[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/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a575def..9c0a16c 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1097,20 +1097,14 @@
return ExprError();
break;
case Builtin::BI__builtin_operator_new:
- case Builtin::BI__builtin_operator_delete:
- if (!getLangOpts().CPlusPlus) {
- Diag(TheCall->getExprLoc(), diag::err_builtin_requires_language)
- << (BuiltinID == Builtin::BI__builtin_operator_new
- ? "__builtin_operator_new"
- : "__builtin_operator_delete")
- << "C++";
- return ExprError();
- }
- // CodeGen assumes it can find the global new and delete to call,
- // so ensure that they are declared.
- DeclareGlobalNewDelete();
- break;
-
+ case Builtin::BI__builtin_operator_delete: {
+ bool IsDelete = BuiltinID == Builtin::BI__builtin_operator_delete;
+ ExprResult Res =
+ SemaBuiltinOperatorNewDeleteOverloaded(TheCallResult, IsDelete);
+ if (Res.isInvalid())
+ CorrectDelayedTyposInExpr(TheCallResult.get());
+ return Res;
+ }
// check secure string manipulation functions where overflows
// are detectable at compile time
case Builtin::BI__builtin___memcpy_chk: