Marking the objc_autoreleaseReturnValue and objc_retainAutoreleaseReturnValue

call sites as tail calls unconditionally.  While it's theoretically true that
this is just an optimization, it's an optimization that we very much want to
happen even at -O0, or else ARC applications become substantially harder to
debug.  See r169796 for the llvm/fast-isel side of things.
rdar://12553082

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169996 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 18 insertions, 13 deletions

diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index c90e4eca84..deac5f6aa4 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -1725,7 +1725,8 @@ static llvm::Constant *createARCRuntimeFunction(CodeGenModule &CGM,
 static llvm::Value *emitARCValueOperation(CodeGenFunction &CGF,
                                           llvm::Value *value,
                                           llvm::Constant *&fn,
-                                          StringRef fnName) {
+                                          StringRef fnName,
+                                          bool isTailCall = false) {
   if (isa<llvm::ConstantPointerNull>(value)) return value;
 
   if (!fn) {
@@ -1742,6 +1743,8 @@ static llvm::Value *emitARCValueOperation(CodeGenFunction &CGF,
   // Call the function.
   llvm::CallInst *call = CGF.Builder.CreateCall(fn, value);
   call->setDoesNotThrow();
+  if (isTailCall)
+    call->setTailCall();
 
   // Cast the result back to the original type.
   return CGF.Builder.CreateBitCast(call, origType);
@@ -2054,7 +2057,8 @@ llvm::Value *
 CodeGenFunction::EmitARCAutoreleaseReturnValue(llvm::Value *value) {
   return emitARCValueOperation(*this, value,
                             CGM.getARCEntrypoints().objc_autoreleaseReturnValue,
-                               "objc_autoreleaseReturnValue");
+                               "objc_autoreleaseReturnValue",
+                               /*isTailCall*/ true);
 }
 
 /// Do a fused retain/autorelease of the given object.
@@ -2063,7 +2067,8 @@ llvm::Value *
 CodeGenFunction::EmitARCRetainAutoreleaseReturnValue(llvm::Value *value) {
   return emitARCValueOperation(*this, value,
                      CGM.getARCEntrypoints().objc_retainAutoreleaseReturnValue,
-                               "objc_retainAutoreleaseReturnValue");
+                               "objc_retainAutoreleaseReturnValue",
+                               /*isTailCall*/ true);
 }
 
 /// Do a fused retain/autorelease of the given object.
diff --git a/test/CodeGenObjC/arc-blocks.m b/test/CodeGenObjC/arc-blocks.m
index f87f9a4b23..48c4f08c71 100644
--- a/test/CodeGenObjC/arc-blocks.m
+++ b/test/CodeGenObjC/arc-blocks.m
@@ -16,7 +16,7 @@ int (^test1(int x))(void) {
   // CHECK-NEXT: [[T2:%.*]] = call i8* @objc_retainBlock(i8* [[T1]]) nounwind
   // CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to i32 ()*
   // CHECK-NEXT: [[T4:%.*]] = bitcast i32 ()* [[T3]] to i8*
-  // CHECK-NEXT: [[T5:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[T4]]) nounwind
+  // CHECK-NEXT: [[T5:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T4]]) nounwind
   // CHECK-NEXT: [[T6:%.*]] = bitcast i8* [[T5]] to i32 ()*
   // CHECK-NEXT: ret i32 ()* [[T6]]
   return ^{ return x; };
@@ -314,7 +314,7 @@ id test9(void) {
 // CHECK:      load i8** getelementptr
 // CHECK-NEXT: bitcast i8*
 // CHECK-NEXT: call i8* 
-// CHECK-NEXT: call i8* @objc_autoreleaseReturnValue
+// CHECK-NEXT: tail call i8* @objc_autoreleaseReturnValue
 // CHECK-NEXT: ret i8*
 
 // CHECK:      call i8* @test9_produce()
diff --git a/test/CodeGenObjC/arc-unopt.m b/test/CodeGenObjC/arc-unopt.m
index c319bf260f..84f5d34b19 100644
--- a/test/CodeGenObjC/arc-unopt.m
+++ b/test/CodeGenObjC/arc-unopt.m
@@ -9,7 +9,7 @@ Test0 *test0(void) {
 
   // CHECK:      [[LD:%.*]] = load [[TEST0:%.*]]** @test0_helper
   // CHECK-NEXT: [[T0:%.*]] = bitcast [[TEST0]]* [[LD]] to i8*
-  // CHECK-NEXT: [[T1:%.*]] = call i8* @objc_retainAutoreleaseReturnValue(i8* [[T0]])
+  // CHECK-NEXT: [[T1:%.*]] = tail call i8* @objc_retainAutoreleaseReturnValue(i8* [[T0]])
   // CHECK-NEXT: [[T2:%.*]] = bitcast i8* [[T1]] to [[TEST0]]*
   // CHECK-NEXT: ret [[TEST0]]* [[T2]]
 }
@@ -19,7 +19,7 @@ id test1(void) {
   return test1_helper;
 
   // CHECK:      [[LD:%.*]] = load i8** @test1_helper
-  // CHECK-NEXT: [[T0:%.*]] = call i8* @objc_retainAutoreleaseReturnValue(i8* [[LD]])
+  // CHECK-NEXT: [[T0:%.*]] = tail call i8* @objc_retainAutoreleaseReturnValue(i8* [[LD]])
   // CHECK-NEXT: ret i8* [[T0]]
 }
 
diff --git a/test/CodeGenObjC/arc-weak-property.m b/test/CodeGenObjC/arc-weak-property.m
index 0a6b2a63bf..e8d57bcfe5 100644
--- a/test/CodeGenObjC/arc-weak-property.m
+++ b/test/CodeGenObjC/arc-weak-property.m
@@ -22,7 +22,7 @@
 // CHECK-NEXT:  [[T3:%.*]] = getelementptr inbounds i8* [[T2]], i64 [[T1]]
 // CHECK-NEXT:  [[T4:%.*]] = bitcast i8* [[T3]] to i8**
 // CHECK-NEXT:  [[T5:%.*]] = call i8* @objc_loadWeakRetained(i8** [[T4]])
-// CHECK-NEXT:  [[T6:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[T5]])
+// CHECK-NEXT:  [[T6:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T5]])
 // CHECK-NEXT:  ret i8* [[T6]]
 
 // CHECK:     define internal void @"\01-[WeakPropertyTest setPROP:]"
diff --git a/test/CodeGenObjC/arc.m b/test/CodeGenObjC/arc.m
index 43a7a30967..bac966165a 100644
--- a/test/CodeGenObjC/arc.m
+++ b/test/CodeGenObjC/arc.m
@@ -29,7 +29,7 @@ id test1(id x) {
   // CHECK-NEXT: call void @objc_release(i8* [[T0]])
   // CHECK-NEXT: [[T1:%.*]] = load i8** [[X]]
   // CHECK-NEXT: call void @objc_release(i8* [[T1]])
-  // CHECK-NEXT: [[T1:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[RET]])
+  // CHECK-NEXT: [[T1:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[RET]])
   // CHECK-NEXT: ret i8* [[T1]]
   id y;
   return y;
@@ -156,7 +156,7 @@ id test4() {
   // Retain/release elided.
   // CHECK-NEXT: bitcast
   // CHECK-NEXT: [[INIT:%.*]] = bitcast
-  // CHECK-NEXT: [[RET:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[INIT]])
+  // CHECK-NEXT: [[RET:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[INIT]])
 
   // CHECK-NEXT: ret i8* [[RET]]
 
@@ -1191,7 +1191,7 @@ id test52(void) {
 // CHECK-NEXT: store i32 5, i32* [[X]],
 // CHECK-NEXT: [[T0:%.*]] = load i32* [[X]],
 // CHECK-NEXT: [[T1:%.*]] = call i8* @test52_helper(i32 [[T0]])
-// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[T1]])
+// CHECK-NEXT: [[T2:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T1]])
 // CHECK-NEXT: ret i8* [[T2]]
 }
 
@@ -1292,7 +1292,7 @@ void test56_test(void) {
 // CHECK-NEXT: [[T3:%.*]] = getelementptr inbounds i8* [[T2]], i64 [[T1]]
 // CHECK-NEXT: [[T4:%.*]] = bitcast i8* [[T3]] to i8**
 // CHECK-NEXT: [[T5:%.*]] = call i8* @objc_loadWeakRetained(i8** [[T4]])
-// CHECK-NEXT: [[T6:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[T5]])
+// CHECK-NEXT: [[T6:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[T5]])
 // CHECK-NEXT: ret i8* [[T6]]
 
 // CHECK: define internal i8* @"\01-[Test57 unsafe]"(
diff --git a/test/CodeGenObjC/objc-arc-container-subscripting.m b/test/CodeGenObjC/objc-arc-container-subscripting.m
index 71339c7085..0961ed1b20 100644
--- a/test/CodeGenObjC/objc-arc-container-subscripting.m
+++ b/test/CodeGenObjC/objc-arc-container-subscripting.m
@@ -15,6 +15,6 @@ id func() {
 // CHECK: [[SIX:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[call]]) nounwind
 // CHECK: [[ARRAY_CASTED:%.*]] = bitcast %0** {{%.*}} to i8**
 // CHECK: call void @objc_storeStrong(i8** [[ARRAY_CASTED]], i8* null)
-// CHECK: [[EIGHT:%.*]] = call i8* @objc_autoreleaseReturnValue(i8* [[SIX]]) nounwind
+// CHECK: [[EIGHT:%.*]] = tail call i8* @objc_autoreleaseReturnValue(i8* [[SIX]]) nounwind
 // CHECK: ret i8* [[EIGHT]]