---------- Forwarded message ---------- From: Vladimir Yakovlev <vbyakov...@gmail.com> Date: 2012/11/9 Subject: Re: [off-list] Re: [PATCH] Vzeroupper placement/47440 To: Uros Bizjak <ubiz...@gmail.com> Копия: "H.J. Lu" <hjl.to...@gmail.com>, Igor Zamyatin <izamya...@gmail.com>
I did changes that moves vzeroupper insertion after reload
2012-11-09 Vladimir Yakovlev <vladimir.b.yakov...@intel.com>
* i386/i386-protos.h (ix86_avx256_optimize_mode_switching): New.
* config/i386/i386.c (ix86_init_machine_status): Deleted
initialization for mode switching.
* i386/i386.h (OPTIMIZE_MODE_SWITCHING1): New.
* mode-switching.c (gate_mode_switching1): New.
(rest_of_handle_mode_switching1): New.
(pass_mode_switching1): New.
* passes.c (init_optimization_passes): New pass pass_mode_switching1.
* tree-pass.h (pass_mode_switching1): New.
But this caused assertion fails in rtl_verify_flow_info_1 () at cfgrtl.c:2291
fatal_insn ("flow control insn inside a basic block", x);
The asserts are called by two calls of mode-switching.c:
commit_edge_insertion and cleanup_cfg. After I commented (see below)
459.GemsFDTD benchspec passed. Your opinion of the patch and haw we
can do something with asserts.
Regards,
Vladimir
--- a/gcc/mode-switching.c
+++ b/gcc/mode-switching.c
@@ -747,7 +747,7 @@ optimize_mode_switching (void)
commit_edge_insertions ();
#if defined (MODE_ENTRY) && defined (MODE_EXIT)
- cleanup_cfg (CLEANUP_NO_INSN_DEL);
+ /*cleanup_cfg (CLEANUP_NO_INSN_DEL);*/
#else
if (!need_commit && !emitted)
return 0;
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -1828,7 +1828,7 @@ commit_edge_insertions (void)
basic_block bb;
#ifdef ENABLE_CHECKING
- verify_flow_info ();
+ /*verify_flow_info ();*/
#endif
2012/11/9 Uros Bizjak <ubiz...@gmail.com>:
> On Thu, Nov 8, 2012 at 6:52 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
>
>> Uh, this is spill around call insn, produced by reload.
>>
>> Please compile this code:
>>
>> double test (double a)
>> {
>> printf ("Hello\n");
>> return a;
>> }
>>
>> You will get at mode switching:
>>
>> 1 NOTE_INSN_DELETED
>> 4 NOTE_INSN_BASIC_BLOCK
>> 2 r60:DF=xmm0:DF
>> REG_DEAD: xmm0:DF
>> 3 NOTE_INSN_FUNCTION_BEG
>> 6 di:DI=`*.LC0'
>> 7 call <...>
>> REG_DEAD: di:DI
>> REG_UNUSED: ax:SI
>> 12 xmm0:DF=r60:DF
>> REG_DEAD: r60:DF
>> 15 use xmm0:DF
>>
>> But reload will insert:
>>
>> 1 NOTE_INSN_DELETED
>> 4 NOTE_INSN_BASIC_BLOCK
>> 2 xmm0:DF=xmm0:DF
>> REG_DEAD: xmm0:DF
>> 18 [sp:DI+0x8]=xmm0:DF
>> REG_DEAD: xmm0:DF
>> 3 NOTE_INSN_FUNCTION_BEG
>> 6 di:DI=`*.LC0'
>> 7 call <...>
>> REG_DEAD: di:DI
>> REG_UNUSED: ax:SI
>> 19 xmm0:DF=[sp:DI+0x8]
>> REG_DEAD: r62:DF
>> 12 xmm0:DF=xmm0:DF
>> REG_DEAD: xmm0:DF
>> 15 use xmm0:DF
>>
>> I was not paying attention to this situation.
>
>
> A viable solution to this issue is through machine-reorg function (AKA
> x86_reorg) that would just move vzeroupper to the close proximity to a
> call insn. This would work on non-64bit-MS-ABI targets, where all SSE
> registers are dead at call insn place.
>
> Please note that 64bit-MS-ABI target declares registers xmm6+ as
> call-saved, so they can live over the call. I am not familiar with
> this target, but it looks to me that we have to remove vzeroupper, if
> one or more call-saved SSE registers are live at the call insn place.
>
> Uros.
prvzu.patch
Description: Binary data
