[CodeGen] Attach no-builtin attributes to function definitions with no Decl
When using -fno-builtin[-<name>], we don't attach the IR attributes to
function definitions with no Decl, like the ones created through
`CreateGlobalInitOrDestructFunction`.
This results in projects using -fno-builtin or -ffreestanding to start
seeing symbols like _memset_pattern16.
The fix changes the behavior to always add the attribute if LangOptions
requests it.
Differential Revision: https://reviews.llvm.org/D73495
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 3a50e2b..d633b3d 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1832,6 +1832,42 @@
F.addAttributes(llvm::AttributeList::FunctionIndex, FuncAttrs);
}
+static void addNoBuiltinAttributes(llvm::AttrBuilder &FuncAttrs,
+ const LangOptions &LangOpts,
+ const NoBuiltinAttr *NBA = nullptr) {
+ auto AddNoBuiltinAttr = [&FuncAttrs](StringRef BuiltinName) {
+ SmallString<32> AttributeName;
+ AttributeName += "no-builtin-";
+ AttributeName += BuiltinName;
+ FuncAttrs.addAttribute(AttributeName);
+ };
+
+ // First, handle the language options passed through -fno-builtin[-<name>]
+ if (LangOpts.NoBuiltin) {
+ // -fno-builtin disables them all.
+ FuncAttrs.addAttribute("no-builtins");
+ return;
+ }
+
+ // Then, add attributes for builtins specified through -fno-builtin-<name>.
+ llvm::for_each(LangOpts.NoBuiltinFuncs, AddNoBuiltinAttr);
+
+ // Now, let's check the __attribute__((no_builtin("...")) attribute added to
+ // the source.
+ if (!NBA)
+ return;
+
+ // If there is a wildcard in the builtin names specified through the
+ // attribute, disable them all.
+ if (llvm::is_contained(NBA->builtinNames(), "*")) {
+ FuncAttrs.addAttribute("no-builtins");
+ return;
+ }
+
+ // And last, add the rest of the builtin names.
+ llvm::for_each(NBA->builtinNames(), AddNoBuiltinAttr);
+}
+
void CodeGenModule::ConstructAttributeList(
StringRef Name, const CGFunctionInfo &FI, CGCalleeInfo CalleeInfo,
llvm::AttributeList &AttrList, unsigned &CallingConv, bool AttrOnCallSite) {
@@ -1850,6 +1886,8 @@
const Decl *TargetDecl = CalleeInfo.getCalleeDecl().getDecl();
bool HasOptnone = false;
+ // The NoBuiltinAttr attached to a TargetDecl (only allowed on FunctionDecls).
+ const NoBuiltinAttr *NBA = nullptr;
// FIXME: handle sseregparm someday...
if (TargetDecl) {
if (TargetDecl->hasAttr<ReturnsTwiceAttr>())
@@ -1875,22 +1913,7 @@
if (!(AttrOnCallSite && IsVirtualCall)) {
if (Fn->isNoReturn())
FuncAttrs.addAttribute(llvm::Attribute::NoReturn);
-
- const auto *NBA = Fn->getAttr<NoBuiltinAttr>();
- bool HasWildcard = NBA && llvm::is_contained(NBA->builtinNames(), "*");
- if (getLangOpts().NoBuiltin || HasWildcard)
- FuncAttrs.addAttribute("no-builtins");
- else {
- auto AddNoBuiltinAttr = [&FuncAttrs](StringRef BuiltinName) {
- SmallString<32> AttributeName;
- AttributeName += "no-builtin-";
- AttributeName += BuiltinName;
- FuncAttrs.addAttribute(AttributeName);
- };
- llvm::for_each(getLangOpts().NoBuiltinFuncs, AddNoBuiltinAttr);
- if (NBA)
- llvm::for_each(NBA->builtinNames(), AddNoBuiltinAttr);
- }
+ NBA = Fn->getAttr<NoBuiltinAttr>();
}
}
@@ -1925,6 +1948,14 @@
}
}
+ // Attach "no-builtins" attributes to:
+ // * call sites: both `nobuiltin` and "no-builtins" or "no-builtin-<name>".
+ // * definitions: "no-builtins" or "no-builtin-<name>" only.
+ // The attributes can come from:
+ // * LangOpts: -ffreestanding, -fno-builtin, -fno-builtin-<name>
+ // * FunctionDecl attributes: __attribute__((no_builtin(...)))
+ addNoBuiltinAttributes(FuncAttrs, getLangOpts(), NBA);
+
ConstructDefaultFnAttrList(Name, HasOptnone, AttrOnCallSite, FuncAttrs);
// This must run after constructing the default function attribute list