[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/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index b874959..56c5e68 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -1307,19 +1307,19 @@
}
RValue CodeGenFunction::EmitBuiltinNewDeleteCall(const FunctionProtoType *Type,
- const Expr *Arg,
+ const CallExpr *TheCall,
bool IsDelete) {
CallArgList Args;
- const Stmt *ArgS = Arg;
- EmitCallArgs(Args, *Type->param_type_begin(), llvm::makeArrayRef(ArgS));
+ EmitCallArgs(Args, Type->getParamTypes(), TheCall->arguments());
// Find the allocation or deallocation function that we're calling.
ASTContext &Ctx = getContext();
DeclarationName Name = Ctx.DeclarationNames
.getCXXOperatorName(IsDelete ? OO_Delete : OO_New);
+
for (auto *Decl : Ctx.getTranslationUnitDecl()->lookup(Name))
if (auto *FD = dyn_cast<FunctionDecl>(Decl))
if (Ctx.hasSameType(FD->getType(), QualType(Type, 0)))
- return EmitNewDeleteCall(*this, cast<FunctionDecl>(Decl), Type, Args);
+ return EmitNewDeleteCall(*this, FD, Type, Args);
llvm_unreachable("predeclared global operator new/delete is missing");
}