[Bug target/114603] aarch64: Invalid SVE cnot optimisation

2024-04-05 Thread rsandifo at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114603

Richard Sandiford  changed:

   What|Removed |Added

   Last reconfirmed||2024-04-05
 Status|UNCONFIRMED |ASSIGNED
   Assignee|unassigned at gcc dot gnu.org  |rsandifo at gcc dot 
gnu.org
 Ever confirmed|0   |1

--- Comment #2 from Richard Sandiford  ---
Fix on trunk so far, but I'll backport if possible.

[Bug target/114603] aarch64: Invalid SVE cnot optimisation

2024-04-05 Thread cvs-commit at gcc dot gnu.org via Gcc-bugs 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114603

--- Comment #1 from GCC Commits  ---
The trunk branch has been updated by Richard Sandiford :

https://gcc.gnu.org/g:67cbb1c638d6ab3a9cb77e674541e2b291fb67df

commit r14-9811-g67cbb1c638d6ab3a9cb77e674541e2b291fb67df
Author: Richard Sandiford 
Date:   Fri Apr 5 14:47:15 2024 +0100

aarch64: Fix bogus cnot optimisation [PR114603]

aarch64-sve.md had a pattern that combined:

cmpeq   pb.T, pa/z, zc.T, #0
mov zd.T, pb/z, #1

into:

cnotzd.T, pa/m, zc.T

But this is only valid if pa.T is a ptrue.  In other cases, the
original would set inactive elements of zd.T to 0, whereas the
combined form would copy elements from zc.T.

gcc/
PR target/114603
* config/aarch64/aarch64-sve.md (@aarch64_pred_cnot): Replace
with...
(@aarch64_ptrue_cnot): ...this, requiring operand 1 to be
a ptrue.
(*cnot): Require operand 1 to be a ptrue.
* config/aarch64/aarch64-sve-builtins-base.cc
(svcnot_impl::expand):
Use aarch64_ptrue_cnot for _x operations that are predicated
with a ptrue.  Represent other _x operations as fully-defined _m
operations.

gcc/testsuite/
PR target/114603
* gcc.target/aarch64/sve/acle/general/cnot_1.c: New test.