Returning poison from a function w/ noundef return attribute is UB

This does for readability of returns within said function as what we do for the caller side when reasoning about what might be poison.

Differential Revision: https://reviews.llvm.org/D111180

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index a21a7a8..b385810 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5418,7 +5418,10 @@ void llvm::getGuaranteedWellDefinedOps(
       }
       break;
     }
-
+    case Instruction::Ret:
+      if (I->getFunction()->hasRetAttribute(Attribute::NoUndef))
+        Operands.insert(I->getOperand(0));
+      break;
     default:
       break;
   }