From 921f871ac438175ca8fcfcafdfcfac4d7ddf3905 Mon Sep 17 00:00:00 2001 From: serge-sans-paille Date: Thu, 5 Dec 2019 17:08:10 +0100 Subject: Allow system header to provide their own implementation of some builtin MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a system header provides an (inline) implementation of some of their function, clang still matches on the function name and generate the appropriate llvm builtin, e.g. memcpy. This behavior is in line with glibc recommendation « users may not provide their own version of symbols » but doesn't account for the fact that glibc itself can provide inline version of some functions. It is the case for the memcpy function when -D_FORTIFY_SOURCE=1 is on. In that case an inline version of memcpy calls __memcpy_chk, a function that performs extra runtime checks. Clang currently ignores the inline version and thus provides no runtime check. This code fixes the issue by detecting functions whose name is a builtin name but also have an inline implementation. Differential Revision: https://reviews.llvm.org/D71082 --- clang/lib/CodeGen/CodeGenModule.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'clang/lib/CodeGen/CodeGenModule.cpp') diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 963cd82210c4..5e0f0db90b01 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -1840,6 +1840,11 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F, else if (const auto *SA = FD->getAttr()) F->setSection(SA->getName()); + if (FD->isInlineBuiltinDeclaration()) { + F->addAttribute(llvm::AttributeList::FunctionIndex, + llvm::Attribute::NoBuiltin); + } + if (FD->isReplaceableGlobalAllocationFunction()) { // A replaceable global allocation function does not act like a builtin by // default, only if it is invoked by a new-expression or delete-expression. -- cgit v1.2.3