commit 41b1e97b12c1407e40d8e5081bf1f9cf183934b0
author Akira Hatanaka <ahatanaka@apple.com> Mon Aug 03 13:25:25 2020 -0700
committer Akira Hatanaka <ahatanaka@apple.com> Mon Aug 03 13:25:25 2020 -0700
tree 1e1c6c11c527b56293cc72d45c89ade00778206c
parent 7209f83112db4dbe15d8328705f9d2aff0624fbd

[CodeGen][ObjC] Mark calls to objc_unsafeClaimAutoreleasedReturnValue as
notail on x86-64

This is needed because the epilogue code inserted before tail calls on
x86-64 breaks the handshake between the caller and callee.

Calls to objc_retainAutoreleasedReturnValue used to have the same
problem, which was fixed in https://reviews.llvm.org/D59656.

rdar://problem/66029552

Differential Revision: https://reviews.llvm.org/D84540

clang/lib/CodeGen/CGObjC.cpp

diff --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index cd2b84f..26dfb62 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -2250,8 +2250,7 @@
 CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
   emitAutoreleasedReturnValueMarker(*this);
   llvm::CallInst::TailCallKind tailKind =
-      CGM.getTargetCodeGenInfo()
-              .shouldSuppressTailCallsOfRetainAutoreleasedReturnValue()
+      CGM.getTargetCodeGenInfo().markARCOptimizedReturnCallsAsNoTail()
           ? llvm::CallInst::TCK_NoTail
           : llvm::CallInst::TCK_None;
   return emitARCValueOperation(
@@ -2270,9 +2269,14 @@
 llvm::Value *
 CodeGenFunction::EmitARCUnsafeClaimAutoreleasedReturnValue(llvm::Value *value) {
   emitAutoreleasedReturnValueMarker(*this);
-  return emitARCValueOperation(*this, value, nullptr,
-              CGM.getObjCEntrypoints().objc_unsafeClaimAutoreleasedReturnValue,
-                     llvm::Intrinsic::objc_unsafeClaimAutoreleasedReturnValue);
+  llvm::CallInst::TailCallKind tailKind =
+      CGM.getTargetCodeGenInfo().markARCOptimizedReturnCallsAsNoTail()
+          ? llvm::CallInst::TCK_NoTail
+          : llvm::CallInst::TCK_None;
+  return emitARCValueOperation(
+      *this, value, nullptr,
+      CGM.getObjCEntrypoints().objc_unsafeClaimAutoreleasedReturnValue,
+      llvm::Intrinsic::objc_unsafeClaimAutoreleasedReturnValue, tailKind);
 }
 
 /// Release the given object.

clang/lib/CodeGen/TargetInfo.cpp

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 9cd63eb..f31d432 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -2404,10 +2404,8 @@
   }
 
   /// Disable tail call on x86-64. The epilogue code before the tail jump blocks
-  /// the autoreleaseRV/retainRV optimization.
-  bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const override {
-    return true;
-  }
+  /// autoreleaseRV/retainRV and autoreleaseRV/unsafeClaimRV optimizations.
+  bool markARCOptimizedReturnCallsAsNoTail() const override { return true; }
 
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     return 7;

clang/lib/CodeGen/TargetInfo.h

diff --git a/clang/lib/CodeGen/TargetInfo.h b/clang/lib/CodeGen/TargetInfo.h
index 1152cab..0df9667 100644
--- a/clang/lib/CodeGen/TargetInfo.h
+++ b/clang/lib/CodeGen/TargetInfo.h
@@ -163,11 +163,9 @@
     return "";
   }
 
-  /// Determine whether a call to objc_retainAutoreleasedReturnValue should be
-  /// marked as 'notail'.
-  virtual bool shouldSuppressTailCallsOfRetainAutoreleasedReturnValue() const {
-    return false;
-  }
+  /// Determine whether a call to objc_retainAutoreleasedReturnValue or
+  /// objc_unsafeClaimAutoreleasedReturnValue should be marked as 'notail'.
+  virtual bool markARCOptimizedReturnCallsAsNoTail() 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.