTest) {
Value *V = nullptr;
// (X & Y) == 0 ? X : X ^ Y --> X & ~Y
- if (Pred == ICmpInst::ICMP_EQ && TrueVal == X &&
+ if (TrueWhenUnset && TrueVal == X &&
match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateAnd(X, ~(*Y));
// (X & Y) != 0 ? X ^ Y : X --> X & ~Y
- else if (Pred == ICmpInst::ICMP_NE && FalseVal == X &&
+ else if (!TrueWhenUnset && FalseVal == X &&
match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateAnd(X, ~(*Y));
// (X & Y) == 0 ? X ^ Y : X --> X | Y
- else if (Pred == ICmpInst::ICMP_EQ && FalseVal == X &&
+ else if (TrueWhenUnset && FalseVal == X &&
match(TrueVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateOr(X, *Y);
// (X & Y) != 0 ? X : X ^ Y --> X | Y
- else if (Pred == ICmpInst::ICMP_NE && TrueVal == X &&
+ else if (!TrueWhenUnset && TrueVal == X &&
match(FalseVal, m_Xor(m_Specific(X), m_APInt(C))) && *Y == *C)
V = Builder->CreateOr(X, *Y);
if (Value *V = foldSelectICmpAndOr(SI, TrueVal, FalseVal, Builder))
return ReplaceInstUsesWith(SI, V);
+ if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
+ return ReplaceInstUsesWith(SI, V);
+
return Changed ? &SI : nullptr;
}
Value *TrueVal = SI.getTrueValue();
Value *FalseVal = SI.getFalseValue();
- if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal, DL, TLI,
- DT, AT))
+ if (Value *V =
+ SimplifySelectInst(CondVal, TrueVal, FalseVal, DL, TLI, DT, AC))
return ReplaceInstUsesWith(SI, V);
if (SI.getType()->isIntegerTy(1)) {
projects / oota-llvm.git / blobdiff