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* Re: [x86] Disable STV pass if -mstackrealign is enabled.
@ 2016-08-31 19:29 Uros Bizjak
  2016-09-07 15:07 ` H.J. Lu
  0 siblings, 1 reply; 6+ messages in thread
From: Uros Bizjak @ 2016-08-31 19:29 UTC (permalink / raw)
  To: gcc-patches; +Cc: Eric Botcazou

> the new STV pass generates SSE instructions in 32-bit mode very late in the
> pipeline and doesn't bother about realigning the stack, so it wreaks havoc on
> OSes where you need to realign the stack, e.g. Windows, but I guess Solaris is
> equally affected.  Therefore the attached patch disables it if -mstackrealign
> is enabled (the option is automatically enabled on Windows and Solaris when
> SSE support is enabled), as already done for -mpreferred-stack-boundary={2,3}
> and -mincoming-stack-boundary={2,3}.
>
> Tested on x86/Windows, OK for mainline and 6 branch?
>
>
> 2016-08-31  Eric Botcazou  <ebotcazou@adacore.com>
>
>        * config/i386/i386.c (ix86_option_override_internal): Also disable the
>        STV pass if -mstackrealign is enabled.

OK for mainline and gcc-6 branch.

Thanks,
Uros.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [x86] Disable STV pass if -mstackrealign is enabled.
@ 2016-08-31 15:53 Eric Botcazou
  0 siblings, 0 replies; 6+ messages in thread
From: Eric Botcazou @ 2016-08-31 15:53 UTC (permalink / raw)
  To: gcc-patches

[-- Attachment #1: Type: text/plain, Size: 765 bytes --]

Hi,

the new STV pass generates SSE instructions in 32-bit mode very late in the 
pipeline and doesn't bother about realigning the stack, so it wreaks havoc on 
OSes where you need to realign the stack, e.g. Windows, but I guess Solaris is 
equally affected.  Therefore the attached patch disables it if -mstackrealign 
is enabled (the option is automatically enabled on Windows and Solaris when 
SSE support is enabled), as already done for -mpreferred-stack-boundary={2,3} 
and -mincoming-stack-boundary={2,3}.

Tested on x86/Windows, OK for mainline and 6 branch?


2016-08-31  Eric Botcazou  <ebotcazou@adacore.com>

        * config/i386/i386.c (ix86_option_override_internal): Also disable the
        STV pass if -mstackrealign is enabled.

-- 
Eric Botcazou

[-- Attachment #2: p.diff --]
[-- Type: text/x-patch, Size: 998 bytes --]

Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 239842)
+++ config/i386/i386.c	(working copy)
@@ -5957,11 +5957,12 @@ ix86_option_override_internal (bool main_args_p,
   if (!(opts_set->x_target_flags & MASK_STV))
     opts->x_target_flags |= MASK_STV;
   /* Disable STV if -mpreferred-stack-boundary={2,3} or
-     -mincoming-stack-boundary={2,3} - the needed
+     -mincoming-stack-boundary={2,3} or -mstackrealign - the needed
      stack realignment will be extra cost the pass doesn't take into
      account and the pass can't realign the stack.  */
   if (ix86_preferred_stack_boundary < 128
-      || ix86_incoming_stack_boundary < 128)
+      || ix86_incoming_stack_boundary < 128
+      || opts->x_ix86_force_align_arg_pointer)
     opts->x_target_flags &= ~MASK_STV;
   if (!ix86_tune_features[X86_TUNE_AVX256_UNALIGNED_LOAD_OPTIMAL]
       && !(opts_set->x_target_flags & MASK_AVX256_SPLIT_UNALIGNED_LOAD))

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-08 16:22 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-08-31 19:29 [x86] Disable STV pass if -mstackrealign is enabled Uros Bizjak
2016-09-07 15:07 ` H.J. Lu
2016-09-08  6:06   ` Eric Botcazou
2016-09-08 14:53     ` H.J. Lu
2016-09-08 16:29       ` Eric Botcazou
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2016-08-31 15:53 Eric Botcazou

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