[PATCH] BTF: Support for BTF_KIND_FLOAT

Richard Biener richard.guenther@gmail.com
Fri Jul 2 07:31:02 GMT 2021


On Thu, Jul 1, 2021 at 7:54 PM David Faust via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Add BTF_KIND_FLOAT, a new BTF type kind which has recently stabilized in
> the linux kernel [1]. This kind is used for encoding floating point
> types, and is of particular use when generating BTF for some s390
> arch-specific kernel headers.
>
> Also update some BTF tests which previously used floating point types to
> check correct behavior for types with no BTF representation.
>
> [1]: https://github.com/torvalds/linux/commit/b1828f0b04828aa8cccadf00a702f459caefeed9
>
> bootstrapped and tested on x86_64-linux-gnu, ok to install?

OK.

Richard.

> include/ChangeLog:
>
>         * btf.h (struct btf_type): Update bit usage comment.
>         (BTF_INFO_KIND): Update bit mask.
>         (BTF_KIND_FLOAT): New define.
>         (BTF_KIND_MAX): Update.
>
> gcc/ChangeLog:
>
>         * btfout.c (get_btf_kind): Support BTF_KIND_FLOAT.
>         (btf_asm_type): Likewise.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/debug/btf/btf-float-1.c: New test.
>         * gcc.dg/debug/btf/btf-function-3.c: Use different unrepresentable type.
>         * gcc.dg/debug/btf/btf-struct-2.c: Likewise.
>         * gcc.dg/debug/btf/btf-variables-2.c: Likewise.
> ---
>  gcc/btfout.c                                  |  2 ++
>  gcc/testsuite/gcc.dg/debug/btf/btf-float-1.c  | 20 +++++++++++++++++++
>  .../gcc.dg/debug/btf/btf-function-3.c         |  2 +-
>  gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c |  2 +-
>  .../gcc.dg/debug/btf/btf-variables-2.c        |  2 +-
>  include/btf.h                                 |  9 +++++----
>  6 files changed, 30 insertions(+), 7 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/debug/btf/btf-float-1.c
>
> diff --git a/gcc/btfout.c b/gcc/btfout.c
> index e58c969825a..8cdd9905fb6 100644
> --- a/gcc/btfout.c
> +++ b/gcc/btfout.c
> @@ -124,6 +124,7 @@ get_btf_kind (uint32_t ctf_kind)
>    switch (ctf_kind)
>      {
>      case CTF_K_INTEGER:  return BTF_KIND_INT;
> +    case CTF_K_FLOAT:   return BTF_KIND_FLOAT;
>      case CTF_K_POINTER:  return BTF_KIND_PTR;
>      case CTF_K_ARRAY:    return BTF_KIND_ARRAY;
>      case CTF_K_FUNCTION: return BTF_KIND_FUNC_PROTO;
> @@ -627,6 +628,7 @@ btf_asm_type (ctf_container_ref ctfc, ctf_dtdef_ref dtd)
>    switch (btf_kind)
>      {
>      case BTF_KIND_INT:
> +    case BTF_KIND_FLOAT:
>      case BTF_KIND_STRUCT:
>      case BTF_KIND_UNION:
>      case BTF_KIND_ENUM:
> diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-float-1.c b/gcc/testsuite/gcc.dg/debug/btf/btf-float-1.c
> new file mode 100644
> index 00000000000..6876df04158
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/debug/btf/btf-float-1.c
> @@ -0,0 +1,20 @@
> +/* Tests for BTF floating point type kinds. We expect a single record for each
> +   of the base types: float, double and long double.  */
> +
> +/* { dg-do compile } */
> +/* { dg-options "-O0 -gbtf -dA" } */
> +
> +/* { dg-final { scan-assembler-times "\[\t \]0x10000000\[\t \]+\[^\n\]*btt_info" 3 } } */
> +
> +/* { dg-final { scan-assembler-times "ascii \"float.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
> +/* { dg-final { scan-assembler-times "ascii \"double.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
> +/* { dg-final { scan-assembler-times "ascii \"long double.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
> +
> +float a;
> +float b = 1.5f;
> +
> +double c;
> +double d = -99.9;
> +
> +long double e;
> +long double f = 1000.01;
> diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-function-3.c b/gcc/testsuite/gcc.dg/debug/btf/btf-function-3.c
> index 35f96a2152c..c83b823d22f 100644
> --- a/gcc/testsuite/gcc.dg/debug/btf/btf-function-3.c
> +++ b/gcc/testsuite/gcc.dg/debug/btf/btf-function-3.c
> @@ -16,7 +16,7 @@
>  /* Exactly one function parameter should have type_id=0.  */
>  /* { dg-final { scan-assembler-times "\[\t \]0\[\t \]+\[^\n\]*farg_type" 1 } } */
>
> -int foo (int a, float f, long b)
> +int foo (int a, float __attribute__((__vector_size__(16))) f, long b)
>  {
>    return 0;
>  }
> diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c b/gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c
> index 24514fcb31e..c3aff09ed9a 100644
> --- a/gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c
> +++ b/gcc/testsuite/gcc.dg/debug/btf/btf-struct-2.c
> @@ -14,6 +14,6 @@
>  struct with_float
>  {
>    int a;
> -  float f;
> +  float __attribute__((__vector_size__(16))) f;
>    char c;
>  } instance;
> diff --git a/gcc/testsuite/gcc.dg/debug/btf/btf-variables-2.c b/gcc/testsuite/gcc.dg/debug/btf/btf-variables-2.c
> index 0f9742e9ac5..db0bdd7be16 100644
> --- a/gcc/testsuite/gcc.dg/debug/btf/btf-variables-2.c
> +++ b/gcc/testsuite/gcc.dg/debug/btf/btf-variables-2.c
> @@ -16,7 +16,7 @@
>  /* { dg-final { scan-assembler-times "ascii \"myst.0\"\[\t \]+\[^\n\]*btf_string" 1 } } */
>
>  int foo;
> -float bar;
> +float __attribute__((__vector_size__(16))) bar;
>  int baz[10];
>
>  struct st
> diff --git a/include/btf.h b/include/btf.h
> index 3b1a4c3093f..bf720ee49b4 100644
> --- a/include/btf.h
> +++ b/include/btf.h
> @@ -62,8 +62,8 @@ struct btf_type
>    uint32_t info;       /* Encoded kind, variant length, kind flag:
>                            - bits  0-15: vlen
>                            - bits 16-23: unused
> -                          - bits 24-27: kind
> -                          - bits 28-30: unused
> +                          - bits 24-28: kind
> +                          - bits 29-30: unused
>                            - bit     31: kind_flag
>                            See accessor macros below.  */
>
> @@ -79,7 +79,7 @@ struct btf_type
>
>  /* The folloing macros access the information encoded in btf_type.info.  */
>  /* Type kind. See below.  */
> -#define BTF_INFO_KIND(info)    (((info) >> 24) & 0x0f)
> +#define BTF_INFO_KIND(info)    (((info) >> 24) & 0x1f)
>  /* Number of entries of variable length data following certain type kinds.
>     For example, number of structure members, number of function parameters.  */
>  #define BTF_INFO_VLEN(info)    ((info) & 0xffff)
> @@ -108,7 +108,8 @@ struct btf_type
>  #define BTF_KIND_FUNC_PROTO    13      /* Function Prototype.  */
>  #define BTF_KIND_VAR           14      /* Variable.  */
>  #define BTF_KIND_DATASEC       15      /* Section such as .bss or .data.  */
> -#define BTF_KIND_MAX           BTF_KIND_DATASEC
> +#define BTF_KIND_FLOAT         16      /* Floating point.  */
> +#define BTF_KIND_MAX           BTF_KIND_FLOAT
>  #define NR_BTF_KINDS           (BTF_KIND_MAX + 1)
>
>  /* For some BTF_KINDs, struct btf_type is immediately followed by
> --
> 2.31.1
>


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