[Bug tree-optimization/112809] New: during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[Bug tree-optimization/112809] New: during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112809

            Bug ID: 112809
           Summary: during GIMPLE pass: bitintlower ICE: in
                    limb_access_type, at gimple-lower-bitint.cc:563 at -O1
                    and above
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Created attachment 56752
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56752&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O testcase.c 
during GIMPLE pass: bitintlower
testcase.c: In function 'foo':
testcase.c:6:1: internal compiler error: in limb_access_type, at
gimple-lower-bitint.cc:563
    6 | foo (void)
      | ^~~
0xd520e1 limb_access_type
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:563
0x2535e97 limb_access_type
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:559
0x2535e97 limb_access
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:578
0x2546609 lower_mergeable_stmt
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:2693
0x254af8d lower_stmt
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:5265
0x254d626 gimple_lower_bitint
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:6394
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r14-6051-20231201105652-gb1fe98dee21-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--disable-bootstrap --with-cloog --with-ppl --with-isl
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r14-6051-20231201105652-gb1fe98dee21-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.0 20231201 (experimental) (GCC)

[Bug tree-optimization/112809] during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112809

--- Comment #1 from Zdenek Sojka <zsojka at seznam dot cz> ---
Created attachment 56791
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56791&action=edit
a simpler testcase using only two variables

$ x86_64-pc-linux-gnu-gcc -O testcase.c
during GIMPLE pass: bitintlower
testcase.c: In function 'foo':
testcase.c:5:1: internal compiler error: in limb_access_type, at
gimple-lower-bitint.cc:563
    5 | foo (void)
      | ^~~
0xd52c07 limb_access_type
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:563
0x25351a7 limb_access_type
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:559
0x25351a7 limb_access
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:578
0x2545989 lower_mergeable_stmt
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:2693
0x254a30d lower_stmt
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:5268
0x254c9a6 gimple_lower_bitint
        /repo/gcc-trunk/gcc/gimple-lower-bitint.cc:6397
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug tree-optimization/112809] during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112809

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
   Last reconfirmed|                            |2023-12-05
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 56806
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56806&action=edit
gcc14-pr112809.patch

Untested fix.

[Bug tree-optimization/112809] during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112809

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:0ca64f846edce3c7b7f26bcc5978118e560e65b1

commit r14-6209-g0ca64f846edce3c7b7f26bcc5978118e560e65b1
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Dec 6 09:55:30 2023 +0100

    lower-bitint: Fix arithmetics followed by extension by many bits [PR112809]

    A zero or sign extension from result of some upwards_2limb operation
    is implemented in lower_mergeable_stmt as an extra loop which fills in
    the extra bits with 0s or 1s.
    If the delta of extended vs. unextended bit count is small, the code
    doesn't use a loop and emits up to a couple of stores to constant indexes,
    but if the delta is large, it uses
              cnt = (bo_bit != 0) + 1 + (rem != 0);
    statements.  bo_bit is non-zero for bit-field loads and is done in that
    case as straight line, the unconditional 1 in there is for a loop which
    handles most of the limbs in the delta and finally (rem != 0) is for the
    case when the extended precision is not a multiple of limb_prec and is
    again done in straight line code (after the loop).
    The testcase ICEs because the decision what idx to use was incorrect
    for kind == bitint_prec_huge (i.e. when the precision delta is very large)
    and rem == 0 (i.e. the extended precision is multiple of limb_prec).
    In that case cnt is either 1 (if bo_bit == 0) or 2, and idx should
    be either first size_int (start) and then result of create_loop (for bo_bit
    != 0) or just result of create_loop, but by mistake the last case
    was size_int (end), which means when precision is multiple of limb_prec
    storing above the precision (which ICEs; but also not emitting the loop
    which is needed).

    2023-12-06  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/112809
            * gimple-lower-bitint.cc (bitint_large_huge::lower_mergeable_stmt):
For
            separate_ext in kind == bitint_prec_huge mode if rem == 0, create
for
            i == cnt - 1 the loop rather than using size_int (end).

            * gcc.dg/bitint-48.c: New test.

[Bug tree-optimization/112809] during GIMPLE pass: bitintlower ICE: in limb_access_type, at gimple-lower-bitint.cc:563 at -O1 and above

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112809

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be fixed now.