[clang] [clang] Support member function poiners in Decl::getFunctionType() (PR #125077)
Benjamin Maxwell via cfe-commits
cfe-commits at lists.llvm.org
Thu Jan 30 07:57:09 PST 2025
https://github.com/MacDue created https://github.com/llvm/llvm-project/pull/125077
This seems consistent with the documentation which claims it:
```
/// Looks through the Decl's underlying type to extract a FunctionType
/// when possible. Will return null if the type underlying the Decl does not
/// have a FunctionType.
const FunctionType *getFunctionType(bool BlocksToo = true) const;
```
Without this, attaching attributes (which use `HasFunctionProto`) to member function pointers errors with:
```
error: '<attr>' only applies to non-K&R-style functions
```
...which does not really make sense, since member functions are not K&C functions.
With this change the Arm SME TypeAttrs work correctly on member function pointers.
Note, however, that not all attributes work correctly when applied to function pointers or member function pointers. For example, `alloc_align` crashes when applied to a function pointer (on truck): https://godbolt.org/z/YvMhnhKfx (as it only expects a `FunctionDecl` not a `ParmVarDecl`). The same crash applies to member function pointers (for the same reason).
>From 620bb22d1b44f3c60e15d2847fdcfd3dd9aafa51 Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxwell at arm.com>
Date: Thu, 30 Jan 2025 15:08:24 +0000
Subject: [PATCH] [clang] Support member function poiners in
Decl::getFunctionType()
This seems consistent with the documentation which claims it:
```
/// Looks through the Decl's underlying type to extract a FunctionType
/// when possible. Will return null if the type underlying the Decl does not
/// have a FunctionType.
const FunctionType *getFunctionType(bool BlocksToo = true) const;
```
Without this, attaching attributes (which use `HasFunctionProto`) to
member function pointers errors with:
```
error: '<attr>' only applies to non-K&R-style functions
```
...which does not really make sense, since member functions are not
K&C functions.
With this change the Arm SME TypeAttrs work correctly on member function
pointers.
Note, however, that not all attributes work correctly when applied to
function pointers or member function pointers. For example,
`alloc_align` crashes when applied to a function pointer (on truck):
https://godbolt.org/z/YvMhnhKfx (as it only expects a `FunctionDecl`
not a `ParmVarDecl`). The same crash applies to member function pointers
(for the same reason).
---
clang/include/clang/Basic/Attr.td | 2 +-
clang/lib/AST/DeclBase.cpp | 2 +
clang/test/AST/attr-print-emit.cpp | 5 +++
...sme-attributes-member-function-pointer.cpp | 37 +++++++++++++++++++
.../CodeGen/xfail-alloc-align-fn-pointers.cpp | 10 +++++
5 files changed, 55 insertions(+), 1 deletion(-)
create mode 100644 clang/test/CodeGen/AArch64/sme-attributes-member-function-pointer.cpp
create mode 100644 clang/test/CodeGen/xfail-alloc-align-fn-pointers.cpp
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index f4ba2bc3c6de31..2a3a29bd2ee1cf 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -198,7 +198,7 @@ def OpenCLKernelFunction
// inclusive nature of subject testing).
def HasFunctionProto : SubsetSubject<DeclBase,
[{(S->getFunctionType(true) != nullptr &&
- isa<FunctionProtoType>(S->getFunctionType())) ||
+ isa<FunctionProtoType>(S->getFunctionType())) ||
isa<ObjCMethodDecl>(S) ||
isa<BlockDecl>(S)}],
"non-K&R-style functions">;
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index c0a331d18cab8d..fc16448cf9e905 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1203,6 +1203,8 @@ const FunctionType *Decl::getFunctionType(bool BlocksToo) const {
if (Ty->isFunctionPointerType())
Ty = Ty->castAs<PointerType>()->getPointeeType();
+ else if (Ty->isMemberFunctionPointerType())
+ Ty = Ty->castAs<MemberPointerType>()->getPointeeType();
else if (Ty->isFunctionReferenceType())
Ty = Ty->castAs<ReferenceType>()->getPointeeType();
else if (BlocksToo && Ty->isBlockPointerType())
diff --git a/clang/test/AST/attr-print-emit.cpp b/clang/test/AST/attr-print-emit.cpp
index a9bca6778d0f1a..77826f8f9af098 100644
--- a/clang/test/AST/attr-print-emit.cpp
+++ b/clang/test/AST/attr-print-emit.cpp
@@ -91,3 +91,8 @@ ANNOTATE_ATTR NONNULL_ATTR void fn_non_null_annotated_attr(int *) __attribute__(
[[gnu::nonnull(1)]] [[gnu::always_inline]] void cxx11_attr(int*) ANNOTATE_ATTR;
// CHECK: {{\[\[}}gnu::nonnull(1)]] {{\[\[}}gnu::always_inline]] void cxx11_attr(int *) __attribute__((annotate("Annotated")));
+
+struct Foo;
+
+// CHECK: void as_member_fn_ptr(int *(Foo::*member)(int) __attribute__((alloc_size(1))));
+void as_member_fn_ptr(int* (Foo::*member)(int) __attribute__((alloc_size(1))));
diff --git a/clang/test/CodeGen/AArch64/sme-attributes-member-function-pointer.cpp b/clang/test/CodeGen/AArch64/sme-attributes-member-function-pointer.cpp
new file mode 100644
index 00000000000000..ee784c816a0606
--- /dev/null
+++ b/clang/test/CodeGen/AArch64/sme-attributes-member-function-pointer.cpp
@@ -0,0 +1,37 @@
+// RUN: %clang_cc1 -triple aarch64 -target-feature +sme -target-feature +sme2 -x c++ -std=c++20 -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK
+
+struct TestStruct;
+
+__arm_new("za", "zt0") void test(TestStruct& TS,
+ void (TestStruct::*streaming_member_ptr)() __arm_streaming,
+ void (TestStruct::*streaming_compat_member)() __arm_streaming_compatible,
+ void (TestStruct::*arm_in_member)() __arm_in("za", "zt0"),
+ void (TestStruct::*arm_inout_member)() __arm_inout("za", "zt0"),
+ void (TestStruct::*arm_preserves_member)() __arm_preserves("za", "zt0"),
+ void (TestStruct::*arm_agnostic_member)() __arm_agnostic("sme_za_state")) {
+
+ // CHECK: call void %{{.*}} [[STREAMING_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*streaming_member_ptr)();
+
+ // CHECK: call void %{{.*}} [[STREAMING_COMPAT_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*streaming_compat_member)();
+
+ // CHECK: call void %{{.*}} [[ARM_IN_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*arm_in_member)();
+
+ // CHECK: call void %{{.*}} [[ARM_INOUT_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*arm_inout_member)();
+
+ // CHECK: call void %{{.*}} [[ARM_PRESERVES_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*arm_preserves_member)();
+
+ // CHECK: call void %{{.*}} [[ARM_AGNOSTIC_MEMBER_CALL_ATTRS:#.+]]
+ (TS.*arm_agnostic_member)();
+}
+
+// CHECK: attributes [[STREAMING_MEMBER_CALL_ATTRS]] = { "aarch64_pstate_sm_enabled" }
+// CHECK: attributes [[STREAMING_COMPAT_MEMBER_CALL_ATTRS]] = { "aarch64_pstate_sm_compatible" }
+// CHECK: attributes [[ARM_IN_MEMBER_CALL_ATTRS]] = { "aarch64_in_za" "aarch64_in_zt0" }
+// CHECK: attributes [[ARM_INOUT_MEMBER_CALL_ATTRS]] = { "aarch64_inout_za" "aarch64_inout_zt0" }
+// CHECK: attributes [[ARM_PRESERVES_MEMBER_CALL_ATTRS]] = { "aarch64_preserves_za" "aarch64_preserves_zt0" }
+// CHECK: attributes [[ARM_AGNOSTIC_MEMBER_CALL_ATTRS]] = { "aarch64_za_state_agnostic" }
diff --git a/clang/test/CodeGen/xfail-alloc-align-fn-pointers.cpp b/clang/test/CodeGen/xfail-alloc-align-fn-pointers.cpp
new file mode 100644
index 00000000000000..80067500284b1e
--- /dev/null
+++ b/clang/test/CodeGen/xfail-alloc-align-fn-pointers.cpp
@@ -0,0 +1,10 @@
+
+// RUN: %clang_cc1 %s
+
+// FIXME: These should not crash!
+// XFAIL: *
+
+void aa_fn_ptr(char* (*member)(char*) __attribute__((alloc_align(1))));
+
+struct Test;
+void aa_member_fn_ptr(char* (Test::*member)(char*) __attribute__((alloc_align(1))));
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