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Latest llvm-project upstream had a change of behavior
related to qualifiers on function return type ([1]).
This caused selftests btf_dump/btf_dump failure.
The following example shows what changed.
$ cat t.c
typedef const char * const (* const (* const fn_ptr_arr2_t[5])())(char * (*)(int));
struct t {
int a;
fn_ptr_arr2_t l;
};
int foo(struct t *arg) {
return arg->a;
}
Compiled with latest upstream llvm15,
$ clang -O2 -g -target bpf -S -emit-llvm t.c
The related generated debuginfo IR looks like:
!16 = !DIDerivedType(tag: DW_TAG_typedef, name: "fn_ptr_arr2_t", file: !1, line: 1, baseType: !17)
!17 = !DICompositeType(tag: DW_TAG_array_type, baseType: !18, size: 320, elements: !32)
!18 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !19)
!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !20, size: 64)
!20 = !DISubroutineType(types: !21)
!21 = !{!22, null}
!22 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !23, size: 64)
!23 = !DISubroutineType(types: !24)
!24 = !{!25, !28}
!25 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !26, size: 64)
!26 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !27)
!27 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
You can see two intermediate const qualifier to pointer are dropped in debuginfo IR.
With llvm14, we have following debuginfo IR:
!16 = !DIDerivedType(tag: DW_TAG_typedef, name: "fn_ptr_arr2_t", file: !1, line: 1, baseType: !17)
!17 = !DICompositeType(tag: DW_TAG_array_type, baseType: !18, size: 320, elements: !34)
!18 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !19)
!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !20, size: 64)
!20 = !DISubroutineType(types: !21)
!21 = !{!22, null}
!22 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !23)
!23 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !24, size: 64)
!24 = !DISubroutineType(types: !25)
!25 = !{!26, !30}
!26 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !27)
!27 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !28, size: 64)
!28 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !29)
!29 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
All const qualifiers are preserved.
To adapt the selftest to both old and new llvm, this patch removed
the intermediate const qualifier in const-to-ptr types, to make the
test succeed again.
[1] https://reviews.llvm.org/D125919
Reported-by: Mykola Lysenko <mykolal@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220523152044.3905809-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Bpftool used to issue forward declarations for a struct used as part of
a pointer to array, which is invalid. Add a test to check that the
struct is fully defined in this case:
@@ -134,9 +134,9 @@
};
};
-struct struct_in_array {};
+struct struct_in_array;
-struct struct_in_array_typed {};
+struct struct_in_array_typed;
typedef struct struct_in_array_typed struct_in_array_t[2];
@@ -189,3 +189,7 @@
struct struct_with_embedded_stuff _14;
};
+struct struct_in_array {};
+
+struct struct_in_array_typed {};
+
...
#13/1 btf_dump: syntax:FAIL
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210319112554.794552-3-jean-philippe@linaro.org
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Currently, BTF_KIND_ENUM type doesn't record whether enum values should be
interpreted as signed or unsigned. In Linux, most enums are unsigned, though,
so interpreting them as unsigned matches real world better.
Change btf_dump test case to test maximum 32-bit value, instead of negative
value.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200303003233.3496043-3-andriin@fb.com
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