1 files changed, 7 insertions, 12 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d01889e..927add4 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4151,11 +4151,14 @@ Value *llvm::GetUnderlyingObject(Value *V, const DataLayout &DL,
       if (GA->isInterposable())
         return V;
       V = GA->getAliasee();
-    } else if (isa<AllocaInst>(V)) {
-      // An alloca can't be further simplified.
-      return V;
     } else {
-      if (auto *Call = dyn_cast<CallBase>(V)) {
+      if (auto *PHI = dyn_cast<PHINode>(V)) {
+        // Look through single-arg phi nodes created by LCSSA.
+        if (PHI->getNumIncomingValues() == 1) {
+          V = PHI->getIncomingValue(0);
+          continue;
+        }
+      } else if (auto *Call = dyn_cast<CallBase>(V)) {
         // CaptureTracking can know about special capturing properties of some
         // intrinsics like launder.invariant.group, that can't be expressed with
         // the attributes, but have properties like returning aliasing pointer.
@@ -4171,14 +4174,6 @@ Value *llvm::GetUnderlyingObject(Value *V, const DataLayout &DL,
         }
       }
 
-      // See if InstructionSimplify knows any relevant tricks.
-      if (Instruction *I = dyn_cast<Instruction>(V))
-        // TODO: Acquire a DominatorTree and AssumptionCache and use them.
-        if (Value *Simplified = SimplifyInstruction(I, {DL, I})) {
-          V = Simplified;
-          continue;
-        }
-
       return V;
     }
     assert(V->getType()->isPointerTy() && "Unexpected operand type!");