[Mesa-dev] [PATCH V2] mesa: use build flag to ensure stack is realigned on x86

[Ian Romanick]

On 12/07/2014 04:13 AM, Timothy Arceri wrote:
> Nowadays GCC assumes stack pointer is 16-byte aligned even on 32-bits, but that is an assumption OpenGL drivers (or any dynamic library for that matter) can't afford to make as there are many closed- and open- source application binaries out there that only assume 4-byte stack alignment.
> 
> V2: use $target_cpu rather than $host_cpu
>  and setup build flags in config rather than makefile
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=86788
> Signed-off-by: Timothy Arceri <t_arceri at yahoo.com.au>
> ---
>  Tested by cross compiling and running 32-bit version of
>  UrbanTerror.
> 
>  Please note if this patch is ok it should also be applied to 10.4 with
>  the last hunk removed.
> 
>  configure.ac               | 11 ++++++++++-
>  src/mesa/Makefile.am       |  2 +-
>  src/mesa/main/sse_minmax.c |  3 ---
>  3 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index b0df1bb..7dc435a 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -253,8 +253,9 @@ AC_SUBST([VISIBILITY_CXXFLAGS])
>  dnl
>  dnl Optional flags, check for compiler support
>  dnl
> +SSE41_CFLAGS="-msse4.1"
>  save_CFLAGS="$CFLAGS"
> -CFLAGS="-msse4.1 $CFLAGS"
> +CFLAGS="$SSE41_CFLAGS $CFLAGS"
>  AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
>  #include <smmintrin.h>
>  int main () {
> @@ -474,6 +475,12 @@ fi
>  dnl
>  dnl Arch/platform-specific settings
>  dnl
> +case "$target_cpu" in
> +    i?86)
> +        SSE41_CFLAGS="$SSE41_CFLAGS -mstackrealign"
> +;;
> +esac

Should we only add -mstackrealign if SSE41_CFLAGS is not empty?

> +
>  AC_ARG_ENABLE([asm],
>      [AS_HELP_STRING([--disable-asm],
>          [disable assembly usage @<:@default=enabled on supported plaforms@:>@])],
> @@ -2091,6 +2098,8 @@ AM_CONDITIONAL(HAVE_X86_ASM, test "x$asm_arch" = xx86 -o "x$asm_arch" = xx86_64)
>  AM_CONDITIONAL(HAVE_X86_64_ASM, test "x$asm_arch" = xx86_64)
>  AM_CONDITIONAL(HAVE_SPARC_ASM, test "x$asm_arch" = xsparc)
>  
> +AC_SUBST([SSE41_CFLAGS], $SSE41_CFLAGS)
> +
>  AC_SUBST([NINE_MAJOR], 1)
>  AC_SUBST([NINE_MINOR], 0)
>  AC_SUBST([NINE_TINY], 0)
> diff --git a/src/mesa/Makefile.am b/src/mesa/Makefile.am
> index 932db4f..3b68573 100644
> --- a/src/mesa/Makefile.am
> +++ b/src/mesa/Makefile.am
> @@ -153,7 +153,7 @@ libmesagallium_la_LIBADD = \
>  libmesa_sse41_la_SOURCES = \
>  	main/streaming-load-memcpy.c \
>  	main/sse_minmax.c
> -libmesa_sse41_la_CFLAGS = $(AM_CFLAGS) -msse4.1
> +libmesa_sse41_la_CFLAGS = $(AM_CFLAGS) $(SSE41_CFLAGS)
>  
>  pkgconfigdir = $(libdir)/pkgconfig
>  pkgconfig_DATA = gl.pc
> diff --git a/src/mesa/main/sse_minmax.c b/src/mesa/main/sse_minmax.c
> index 93cf2a6..222ac14 100644
> --- a/src/mesa/main/sse_minmax.c
> +++ b/src/mesa/main/sse_minmax.c
> @@ -31,9 +31,6 @@
>  #include <stdint.h>
>  
>  void
> -#if !defined(__x86_64__)
> -   __attribute__((force_align_arg_pointer))
> -#endif
>  _mesa_uint_array_min_max(const unsigned *ui_indices, unsigned *min_index,
>                           unsigned *max_index, const unsigned count)
>  {
>