diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index 6bee87c5d10..06b769bc05a 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -1308,15 +1308,14 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { if ((SPF == SPF_SMAX || SPF == SPF_UMAX) && IsFreeToInvert(LHS, LHS->hasNUses(2)) && IsFreeToInvert(RHS, RHS->hasNUses(2))) { - // This transform adds a not operation, and that extra cost needs to be - // justified. We look for simplifications that will result from applying - // this rule: - bool Profitable = - (LHS->hasNUses(2) && match(LHS, m_Not(m_Value()))) || - (RHS->hasNUses(2) && match(RHS, m_Not(m_Value()))) || + // For this transform to be profitable, we need to eliminate at least two + // 'not' instructions if we're going to add one 'not' instruction. + int NumberOfNots = + (LHS->hasNUses(2) && match(LHS, m_Not(m_Value()))) + + (RHS->hasNUses(2) && match(RHS, m_Not(m_Value()))) + (SI.hasOneUse() && match(*SI.user_begin(), m_Not(m_Value()))); - if (Profitable) { + if (NumberOfNots >= 2) { Value *NewLHS = Builder->CreateNot(LHS); Value *NewRHS = Builder->CreateNot(RHS); Value *NewCmp = SPF == SPF_SMAX |
