Re: [PATCHv2] gdb: Ignore some stringop-overflow and restrict warnings on sparc

[Enze Li <enze.li@hotmail.com>]

On Tue, Jan 24 2023 at 01:44:44 AM +0100, Mark Wielaard wrote:

> For some reason g++ 12.2.1 on sparc produces a spurious warning for
> stringop-overread and restrict in fbsd-tdep.c for some memcpy calls.
> Add new DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW and
> DIAGNOSTIC_IGNORE_RESTRICT macro to suppress these warnings:
>
> In function ‘void* memcpy(void*, const void*, size_t)’,
>     inlined from ‘gdb::optional<std::vector<unsigned char, gdb::default_init_allocator<unsigned char, std::allocator<unsigned char> > > > fbsd_make_note_desc(target_object, uint32_t)’ at ../../binutils-gdb/gdb/fbsd-tdep.c:666:10:
> /usr/include/bits/string_fortified.h:29:33: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ specified bound 18446744073709551612 exceeds maximum object size 9223372036854775807 [-Werror=stringop-overflow=]
>
> In function ‘void* memcpy(void*, const void*, size_t)’,
>     inlined from ‘gdb::optional<std::vector<unsigned char, gdb::default_init_allocator<unsigned char, std::allocator<unsigned char> > > > fbsd_make_note_desc(target_object, uint32_t)’ at ../../binutils-gdb/gdb/fbsd-tdep.c:673:10:
> /usr/include/bits/string_fortified.h:29:33: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 18446744073709551612 bytes at offsets 0 and 0 overlaps 9223372036854775801 bytes at offset -9223372036854775805 [-Werror=restrict]
>
> include/ChangeLog:
>
> 	* diagnostics.h (DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW): New
> 	macro.
> 	(DIAGNOSTIC_IGNORE_RESTRICT): Likewise.
>
> gdb/ChangeLog:
>
> 	* fbsd-tdep.c (fbsd_make_note_desc): Use
> 	DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW and
> 	DIAGNOSTIC_IGNORE_RESTRICT on sparc.
> ---

Hi Mark,

Since GDB 12, ChangeLog entries are no longer required.  See here[1].

[1] https://sourceware.org/pipermail/gdb-patches/2021-June/179872.html

Thanks,
Enze

>
> V2: Fix typos and add example errors to commit messages
>
>  gdb/fbsd-tdep.c       | 10 ++++++++++
>  include/diagnostics.h | 10 ++++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/gdb/fbsd-tdep.c b/gdb/fbsd-tdep.c
> index 203390d9880..ee2a4b54e85 100644
> --- a/gdb/fbsd-tdep.c
> +++ b/gdb/fbsd-tdep.c
> @@ -19,6 +19,7 @@
>  
>  #include "defs.h"
>  #include "auxv.h"
> +#include "diagnostics.h"
>  #include "gdbcore.h"
>  #include "inferior.h"
>  #include "objfiles.h"
> @@ -663,7 +664,16 @@ fbsd_make_note_desc (enum target_object object, uint32_t structsize)
>  
>    gdb::byte_vector desc (sizeof (structsize) + buf->size ());
>    memcpy (desc.data (), &structsize, sizeof (structsize));
> +#if defined (__sparc__)
> +  /* g++ 12.2.1 on sparc seems confused about the vector buf sizes.  */
> +  DIAGNOSTIC_PUSH
> +  DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW
> +  DIAGNOSTIC_IGNORE_RESTRICT
> +#endif
>    memcpy (desc.data () + sizeof (structsize), buf->data (), buf->size ());
> +#if defined (__sparc__)
> +  DIAGNOSTIC_POP
> +#endif
>    return desc;
>  }
>  
> diff --git a/include/diagnostics.h b/include/diagnostics.h
> index d3ff27bc008..617943ae0d7 100644
> --- a/include/diagnostics.h
> +++ b/include/diagnostics.h
> @@ -94,6 +94,11 @@
>    DIAGNOSTIC_IGNORE ("-Wstringop-overread")
>  #endif
>  
> +# if __GNUC__ >= 7
> +# define DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW \
> +  DIAGNOSTIC_IGNORE ("-Wstringop-overflow")
> +#endif
> +
>  # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
>    DIAGNOSTIC_IGNORE ("-Wformat-nonliteral")
>  
> @@ -113,6 +118,7 @@
>  #  define DIAGNOSTIC_ERROR_SWITCH DIAGNOSTIC_ERROR ("-Wswitch")
>  # endif
>  
> +#define DIAGNOSTIC_IGNORE_RESTRICT DIAGNOSTIC_IGNORE ("-Wrestrict")
>  #endif
>  
>  #ifndef DIAGNOSTIC_IGNORE_SELF_MOVE
> @@ -139,6 +145,10 @@
>  # define DIAGNOSTIC_IGNORE_STRINGOP_OVERREAD
>  #endif
>  
> +#ifndef DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW
> +# define DIAGNOSTIC_IGNORE_STRINGOP_OVERFLOW
> +#endif
> +
>  #ifndef DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL
>  # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL
>  #endif