[MoveAutoInit] Gracefully handle auto-init annotation on unexpected instr (PR64661)

Abort the transform instead of asserting.

Fixes llvm#64661.

Author: nikic

llvm/lib/Transforms/Utils/MoveAutoInit.cpp

@@ -50,7 +50,7 @@ static std::optional<MemoryLocation> writeToAlloca(const Instruction &I) {
   else if (auto *SI = dyn_cast<StoreInst>(&I))
     ML = MemoryLocation::get(SI);
   else
-    assert(false && "memory location set");
+    return std::nullopt;
 
   if (isa<AllocaInst>(getUnderlyingObject(ML.Ptr)))
     return ML;

llvm/test/Transforms/MoveAutoInit/invalid-annotation.ll

@@ -0,0 +1,14 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt -S -passes=move-auto-init < %s | FileCheck %s
+
+define i1 @test(ptr %a, ptr %b) {
+; CHECK-LABEL: define i1 @test
+; CHECK-SAME: (ptr [[A:%.*]], ptr [[B:%.*]]) {
+; CHECK-NEXT:    [[C:%.*]] = icmp uge ptr [[A]], [[B]], !annotation !0
+; CHECK-NEXT:    ret i1 [[C]]
+;
+  %c = icmp uge ptr %a, %b, !annotation !0
+  ret i1 %c
+}
+
+!0 = !{ !"auto-init" }