[FunctionAttrs] Fix incorrect nonnull inference for non-inbounds GEP (#91180)

For inbounds GEPs, if the source pointer is non-null, the result must
also be non-null. However, this does not hold for non-inbounds GEPs.
    
Fixes https://github.com/llvm/llvm-project/issues/91177.

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 8e11cbf..26a4508 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -1186,10 +1186,15 @@ static bool isReturnNonNull(Function *F, const SCCNodeSet &SCCNodes,
     switch (RVI->getOpcode()) {
     // Extend the analysis by looking upwards.
     case Instruction::BitCast:
-    case Instruction::GetElementPtr:
     case Instruction::AddrSpaceCast:
       FlowsToReturn.insert(RVI->getOperand(0));
       continue;
+    case Instruction::GetElementPtr:
+      if (cast<GEPOperator>(RVI)->isInBounds()) {
+        FlowsToReturn.insert(RVI->getOperand(0));
+        continue;
+      }
+      return false;
     case Instruction::Select: {
       SelectInst *SI = cast<SelectInst>(RVI);
       FlowsToReturn.insert(SI->getTrueValue());