[Utils] Fix incorrect dbg.declare store conversion

Summary: The dbg.declare -> dbg.value conversion did not check which operand of
the store instruction the alloca was passed to. As a result code that stored the
address of an alloca, rather than storing to the alloca, would still trigger
the conversion routine, leading to the insertion of an incorrect dbg.value
intrinsic.

Reviewers: aprantl

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16169

llvm-svn: 257787

1 files changed, 8 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index d2793e5ecb5..e28232c4201 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1133,12 +1133,14 @@ bool llvm::LowerDbgDeclare(Function &F) {
     // the stack slot (and at a lexical-scope granularity). Later
     // passes will attempt to elide the stack slot.
     if (AI && !isArray(AI)) {
-      for (User *U : AI->users())
-        if (StoreInst *SI = dyn_cast<StoreInst>(U))
-          ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
-        else if (LoadInst *LI = dyn_cast<LoadInst>(U))
+      for (auto &AIUse : AI->uses()) {
+        User *U = AIUse.getUser();
+        if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+          if (AIUse.getOperandNo() == 1)
+            ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
+        } else if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
           ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
-        else if (CallInst *CI = dyn_cast<CallInst>(U)) {
+        } else if (CallInst *CI = dyn_cast<CallInst>(U)) {
           // This is a call by-value or some other instruction that
           // takes a pointer to the variable. Insert a *value*
           // intrinsic that describes the alloca.
@@ -1150,6 +1152,7 @@ bool llvm::LowerDbgDeclare(Function &F) {
                                       DIB.createExpression(NewDIExpr),
                                       DDI->getDebugLoc(), CI);
         }
+      }
       DDI->eraseFromParent();
     }
   }