Preserve setNoSignedWrap if LogBase2 isn't BitWidth - 1

[AZero13]

No description provided.

[llvmbot]

@llvm/pr-subscribers-llvm-selectiondag

Author: AZero13 (AZero13)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/163095.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+2-1)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b1accdd066dfd..f12b73f82e402 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4749,7 +4749,8 @@ template <class MatchContextClass> SDValue DAGCombiner::visitMUL(SDNode *N) {
       SDValue Trunc = DAG.getZExtOrTrunc(LogBase2, DL, ShiftVT);
       SDNodeFlags Flags;
       Flags.setNoUnsignedWrap(N->getFlags().hasNoUnsignedWrap());
-      // TODO: Preserve setNoSignedWrap if LogBase2 isn't BitWidth - 1.
+      if (LogBase2.getZExtValue() != BitWidth - 1)
+        Flags.setNoSignedWrap(N->getFlags().hasNoSignedWrap());
       return Matcher.getNode(ISD::SHL, DL, VT, N0, Trunc, Flags);
     }
   }