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[Clang] Improve testing for the flexible array member #89462

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Merged
merged 3 commits into from
Apr 24, 2024
Merged

[Clang] Improve testing for the flexible array member #89462

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2a6b335
[Clang][NFC] Improve testing for the flexible array member
bwendling Apr 19, 2024
a12d8a3
Return early if it's not a FieldDecl
bwendling Apr 19, 2024
3d5dbd3
Merge branch 'llvm:main' into counted-by-improvement-1
bwendling Apr 22, 2024
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23 changes: 14 additions & 9 deletions clang/lib/CodeGen/CGBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -822,8 +822,9 @@ CodeGenFunction::evaluateOrEmitBuiltinObjectSize(const Expr *E, unsigned Type,
return ConstantInt::get(ResType, ObjectSize, /*isSigned=*/true);
}

const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberField(
ASTContext &Ctx, const RecordDecl *RD, StringRef Name, uint64_t &Offset) {
const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberFieldAndOffset(
ASTContext &Ctx, const RecordDecl *RD, const FieldDecl *FAMDecl,
uint64_t &Offset) {
const LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel =
getLangOpts().getStrictFlexArraysLevel();
uint32_t FieldNo = 0;
Expand All @@ -832,7 +833,7 @@ const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberField(
return nullptr;

for (const FieldDecl *FD : RD->fields()) {
if ((Name.empty() || FD->getNameAsString() == Name) &&
if ((!FAMDecl || FD == FAMDecl) &&
Decl::isFlexibleArrayMemberLike(
Ctx, FD, FD->getType(), StrictFlexArraysLevel,
/*IgnoreTemplateOrMacroSubstitution=*/true)) {
Expand All @@ -843,8 +844,8 @@ const FieldDecl *CodeGenFunction::FindFlexibleArrayMemberField(

QualType Ty = FD->getType();
if (Ty->isRecordType()) {
if (const FieldDecl *Field = FindFlexibleArrayMemberField(
Ctx, Ty->getAsRecordDecl(), Name, Offset)) {
if (const FieldDecl *Field = FindFlexibleArrayMemberFieldAndOffset(
Ctx, Ty->getAsRecordDecl(), FAMDecl, Offset)) {
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(RD);
Offset += Layout.getFieldOffset(FieldNo);
return Field;
Expand Down Expand Up @@ -930,12 +931,14 @@ CodeGenFunction::emitFlexibleArrayMemberSize(const Expr *E, unsigned Type,

// Get the flexible array member Decl.
const RecordDecl *OuterRD = nullptr;
std::string FAMName;
const FieldDecl *FAMDecl = nullptr;
if (const auto *ME = dyn_cast<MemberExpr>(Base)) {
// Check if \p Base is referencing the FAM itself.
const ValueDecl *VD = ME->getMemberDecl();
OuterRD = VD->getDeclContext()->getOuterLexicalRecordContext();
FAMName = VD->getNameAsString();
FAMDecl = dyn_cast<FieldDecl>(VD);
if (!FAMDecl)
return nullptr;
} else if (const auto *DRE = dyn_cast<DeclRefExpr>(Base)) {
// Check if we're pointing to the whole struct.
QualType Ty = DRE->getDecl()->getType();
Expand Down Expand Up @@ -974,9 +977,11 @@ CodeGenFunction::emitFlexibleArrayMemberSize(const Expr *E, unsigned Type,
if (!OuterRD)
return nullptr;

// We call FindFlexibleArrayMemberAndOffset even if FAMDecl is non-null to
// get its offset.
uint64_t Offset = 0;
const FieldDecl *FAMDecl =
FindFlexibleArrayMemberField(Ctx, OuterRD, FAMName, Offset);
FAMDecl =
FindFlexibleArrayMemberFieldAndOffset(Ctx, OuterRD, FAMDecl, Offset);
Offset = Ctx.toCharUnitsFromBits(Offset).getQuantity();

if (!FAMDecl || !FAMDecl->getType()->isCountAttributedType())
Expand Down
12 changes: 6 additions & 6 deletions clang/lib/CodeGen/CodeGenFunction.h
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Expand Up @@ -3204,12 +3204,12 @@ class CodeGenFunction : public CodeGenTypeCache {
llvm::Value *Index, QualType IndexType,
QualType IndexedType, bool Accessed);

// Find a struct's flexible array member. It may be embedded inside multiple
// sub-structs, but must still be the last field.
const FieldDecl *FindFlexibleArrayMemberField(ASTContext &Ctx,
const RecordDecl *RD,
StringRef Name,
uint64_t &Offset);
// Find a struct's flexible array member and get its offset. It may be
// embedded inside multiple sub-structs, but must still be the last field.
const FieldDecl *
FindFlexibleArrayMemberFieldAndOffset(ASTContext &Ctx, const RecordDecl *RD,
const FieldDecl *FAMDecl,
uint64_t &Offset);

/// Find the FieldDecl specified in a FAM's "counted_by" attribute. Returns
/// \p nullptr if either the attribute or the field doesn't exist.
Expand Down