Fix for a crash due to performLocalReleaseMotion and performLocalRetainMotion (swiftlang#38150)

In low level LLVMARCOptimizer, during canonicalization we don't rauw the result of RT_Retain with its arg similarly to RT_ObjCRetain and RT_BridgeRetain.
And during performLocalReleaseMotion, we assert that we have canonicalized RT_Retain.
In a release compiler, if we optimize such an RT_Retain with a RT_Release, then this can result in a compiler crash

Similarly not rauw'ing, can cause a crash due to performLocalRetainMotion

Fixes rdar://79238115

Author: meg-gupta

lib/LLVMPasses/LLVMARCOpts.cpp

@@ -116,6 +116,12 @@ static bool canonicalizeInputFunction(Function &F, ARCEntryPointBuilder &B,
           ++NumNoopDeleted;
           continue;
         }
+        if (!CI.use_empty()) {
+          // Do not get RC identical value here, could end up with a
+          // crash in replaceAllUsesWith as the type maybe different.
+          CI.replaceAllUsesWith(CI.getArgOperand(0));
+          Changed = true;
+        }
         // Rewrite unknown retains into swift_retains.
         NativeRefs.insert(ArgVal);
         for (auto &X : UnknownObjectRetains[ArgVal]) {
@@ -138,7 +144,12 @@ static bool canonicalizeInputFunction(Function &F, ARCEntryPointBuilder &B,
           ++NumNoopDeleted;
           continue;
         }
-
+        if (!CI.use_empty()) {
+          // Do not get RC identical value here, could end up with a
+          // crash in replaceAllUsesWith as the type maybe different.
+          CI.replaceAllUsesWith(CI.getArgOperand(0));
+          Changed = true;
+        }
         // Have not encountered a strong retain/release. keep it in the
         // unknown retain/release list for now. It might get replaced
         // later.

test/LLVMPasses/basic.ll

@@ -369,6 +369,59 @@ bb1:
   ret void
 }
 
+; CHECK-LABEL: @releasemotion_forwarding
+; CHECK-NOT: swift_retain
+; CHECK-NOT: swift_release
+; CHECK: call void @user(%swift.refcounted* %P)
+; CHECK: ret
+define void @releasemotion_forwarding(%swift.refcounted* %P, i8* %O, %swift.bridge* %B) {
+entry:
+  %res = tail call %swift.refcounted* @swift_retain(%swift.refcounted* %P)
+  tail call void @swift_release(%swift.refcounted* %res) nounwind
+  call void @user(%swift.refcounted* %res) nounwind
+  ret void
+}
+
+; CHECK-LABEL: @retainmotion_forwarding
+; CHECK: store %swift.refcounted* %P, %swift.refcounted** %R, align 4
+; CHECK-NOT: swift_retain
+; CHECK-NOT: swift_release
+; CHECK: ret
+define void @retainmotion_forwarding(%swift.refcounted* %P, %swift.refcounted** %R, %swift.bridge* %B) {
+entry:
+  %res = tail call %swift.refcounted* @swift_retain(%swift.refcounted* %P)
+  store %swift.refcounted* %res, %swift.refcounted** %R, align 4
+  call void @swift_bridgeObjectRelease(%swift.bridge* %B)
+  tail call void @swift_release(%swift.refcounted* %res) nounwind
+  ret void
+}
+
+; CHECK-LABEL: @unknownreleasemotion_forwarding
+; CHECK-NOT: swift_unknownObjectRetain
+; CHECK-NOT: swift_unknownObjectRelease
+; CHECK: call void @user(%swift.refcounted* %P)
+; CHECK: ret
+define void @unknownreleasemotion_forwarding(%swift.refcounted* %P, i8* %O, %swift.bridge* %B) {
+entry:
+  %res = tail call %swift.refcounted* @swift_unknownObjectRetain(%swift.refcounted* %P)
+  tail call void @swift_unknownObjectRelease(%swift.refcounted* %res) nounwind
+  call void @user(%swift.refcounted* %res) nounwind
+  ret void
+}
+
+; CHECK-LABEL: @unknownretainmotion_forwarding
+; CHECK: store %swift.refcounted* %P, %swift.refcounted** %R, align 4
+; CHECK-NOT: swift_unknownObjectRetain
+; CHECK-NOT: swift_unknownObjectRelease
+; CHECK: ret
+define void @unknownretainmotion_forwarding(%swift.refcounted* %P, %swift.refcounted** %R, %swift.bridge* %B) {
+entry:
+  %res = tail call %swift.refcounted* @swift_unknownObjectRetain(%swift.refcounted* %P)
+  store %swift.refcounted* %res, %swift.refcounted** %R, align 4
+  call void @swift_bridgeObjectRelease(%swift.bridge* %B)
+  tail call void @swift_unknownObjectRelease(%swift.refcounted* %res) nounwind
+  ret void
+}
 
 !llvm.dbg.cu = !{!1}
 !llvm.module.flags = !{!4}