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* [Bug target/110331] New: ppc64 vec_extract with constant index is suboptimal on P8
@ 2023-06-21  3:19 guihaoc at gcc dot gnu.org
  2023-06-29  8:35 ` [Bug target/110331] " guihaoc at gcc dot gnu.org
  0 siblings, 1 reply; 2+ messages in thread
From: guihaoc at gcc dot gnu.org @ 2023-06-21  3:19 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110331

            Bug ID: 110331
           Summary: ppc64 vec_extract with constant index is suboptimal on
                    P8
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: guihaoc at gcc dot gnu.org
  Target Milestone: ---

//test.c
#include <altivec.h>

#ifdef __BIG_ENDIAN__
#define LANE_B 3
#else
#define LANE_B 12
#endif

unsigned char foo1 (vector unsigned char v)
{
  return vec_extract (v, LANE_B);
}

Trunk generates:
        vspltb 2,2,3
        mfvsrd 3,34
        rlwinm 3,3,0,0xff

While it can be optimized as:
        mfvsrd 3,34
        rldicl 3,3,32,56

^ permalink raw reply	[flat|nested] 2+ messages in thread
* [Bug target/110331] ppc64 vec_extract with constant index is suboptimal on P8
  2023-06-21  3:19 [Bug target/110331] New: ppc64 vec_extract with constant index is suboptimal on P8 guihaoc at gcc dot gnu.org
@ 2023-06-29  8:35 ` guihaoc at gcc dot gnu.org
  0 siblings, 0 replies; 2+ messages in thread
From: guihaoc at gcc dot gnu.org @ 2023-06-29  8:35 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110331

--- Comment #1 from HaoChen Gui <guihaoc at gcc dot gnu.org> ---
Even the P9 assembly is not good, as vextu* has a higher lantency than mfvsrd. 
        li 9,12
        vextubrx 3,9,2

^ permalink raw reply	[flat|nested] 2+ messages in thread
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2023-06-21  3:19 [Bug target/110331] New: ppc64 vec_extract with constant index is suboptimal on P8 guihaoc at gcc dot gnu.org
2023-06-29  8:35 ` [Bug target/110331] " guihaoc at gcc dot gnu.org

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