Re: [PATCH, i386, AVX512] PR target/67849: Avoid upper-bank registers when splitting vec_extract_lo instruction.

[Alexander Fomin]

On Tue, Oct 06, 2015 at 03:23:39PM +0300, Kirill Yukhin wrote:
> Hi,
> On 05 Oct 18:01, Uros Bizjak wrote:
> > On Mon, Oct 5, 2015 at 5:54 PM, Alexander Fomin
> > <afomin.mail...@gmail.com> wrote:
> > > This patch addresses PR target/67849. Given a machine that does not
> > > support AVX512VL, following "else" branch for vec_exract_lo insn
> > > may result in a split using YMMs from upper-bank, hence invalid
> > > assembly. Tuning define_insn pattern and define_split constraints
> > > eliminates this problem.
> > >
> > > Please take a look at ChangeLog entries - not sure how to reference
> > > to corresponding split in md.
> > 
> > Just describe it as "<what_it_does> splitter". There are some examples
> > in ChangeLog.
> W/ proper ChangeLog entry, change is OK for main trunk.
> 
> --
> Thanks, K
> > 
> > > Regards,
> > > Alexander
> > > ---

Thanks, Uros. I've fixed ChangeLog entry for the splitter as
well as operand predicate.

Kirill, so could you check it in please?
Regression testing is OK on x86_64-linux-gnu.

Regards,
Alexander
---
gcc/

        PR target/67849
        * config/i386/sse.md (define_split vec_select/V8FI): Restrict
        split for upper-bank registers when target does not support
        AVX512VL.
        (define_insn "vec_extract_lo_<mode><mask_name>"): Restrict
        split when target does not support AVX512VL.
---
 gcc/config/i386/sse.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 9b7a338..1f2b275 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -6924,7 +6924,8 @@
          (parallel [(const_int 0) (const_int 1)
             (const_int 2) (const_int 3)])))]
   "TARGET_AVX512F && !(MEM_P (operands[0]) && MEM_P (operands[1]))
-  && reload_completed"
+  && reload_completed
+  && (TARGET_AVX512VL || (REG_P (operands[0]) && !EXT_REX_SSE_REG_P 
(operands[1])))"
   [(const_int 0)]
 {
   rtx op1 = operands[1];
@@ -6962,7 +6963,7 @@
             (const_int 2) (const_int 3)])))]
   "TARGET_AVX512F && !(MEM_P (operands[0]) && MEM_P (operands[1]))"
 {
-  if (<mask_applied>)
+  if (<mask_applied> || !TARGET_AVX512VL)
     return "vextract<shuffletype>64x4\t{$0x0, %1, 
%0<mask_operand2>|%0<mask_operand2>, %1, 0x0}";
   else
     return "#";
-- 
1.8.3.1