[Bug tree-optimization/102832] New: [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[Bug tree-optimization/102832] New: [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

            Bug ID: 102832
           Summary: [12 Regression] ICE in vect_create_partial_epilog with
                    -O3 -msve-vector-bits=128
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

The following fails:

$ cat t.c
int a, b;
char c;
signed char d(int e, int f) { return e - f; }
void g() {
  a = 0;
  for (; a >= -17; a = d(a, 1))
    c ^= b;
}
$ aarch64-linux-gnu-gcc -c t.c -march=armv8.2-a+sve -O3 -msve-vector-bits=128
during GIMPLE pass: vect
t.c: In function ‘g’:
t.c:4:6: internal compiler error: in vect_create_partial_epilog, at
tree-vect-loop.c:5038
    4 | void g() {
      |      ^
0x1156110 vect_create_partial_epilog
        /home/alecop01/toolchain/src/gcc/gcc/tree-vect-loop.c:5035
0x1164be3 vect_transform_cycle_phi(_loop_vec_info*, _stmt_vec_info*, gimple**,
_slp_tree*, _slp_instance*)
        /home/alecop01/toolchain/src/gcc/gcc/tree-vect-loop.c:7772
0x1150a1c vect_transform_stmt(vec_info*, _stmt_vec_info*,
gimple_stmt_iterator*, _slp_tree*, _slp_instance*)
        /home/alecop01/toolchain/src/gcc/gcc/tree-vect-stmts.c:11107
0x1174723 vect_transform_loop(_loop_vec_info*, gimple*)
        /home/alecop01/toolchain/src/gcc/gcc/tree-vect-loop.c:9731
0x11b0f44 try_vectorize_loop_1
        /home/alecop01/toolchain/src/gcc/gcc/tree-vectorizer.c:1111
0x11b1662 try_vectorize_loop_1
        /home/alecop01/toolchain/src/gcc/gcc/tree-vectorizer.c:1148
0x11b170b try_vectorize_loop
        /home/alecop01/toolchain/src/gcc/gcc/tree-vectorizer.c:1168
0x11b19e9 vectorize_loops()
        /home/alecop01/toolchain/src/gcc/gcc/tree-vectorizer.c:1249
0x1030ef3 execute
        /home/alecop01/toolchain/src/gcc/gcc/tree-ssa-loop.c:413
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

Alex Coplan <acoplan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rsandifo at gcc dot gnu.org

--- Comment #1 from Alex Coplan <acoplan at gcc dot gnu.org> ---
Started with r12-2739-g5a1017dc, FWIW:

commit 5a1017dc305c49c59129d45536630d02dbc01c45
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Wed Aug 4 16:52:09 2021

    vect: Tweak comparisons with existing epilogue loops

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
   Target Milestone|---                         |12.0

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-10-22

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
My patch for PR104445 also fixes this one.

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:da2bf62d9e2a25f2d6a99176144c250b51fbdee7

commit r12-7127-gda2bf62d9e2a25f2d6a99176144c250b51fbdee7
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Feb 9 10:55:18 2022 +0100

    tree-optimization/104445 - check for vector extraction support

    This adds a missing check to epilogue reduction re-use, namely
    that we can do hi/lo extracts from the vector when demoting it
    to the epilogue vector size.

    I've chosen to add a can_vec_extract helper to optabs-query.h,
    in the future we might want to simplify the vectorizers life by
    handling vector-from-vector extraction via BIT_FIELD_REFs during
    RTL expansion via the mode punning when the vec_extract is not
    directly supported.

    I'm not 100% sure we can always do the punning of the
    vec_extract result to a vector mode of the same size, but then
    I'm also not sure how to check for that (the vectorizer doesn't
    in other places it does that at the moment, but I suppose we
    eventually just go through memory there)?

    2022-02-09  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/104445
            PR tree-optimization/102832
            * optabs-query.h (can_vec_extract): New.
            * optabs-query.cc (can_vec_extract): Likewise.
            * tree-vect-loop.cc (vect_find_reusable_accumulator): Check
            we can extract a hi/lo part from the larger vector, rework
            check iteration from larger to smaller sizes.

            * gcc.dg/vect/pr104445.c: New testcase.

[Bug tree-optimization/102832] [12 Regression] ICE in vect_create_partial_epilog with -O3 -msve-vector-bits=128

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102832

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.