[Bug target/121113] New: ICE: in riscv_sched_variable_issue, at config/riscv/riscv.cc:10243 with -mcpu=xiangshan-kunminghu and _Float16

[zsojka at seznam dot cz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121113

            Bug ID: 121113
           Summary: ICE: in riscv_sched_variable_issue, at
                    config/riscv/riscv.cc:10243 with
                    -mcpu=xiangshan-kunminghu and _Float16
           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 61881
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61881&action=edit
reduced testcase

Compiler output:
$ riscv64-unknown-linux-gnu-gcc -Os -mcpu=xiangshan-kunminghu testcase.c 
during RTL pass: sched2
testcase.c: In function 'foo':
testcase.c:2:22: internal compiler error: in riscv_sched_variable_issue, at
config/riscv/riscv.cc:10243
    2 | void foo() { f /= g; }
      |                      ^
0x323a881 internal_error(char const*, ...)
        /repo/gcc-trunk/gcc/diagnostic-global-context.cc:517
0x1005eb5 fancy_abort(char const*, int, char const*)
        /repo/gcc-trunk/gcc/diagnostic.cc:1818
0xcac36c riscv_sched_variable_issue
        /repo/gcc-trunk/gcc/config/riscv/riscv.cc:10243
0xcac36c riscv_sched_variable_issue
        /repo/gcc-trunk/gcc/config/riscv/riscv.cc:10223
0x2d536c8 schedule_block(basic_block_def**, void*)
        /repo/gcc-trunk/gcc/haifa-sched.cc:6928
0x17b043a schedule_region
        /repo/gcc-trunk/gcc/sched-rgn.cc:3213
0x17b043a schedule_insns()
        /repo/gcc-trunk/gcc/sched-rgn.cc:3535
0x17b08cd schedule_insns()
        /repo/gcc-trunk/gcc/sched-rgn.cc:3521
0x17b08cd rest_of_handle_sched2
        /repo/gcc-trunk/gcc/sched-rgn.cc:3759
0x17b08cd execute
        /repo/gcc-trunk/gcc/sched-rgn.cc:3898
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-20250716071657-r16-2282-g82e912344d28cf-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-20250716071657-r16-2282-g82e912344d28cf-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.0 20250716 (experimental) (GCC)