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[NFC][CodeGen] Extract HasStrictReturn

This commit is contained in:
Vitaly Buka 2022-12-02 15:22:29 -08:00
parent 487edfa432
commit a3b48e0945
1 changed files with 28 additions and 20 deletions
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48
clang/lib/CodeGen/CGCall.cpp
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@ -1796,6 +1796,32 @@ bool CodeGenModule::MayDropFunctionReturn(const ASTContext &Context,
return ReturnType.isTriviallyCopyableType(Context);
}
static bool HasStrictReturn(const CodeGenModule &Module, QualType RetTy,
const Decl *TargetDecl) {
// C++ explicitly makes returning undefined values UB. C's rule only applies
// to used values, so we never mark them noundef for now.
if (!Module.getLangOpts().CPlusPlus)
return false;
if (TargetDecl) {
if (const FunctionDecl *FDecl = dyn_cast<FunctionDecl>(TargetDecl)) {
if (FDecl->isExternC())
return false;
} else if (const VarDecl *VDecl = dyn_cast<VarDecl>(TargetDecl)) {
// Function pointer.
if (VDecl->isExternC())
return false;
}
}
// We don't want to be too aggressive with the return checking, unless
// it's explicit in the code opts or we're using an appropriate sanitizer.
// Try to respect what the programmer intended.
return Module.getCodeGenOpts().StrictReturn ||
!Module.MayDropFunctionReturn(Module.getContext(), RetTy) ||
Module.getLangOpts().Sanitize.has(SanitizerKind::Memory) ||
Module.getLangOpts().Sanitize.has(SanitizerKind::Return);
}
void CodeGenModule::getDefaultFunctionAttributes(StringRef Name,
bool HasOptnone,
bool AttrOnCallSite,
@ -2325,27 +2351,9 @@ void CodeGenModule::ConstructAttributeList(StringRef Name,
const ABIArgInfo &RetAI = FI.getReturnInfo();
const llvm::DataLayout &DL = getDataLayout();
// C++ explicitly makes returning undefined values UB. C's rule only applies
// to used values, so we never mark them noundef for now.
bool HasStrictReturn = getLangOpts().CPlusPlus;
if (TargetDecl && HasStrictReturn) {
if (const FunctionDecl *FDecl = dyn_cast<FunctionDecl>(TargetDecl))
HasStrictReturn &= !FDecl->isExternC();
else if (const VarDecl *VDecl = dyn_cast<VarDecl>(TargetDecl))
// Function pointer
HasStrictReturn &= !VDecl->isExternC();
}
// We don't want to be too aggressive with the return checking, unless
// it's explicit in the code opts or we're using an appropriate sanitizer.
// Try to respect what the programmer intended.
HasStrictReturn &= getCodeGenOpts().StrictReturn ||
!MayDropFunctionReturn(getContext(), RetTy) ||
getLangOpts().Sanitize.has(SanitizerKind::Memory) ||
getLangOpts().Sanitize.has(SanitizerKind::Return);
// Determine if the return type could be partially undef
if (CodeGenOpts.EnableNoundefAttrs && HasStrictReturn) {
if (CodeGenOpts.EnableNoundefAttrs &&
HasStrictReturn(*this, RetTy, TargetDecl)) {
if (!RetTy->isVoidType() && RetAI.getKind() != ABIArgInfo::Indirect &&
DetermineNoUndef(RetTy, getTypes(), DL, RetAI))
RetAttrs.addAttribute(llvm::Attribute::NoUndef);