[CodeGen][ObjC] Annotate calls to objc_retainAutoreleasedReturnValue

with notail on x86-64.

On x86-64, the epilogue code inserted before the tail jump blocks the
autoreleased return optimization.

rdar://problem/38675807

Differential Revision: https://reviews.llvm.org/D59656

llvm-svn: 356705

3 files changed, 28 insertions, 11 deletions

diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index 561f21afdb1..69ced587957 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -1958,10 +1958,10 @@ static void setARCRuntimeFunctionLinkage(CodeGenModule &CGM,
 /// Perform an operation having the signature
 ///   i8* (i8*)
 /// where a null input causes a no-op and returns null.
-static llvm::Value *
-emitARCValueOperation(CodeGenFunction &CGF, llvm::Value *value,
-                      llvm::Type *returnType, llvm::Function *&fn,
-                      llvm::Intrinsic::ID IntID, bool isTailCall = false) {
+static llvm::Value *emitARCValueOperation(
+    CodeGenFunction &CGF, llvm::Value *value, llvm::Type *returnType,
+    llvm::Function *&fn, llvm::Intrinsic::ID IntID,
+    llvm::CallInst::TailCallKind tailKind = llvm::CallInst::TCK_None) {
   if (isa<llvm::ConstantPointerNull>(value))
     return value;
 
@@ -1976,8 +1976,7 @@ emitARCValueOperation(CodeGenFunction &CGF, llvm::Value *value,
 
   // Call the function.
   llvm::CallInst *call = CGF.EmitNounwindRuntimeCall(fn, value);
-  if (isTailCall)
-    call->setTailCall();
+  call->setTailCallKind(tailKind);
 
   // Cast the result back to the original type.
   return CGF.Builder.CreateBitCast(call, origType);
@@ -2187,9 +2186,15 @@ static void emitAutoreleasedReturnValueMarker(CodeGenFunction &CGF) {
 llvm::Value *
 CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
   emitAutoreleasedReturnValueMarker(*this);
-  return emitARCValueOperation(*this, value, nullptr,
-              CGM.getObjCEntrypoints().objc_retainAutoreleasedReturnValue,
-                           llvm::Intrinsic::objc_retainAutoreleasedReturnValue);
+  llvm::CallInst::TailCallKind tailKind =
+      CGM.getTargetCodeGenInfo()
+              .shouldSuppressTailCallsOfRetainAutoreleasedReturnValue()
+          ? llvm::CallInst::TCK_NoTail
+          : llvm::CallInst::TCK_None;
+  return emitARCValueOperation(
+      *this, value, nullptr,
+      CGM.getObjCEntrypoints().objc_retainAutoreleasedReturnValue,
+      llvm::Intrinsic::objc_retainAutoreleasedReturnValue, tailKind);
 }
 
 /// Claim a possibly-autoreleased return value at +0.  This is only
@@ -2326,7 +2331,7 @@ CodeGenFunction::EmitARCAutoreleaseReturnValue(llvm::Value *value) {
   return emitARCValueOperation(*this, value, nullptr,
                             CGM.getObjCEntrypoints().objc_autoreleaseReturnValue,
                                llvm::Intrinsic::objc_autoreleaseReturnValue,
-                               /*isTailCall*/ true);
+                               llvm::CallInst::TCK_Tail);
 }
 
 /// Do a fused retain/autorelease of the given object.
@@ -2336,7 +2341,7 @@ CodeGenFunction::EmitARCRetainAutoreleaseReturnValue(llvm::Value *value) {
   return emitARCValueOperation(*this, value, nullptr,
                      CGM.getObjCEntrypoints().objc_retainAutoreleaseReturnValue,
                              llvm::Intrinsic::objc_retainAutoreleaseReturnValue,
-                               /*isTailCall*/ true);
+                               llvm::CallInst::TCK_Tail);
 }
 
 /// Do a fused retain/autorelease of the given object.
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 63e991c9370..f48f19966e5 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -2268,6 +2268,12 @@ public:
     return static_cast<const X86_64ABIInfo&>(TargetCodeGenInfo::getABIInfo());
   }
 
+  /// Disable tail call on x86-64. The epilogue code before the tail jump blocks
+  /// the autoreleaseRV/retainRV optimization.
+  bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const override {
+    return true;
+  }
+
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     return 7;
   }
diff --git a/clang/lib/CodeGen/TargetInfo.h b/clang/lib/CodeGen/TargetInfo.h
index b5d5c1fb300..8a4154030ce 100644
--- a/clang/lib/CodeGen/TargetInfo.h
+++ b/clang/lib/CodeGen/TargetInfo.h
@@ -156,6 +156,12 @@ public:
     return "";
   }
 
+  /// Determine whether a call to objc_retainAutoreleasedReturnValue should be
+  /// marked as 'notail'.
+  virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const {
+    return false;
+  }
+
   /// Return a constant used by UBSan as a signature to identify functions
   /// possessing type information, or 0 if the platform is unsupported.
   virtual llvm::Constant *