[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
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 084bf50..996e5e7 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -2611,11 +2611,12 @@
case Builtin::BI__builtin_addressof:
return RValue::get(EmitLValue(E->getArg(0)).getPointer());
case Builtin::BI__builtin_operator_new:
- return EmitBuiltinNewDeleteCall(FD->getType()->castAs<FunctionProtoType>(),
- E->getArg(0), false);
+ return EmitBuiltinNewDeleteCall(
+ E->getCallee()->getType()->castAs<FunctionProtoType>(), E, false);
case Builtin::BI__builtin_operator_delete:
- return EmitBuiltinNewDeleteCall(FD->getType()->castAs<FunctionProtoType>(),
- E->getArg(0), true);
+ return EmitBuiltinNewDeleteCall(
+ E->getCallee()->getType()->castAs<FunctionProtoType>(), E, true);
+
case Builtin::BI__noop:
// __noop always evaluates to an integer literal zero.
return RValue::get(ConstantInt::get(IntTy, 0));