[Builtins] Overload __builtin_operator_new/delete to allow forwarding to usual allocation/deallocation functions.

Summary:
Libc++'s default allocator uses `__builtin_operator_new` and `__builtin_operator_delete` in order to allow the calls to new/delete to be ellided. However, libc++ now needs to support over-aligned types in the default allocator. In order to support this without disabling the existing optimization Clang needs to support calling the aligned new overloads from the builtins.

See llvm.org/PR22634 for more information about the libc++ bug.

This patch changes `__builtin_operator_new`/`__builtin_operator_delete` to call any usual `operator new`/`operator delete` function. It does this by performing overload resolution with the arguments passed to the builtin to determine which allocation function to call. If the selected function is not a usual allocation function a diagnostic is issued.

One open issue is if the `align_val_t` overloads should be considered "usual" when `LangOpts::AlignedAllocation` is disabled.


In order to allow libc++ to detect this new behavior the value for `__has_builtin(__builtin_operator_new)` has been updated to `201802`.

Reviewers: rsmith, majnemer, aaron.ballman, erik.pilkington, bogner, ahatanak

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D43047

llvm-svn: 328134

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 709e7f4..7cdec6e 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2356,7 +2356,7 @@ public:
                       CharUnits CookieSize = CharUnits());
 
   RValue EmitBuiltinNewDeleteCall(const FunctionProtoType *Type,
-                                  const Expr *Arg, bool IsDelete);
+                                  const CallExpr *TheCallExpr, bool IsDelete);
 
   llvm::Value *EmitCXXTypeidExpr(const CXXTypeidExpr *E);
   llvm::Value *EmitDynamicCast(Address V, const CXXDynamicCastExpr *DCE);