[clang] 79a28aa - [clang] Ignore GCC 11 [[malloc(x)]] attribute
via cfe-commits
cfe-commits at lists.llvm.org
Thu Feb 27 08:07:03 PST 2025
Author: Alois Klink
Date: 2025-02-27T08:06:58-08:00
New Revision: 79a28aa0a48feba34ddc3c1791ea0be88f354542
URL: https://github.com/llvm/llvm-project/commit/79a28aa0a48feba34ddc3c1791ea0be88f354542
DIFF: https://github.com/llvm/llvm-project/commit/79a28aa0a48feba34ddc3c1791ea0be88f354542.diff
LOG: [clang] Ignore GCC 11 [[malloc(x)]] attribute
Ignore the `[[malloc(x)]]` or `[[malloc(x, 1)]]` function attribute
syntax added in [GCC 11][1] and print a warning instead of an error.
Unlike `[[malloc]]` with no arguments (which is supported by Clang),
GCC uses the one or two argument form to specify a deallocator for
GCC's static analyzer.
Code currently compiled with `[[malloc(x)]]` or
`__attribute((malloc(x)))` fails with the following error:
`'malloc' attribute takes no arguments`.
[1]: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;f=gcc/doc/extend.texi;h=dce6c58db87ebf7f4477bd3126228e73e4eeee97#patch6
Fixes: https://github.com/llvm/llvm-project/issues/51607
Partial-Bug: https://github.com/llvm/llvm-project/issues/53152
Added:
clang/test/CodeGen/attr-malloc.c
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/CodeGen/CGCall.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/Sema/attr-args.c
clang/test/SemaCXX/attr-print.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 431a4c73efd25..b7225e50d83a3 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -233,6 +233,11 @@ Bug Fixes to Attribute Support
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
- Fixed crash when a parameter to the ``clang::annotate`` attribute evaluates to ``void``. See #GH119125
+- Clang now emits a warning instead of an error when using the one or two
+ argument form of GCC 11's ``__attribute__((malloc(deallocator)))``
+ or ``__attribute__((malloc(deallocator, ptr-index)))``
+ (`#51607 <https://github.com/llvm/llvm-project/issues/51607>`_).
+
Bug Fixes to C++ Support
^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 7cf15f503868e..80a51c92cc520 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1904,6 +1904,8 @@ def IFunc : Attr, TargetSpecificAttr<TargetIFuncSupport> {
def Restrict : InheritableAttr {
let Spellings = [Declspec<"restrict">, GCC<"malloc">];
+ let Args = [ExprArgument<"Deallocator", /*opt=*/ 1>,
+ ParamIdxArgument<"DeallocatorPtrArgIndex", /*opt=*/ 1>];
let Subjects = SubjectList<[Function]>;
let Documentation = [RestrictDocs];
}
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 8fc7edcffd25b..d6d43df44fb21 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -4966,9 +4966,17 @@ def RestrictDocs : Documentation {
let Category = DocCatFunction;
let Heading = "malloc";
let Content = [{
-The ``malloc`` attribute indicates that the function acts like a system memory
-allocation function, returning a pointer to allocated storage disjoint from the
-storage for any other object accessible to the caller.
+The ``malloc`` attribute has two forms with
diff erent functionality. The first
+is when it is used without arguments, where it marks that a function acts like
+a system memory allocation function, returning a pointer to allocated storage
+that does not alias storage from any other object accessible to the caller.
+
+The second form is when ``malloc`` takes one or two arguments. The first
+argument names a function that should be associated with this function as its
+deallocation function. When this form is used, it enables the compiler to
+diagnose when the incorrect deallocation function is used with this variable.
+However the associated warning, spelled `-Wmismatched-dealloc` in GCC, is not
+yet implemented in clang.
}];
}
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 12e2e471d0307..d094c075ecee2 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3155,6 +3155,10 @@ def warn_auto_var_is_id : Warning<
InGroup<DiagGroup<"auto-var-id">>;
// Attributes
+def warn_attribute_form_ignored : Warning<
+ "%0 attribute ignored because Clang does not yet support this attribute signature">,
+ InGroup<IgnoredAttributes>;
+
def warn_attribute_ignored_no_calls_in_stmt: Warning<
"%0 attribute is ignored because there exists no call expression inside the "
"statement">,
@@ -4528,6 +4532,12 @@ def err_attribute_cleanup_func_must_take_one_arg : Error<
def err_attribute_cleanup_func_arg_incompatible_type : Error<
"'cleanup' function %0 parameter has "
"%
diff {type $ which is incompatible with type $|incompatible type}1,2">;
+def err_attribute_malloc_arg_not_function : Error<
+ "'malloc' argument %select{for deallocator |%1 |%1 }0is not a %select{||single }0function">;
+def err_attribute_malloc_arg_not_function_with_pointer_arg : Error<
+ "'malloc' argument %0 must take a pointer type as its first argument">;
+def err_attribute_malloc_arg_refers_to_non_pointer_type : Error<
+ "'malloc' argument '%0' refers to non-pointer type %1 of %2">; // in GCC, this is a warning, not an error
def err_attribute_regparm_wrong_platform : Error<
"'regparm' is not valid on this platform">;
def err_attribute_regparm_invalid_number : Error<
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 88b1a8aebfa50..916455bc69393 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -2434,7 +2434,8 @@ void CodeGenModule::ConstructAttributeList(StringRef Name,
FuncAttrs.addMemoryAttr(llvm::MemoryEffects::inaccessibleOrArgMemOnly());
FuncAttrs.addAttribute(llvm::Attribute::NoUnwind);
}
- if (TargetDecl->hasAttr<RestrictAttr>())
+ if (const auto *RA = TargetDecl->getAttr<RestrictAttr>();
+ RA && RA->getDeallocator() == nullptr)
RetAttrs.addAttribute(llvm::Attribute::NoAlias);
if (TargetDecl->hasAttr<ReturnsNonNullAttr>() &&
!CodeGenOpts.NullPointerIsValid)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index fdf3b9c636127..942259b57c88b 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1780,13 +1780,89 @@ static void handleTLSModelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
static void handleRestrictAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
QualType ResultType = getFunctionOrMethodResultType(D);
- if (ResultType->isAnyPointerType() || ResultType->isBlockPointerType()) {
+ if (!ResultType->isAnyPointerType() && !ResultType->isBlockPointerType()) {
+ S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
+ << AL << getFunctionOrMethodResultSourceRange(D);
+ return;
+ }
+
+ if (AL.getNumArgs() == 0) {
D->addAttr(::new (S.Context) RestrictAttr(S.Context, AL));
return;
}
- S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
- << AL << getFunctionOrMethodResultSourceRange(D);
+ if (AL.getAttributeSpellingListIndex() == RestrictAttr::Declspec_restrict) {
+ // __declspec(restrict) accepts no arguments
+ S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 0;
+ return;
+ }
+
+ // [[gnu::malloc(deallocator)]] with args specifies a deallocator function
+ Expr *DeallocE = AL.getArgAsExpr(0);
+ SourceLocation DeallocLoc = DeallocE->getExprLoc();
+ FunctionDecl *DeallocFD = nullptr;
+ DeclarationNameInfo DeallocNI;
+
+ if (auto *DRE = dyn_cast<DeclRefExpr>(DeallocE)) {
+ DeallocFD = dyn_cast<FunctionDecl>(DRE->getDecl());
+ DeallocNI = DRE->getNameInfo();
+ if (!DeallocFD) {
+ S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function)
+ << 1 << DeallocNI.getName();
+ return;
+ }
+ } else if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(DeallocE)) {
+ DeallocFD = S.ResolveSingleFunctionTemplateSpecialization(ULE, true);
+ DeallocNI = ULE->getNameInfo();
+ if (!DeallocFD) {
+ S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function)
+ << 2 << DeallocNI.getName();
+ if (ULE->getType() == S.Context.OverloadTy)
+ S.NoteAllOverloadCandidates(ULE);
+ return;
+ }
+ } else {
+ S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function) << 0;
+ return;
+ }
+
+ // 2nd arg of [[gnu::malloc(deallocator, 2)]] with args specifies the param
+ // of deallocator that deallocates the pointer (defaults to 1)
+ ParamIdx DeallocPtrIdx;
+ if (AL.getNumArgs() == 1) {
+ DeallocPtrIdx = ParamIdx(1, DeallocFD);
+
+ if (!DeallocPtrIdx.isValid() ||
+ !getFunctionOrMethodParamType(DeallocFD, DeallocPtrIdx.getASTIndex())
+ .getCanonicalType()
+ ->isPointerType()) {
+ S.Diag(DeallocLoc,
+ diag::err_attribute_malloc_arg_not_function_with_pointer_arg)
+ << DeallocNI.getName();
+ return;
+ }
+ } else {
+ if (!S.checkFunctionOrMethodParameterIndex(
+ DeallocFD, AL, 2, AL.getArgAsExpr(1), DeallocPtrIdx,
+ /* CanIndexImplicitThis=*/false))
+ return;
+
+ QualType DeallocPtrArgType =
+ getFunctionOrMethodParamType(DeallocFD, DeallocPtrIdx.getASTIndex());
+ if (!DeallocPtrArgType.getCanonicalType()->isPointerType()) {
+ S.Diag(DeallocLoc,
+ diag::err_attribute_malloc_arg_refers_to_non_pointer_type)
+ << DeallocPtrIdx.getSourceIndex() << DeallocPtrArgType
+ << DeallocNI.getName();
+ return;
+ }
+ }
+
+ // FIXME: we should add this attribute to Clang's AST, so that clang-analyzer
+ // can use it, see -Wmismatched-dealloc in GCC for what we can do with this.
+ S.Diag(AL.getLoc(), diag::warn_attribute_form_ignored) << AL;
+ D->addAttr(::new (S.Context)
+ RestrictAttr(S.Context, AL, DeallocE, DeallocPtrIdx));
}
static void handleCPUSpecificAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
diff --git a/clang/test/CodeGen/attr-malloc.c b/clang/test/CodeGen/attr-malloc.c
new file mode 100644
index 0000000000000..e69f8bce55f3b
--- /dev/null
+++ b/clang/test/CodeGen/attr-malloc.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+int *Mem;
+void dealloc(int*);
+
+__attribute__((malloc)) int *MallocFunc(){ return Mem;}
+// CHECK: define[[BEFORE:.*]] noalias[[AFTER:.*]]@MallocFunc
+// Ensure these two do not generate noalias here.
+__attribute__((malloc(dealloc))) int *MallocFunc2(){ return Mem;}
+// CHECK: define[[BEFORE]][[AFTER]]@MallocFunc2
+__attribute__((malloc(dealloc, 1))) int *MallocFunc3(){ return Mem;}
+// CHECK: define[[BEFORE]][[AFTER]]@MallocFunc3
diff --git a/clang/test/Sema/attr-args.c b/clang/test/Sema/attr-args.c
index e275c90be1f9d..db69a99bdee3b 100644
--- a/clang/test/Sema/attr-args.c
+++ b/clang/test/Sema/attr-args.c
@@ -1,12 +1,24 @@
-// RUN: %clang_cc1 -verify -Wunused -Wused-but-marked-unused -Wunused-parameter -fsyntax-only %s
+// RUN: %clang_cc1 -verify -Wunused -Wused-but-marked-unused -Wunused-parameter -fsyntax-only -fdeclspec %s
int a;
+void func_a(void * ptr, int a);
+void func_b(int a);
+void __attribute__((overloadable)) ambigious_func(void *); // expected-note {{candidate function}}
+void __attribute__((overloadable)) ambigious_func(void *, int); // expected-note {{candidate function}}
inline __attribute__((noreturn(a))) void *f1(void); // expected-error {{'noreturn' attribute takes no arguments}}
inline __attribute__((always_inline(a))) void *f2(void); // expected-error {{'always_inline' attribute takes no arguments}}
inline __attribute__((cdecl(a))) void *f3(void); // expected-error {{'cdecl' attribute takes no arguments}}
inline __attribute__((const(a))) void *f4(void); // expected-error {{'const' attribute takes no arguments}}
inline __attribute__((fastcall(a))) void *f5(void); // expected-error {{'fastcall' attribute takes no arguments}}
-inline __attribute__((malloc(a))) void *f5(void); // expected-error {{'malloc' attribute takes no arguments}}
+inline __declspec(restrict(a)) void *f6_a(void); // expected-error {{'restrict' attribute takes no arguments}}
+inline __attribute__((malloc(func_a, 1, a))) void *f6_b(void); // expected-error {{'malloc' attribute takes no more than 2 arguments}}
+inline __attribute__((malloc(func_a, 1))) void *f6_c(void); // expected-warning {{'malloc' attribute ignored because Clang does not yet support this attribute signature}}
+inline __attribute__((malloc(1234))) void *f6_d(void); // expected-error {{'malloc' argument for deallocator is not a function}}
+inline __attribute__((malloc(a))) void *f6_e(void); // expected-error {{'malloc' argument 'a' is not a function}}
+inline __attribute__((malloc(ambigious_func))) void *f6_f(void); // expected-error {{'malloc' argument 'ambigious_func' is not a single function}}
+inline __attribute__((malloc(func_b))) void *f6_g(void); // expected-error {{'malloc' argument 'func_b' must take a pointer type as its first argument}}
+inline __attribute__((malloc(func_a, 3))) void *f6_h(void); // expected-error {{'malloc' attribute parameter 2 is out of bounds}}
+inline __attribute__((malloc(func_a, 2))) void *f6_i(void); // expected-error {{'malloc' argument '2' refers to non-pointer type 'int' of 'func_a'}}
inline __attribute__((nothrow(a))) void *f7(void); // expected-error {{'nothrow' attribute takes no arguments}}
inline __attribute__((stdcall(a))) void *f8(void); // expected-error {{'stdcall' attribute takes no arguments}}
inline __attribute__((used(a))) void *f9(void); // expected-error {{'used' attribute takes no arguments}}
diff --git a/clang/test/SemaCXX/attr-print.cpp b/clang/test/SemaCXX/attr-print.cpp
index c7c58a25504ee..0e01d9d8471c6 100644
--- a/clang/test/SemaCXX/attr-print.cpp
+++ b/clang/test/SemaCXX/attr-print.cpp
@@ -28,6 +28,14 @@ int v __attribute__((visibility("hidden")));
// CHECK: char *PR24565() __attribute__((malloc))
char *PR24565() __attribute__((__malloc__));
+void my_cleanup_func(char *);
+
+// using __attribute__(malloc()) with args is currently ignored by Clang
+// CHECK: char *PR52265_a()
+__attribute__((malloc(my_cleanup_func))) char *PR52265_a();
+// CHECK: char *PR52265_b()
+__attribute__((malloc(my_cleanup_func, 1))) char *PR52265_b();
+
// CHECK: class __attribute__((consumable("unknown"))) AttrTester1
class __attribute__((consumable(unknown))) AttrTester1 {
// CHECK: void callableWhen() __attribute__((callable_when("unconsumed", "consumed")));
More information about the cfe-commits
mailing list