diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index b39a4648579..582353eba1c 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -1566,7 +1566,7 @@ static Instruction *foldSelectCmpXchg(SelectInst &SI) { static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X, Value *Y, InstCombiner::BuilderTy &Builder) { - assert (SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern"); + assert(SelectPatternResult::isMinOrMax(SPF) && "Expected min/max pattern"); bool IsUnsigned = SPF == SelectPatternFlavor::SPF_UMIN || SPF == SelectPatternFlavor::SPF_UMAX; // TODO: If InstSimplify could fold all cases where C2 <= C1, we could change @@ -1582,8 +1582,21 @@ static Instruction *moveAddAfterMinMax(SelectPatternFlavor SPF, Value *X, return BinaryOperator::CreateNUW(BinaryOperator::Add, NewMinMax, ConstantInt::get(X->getType(), *C1)); } - // TODO: Handle SMIN/SMAX (similar to unsigned, but the signed subtraction of - // the constants must not overflow). + + if (!IsUnsigned && match(X, m_NSWAdd(m_Value(A), m_APInt(C1))) && + match(Y, m_APInt(C2)) && X->hasNUses(2)) { + bool Overflow; + APInt Diff = C2->ssub_ov(*C1, Overflow); + if (!Overflow) { + // smin (add nsw A, C1), C2 --> add nsw (smin A, C2 - C1), C1 + // smax (add nsw A, C1), C2 --> add nsw (smax A, C2 - C1), C1 + Value *NewMinMax = createMinMax(Builder, SPF, A, + ConstantInt::get(X->getType(), Diff)); + return BinaryOperator::CreateNSW(BinaryOperator::Add, NewMinMax, + ConstantInt::get(X->getType(), *C1)); + } + } + return nullptr; } |
