Merge commit '4450780182d3' from apple/stable/20190619 into swift/master

Author: git apple-llvm automerger

llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp

@@ -588,6 +588,33 @@ void ObjCARCOpt::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesCFG();
 }
 
+static bool isSafeBetweenRVCalls(const Instruction *I) {
+  if (IsNoopInstruction(I))
+    return true;
+
+  auto *CB = dyn_cast<CallBase>(I);
+  if (!CB)
+    return false;
+
+  Intrinsic::ID IID = CB->getIntrinsicID();
+  if (IID == Intrinsic::not_intrinsic)
+    return false;
+
+  switch (IID) {
+  case Intrinsic::lifetime_start:
+  case Intrinsic::lifetime_end:
+    // The inliner adds new lifetime markers as part of the return sequence,
+    // which should be skipped when looking for paired return RV call.
+    LLVM_FALLTHROUGH;
+  case Intrinsic::stacksave:
+  case Intrinsic::stackrestore:
+    // If the inlined code contains dynamic allocas, the above applies as well.
+    return true;
+  default:
+    return false;
+  }
+}
+
 /// Turn objc_retainAutoreleasedReturnValue into objc_retain if the operand is
 /// not a return value.  Or, if it can be paired with an
 /// objc_autoreleaseReturnValue, delete the pair and return true.
@@ -634,7 +661,7 @@ ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
   if (I != Begin) {
     do
       --I;
-    while (I != Begin && IsNoopInstruction(&*I));
+    while (I != Begin && isSafeBetweenRVCalls(&*I));
     if (GetBasicARCInstKind(&*I) == ARCInstKind::AutoreleaseRV &&
         EquivalentArgs.count(GetArgRCIdentityRoot(&*I))) {
       Changed = true;

llvm/test/Transforms/ObjCARC/post-inlining.ll

@@ -46,3 +46,67 @@ entry:
   call void @use_pointer(i8* %p)
   ret void
 }
+
+; Check that we can delete the autoreleaseRV+retainAutoreleasedRV pair even in
+; presence of instructions added by the inliner as part of the return sequence.
+
+; 1) Noop instructions: bitcasts and zero-indices GEPs.
+
+; CHECK-LABEL: define i8* @testNoop(
+; CHECK: entry:
+; CHECK-NEXT: %noop0 = bitcast i8* %call.i to i64*
+; CHECK-NEXT: %noop1 = getelementptr i8, i8* %call.i, i32 0
+; CHECK-NEXT: ret i8* %call.i
+; CHECK-NEXT: }
+define i8* @testNoop(i8* %call.i) {
+entry:
+  %0 = tail call i8* @llvm.objc.autoreleaseReturnValue(i8* %call.i) nounwind
+  %noop0 = bitcast i8* %call.i to i64*
+  %noop1 = getelementptr i8, i8* %call.i, i32 0
+  %1 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %call.i) nounwind
+  ret i8* %call.i
+}
+
+; 2) Lifetime markers.
+
+declare void @llvm.lifetime.start.p0i8(i64, i8*)
+declare void @llvm.lifetime.end.p0i8(i64, i8*)
+
+; CHECK-LABEL: define i8* @testLifetime(
+; CHECK: entry:
+; CHECK-NEXT: %obj = alloca i8
+; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 8, i8* %obj)
+; CHECK-NEXT: call void @llvm.lifetime.end.p0i8(i64 8, i8* %obj)
+; CHECK-NEXT: ret i8* %call.i
+; CHECK-NEXT: }
+define i8* @testLifetime(i8* %call.i) {
+entry:
+  %obj = alloca i8
+  call void @llvm.lifetime.start.p0i8(i64 8, i8* %obj)
+  %0 = tail call i8* @llvm.objc.autoreleaseReturnValue(i8* %call.i) nounwind
+  call void @llvm.lifetime.end.p0i8(i64 8, i8* %obj)
+  %1 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %call.i) nounwind
+  ret i8* %call.i
+}
+
+; 3) Dynamic alloca markers.
+
+declare i8* @llvm.stacksave()
+declare void @llvm.stackrestore(i8*)
+
+; CHECK-LABEL: define i8* @testStack(
+; CHECK: entry:
+; CHECK-NEXT: %save = tail call i8* @llvm.stacksave()
+; CHECK-NEXT: %obj = alloca i8, i8 %arg
+; CHECK-NEXT: call void @llvm.stackrestore(i8* %save)
+; CHECK-NEXT: ret i8* %call.i
+; CHECK-NEXT: }
+define i8* @testStack(i8* %call.i, i8 %arg) {
+entry:
+  %save = tail call i8* @llvm.stacksave()
+  %obj = alloca i8, i8 %arg
+  %0 = tail call i8* @llvm.objc.autoreleaseReturnValue(i8* %call.i) nounwind
+  call void @llvm.stackrestore(i8* %save)
+  %1 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %call.i) nounwind
+  ret i8* %call.i
+}