Fix detection of stack-use-after scope for char arrays.

Summary:
Clang inserts GetElementPtrInst so findAllocaForValue was not
able to find allocas.

PR27453

Reviewers: kcc, eugenis

Differential Revision: https://reviews.llvm.org/D22657

llvm-svn: 276374

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 43d1b377f85..27b68b0387d 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2286,6 +2286,10 @@ AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
         return nullptr;
       Res = IncValueAI;
     }
+  } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
+    Res = findAllocaForValue(EP->getPointerOperand());
+  } else {
+    DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
   }
   if (Res) AllocaForValue[V] = Res;
   return Res;