[Bug rtl-optimization/102986] New: [12 Regression] ICE: in expand_shift_1, at expmed.c:2671 with a negative shift of a vector

["zsojka at seznam dot cz" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102986

            Bug ID: 102986
           Summary: [12 Regression] ICE: in expand_shift_1, at
                    expmed.c:2671 with a negative shift of a vector
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu

Created attachment 51689
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51689&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc testcase.c 
testcase.c: In function 'foo':
testcase.c:8:5: warning: right shift count is negative [-Wshift-count-negative]
    8 |   v >>= -1;
      |     ^~~
during RTL pass: expand
testcase.c:8:5: internal compiler error: in expand_shift_1, at expmed.c:2671
    8 |   v >>= -1;
      |     ^~~
0x6b5040 expand_shift_1
        /repo/gcc-trunk/gcc/expmed.c:2671
0xf62135 expand_variable_shift(tree_code, machine_mode, rtx_def*, tree_node*,
rtx_def*, int)
        /repo/gcc-trunk/gcc/expmed.c:2712
0xf774cf expand_expr_real_2(separate_ops*, rtx_def*, machine_mode,
expand_modifier)
        /repo/gcc-trunk/gcc/expr.c:9945
0xe4109f expand_gimple_stmt_1
        /repo/gcc-trunk/gcc/cfgexpand.c:3979
0xe4109f expand_gimple_stmt
        /repo/gcc-trunk/gcc/cfgexpand.c:4040
0xe46ed8 expand_gimple_basic_block
        /repo/gcc-trunk/gcc/cfgexpand.c:6085
0xe490c7 execute
        /repo/gcc-trunk/gcc/cfgexpand.c:6811
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.

$ 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-r12-4764-20211028112842-ga84b9d5373c-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.0.0/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-r12-4764-20211028112842-ga84b9d5373c-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20211028 (experimental) (GCC)