1 files changed, 15 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 4bd1246cbf7..1b247245c4c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1194,10 +1194,21 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
     return CallInst::Create(F, {X, II.getArgOperand(1)});
   }
 
-  // cttz(-x) -> cttz(x)
-  if (IsTZ && match(Op0, m_Neg(m_Value(X)))) {
-    II.setOperand(0, X);
-    return ⅈ
+  if (IsTZ) {
+    // cttz(-x) -> cttz(x)
+    if (match(Op0, m_Neg(m_Value(X)))) {
+      II.setOperand(0, X);
+      return ⅈ
+    }
+
+    // cttz(abs(x)) -> cttz(x)
+    // cttz(nabs(x)) -> cttz(x)
+    Value *Y;
+    SelectPatternFlavor SPF = matchSelectPattern(Op0, X, Y).Flavor;
+    if (SPF == SPF_ABS || SPF == SPF_NABS) {
+      II.setOperand(0, X);
+      return ⅈ
+    }
   }
 
   KnownBits Known = IC.computeKnownBits(Op0, 0, &II);