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btf: do not skip members of data type with type id BTF_VOID_TYPEID

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The previous fix in gen_ctf_sou_type () exposes an issue in BTF
generation, however: BTF emission was currently decrementing the vlen
(indicating the number of members) to skip members of type CTF_K_UNKNOWN
altogether, but still emitting the BTF for the corresponding member (in
output_asm_btf_sou_fields ()).

One can see malformed BTF by executing the newly added CTF testcase
(gcc.dg/debug/ctf/ctf-bitfields-5.c) with -gbtf instead or even existing
btf-struct-2.c without this patch.

To fix the issue, it makes sense to rather _not_ skip members of data
type of type id BTF_VOID_TYPEID.

gcc/ChangeLog:
	* btfout.cc (btf_asm_type): Do not skip emitting members of
	unknown type.

gcc/testsuite/ChangeLog:
	* gcc.dg/debug/btf/btf-bitfields-4.c: Update the vlen check.
	* gcc.dg/debug/btf/btf-struct-2.c: Check that member named 'f'
	with void data type is emitted.
This commit is contained in:
Indu Bhagat 2024-04-08 11:01:45 -07:00
parent 5c869aa8a4
commit 936dd627cd
3 changed files with 8 additions and 12 deletions
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5
gcc/btfout.cc
View file

@ -820,11 +820,6 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
/* Set kflag if this member is a representable bitfield. */
if (btf_dmd_representable_bitfield_p (ctfc, dmd))
btf_kflag = 1;
/* Struct members that refer to unsupported types or bitfield formats
shall be skipped. These are marked during preprocessing. */
else if (!btf_emit_id_p (dmd->dmd_type))
btf_vlen -= 1;
}
}

6
gcc/testsuite/gcc.dg/debug/btf/btf-bitfields-4.c
View file

@ -6,14 +6,14 @@
In this test, we construct a structure such that the bitfield will have
an offset so large as to be unrepresentable in BTF. We expect that the
resulting BTF will describe the rest of the structure, ignoring the
non-representable bitfield. */
non-representable bitfield by simply using void data type for the same. */
/* { dg-do compile } */
/* { dg-options "-O0 -gbtf -dA" } */
/* { dg-require-effective-target size32plus } */
/* Struct with 3 members and no bitfield (kind_flag not set). */
/* { dg-final { scan-assembler-times "\[\t \]0x4000003\[\t \]+\[^\n\]*btt_info" 1 } } */
/* Struct with 4 members and no bitfield (kind_flag not set). */
/* { dg-final { scan-assembler-times "\[\t \]0x4000004\[\t \]+\[^\n\]*btt_info" 1 } } */
struct bigly
{

9
gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c
View file

@ -2,14 +2,15 @@
unsupported type.
BTF does not support vector types (among other things). When
generating BTF for a struct (or union) type, members which refer to
unsupported types should be skipped. */
generating BTF for a struct (or union) type. Members which refer to
unsupported types should not be skipped, however. */
/* { dg-do compile } */
/* { dg-options "-O0 -gbtf -dA" } */
/* Expect a struct with only 2 members - 'f' should not be present. */
/* { dg-final { scan-assembler-times "\[\t \]0x4000002\[\t \]+\[^\n\]*btt_info" 1 } } */
/* Expect a struct with 3 members - 'f' is present but is of data type void. */
/* { dg-final { scan-assembler-times "\[\t \]0x4000003\[\t \]+\[^\n\]*btt_info" 1 } } */
/* { dg-final { scan-assembler-times " MEMBER 'f' idx=1\[\\r\\n\]+\[^\\r\\n\]*0\[\t \]+\[^\n\]*btm_type: void" 1 } } */
struct with_float
{