ubsan created this revision.
ubsan added a reviewer: rsmith.
Herald added a subscriber: cfe-commits.
- Add `UETT_PreferredAlignOf` to account for the difference between `__alignof`
and `alignof`
- `AlignOfType` now returns ABI alignment instead of preferred alignment iff
clang-abi-compat > 7, and one uses _Alignof or alignof
bug link: https://bugs.llvm.org/show_bug.cgi?id=26547
Repository:
rC Clang
https://reviews.llvm.org/D53207
Files:
include/clang/ASTMatchers/ASTMatchers.h
include/clang/Basic/LangOptions.h
include/clang/Basic/TypeTraits.h
lib/AST/ASTDumper.cpp
lib/AST/Expr.cpp
lib/AST/ExprConstant.cpp
lib/AST/ItaniumMangle.cpp
lib/AST/StmtPrinter.cpp
lib/Parse/ParseExpr.cpp
lib/Sema/SemaChecking.cpp
lib/Sema/SemaExpr.cpp
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -3596,7 +3596,8 @@
// C99 6.5.3.4p1:
if (T->isFunctionType() &&
- (TraitKind == UETT_SizeOf || TraitKind == UETT_AlignOf)) {
+ (TraitKind == UETT_SizeOf || TraitKind == UETT_AlignOf ||
+ TraitKind == UETT_PreferredAlignOf)) {
// sizeof(function)/alignof(function) is allowed as an extension.
S.Diag(Loc, diag::ext_sizeof_alignof_function_type)
<< TraitKind << ArgRange;
@@ -3674,7 +3675,7 @@
// the expression to be complete. 'sizeof' requires the expression's type to
// be complete (and will attempt to complete it if it's an array of unknown
// bound).
- if (ExprKind == UETT_AlignOf) {
+ if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
if (RequireCompleteType(E->getExprLoc(),
Context.getBaseElementType(E->getType()),
diag::err_sizeof_alignof_incomplete_type, ExprKind,
@@ -3698,7 +3699,8 @@
// The operand for sizeof and alignof is in an unevaluated expression context,
// so side effects could result in unintended consequences.
- if ((ExprKind == UETT_SizeOf || ExprKind == UETT_AlignOf) &&
+ if ((ExprKind == UETT_SizeOf || ExprKind == UETT_AlignOf ||
+ ExprKind == UETT_PreferredAlignOf) &&
!inTemplateInstantiation() && E->HasSideEffects(Context, false))
Diag(E->getExprLoc(), diag::warn_side_effects_unevaluated_context);
@@ -3767,7 +3769,8 @@
// C11 6.5.3.4/3, C++11 [expr.alignof]p3:
// When alignof or _Alignof is applied to an array type, the result
// is the alignment of the element type.
- if (ExprKind == UETT_AlignOf || ExprKind == UETT_OpenMPRequiredSimdAlign)
+ if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf ||
+ ExprKind == UETT_OpenMPRequiredSimdAlign)
ExprType = Context.getBaseElementType(ExprType);
if (ExprKind == UETT_VecStep)
@@ -4046,14 +4049,14 @@
bool isInvalid = false;
if (E->isTypeDependent()) {
// Delay type-checking for type-dependent expressions.
- } else if (ExprKind == UETT_AlignOf) {
+ } else if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
isInvalid = CheckAlignOfExpr(*this, E);
} else if (ExprKind == UETT_VecStep) {
isInvalid = CheckVecStepExpr(E);
} else if (ExprKind == UETT_OpenMPRequiredSimdAlign) {
- Diag(E->getExprLoc(), diag::err_openmp_default_simd_align_expr);
- isInvalid = true;
- } else if (E->refersToBitField()) { // C99 6.5.3.4p1.
+ Diag(E->getExprLoc(), diag::err_openmp_default_simd_align_expr);
+ isInvalid = true;
+ } else if (E->refersToBitField()) { // C99 6.5.3.4p1.
Diag(E->getExprLoc(), diag::err_sizeof_alignof_typeof_bitfield) << 0;
isInvalid = true;
} else {
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -5695,7 +5695,8 @@
if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
if (const auto *UE =
dyn_cast<UnaryExprOrTypeTraitExpr>(Arg->IgnoreParenImpCasts()))
- if (UE->getKind() == UETT_AlignOf)
+ if (UE->getKind() == UETT_AlignOf ||
+ UE->getKind() == UETT_PreferredAlignOf)
Diag(TheCall->getBeginLoc(), diag::warn_alloca_align_alignof)
<< Arg->getSourceRange();
@@ -10313,7 +10314,7 @@
}
AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
-
+
// Diagnose implicitly sequentially-consistent atomic assignment.
if (E->getLHS()->getType()->isAtomicType())
S.Diag(E->getRHS()->getBeginLoc(), diag::warn_atomic_implicit_seq_cst);
Index: lib/Parse/ParseExpr.cpp
===================================================================
--- lib/Parse/ParseExpr.cpp
+++ lib/Parse/ParseExpr.cpp
@@ -2022,7 +2022,9 @@
CastRange);
UnaryExprOrTypeTrait ExprKind = UETT_SizeOf;
- if (OpTok.isOneOf(tok::kw_alignof, tok::kw___alignof, tok::kw__Alignof))
+ if (OpTok.is(tok::kw___alignof))
+ ExprKind = UETT_PreferredAlignOf;
+ else if (OpTok.isOneOf(tok::kw_alignof, tok::kw__Alignof))
ExprKind = UETT_AlignOf;
else if (OpTok.is(tok::kw_vec_step))
ExprKind = UETT_VecStep;
Index: lib/AST/StmtPrinter.cpp
===================================================================
--- lib/AST/StmtPrinter.cpp
+++ lib/AST/StmtPrinter.cpp
@@ -1686,6 +1686,9 @@
else
OS << "__alignof";
break;
+ case UETT_PreferredAlignOf:
+ OS << "__alignof";
+ break;
case UETT_VecStep:
OS << "vec_step";
break;
Index: lib/AST/ItaniumMangle.cpp
===================================================================
--- lib/AST/ItaniumMangle.cpp
+++ lib/AST/ItaniumMangle.cpp
@@ -3881,6 +3881,7 @@
case UETT_SizeOf:
Out << 's';
break;
+ case UETT_PreferredAlignOf:
case UETT_AlignOf:
Out << 'a';
break;
Index: lib/AST/ExprConstant.cpp
===================================================================
--- lib/AST/ExprConstant.cpp
+++ lib/AST/ExprConstant.cpp
@@ -5946,21 +5946,33 @@
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
-static CharUnits GetAlignOfType(EvalInfo &Info, QualType T) {
+static CharUnits GetAlignOfType(EvalInfo &Info, QualType T,
+ bool PreferredAlignOf) {
// C++ [expr.alignof]p3:
// When alignof is applied to a reference type, the result is the
// alignment of the referenced type.
if (const ReferenceType *Ref = T->getAs<ReferenceType>())
T = Ref->getPointeeType();
- // __alignof is defined to return the preferred alignment.
if (T.getQualifiers().hasUnaligned())
return CharUnits::One();
- return Info.Ctx.toCharUnitsFromBits(
- Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
+
+ const bool alignOfReturnsPreferred =
+ Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
+ // __alignof is defined to return the preferred alignment.
+ // before 8, clang returned the preferred alignment for alignof and _Alignof
+ // as well
+ if (PreferredAlignOf || alignOfReturnsPreferred)
+ return Info.Ctx.toCharUnitsFromBits(
+ Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
+ // alignof (C++) and _Alignof (C11) are defined to return the ABI alignment
+ // see https://bugs.llvm.org/show_bug.cgi?id=26547 for explanation
+ else
+ return Info.Ctx.getTypeAlignInChars(T.getTypePtr());
}
-static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E) {
+static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E,
+ bool PreferredAlignOf) {
E = E->IgnoreParens();
// The kinds of expressions that we have special-case logic here for
@@ -5977,7 +5989,7 @@
return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
/*RefAsPointee*/true);
- return GetAlignOfType(Info, E->getType());
+ return GetAlignOfType(Info, E->getType(), PreferredAlignOf);
}
// To be clear: this happily visits unsupported builtins. Better name welcomed.
@@ -6039,7 +6051,7 @@
BaseAlignment = Info.Ctx.getDeclAlign(VD);
} else {
BaseAlignment =
- GetAlignOfExpr(Info, OffsetResult.Base.get<const Expr*>());
+ GetAlignOfExpr(Info, OffsetResult.Base.get<const Expr *>(), false);
}
if (BaseAlignment < Align) {
@@ -9357,12 +9369,18 @@
/// a result as the expression's type.
bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
const UnaryExprOrTypeTraitExpr *E) {
- switch(E->getKind()) {
+ auto const kind = E->getKind();
+ switch (kind) {
+ case UETT_PreferredAlignOf:
case UETT_AlignOf: {
if (E->isArgumentType())
- return Success(GetAlignOfType(Info, E->getArgumentType()), E);
+ return Success(GetAlignOfType(Info, E->getArgumentType(),
+ kind == UETT_PreferredAlignOf),
+ E);
else
- return Success(GetAlignOfExpr(Info, E->getArgumentExpr()), E);
+ return Success(GetAlignOfExpr(Info, E->getArgumentExpr(),
+ kind == UETT_PreferredAlignOf),
+ E);
}
case UETT_VecStep: {
Index: lib/AST/Expr.cpp
===================================================================
--- lib/AST/Expr.cpp
+++ lib/AST/Expr.cpp
@@ -1446,7 +1446,7 @@
// Check to see if we are in the situation where alignof(decl) should be
// dependent because decl's alignment is dependent.
- if (ExprKind == UETT_AlignOf) {
+ if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
if (!isValueDependent() || !isInstantiationDependent()) {
E = E->IgnoreParens();
Index: lib/AST/ASTDumper.cpp
===================================================================
--- lib/AST/ASTDumper.cpp
+++ lib/AST/ASTDumper.cpp
@@ -2272,6 +2272,9 @@
case UETT_SizeOf:
OS << " sizeof";
break;
+ case UETT_PreferredAlignOf:
+ OS << " __alignof";
+ break;
case UETT_AlignOf:
OS << " alignof";
break;
Index: include/clang/Basic/TypeTraits.h
===================================================================
--- include/clang/Basic/TypeTraits.h
+++ include/clang/Basic/TypeTraits.h
@@ -96,6 +96,12 @@
/// Names for the "expression or type" traits.
enum UnaryExprOrTypeTrait {
UETT_SizeOf,
+ // used for GCC's __alignof,
+ UETT_PreferredAlignOf,
+ // used for C's _Alignof and C++'s alignof
+ // this distinction is important because __alignof
+ // returns preferred alignment
+ // _Alignof and alignof return the required alignment
UETT_AlignOf,
UETT_VecStep,
UETT_OpenMPRequiredSimdAlign,
Index: include/clang/Basic/LangOptions.h
===================================================================
--- include/clang/Basic/LangOptions.h
+++ include/clang/Basic/LangOptions.h
@@ -124,6 +124,13 @@
/// whether we reuse base class tail padding in some ABIs.
Ver6,
+ /// Attempt to be ABI-compatible with code generated by Clang 7.0.x
+ /// (SVN r344257). This causes alignof (C++) and _Alignof (C11) to be
+ /// compatible with __alignof (i.e., return the preferred alignment)
+ /// rather than returning the required alignment.
+ /// see https://bugs.llvm.org/show_bug.cgi?id=26547 for explanation
+ Ver7,
+
/// Conform to the underlying platform's C and C++ ABIs as closely
/// as we can.
Latest
@@ -273,8 +280,8 @@
/// Floating point control options
class FPOptions {
public:
- FPOptions() : fp_contract(LangOptions::FPC_Off),
- fenv_access(LangOptions::FEA_Off) {}
+ FPOptions()
+ : fp_contract(LangOptions::FPC_Off), fenv_access(LangOptions::FEA_Off) {}
// Used for serializing.
explicit FPOptions(unsigned I)
@@ -319,7 +326,7 @@
unsigned getInt() const { return fp_contract | (fenv_access << 2); }
private:
- /// Adjust BinaryOperator::FPFeatures to match the total bit-field size
+ /// Adjust BinaryOperator::FPFeatures to match the total bit-field size
/// of these two.
unsigned fp_contract : 2;
unsigned fenv_access : 1;
Index: include/clang/ASTMatchers/ASTMatchers.h
===================================================================
--- include/clang/ASTMatchers/ASTMatchers.h
+++ include/clang/ASTMatchers/ASTMatchers.h
@@ -2425,8 +2425,9 @@
/// alignof.
inline internal::Matcher<Stmt> alignOfExpr(
const internal::Matcher<UnaryExprOrTypeTraitExpr> &InnerMatcher) {
- return stmt(unaryExprOrTypeTraitExpr(allOf(
- ofKind(UETT_AlignOf), InnerMatcher)));
+ return stmt(unaryExprOrTypeTraitExpr(
+ allOf(anyOf(ofKind(UETT_AlignOf), ofKind(UETT_PreferredAlignOf)),
+ InnerMatcher)));
}
/// Same as unaryExprOrTypeTraitExpr, but only matching
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