diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index f5f3716..694b180 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -504,6 +504,11 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) { return IC.replaceInstUsesWith(II, ConstantInt::getNullValue(II.getType())); } + // If ctlz/cttz is only used as a shift amount, set is_zero_poison to true. + if (II.hasOneUse() && match(Op1, m_Zero()) && + match(II.user_back(), m_Shift(m_Value(), m_Specific(&II)))) + return IC.replaceOperand(II, 1, IC.Builder.getTrue()); + Constant *C; if (IsTZ) { |