https://github.com/JustinStitt updated
https://github.com/llvm/llvm-project/pull/86618
>From 10ee32826fc2acb6bd993c88bdb7142360b6f263 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Tue, 5 Mar 2024 03:14:49 +0000
Subject: [PATCH 01/10] implement wraps attribute
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/docs/ReleaseNotes.rst | 9 +++
clang/include/clang/AST/Expr.h | 3 +
clang/include/clang/Basic/Attr.td | 6 ++
clang/include/clang/Basic/AttrDocs.td | 66 +++++++++++++++++++
.../clang/Basic/DiagnosticSemaKinds.td | 3 +
clang/include/clang/Sema/Sema.h | 4 ++
clang/lib/AST/Expr.cpp | 19 ++++++
clang/lib/AST/ExprConstant.cpp | 6 +-
clang/lib/AST/TypePrinter.cpp | 3 +
clang/lib/CodeGen/CGExprScalar.cpp | 40 +++++++++--
clang/lib/Sema/SemaDeclAttr.cpp | 12 +++-
clang/lib/Sema/SemaType.cpp | 15 +++++
clang/test/CodeGen/integer-overflow.c | 56 ++++++++++++++++
clang/test/CodeGen/unsigned-overflow.c | 63 +++++++++++++++---
clang/test/Sema/attr-wraps.c | 9 +++
15 files changed, 298 insertions(+), 16 deletions(-)
create mode 100644 clang/test/Sema/attr-wraps.c
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f96cebbde3d825..cb02af7e948989 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -282,6 +282,15 @@ Attribute Changes in Clang
This allows the ``_Nullable`` and ``_Nonnull`` family of type attributes to
apply to this class.
+- Introduced ``__attribute((wraps))__`` which can be added to type or variable
+ declarations. Using an attributed type or variable in an arithmetic
+ expression will define the overflow behavior for that expression as having
+ two's complement wrap-around. These expressions cannot trigger integer
+ overflow warnings or sanitizer warnings. They also cannot be optimized away
+ by some eager UB optimizations.
+
+ This attribute is ignored in C++.
+
Improvements to Clang's diagnostics
-----------------------------------
- Clang now applies syntax highlighting to the code snippets it
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 2bfefeabc348be..68cd7d7c0fac3b 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -4077,6 +4077,9 @@ class BinaryOperator : public Expr {
static unsigned sizeOfTrailingObjects(bool HasFPFeatures) {
return HasFPFeatures * sizeof(FPOptionsOverride);
}
+
+ /// Do one of the subexpressions have the wraps attribute?
+ bool oneOfWraps(const ASTContext &Ctx) const;
};
/// CompoundAssignOperator - For compound assignments (e.g. +=), we keep
diff --git a/clang/include/clang/Basic/Attr.td
b/clang/include/clang/Basic/Attr.td
index dc87a8c6f022dc..06e41fcee206c4 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -4506,3 +4506,9 @@ def CodeAlign: StmtAttr {
static constexpr int MaximumAlignment = 4096;
}];
}
+
+def Wraps : DeclOrTypeAttr {
+ let Spellings = [Clang<"wraps">, CXX11<"", "wraps", 202403>];
+ let Subjects = SubjectList<[Var, TypedefName, Field]>;
+ let Documentation = [WrapsDocs];
+}
diff --git a/clang/include/clang/Basic/AttrDocs.td
b/clang/include/clang/Basic/AttrDocs.td
index 0ca4ea377fc36a..a2adb923e3c47c 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -8044,3 +8044,69 @@ requirement:
}
}];
}
+
+def WrapsDocs : Documentation {
+ let Category = DocCatField;
+ let Content = [{
+This attribute can be used with type or variable declarations to denote that
+arithmetic containing these marked components have defined overflow behavior.
+Specifically, the behavior is defined as being consistent with two's complement
+wrap-around. For the purposes of sanitizers or warnings that concern themselves
+with the definedness of integer arithmetic, they will cease to instrument or
+warn about arithmetic that directly involves a "wrapping" component.
+
+For example, ``-fsanitize=signed-integer-overflow`` or ``-Winteger-overflow``
+will not warn about suspicious overflowing arithmetic -- assuming correct usage
+of the wraps attribute.
+
+This example shows some basic usage of ``__attribute__((wraps))`` on a type
+definition when building with ``-fsanitize=signed-integer-overflow``
+
+.. code-block:: c
+ typedef int __attribute__((wraps)) wrapping_int;
+
+ void foo() {
+ wrapping_int a = INT_MAX;
+ ++a; // no sanitizer warning
+ }
+
+ int main() { foo(); }
+
+In the following example, we use ``__attribute__((wraps))`` on a variable to
+disable overflow instrumentation for arithmetic expressions it appears in. We
+do so with a popular overflow-checking pattern which we might not want to trip
+sanitizers (like ``-fsanitize=unsigned-integer-overflow``).
+
+.. code-block:: c
+ void foo(int offset) {
+ unsigned int A __attribute__((wraps)) = UINT_MAX;
+
+ // to check for overflow using this pattern, we may perform a real overflow
+ // thus triggering sanitizers to step in. Since A is "wrapping", we can be
+ // sure there are no sanitizer warnings.
+ if (A + offset < A) {
+ // handle overflow manually
+ // ...
+ return;
+ }
+
+ // now, handle non-overflow case
+ // ...
+ }
+
+The above example demonstrates some of the power and elegance this attribute
+provides. We can use code patterns we are already familiar with (like ``if (x +
+y < x)``) while gaining control over the overflow behavior on a case-by-case
+basis.
+
+When combined with ``-fwrapv``, this attribute can still be applied as normal
+but has no function apart from annotating types and variables for readers. This
+is because ``-fwrapv`` defines all arithmetic as being "wrapping", rending this
+attribute's efforts redundant.
+
+When using this attribute without ``-fwrapv`` and without any sanitizers, it
+still has an impact on the definedness of arithmetic expressions containing
+wrapping components. Since the behavior of said expressions is now technically
+defined, the compiler will forgo some eager optimizations that are used on
+expressions containing UB.}];
+}
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 1c068f6cdb4293..0d90fc2d9bcf17 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6529,6 +6529,9 @@ def err_counted_by_attr_refer_to_union : Error<
def note_flexible_array_counted_by_attr_field : Note<
"field %0 declared here">;
+def warn_wraps_attr_var_decl_type_not_integer : Warning<
+ "using attribute 'wraps' with non-integer type '%0' has no function">;
+
let CategoryName = "ARC Semantic Issue" in {
// ARC-mode diagnostics.
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index f311f9f3743454..8d47ac79272fa0 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -3630,6 +3630,10 @@ class Sema final : public SemaBase {
void AddAnnotationAttr(Decl *D, const AttributeCommonInfo &CI,
StringRef Annot, MutableArrayRef<Expr *> Args);
+ /// AddWrapsAttr - Adds the "wraps" attribute to a particular
+ /// declaration.
+ void AddWrapsAttr(Decl *D, const AttributeCommonInfo &CI);
+
bool checkMSInheritanceAttrOnDefinition(CXXRecordDecl *RD, SourceRange Range,
bool BestCase,
MSInheritanceModel SemanticSpelling);
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 07c9f287dd0767..f8cf0559f8eac4 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2237,6 +2237,21 @@ bool
BinaryOperator::isNullPointerArithmeticExtension(ASTContext &Ctx,
return true;
}
+bool BinaryOperator::oneOfWraps(const ASTContext &Ctx) const {
+ llvm::SmallVector<Expr *, 2> Both = {getLHS(), getRHS()};
+
+ for (const Expr *oneOf : Both) {
+ if (!oneOf)
+ continue;
+ if (auto *TypePtr =
+ oneOf->IgnoreParenImpCasts()->getType().getTypePtrOrNull())
+ if (TypePtr->hasAttr(attr::Wraps)) {
+ return true;
+ }
+ }
+ return false;
+}
+
SourceLocExpr::SourceLocExpr(const ASTContext &Ctx, SourceLocIdentKind Kind,
QualType ResultTy, SourceLocation BLoc,
SourceLocation RParenLoc,
@@ -4751,6 +4766,8 @@ BinaryOperator::BinaryOperator(const ASTContext &Ctx,
Expr *lhs, Expr *rhs,
if (hasStoredFPFeatures())
setStoredFPFeatures(FPFeatures);
setDependence(computeDependence(this));
+ if (oneOfWraps(Ctx))
+ setType(Ctx.getAttributedType(attr::Wraps, getType(), getType()));
}
BinaryOperator::BinaryOperator(const ASTContext &Ctx, Expr *lhs, Expr *rhs,
@@ -4768,6 +4785,8 @@ BinaryOperator::BinaryOperator(const ASTContext &Ctx,
Expr *lhs, Expr *rhs,
if (hasStoredFPFeatures())
setStoredFPFeatures(FPFeatures);
setDependence(computeDependence(this));
+ if (oneOfWraps(Ctx))
+ setType(Ctx.getAttributedType(attr::Wraps, getType(), getType()));
}
BinaryOperator *BinaryOperator::CreateEmpty(const ASTContext &C,
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 88c8eaf6ef9b6e..51dd73bf1ee897 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2775,7 +2775,8 @@ static bool CheckedIntArithmetic(EvalInfo &Info, const
Expr *E,
APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
Result = Value.trunc(LHS.getBitWidth());
if (Result.extend(BitWidth) != Value) {
- if (Info.checkingForUndefinedBehavior())
+ if (Info.checkingForUndefinedBehavior() &&
+ !E->getType().getTypePtr()->hasAttr(attr::Wraps))
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Result, 10, Result.isSigned(),
/*formatAsCLiteral=*/false,
@@ -13993,7 +13994,8 @@ bool IntExprEvaluator::VisitUnaryOperator(const
UnaryOperator *E) {
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
- if (Info.checkingForUndefinedBehavior())
+ if (Info.checkingForUndefinedBehavior() &&
+ !E->getType().getTypePtr()->hasAttr(attr::Wraps))
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Value, 10, Value.isSigned(),
/*formatAsCLiteral=*/false,
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index 075c8aba11fcb9..2a9346d8253d20 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -1962,6 +1962,9 @@ void TypePrinter::printAttributedAfter(const
AttributedType *T,
case attr::AArch64SVEPcs: OS << "aarch64_sve_pcs"; break;
case attr::AMDGPUKernelCall: OS << "amdgpu_kernel"; break;
case attr::IntelOclBicc: OS << "inteloclbicc"; break;
+ case attr::Wraps:
+ OS << "wraps";
+ break;
case attr::PreserveMost:
OS << "preserve_most";
break;
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index 1f18e0d5ba409a..be1cae5ca8ea42 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -147,6 +147,15 @@ struct BinOpInfo {
return UnOp->getSubExpr()->getType()->isFixedPointType();
return false;
}
+
+ /// Does the BinaryOperator have the wraps attribute?
+ /// If so, we can ellide overflow sanitizer checks.
+ bool oneOfWraps() const {
+ const Type *TyPtr = E->getType().getTypePtrOrNull();
+ if (TyPtr)
+ return TyPtr->hasAttr(attr::Wraps);
+ return false;
+ }
};
static bool MustVisitNullValue(const Expr *E) {
@@ -726,6 +735,11 @@ class ScalarExprEmitter
// Binary Operators.
Value *EmitMul(const BinOpInfo &Ops) {
+ if ((Ops.Ty->isSignedIntegerOrEnumerationType() ||
+ Ops.Ty->isUnsignedIntegerType()) &&
+ Ops.oneOfWraps())
+ return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
+
if (Ops.Ty->isSignedIntegerOrEnumerationType()) {
switch (CGF.getLangOpts().getSignedOverflowBehavior()) {
case LangOptions::SOB_Defined:
@@ -2822,6 +2836,9 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const
UnaryOperator *E, LValue LV,
} else if (type->isIntegerType()) {
QualType promotedType;
bool canPerformLossyDemotionCheck = false;
+ BinOpInfo Ops = (createBinOpInfoFromIncDec(
+ E, value, isInc, E->getFPFeaturesInEffect(CGF.getLangOpts())));
+
if (CGF.getContext().isPromotableIntegerType(type)) {
promotedType = CGF.getContext().getPromotedIntegerType(type);
assert(promotedType != type && "Shouldn't promote to the same type.");
@@ -2878,10 +2895,12 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const
UnaryOperator *E, LValue LV,
// Note that signed integer inc/dec with width less than int can't
// overflow because of promotion rules; we're just eliding a few steps
// here.
- } else if (E->canOverflow() && type->isSignedIntegerOrEnumerationType()) {
+ } else if (E->canOverflow() && type->isSignedIntegerOrEnumerationType() &&
+ !Ops.oneOfWraps()) {
value = EmitIncDecConsiderOverflowBehavior(E, value, isInc);
} else if (E->canOverflow() && type->isUnsignedIntegerType() &&
- CGF.SanOpts.has(SanitizerKind::UnsignedIntegerOverflow)) {
+ CGF.SanOpts.has(SanitizerKind::UnsignedIntegerOverflow) &&
+ !Ops.oneOfWraps()) {
value = EmitOverflowCheckedBinOp(createBinOpInfoFromIncDec(
E, value, isInc, E->getFPFeaturesInEffect(CGF.getLangOpts())));
} else {
@@ -3670,7 +3689,8 @@ Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
if ((CGF.SanOpts.has(SanitizerKind::IntegerDivideByZero) ||
CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow)) &&
Ops.Ty->isIntegerType() &&
- (Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow())) {
+ (Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow()) &&
+ !Ops.oneOfWraps()) {
llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, true);
} else if (CGF.SanOpts.has(SanitizerKind::FloatDivideByZero) &&
@@ -3719,7 +3739,8 @@ Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
if ((CGF.SanOpts.has(SanitizerKind::IntegerDivideByZero) ||
CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow)) &&
Ops.Ty->isIntegerType() &&
- (Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow())) {
+ (Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow()) &&
+ !Ops.oneOfWraps()) {
CodeGenFunction::SanitizerScope SanScope(&CGF);
llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, false);
@@ -4084,6 +4105,11 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
op.RHS->getType()->isPointerTy())
return emitPointerArithmetic(CGF, op, CodeGenFunction::NotSubtraction);
+ if ((op.Ty->isSignedIntegerOrEnumerationType() ||
+ op.Ty->isUnsignedIntegerType()) &&
+ op.oneOfWraps())
+ return Builder.CreateAdd(op.LHS, op.RHS, "add");
+
if (op.Ty->isSignedIntegerOrEnumerationType()) {
switch (CGF.getLangOpts().getSignedOverflowBehavior()) {
case LangOptions::SOB_Defined:
@@ -4240,6 +4266,10 @@ Value *ScalarExprEmitter::EmitFixedPointBinOp(const
BinOpInfo &op) {
Value *ScalarExprEmitter::EmitSub(const BinOpInfo &op) {
// The LHS is always a pointer if either side is.
if (!op.LHS->getType()->isPointerTy()) {
+ if ((op.Ty->isSignedIntegerOrEnumerationType() ||
+ op.Ty->isUnsignedIntegerType()) &&
+ op.oneOfWraps())
+ return Builder.CreateSub(op.LHS, op.RHS, "sub");
if (op.Ty->isSignedIntegerOrEnumerationType()) {
switch (CGF.getLangOpts().getSignedOverflowBehavior()) {
case LangOptions::SOB_Defined:
@@ -4390,7 +4420,7 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
bool SanitizeSignedBase = CGF.SanOpts.has(SanitizerKind::ShiftBase) &&
Ops.Ty->hasSignedIntegerRepresentation() &&
!CGF.getLangOpts().isSignedOverflowDefined() &&
- !CGF.getLangOpts().CPlusPlus20;
+ !CGF.getLangOpts().CPlusPlus20 &&
!Ops.oneOfWraps();
bool SanitizeUnsignedBase =
CGF.SanOpts.has(SanitizerKind::UnsignedShiftBase) &&
Ops.Ty->hasUnsignedIntegerRepresentation();
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 8bce04640e748e..45dedb4cb34186 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4413,6 +4413,14 @@ void Sema::AddAlignValueAttr(Decl *D, const
AttributeCommonInfo &CI, Expr *E) {
D->addAttr(::new (Context) AlignValueAttr(Context, CI, E));
}
+static void handleWrapsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+ S.AddWrapsAttr(D, AL);
+}
+
+void Sema::AddWrapsAttr(Decl *D, const AttributeCommonInfo &CI) {
+ D->addAttr(::new (Context) WrapsAttr(Context, CI));
+}
+
static void handleAlignedAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
if (AL.hasParsedType()) {
const ParsedType &TypeArg = AL.getTypeArg();
@@ -9704,10 +9712,12 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
const ParsedAttr &AL,
case ParsedAttr::AT_AvailableOnlyInDefaultEvalMethod:
handleAvailableOnlyInDefaultEvalMethod(S, D, AL);
break;
-
case ParsedAttr::AT_CountedBy:
handleCountedByAttrField(S, D, AL);
break;
+ case ParsedAttr::AT_Wraps:
+ handleWrapsAttr(S, D, AL);
+ break;
// Microsoft attributes:
case ParsedAttr::AT_LayoutVersion:
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 8762744396f4dd..93c34ba9b58f59 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -6954,6 +6954,18 @@ static void HandleBTFTypeTagAttribute(QualType &Type,
const ParsedAttr &Attr,
::new (Ctx) BTFTypeTagAttr(Ctx, Attr, BTFTypeTag), Type);
}
+static void handleWrapsAttr(QualType &Type, const ParsedAttr &Attr,
+ TypeProcessingState &State) {
+ Sema &S = State.getSema();
+ ASTContext &Ctx = S.Context;
+
+ if (!Type->isIntegerType())
+ S.Diag(Attr.getLoc(), diag::warn_wraps_attr_var_decl_type_not_integer)
+ << Type.getAsString();
+
+ Type = State.getAttributedType(::new (Ctx) WrapsAttr(Ctx, Attr), Type, Type);
+}
+
/// HandleAddressSpaceTypeAttribute - Process an address_space attribute on the
/// specified type. The attribute contains 1 argument, the id of the address
/// space for the type.
@@ -8945,6 +8957,9 @@ static void processTypeAttrs(TypeProcessingState &state,
QualType &type,
HandleBTFTypeTagAttribute(type, attr, state);
attr.setUsedAsTypeAttr();
break;
+ case ParsedAttr::AT_Wraps:
+ handleWrapsAttr(type, attr, state);
+ break;
case ParsedAttr::AT_MayAlias:
// FIXME: This attribute needs to actually be handled, but if we ignore
diff --git a/clang/test/CodeGen/integer-overflow.c
b/clang/test/CodeGen/integer-overflow.c
index 461b026d39615b..44c42ed9efe577 100644
--- a/clang/test/CodeGen/integer-overflow.c
+++ b/clang/test/CodeGen/integer-overflow.c
@@ -105,3 +105,59 @@ void test1(void) {
// TRAPV: call ptr @llvm.frameaddress.p0(i32 0)
// CATCH_UB: call ptr @llvm.frameaddress.p0(i32 0)
}
+
+// Tests for integer overflow using __attribute__((wraps))
+typedef int __attribute__((wraps)) wrapping_int;
+
+void test2(void) {
+ // DEFAULT-LABEL: define{{.*}} void @test2
+ // WRAPV-LABEL: define{{.*}} void @test2
+ // TRAPV-LABEL: define{{.*}} void @test2
+ extern volatile wrapping_int a, b, c;
+
+ // Basically, all cases should match the WRAPV case since this attribute
+ // effectively enables wrapv for expressions containing wrapping types.
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32
+ a = b + c;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: sub i32
+ a = b - c;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: mul i32
+ a = b * c;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: sub i32 0,
+ a = -b;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32 {{.*}}, 1
+ ++b;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32 {{.*}}, -1
+ --b;
+
+ // Less trivial cases
+ extern volatile wrapping_int u, v;
+ extern volatile int w;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32
+ if (u + v < u) {}
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32
+ for (;u + v < u;) {}
+
+ // this (w+1) should have instrumentation
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: call {{.*}}
@llvm.sadd.with.overflow.i32
+ u = (w+1) + v;
+
+ // no parts of this expression should have instrumentation
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: add i32 {{.*}}, 1
+ u = (v+1) + w;
+
+ // downcast off the wraps attribute
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: call { i32, i1 }
@llvm.sadd.with.overflow.i32
+ u = (int) u + (int) v;
+
+ // DEFAULT,WRAPV,TRAPV,CATCH_UB,TRAPV_HANDLER: call { i32, i1 }
@llvm.sadd.with.overflow.i32
+ u = (int) u + w;
+}
diff --git a/clang/test/CodeGen/unsigned-overflow.c
b/clang/test/CodeGen/unsigned-overflow.c
index 6c2f0c1efc145e..471a06e5fa63ff 100644
--- a/clang/test/CodeGen/unsigned-overflow.c
+++ b/clang/test/CodeGen/unsigned-overflow.c
@@ -5,6 +5,11 @@
unsigned long li, lj, lk;
unsigned int ii, ij, ik;
+// The wraps attribute disables sanitizer instrumentation for arithmetic
+// expressions containing these types.
+unsigned long __attribute__((wraps)) li_w, lj_w, lk_w;
+unsigned int __attribute__((wraps)) ii_w, ij_w, ik_w;
+
extern void opaquelong(unsigned long);
extern void opaqueint(unsigned int);
@@ -18,6 +23,11 @@ void testlongadd(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i64, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_add_overflow
li = lj + lk;
+
+ // CHECK: [[T6:%.*]] = load i64, ptr @lj_w
+ // CHECK-NEXT: [[T7:%.*]] = load i64, ptr @lk_w
+ // CHECK-NEXT: add i64 [[T6]], [[T7]]
+ li_w = lj_w + lk_w;
}
// CHECK-LABEL: define{{.*}} void @testlongsub()
@@ -30,6 +40,11 @@ void testlongsub(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i64, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_sub_overflow
li = lj - lk;
+
+ // CHECK: [[T6:%.*]] = load i64, ptr @lj_w
+ // CHECK-NEXT: [[T7:%.*]] = load i64, ptr @lk_w
+ // CHECK-NEXT: sub i64 [[T6]], [[T7]]
+ li_w = lj_w - lk_w;
}
// CHECK-LABEL: define{{.*}} void @testlongmul()
@@ -42,28 +57,39 @@ void testlongmul(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i64, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_mul_overflow
li = lj * lk;
+
+ // CHECK: [[T6:%.*]] = load i64, ptr @lj_w
+ // CHECK-NEXT: [[T7:%.*]] = load i64, ptr @lk_w
+ // CHECK-NEXT: mul i64 [[T6]], [[T7]]
+ li_w = lj_w * lk_w;
}
// CHECK-LABEL: define{{.*}} void @testlongpostinc()
void testlongpostinc(void) {
- opaquelong(li++);
-
// CHECK: [[T1:%.*]] = load i64, ptr @li
// CHECK-NEXT: [[T2:%.*]] = call { i64, i1 }
@llvm.uadd.with.overflow.i64(i64 [[T1]], i64 1)
// CHECK-NEXT: [[T3:%.*]] = extractvalue { i64, i1 } [[T2]], 0
// CHECK-NEXT: [[T4:%.*]] = extractvalue { i64, i1 } [[T2]], 1
// CHECK: call void @__ubsan_handle_add_overflow
+ opaquelong(li++);
+
+ // CHECK: [[T5:%.*]] = load i64, ptr @li_w
+ // CHECK-NEXT: add i64 [[T5]], 1
+ opaquelong(li_w++);
}
// CHECK-LABEL: define{{.*}} void @testlongpreinc()
void testlongpreinc(void) {
- opaquelong(++li);
-
// CHECK: [[T1:%.*]] = load i64, ptr @li
// CHECK-NEXT: [[T2:%.*]] = call { i64, i1 }
@llvm.uadd.with.overflow.i64(i64 [[T1]], i64 1)
// CHECK-NEXT: [[T3:%.*]] = extractvalue { i64, i1 } [[T2]], 0
// CHECK-NEXT: [[T4:%.*]] = extractvalue { i64, i1 } [[T2]], 1
// CHECK: call void @__ubsan_handle_add_overflow
+ opaquelong(++li);
+
+ // CHECK: [[T5:%.*]] = load i64, ptr @li_w
+ // CHECK-NEXT: add i64 [[T5]], 1
+ opaquelong(++li_w);
}
// CHECK-LABEL: define{{.*}} void @testintadd()
@@ -76,6 +102,11 @@ void testintadd(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i32, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_add_overflow
ii = ij + ik;
+
+ // CHECK: [[T6:%.*]] = load i32, ptr @ij_w
+ // CHECK-NEXT: [[T7:%.*]] = load i32, ptr @ik_w
+ // CHECK-NEXT: add i32 [[T6]], [[T7]]
+ ii_w = ij_w + ik_w;
}
// CHECK-LABEL: define{{.*}} void @testintsub()
@@ -88,6 +119,11 @@ void testintsub(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i32, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_sub_overflow
ii = ij - ik;
+
+ // CHECK: [[T6:%.*]] = load i32, ptr @ij_w
+ // CHECK-NEXT: [[T7:%.*]] = load i32, ptr @ik_w
+ // CHECK-NEXT: sub i32 [[T6]], [[T7]]
+ ii_w = ij_w - ik_w;
}
// CHECK-LABEL: define{{.*}} void @testintmul()
@@ -100,26 +136,37 @@ void testintmul(void) {
// CHECK-NEXT: [[T5:%.*]] = extractvalue { i32, i1 } [[T3]], 1
// CHECK: call void @__ubsan_handle_mul_overflow
ii = ij * ik;
+
+ // CHECK: [[T6:%.*]] = load i32, ptr @ij_w
+ // CHECK-NEXT: [[T7:%.*]] = load i32, ptr @ik_w
+ // CHECK-NEXT: mul i32 [[T6]], [[T7]]
+ ii_w = ij_w * ik_w;
}
// CHECK-LABEL: define{{.*}} void @testintpostinc()
void testintpostinc(void) {
- opaqueint(ii++);
-
// CHECK: [[T1:%.*]] = load i32, ptr @ii
// CHECK-NEXT: [[T2:%.*]] = call { i32, i1 }
@llvm.uadd.with.overflow.i32(i32 [[T1]], i32 1)
// CHECK-NEXT: [[T3:%.*]] = extractvalue { i32, i1 } [[T2]], 0
// CHECK-NEXT: [[T4:%.*]] = extractvalue { i32, i1 } [[T2]], 1
// CHECK: call void @__ubsan_handle_add_overflow
+ opaqueint(ii++);
+
+ // CHECK: [[T5:%.*]] = load i32, ptr @ii_w
+ // CHECK-NEXT: add i32 [[T5]], 1
+ opaqueint(ii_w++);
}
// CHECK-LABEL: define{{.*}} void @testintpreinc()
void testintpreinc(void) {
- opaqueint(++ii);
-
// CHECK: [[T1:%.*]] = load i32, ptr @ii
// CHECK-NEXT: [[T2:%.*]] = call { i32, i1 }
@llvm.uadd.with.overflow.i32(i32 [[T1]], i32 1)
// CHECK-NEXT: [[T3:%.*]] = extractvalue { i32, i1 } [[T2]], 0
// CHECK-NEXT: [[T4:%.*]] = extractvalue { i32, i1 } [[T2]], 1
// CHECK: call void @__ubsan_handle_add_overflow
+ opaqueint(++ii);
+
+ // CHECK: [[T5:%.*]] = load i32, ptr @ii_w
+ // CHECK-NEXT: add i32 [[T5]], 1
+ opaqueint(++ii_w);
}
diff --git a/clang/test/Sema/attr-wraps.c b/clang/test/Sema/attr-wraps.c
new file mode 100644
index 00000000000000..97aff317120633
--- /dev/null
+++ b/clang/test/Sema/attr-wraps.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only -triple x86_64-pc-linux-gnu
+// expected-no-diagnostics
+typedef int __attribute__((wraps)) wrapping_int;
+
+void foo(void) {
+ const wrapping_int A = 1;
+ int D = 2147483647 + A;
+ (void)D;
+}
>From 6794e45c63a396c18707e10f20a12d36a775457a Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Tue, 26 Mar 2024 23:29:29 +0000
Subject: [PATCH 02/10] add wraps bypass for
implicit-(un)signed-integer-truncation sanitizers
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/lib/CodeGen/CGExprScalar.cpp | 3 ++-
clang/lib/Sema/SemaChecking.cpp | 5 +++--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index be1cae5ca8ea42..f07388fdec6869 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1108,7 +1108,8 @@ void ScalarExprEmitter::EmitIntegerTruncationCheck(Value
*Src, QualType SrcType,
// If the comparison result is 'i1 false', then the truncation was lossy.
// Do we care about this type of truncation?
- if (!CGF.SanOpts.has(Check.second.second))
+ if (!CGF.SanOpts.has(Check.second.second) ||
+ DstType.getTypePtr()->hasAttr(attr::Wraps))
return;
llvm::Constant *StaticArgs[] = {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index b84a779b7189c0..65504da36f9751 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -16439,7 +16439,8 @@ static void CheckImplicitConversion(Sema &S, Expr *E,
QualType T,
S.Context, E, S.isConstantEvaluatedContext(), /*Approximate=*/true);
IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
- if (LikelySourceRange.Width > TargetRange.Width) {
+ if (LikelySourceRange.Width > TargetRange.Width &&
+ !T.getTypePtr()->hasAttr(attr::Wraps)) {
// If the source is a constant, use a default-on diagnostic.
// TODO: this should happen for bitfield stores, too.
Expr::EvalResult Result;
@@ -16487,7 +16488,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E,
QualType T,
if (TargetRange.Width == LikelySourceRange.Width &&
!TargetRange.NonNegative && LikelySourceRange.NonNegative &&
- Source->isSignedIntegerType()) {
+ Source->isSignedIntegerType() && !T.getTypePtr()->hasAttr(attr::Wraps)) {
// Warn when doing a signed to signed conversion, warn if the positive
// source value is exactly the width of the target type, which will
// cause a negative value to be stored.
>From 0f7e8c96cd197dc273c19b071f98e41fd9185b26 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Tue, 9 Apr 2024 21:29:35 +0000
Subject: [PATCH 03/10] don't support c++
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/include/clang/Basic/Attr.td | 2 +-
clang/lib/Sema/SemaDeclAttr.cpp | 5 +++++
clang/lib/Sema/SemaType.cpp | 5 +++++
3 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/clang/include/clang/Basic/Attr.td
b/clang/include/clang/Basic/Attr.td
index 06e41fcee206c4..26c152e50845ce 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -4508,7 +4508,7 @@ def CodeAlign: StmtAttr {
}
def Wraps : DeclOrTypeAttr {
- let Spellings = [Clang<"wraps">, CXX11<"", "wraps", 202403>];
+ let Spellings = [GNU<"wraps">];
let Subjects = SubjectList<[Var, TypedefName, Field]>;
let Documentation = [WrapsDocs];
}
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 45dedb4cb34186..15380ecc3bba6d 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4414,6 +4414,11 @@ void Sema::AddAlignValueAttr(Decl *D, const
AttributeCommonInfo &CI, Expr *E) {
}
static void handleWrapsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+ if (S.getLangOpts().CPlusPlus) {
+ S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
+ return;
+ }
+
S.AddWrapsAttr(D, AL);
}
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 93c34ba9b58f59..52cf8d730dadd5 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -6959,6 +6959,11 @@ static void handleWrapsAttr(QualType &Type, const
ParsedAttr &Attr,
Sema &S = State.getSema();
ASTContext &Ctx = S.Context;
+ // No need to warn here, that is handled by SemaDeclAttr.
+ // Simply disable applying this attribute.
+ if (S.getLangOpts().CPlusPlus)
+ return;
+
if (!Type->isIntegerType())
S.Diag(Attr.getLoc(), diag::warn_wraps_attr_var_decl_type_not_integer)
<< Type.getAsString();
>From 44d6238ceb627ee50a056f7fcb35c82fe828ad48 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Tue, 9 Apr 2024 22:57:55 +0000
Subject: [PATCH 04/10] fix AttrDocs code block syntax error
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/include/clang/Basic/AttrDocs.td | 2 ++
1 file changed, 2 insertions(+)
diff --git a/clang/include/clang/Basic/AttrDocs.td
b/clang/include/clang/Basic/AttrDocs.td
index a2adb923e3c47c..d8a65dbeca0aaf 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -8071,6 +8071,7 @@ definition when building with
``-fsanitize=signed-integer-overflow``
}
int main() { foo(); }
+}
In the following example, we use ``__attribute__((wraps))`` on a variable to
disable overflow instrumentation for arithmetic expressions it appears in. We
@@ -8093,6 +8094,7 @@ sanitizers (like
``-fsanitize=unsigned-integer-overflow``).
// now, handle non-overflow case
// ...
}
+}
The above example demonstrates some of the power and elegance this attribute
provides. We can use code patterns we are already familiar with (like ``if (x +
>From 5e6d926532c2cff3288f25e9b8f872e7f2ec9b65 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Wed, 10 Apr 2024 21:49:12 +0000
Subject: [PATCH 05/10] rename oneOfWraps -> hasWrappingOperand
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/include/clang/AST/Expr.h | 2 +-
clang/lib/AST/Expr.cpp | 6 +++---
clang/lib/CodeGen/CGExprScalar.cpp | 18 +++++++++---------
3 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 68cd7d7c0fac3b..6d053cf4304f07 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -4079,7 +4079,7 @@ class BinaryOperator : public Expr {
}
/// Do one of the subexpressions have the wraps attribute?
- bool oneOfWraps(const ASTContext &Ctx) const;
+ bool hasWrappingOperand(const ASTContext &Ctx) const;
};
/// CompoundAssignOperator - For compound assignments (e.g. +=), we keep
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index f8cf0559f8eac4..97067df05bdc24 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2237,7 +2237,7 @@ bool
BinaryOperator::isNullPointerArithmeticExtension(ASTContext &Ctx,
return true;
}
-bool BinaryOperator::oneOfWraps(const ASTContext &Ctx) const {
+bool BinaryOperator::hasWrappingOperand(const ASTContext &Ctx) const {
llvm::SmallVector<Expr *, 2> Both = {getLHS(), getRHS()};
for (const Expr *oneOf : Both) {
@@ -4766,7 +4766,7 @@ BinaryOperator::BinaryOperator(const ASTContext &Ctx,
Expr *lhs, Expr *rhs,
if (hasStoredFPFeatures())
setStoredFPFeatures(FPFeatures);
setDependence(computeDependence(this));
- if (oneOfWraps(Ctx))
+ if (hasWrappingOperand(Ctx))
setType(Ctx.getAttributedType(attr::Wraps, getType(), getType()));
}
@@ -4785,7 +4785,7 @@ BinaryOperator::BinaryOperator(const ASTContext &Ctx,
Expr *lhs, Expr *rhs,
if (hasStoredFPFeatures())
setStoredFPFeatures(FPFeatures);
setDependence(computeDependence(this));
- if (oneOfWraps(Ctx))
+ if (hasWrappingOperand(Ctx))
setType(Ctx.getAttributedType(attr::Wraps, getType(), getType()));
}
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index f07388fdec6869..005affc4ffafa2 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -150,7 +150,7 @@ struct BinOpInfo {
/// Does the BinaryOperator have the wraps attribute?
/// If so, we can ellide overflow sanitizer checks.
- bool oneOfWraps() const {
+ bool hasWrappingOperand() const {
const Type *TyPtr = E->getType().getTypePtrOrNull();
if (TyPtr)
return TyPtr->hasAttr(attr::Wraps);
@@ -737,7 +737,7 @@ class ScalarExprEmitter
Value *EmitMul(const BinOpInfo &Ops) {
if ((Ops.Ty->isSignedIntegerOrEnumerationType() ||
Ops.Ty->isUnsignedIntegerType()) &&
- Ops.oneOfWraps())
+ Ops.hasWrappingOperand())
return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
if (Ops.Ty->isSignedIntegerOrEnumerationType()) {
@@ -2897,11 +2897,11 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const
UnaryOperator *E, LValue LV,
// overflow because of promotion rules; we're just eliding a few steps
// here.
} else if (E->canOverflow() && type->isSignedIntegerOrEnumerationType() &&
- !Ops.oneOfWraps()) {
+ !Ops.hasWrappingOperand()) {
value = EmitIncDecConsiderOverflowBehavior(E, value, isInc);
} else if (E->canOverflow() && type->isUnsignedIntegerType() &&
CGF.SanOpts.has(SanitizerKind::UnsignedIntegerOverflow) &&
- !Ops.oneOfWraps()) {
+ !Ops.hasWrappingOperand()) {
value = EmitOverflowCheckedBinOp(createBinOpInfoFromIncDec(
E, value, isInc, E->getFPFeaturesInEffect(CGF.getLangOpts())));
} else {
@@ -3691,7 +3691,7 @@ Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow)) &&
Ops.Ty->isIntegerType() &&
(Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow()) &&
- !Ops.oneOfWraps()) {
+ !Ops.hasWrappingOperand()) {
llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, true);
} else if (CGF.SanOpts.has(SanitizerKind::FloatDivideByZero) &&
@@ -3741,7 +3741,7 @@ Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
CGF.SanOpts.has(SanitizerKind::SignedIntegerOverflow)) &&
Ops.Ty->isIntegerType() &&
(Ops.mayHaveIntegerDivisionByZero() || Ops.mayHaveIntegerOverflow()) &&
- !Ops.oneOfWraps()) {
+ !Ops.hasWrappingOperand()) {
CodeGenFunction::SanitizerScope SanScope(&CGF);
llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, false);
@@ -4108,7 +4108,7 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &op) {
if ((op.Ty->isSignedIntegerOrEnumerationType() ||
op.Ty->isUnsignedIntegerType()) &&
- op.oneOfWraps())
+ op.hasWrappingOperand())
return Builder.CreateAdd(op.LHS, op.RHS, "add");
if (op.Ty->isSignedIntegerOrEnumerationType()) {
@@ -4269,7 +4269,7 @@ Value *ScalarExprEmitter::EmitSub(const BinOpInfo &op) {
if (!op.LHS->getType()->isPointerTy()) {
if ((op.Ty->isSignedIntegerOrEnumerationType() ||
op.Ty->isUnsignedIntegerType()) &&
- op.oneOfWraps())
+ op.hasWrappingOperand())
return Builder.CreateSub(op.LHS, op.RHS, "sub");
if (op.Ty->isSignedIntegerOrEnumerationType()) {
switch (CGF.getLangOpts().getSignedOverflowBehavior()) {
@@ -4421,7 +4421,7 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
bool SanitizeSignedBase = CGF.SanOpts.has(SanitizerKind::ShiftBase) &&
Ops.Ty->hasSignedIntegerRepresentation() &&
!CGF.getLangOpts().isSignedOverflowDefined() &&
- !CGF.getLangOpts().CPlusPlus20 &&
!Ops.oneOfWraps();
+ !CGF.getLangOpts().CPlusPlus20 &&
!Ops.hasWrappingOperand();
bool SanitizeUnsignedBase =
CGF.SanOpts.has(SanitizerKind::UnsignedShiftBase) &&
Ops.Ty->hasUnsignedIntegerRepresentation();
>From 0d7566777f06b3f2058d93dd77624ab2c66f1127 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Wed, 10 Apr 2024 21:52:43 +0000
Subject: [PATCH 06/10] fixup C-only rules and checks
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/docs/ReleaseNotes.rst | 3 ++-
clang/include/clang/Basic/Attr.td | 3 ++-
clang/lib/Sema/SemaDeclAttr.cpp | 5 -----
clang/lib/Sema/SemaType.cpp | 5 -----
4 files changed, 4 insertions(+), 12 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index cb02af7e948989..9dfe18822496a6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -289,7 +289,8 @@ Attribute Changes in Clang
overflow warnings or sanitizer warnings. They also cannot be optimized away
by some eager UB optimizations.
- This attribute is ignored in C++.
+ This attribute is only valid for C, as there are built-in language
+ alternatives for other languages.
Improvements to Clang's diagnostics
-----------------------------------
diff --git a/clang/include/clang/Basic/Attr.td
b/clang/include/clang/Basic/Attr.td
index 26c152e50845ce..f23cfc3b12d2de 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -4508,7 +4508,8 @@ def CodeAlign: StmtAttr {
}
def Wraps : DeclOrTypeAttr {
- let Spellings = [GNU<"wraps">];
+ let Spellings = [Clang<"wraps">];
let Subjects = SubjectList<[Var, TypedefName, Field]>;
let Documentation = [WrapsDocs];
+ let LangOpts = [COnly];
}
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 15380ecc3bba6d..45dedb4cb34186 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4414,11 +4414,6 @@ void Sema::AddAlignValueAttr(Decl *D, const
AttributeCommonInfo &CI, Expr *E) {
}
static void handleWrapsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
- if (S.getLangOpts().CPlusPlus) {
- S.Diag(AL.getLoc(), diag::warn_attribute_ignored) << AL;
- return;
- }
-
S.AddWrapsAttr(D, AL);
}
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 52cf8d730dadd5..93c34ba9b58f59 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -6959,11 +6959,6 @@ static void handleWrapsAttr(QualType &Type, const
ParsedAttr &Attr,
Sema &S = State.getSema();
ASTContext &Ctx = S.Context;
- // No need to warn here, that is handled by SemaDeclAttr.
- // Simply disable applying this attribute.
- if (S.getLangOpts().CPlusPlus)
- return;
-
if (!Type->isIntegerType())
S.Diag(Attr.getLoc(), diag::warn_wraps_attr_var_decl_type_not_integer)
<< Type.getAsString();
>From a2f63982920f22d795c4971800bcc5cb55356570 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Wed, 10 Apr 2024 22:31:10 +0000
Subject: [PATCH 07/10] simplify hasWrappingOperand with QualType additions
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/include/clang/AST/Type.h | 2 ++
clang/lib/AST/Expr.cpp | 14 ++------------
clang/lib/AST/Type.cpp | 4 ++++
clang/lib/CodeGen/CGExprScalar.cpp | 5 +----
4 files changed, 9 insertions(+), 16 deletions(-)
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 99f45d518c7960..687711ecd6c6eb 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -1239,6 +1239,8 @@ class QualType {
return getQualifiers().hasStrongOrWeakObjCLifetime();
}
+ bool hasWrapsAttr() const;
+
// true when Type is objc's weak and weak is enabled but ARC isn't.
bool isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const;
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 97067df05bdc24..dcaaabf224e610 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2238,18 +2238,8 @@ bool
BinaryOperator::isNullPointerArithmeticExtension(ASTContext &Ctx,
}
bool BinaryOperator::hasWrappingOperand(const ASTContext &Ctx) const {
- llvm::SmallVector<Expr *, 2> Both = {getLHS(), getRHS()};
-
- for (const Expr *oneOf : Both) {
- if (!oneOf)
- continue;
- if (auto *TypePtr =
- oneOf->IgnoreParenImpCasts()->getType().getTypePtrOrNull())
- if (TypePtr->hasAttr(attr::Wraps)) {
- return true;
- }
- }
- return false;
+ return getLHS()->getType().hasWrapsAttr() ||
+ getRHS()->getType().hasWrapsAttr();
}
SourceLocExpr::SourceLocExpr(const ASTContext &Ctx, SourceLocIdentKind Kind,
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index cb22c91a12aa89..3dddfaf328886a 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -2807,6 +2807,10 @@ bool QualType::isTriviallyEqualityComparableType(
CanonicalType, /*CheckIfTriviallyCopyable=*/false);
}
+bool QualType::hasWrapsAttr() const {
+ return !isNull() && getTypePtr()->hasAttr(attr::Wraps);
+}
+
bool QualType::isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const {
return !Context.getLangOpts().ObjCAutoRefCount &&
Context.getLangOpts().ObjCWeak &&
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index 005affc4ffafa2..a001cdc7b5f7f7 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -151,10 +151,7 @@ struct BinOpInfo {
/// Does the BinaryOperator have the wraps attribute?
/// If so, we can ellide overflow sanitizer checks.
bool hasWrappingOperand() const {
- const Type *TyPtr = E->getType().getTypePtrOrNull();
- if (TyPtr)
- return TyPtr->hasAttr(attr::Wraps);
- return false;
+ return E->getType().hasWrapsAttr();
}
};
>From a3e9abdfdeb3ca4ae0cddd9c9c76b9c7a717be57 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Wed, 10 Apr 2024 22:37:17 +0000
Subject: [PATCH 08/10] run git-clang-format
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/lib/CodeGen/CGExprScalar.cpp | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index a001cdc7b5f7f7..4d996b4c5741bc 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -150,9 +150,7 @@ struct BinOpInfo {
/// Does the BinaryOperator have the wraps attribute?
/// If so, we can ellide overflow sanitizer checks.
- bool hasWrappingOperand() const {
- return E->getType().hasWrapsAttr();
- }
+ bool hasWrappingOperand() const { return E->getType().hasWrapsAttr(); }
};
static bool MustVisitNullValue(const Expr *E) {
@@ -4418,7 +4416,8 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
bool SanitizeSignedBase = CGF.SanOpts.has(SanitizerKind::ShiftBase) &&
Ops.Ty->hasSignedIntegerRepresentation() &&
!CGF.getLangOpts().isSignedOverflowDefined() &&
- !CGF.getLangOpts().CPlusPlus20 &&
!Ops.hasWrappingOperand();
+ !CGF.getLangOpts().CPlusPlus20 &&
+ !Ops.hasWrappingOperand();
bool SanitizeUnsignedBase =
CGF.SanOpts.has(SanitizerKind::UnsignedShiftBase) &&
Ops.Ty->hasUnsignedIntegerRepresentation();
>From eb08ca00a05f3339ed389a5cca88042002e7e7e7 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Wed, 10 Apr 2024 22:57:35 +0000
Subject: [PATCH 09/10] fixup cases where hasWrapsAttr should be used
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/lib/AST/ExprConstant.cpp | 4 ++--
clang/lib/CodeGen/CGExprScalar.cpp | 2 +-
clang/lib/Sema/SemaChecking.cpp | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 51dd73bf1ee897..269f22ab4b56d0 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2776,7 +2776,7 @@ static bool CheckedIntArithmetic(EvalInfo &Info, const
Expr *E,
Result = Value.trunc(LHS.getBitWidth());
if (Result.extend(BitWidth) != Value) {
if (Info.checkingForUndefinedBehavior() &&
- !E->getType().getTypePtr()->hasAttr(attr::Wraps))
+ !E->getType().hasWrapsAttr())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Result, 10, Result.isSigned(),
/*formatAsCLiteral=*/false,
@@ -13995,7 +13995,7 @@ bool IntExprEvaluator::VisitUnaryOperator(const
UnaryOperator *E) {
const APSInt &Value = Result.getInt();
if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
if (Info.checkingForUndefinedBehavior() &&
- !E->getType().getTypePtr()->hasAttr(attr::Wraps))
+ !E->getType().hasWrapsAttr())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Value, 10, Value.isSigned(),
/*formatAsCLiteral=*/false,
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index 4d996b4c5741bc..5a12f1187a68f6 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1104,7 +1104,7 @@ void ScalarExprEmitter::EmitIntegerTruncationCheck(Value
*Src, QualType SrcType,
// Do we care about this type of truncation?
if (!CGF.SanOpts.has(Check.second.second) ||
- DstType.getTypePtr()->hasAttr(attr::Wraps))
+ DstType.hasWrapsAttr())
return;
llvm::Constant *StaticArgs[] = {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 65504da36f9751..05e1dfde5f6281 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -16440,7 +16440,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E,
QualType T,
IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
if (LikelySourceRange.Width > TargetRange.Width &&
- !T.getTypePtr()->hasAttr(attr::Wraps)) {
+ !T.hasWrapsAttr()) {
// If the source is a constant, use a default-on diagnostic.
// TODO: this should happen for bitfield stores, too.
Expr::EvalResult Result;
@@ -16488,7 +16488,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E,
QualType T,
if (TargetRange.Width == LikelySourceRange.Width &&
!TargetRange.NonNegative && LikelySourceRange.NonNegative &&
- Source->isSignedIntegerType() && !T.getTypePtr()->hasAttr(attr::Wraps)) {
+ Source->isSignedIntegerType() && !T.hasWrapsAttr()) {
// Warn when doing a signed to signed conversion, warn if the positive
// source value is exactly the width of the target type, which will
// cause a negative value to be stored.
>From 85a9b2f0e71eb1893d28aa3a8e35b29172c10521 Mon Sep 17 00:00:00 2001
From: Justin Stitt <justinst...@google.com>
Date: Thu, 11 Apr 2024 23:38:27 +0000
Subject: [PATCH 10/10] git-clang-format
Signed-off-by: Justin Stitt <justinst...@google.com>
---
clang/lib/AST/ExprConstant.cpp | 6 ++----
clang/lib/CodeGen/CGExprScalar.cpp | 3 +--
clang/lib/Sema/SemaChecking.cpp | 3 +--
3 files changed, 4 insertions(+), 8 deletions(-)
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 269f22ab4b56d0..9ff28863fb9a74 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2775,8 +2775,7 @@ static bool CheckedIntArithmetic(EvalInfo &Info, const
Expr *E,
APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
Result = Value.trunc(LHS.getBitWidth());
if (Result.extend(BitWidth) != Value) {
- if (Info.checkingForUndefinedBehavior() &&
- !E->getType().hasWrapsAttr())
+ if (Info.checkingForUndefinedBehavior() && !E->getType().hasWrapsAttr())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Result, 10, Result.isSigned(),
/*formatAsCLiteral=*/false,
@@ -13994,8 +13993,7 @@ bool IntExprEvaluator::VisitUnaryOperator(const
UnaryOperator *E) {
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
- if (Info.checkingForUndefinedBehavior() &&
- !E->getType().hasWrapsAttr())
+ if (Info.checkingForUndefinedBehavior() && !E->getType().hasWrapsAttr())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< toString(Value, 10, Value.isSigned(),
/*formatAsCLiteral=*/false,
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp
b/clang/lib/CodeGen/CGExprScalar.cpp
index 5a12f1187a68f6..f13128df57b849 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -1103,8 +1103,7 @@ void ScalarExprEmitter::EmitIntegerTruncationCheck(Value
*Src, QualType SrcType,
// If the comparison result is 'i1 false', then the truncation was lossy.
// Do we care about this type of truncation?
- if (!CGF.SanOpts.has(Check.second.second) ||
- DstType.hasWrapsAttr())
+ if (!CGF.SanOpts.has(Check.second.second) || DstType.hasWrapsAttr())
return;
llvm::Constant *StaticArgs[] = {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 05e1dfde5f6281..cddcc1e9ae752d 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -16439,8 +16439,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E,
QualType T,
S.Context, E, S.isConstantEvaluatedContext(), /*Approximate=*/true);
IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
- if (LikelySourceRange.Width > TargetRange.Width &&
- !T.hasWrapsAttr()) {
+ if (LikelySourceRange.Width > TargetRange.Width && !T.hasWrapsAttr()) {
// If the source is a constant, use a default-on diagnostic.
// TODO: this should happen for bitfield stores, too.
Expr::EvalResult Result;
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