[Bug target/120642] New: ICE: in validate_change_or_fail, at config/riscv/riscv-v.cc:5705 with -O -mcpu=xt-c920 -mrvv-vector-bits=zvl

[zsojka at seznam dot cz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120642

            Bug ID: 120642
           Summary: ICE: in validate_change_or_fail, at
                    config/riscv/riscv-v.cc:5705 with -O -mcpu=xt-c920
                    -mrvv-vector-bits=zvl
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: riscv64-unknown-linux-gnu

Created attachment 61629
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61629&action=edit
reduced testcase

Compiler output:
$ riscv64-unknown-linux-gnu-gcc -O -mcpu=xt-c920 -mrvv-vector-bits=zvl
testcase.c 
during RTL pass: avlprop
testcase.c: In function 'foo':
testcase.c:2:22: internal compiler error: in validate_change_or_fail, at
config/riscv/riscv-v.cc:5705
    2 | void foo() { v /= 3; }
      |                      ^
0x30faec1 internal_error(char const*, ...)
        /repo/gcc-trunk/gcc/diagnostic-global-context.cc:517
0xf881d7 fancy_abort(char const*, int, char const*)
        /repo/gcc-trunk/gcc/diagnostic.cc:1803
0xca6ec6 riscv_vector::validate_change_or_fail(rtx_def*, rtx_def**, rtx_def*,
bool)
        /repo/gcc-trunk/gcc/config/riscv/riscv-v.cc:5705
0x1ce535b simplify_replace_vlmax_avl
        /repo/gcc-trunk/gcc/config/riscv/riscv-avlprop.cc:201
0x1ce64ca pass_avlprop::execute(function*)
        /repo/gcc-trunk/gcc/config/riscv/riscv-avlprop.cc:535
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.

$ riscv64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-riscv64/bin/riscv64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-20250612182937-r16-1487-g774ae8734f0e19-checking-yes-rtl-df-extra-riscv64/bin/../libexec/gcc/riscv64-unknown-linux-gnu/16.0.0/lto-wrapper
Target: riscv64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-isa-spec=2.2 --with-sysroot=/usr/riscv64-unknown-linux-gnu
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=riscv64-unknown-linux-gnu
--with-ld=/usr/bin/riscv64-unknown-linux-gnu-ld
--with-as=/usr/bin/riscv64-unknown-linux-gnu-as --disable-multilib
--enable-libsanitizer --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-20250612182937-r16-1487-g774ae8734f0e19-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.0 20250612 (experimental) (GCC)