On Fri, May 25, 2012 at 6:53 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
> On Sun, May 20, 2012 at 7:47 AM, H.J. Lu <hongjiu...@intel.com> wrote:
>> Hi,
>>
>> This patch allows -mpreferred-stack-boundary=3 on x86-64 when SSE is
>> disabled. Since this option changes ABI, I also added a warning for
>> -mpreferred-stack-boundary=3. OK for trunk?
>>
>> Thanks.
>>
>>
>> H.J.
>> ----
>> PR target/53383
>> * doc/invoke.texi: Add a warning for -mpreferred-stack-boundary=3.
>>
>> * config/i386/i386.c (ix86_option_override_internal): Allow
>> -mpreferred-stack-boundary=3 for 64-bit if SSE is disenabled.
>>
>> * config/i386/i386.h (MIN_STACK_BOUNDARY): Set to 64 for 64-bit
>> if SSE is disenabled.
>>
>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> index eca542c..338d387 100644
>> --- a/gcc/config/i386/i386.c
>> +++ b/gcc/config/i386/i386.c
>> @@ -3660,7 +3660,7 @@ ix86_option_override_internal (bool main_args_p)
>> ix86_preferred_stack_boundary = PREFERRED_STACK_BOUNDARY_DEFAULT;
>> if (global_options_set.x_ix86_preferred_stack_boundary_arg)
>> {
>> - int min = (TARGET_64BIT ? 4 : 2);
>> + int min = (TARGET_64BIT ? (TARGET_SSE ? 4 : 3) : 2);
>> int max = (TARGET_SEH ? 4 : 12);
>>
>> if (ix86_preferred_stack_boundary_arg < min
>> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
>> index ddb3645..f7f13d2 100644
>> --- a/gcc/config/i386/i386.h
>> +++ b/gcc/config/i386/i386.h
>> @@ -708,7 +708,7 @@ enum target_cpu_default
>> #define MAIN_STACK_BOUNDARY (TARGET_64BIT ? 128 : 32)
>>
>> /* Minimum stack boundary. */
>> -#define MIN_STACK_BOUNDARY (TARGET_64BIT ? 128 : 32)
>> +#define MIN_STACK_BOUNDARY (TARGET_64BIT ? (TARGET_SSE ? 128 : 64) : 32)
>>
>> /* Boundary (in *bits*) on which the stack pointer prefers to be
>> aligned; the compiler cannot rely on having this alignment. */
>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index 4c5c79f..daa1f3a 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -13521,6 +13521,12 @@ Attempt to keep the stack boundary aligned to a 2
>> raised to @var{num}
>> byte boundary. If @option{-mpreferred-stack-boundary} is not specified,
>> the default is 4 (16 bytes or 128 bits).
>>
>> +@strong{Warning:} When generating code for the x86-64 architecture with
>> +SSE extensions disabled, @option{-mpreferred-stack-boundary=3} can be
>> +used to keep the stack boundary aligned to 8 byte boundary. You must
>> +build all modules with @option{-mpreferred-stack-boundary=3}, including
>> +any libraries. This includes the system libraries and startup modules.
>> +
>> @item -mincoming-stack-boundary=@var{num}
>> @opindex mincoming-stack-boundary
>> Assume the incoming stack is aligned to a 2 raised to @var{num} byte
>
> I applied the above patch to GCC 4.7 and the following patch to
> Linux kernel 3.4.0. Kernel boots and runs correctly. Is the patch
> OK for trunk?
>
> Thanks.
>
> --
> H.J.
> ---
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 94e91e4..cd4a4f7 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -49,6 +49,9 @@ else
> KBUILD_AFLAGS += -m64
> KBUILD_CFLAGS += -m64
>
> + # Use -mpreferred-stack-boundary=3 if supported.
> + KBUILD_CFLAGS += $(call cc-option,-mno-sse
> -mpreferred-stack-boundary=3)
> +
> # FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
> cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
> cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
Ping
--
H.J.
