[CodeGen] Remove handling for lifetime.start/end on non-alloca (#149838)

After https://github.com/llvm/llvm-project/pull/149310 we are guaranteed
that the argument is an alloca, so we don't need to look at underlying
objects (which was not a correct thing to do anyway).

This also drops the offset argument for lifetime nodes in SDAG. The
offset is fixed to zero now. (Peculiarly, while SDAG pretended to have
an offset, it just gets silently dropped during selection.)

1 files changed, 9 insertions, 24 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 01e5312..1636465 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7596,32 +7596,17 @@ void SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I,
 
     const int64_t ObjectSize =
         cast<ConstantInt>(I.getArgOperand(0))->getSExtValue();
-    Value *const ObjectPtr = I.getArgOperand(1);
-    SmallVector<const Value *, 4> Allocas;
-    getUnderlyingObjects(ObjectPtr, Allocas);
+    const AllocaInst *LifetimeObject = cast<AllocaInst>(I.getArgOperand(1));
 
-    for (const Value *Alloca : Allocas) {
-      const AllocaInst *LifetimeObject = dyn_cast_or_null<AllocaInst>(Alloca);
-
-      // Could not find an Alloca.
-      if (!LifetimeObject)
-        continue;
-
-      // First check that the Alloca is static, otherwise it won't have a
-      // valid frame index.
-      auto SI = FuncInfo.StaticAllocaMap.find(LifetimeObject);
-      if (SI == FuncInfo.StaticAllocaMap.end())
-        return;
+    // First check that the Alloca is static, otherwise it won't have a
+    // valid frame index.
+    auto SI = FuncInfo.StaticAllocaMap.find(LifetimeObject);
+    if (SI == FuncInfo.StaticAllocaMap.end())
+      return;
 
-      const int FrameIndex = SI->second;
-      int64_t Offset;
-      if (GetPointerBaseWithConstantOffset(
-              ObjectPtr, Offset, DAG.getDataLayout()) != LifetimeObject)
-        Offset = -1; // Cannot determine offset from alloca to lifetime object.
-      Res = DAG.getLifetimeNode(IsStart, sdl, getRoot(), FrameIndex, ObjectSize,
-                                Offset);
-      DAG.setRoot(Res);
-    }
+    const int FrameIndex = SI->second;
+    Res = DAG.getLifetimeNode(IsStart, sdl, getRoot(), FrameIndex, ObjectSize);
+    DAG.setRoot(Res);
     return;
   }
   case Intrinsic::pseudoprobe: {