[Bug target/43147] SSE shuffle merge

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43147

H.J. Lu  changed:

   What|Removed |Added

   Keywords||patch
URL||https://gcc.gnu.org/piperma
   ||il/gcc-patches/2021-August/
   ||577884.html

--- Comment #13 from H.J. Lu  ---
A patch is posted at

https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577884.html

[Bug target/43147] SSE shuffle merge

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43147

H.J. Lu  changed:

   What|Removed |Added

   Assignee|unassigned at gcc dot gnu.org  |hjl.tools at gmail dot 
com

--- Comment #12 from H.J. Lu  ---
Created attachment 51345
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51345&action=edit
A patch

[Bug target/43147] SSE shuffle merge

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43147

Andrew Pinski  changed:

   What|Removed |Added

  Component|rtl-optimization|target

--- Comment #11 from Andrew Pinski  ---
We produce:
Trying 5, 7 -> 11:
5: r86:V4SF=[`*.LC0']
  REG_EQUAL const_vector
7: r85:V4SF=vec_select(vec_concat(r86:V4SF,r86:V4SF),parallel)
  REG_DEAD r86:V4SF
  REG_EQUAL const_vector
   11: r88:V4SF=vec_select(vec_concat(r85:V4SF,r85:V4SF),parallel)
  REG_DEAD r85:V4SF
  REG_EQUAL const_vector
Failed to match this instruction:
(set (reg:V4SF 88)
(const_vector:V4SF [
(const_double:SF 2.0e+0 [0x0.8p+2])
(const_double:SF 1.0e+0 [0x0.8p+1])
(const_double:SF 4.0e+0 [0x0.8p+3])
(const_double:SF 3.0e+0 [0x0.cp+2])
]))

Which means the vec_select are merging at the rtl level just fine.

Anyways if the target expands __builtin_ia32_shufps to VEC_PERM_EXPR we would
have gotten this optimized at the gimple level.  So this is a target issue.