[Bug target/123278] New: ICE: in riscv_sched_variable_issue, at config/riscv/riscv.cc:10950 with -mcpu=xt-c910v2 -mtune=andes-n45 and _Float16

[zsojka at seznam dot cz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123278

            Bug ID: 123278
           Summary: ICE: in riscv_sched_variable_issue, at
                    config/riscv/riscv.cc:10950 with -mcpu=xt-c910v2
                    -mtune=andes-n45 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 63136
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63136&action=edit
reduced testcase

Compiler output:
$ riscv64-unknown-linux-gnu-gcc -O2 -mcpu=xt-c910v2 -mtune=andes-n45 testcase.c 
during RTL pass: sched1
testcase.c: In function 'foo':
testcase.c:7:1: internal compiler error: in riscv_sched_variable_issue, at
config/riscv/riscv.cc:10950
    7 | }
      | ^
0x36448fd internal_error(char const*, ...)
        /repo/gcc-trunk/gcc/diagnostic-global-context.cc:787
0x11332bf fancy_abort(char const*, int, char const*)
        /repo/gcc-trunk/gcc/diagnostics/context.cc:1805
0xd88bc7 riscv_sched_variable_issue
        /repo/gcc-trunk/gcc/config/riscv/riscv.cc:10950
0xd88bc7 riscv_sched_variable_issue
        /repo/gcc-trunk/gcc/config/riscv/riscv.cc:10930
0x345d098 schedule_block(basic_block_def**, void*)
        /repo/gcc-trunk/gcc/haifa-sched.cc:6933
0x1916e1a schedule_region
        /repo/gcc-trunk/gcc/sched-rgn.cc:3218
0x1916e1a schedule_insns()
        /repo/gcc-trunk/gcc/sched-rgn.cc:3540
0x191725c schedule_insns()
        /repo/gcc-trunk/gcc/sched-rgn.cc:3526
0x191725c rest_of_handle_sched
        /repo/gcc-trunk/gcc/sched-rgn.cc:3744
0x191725c execute
        /repo/gcc-trunk/gcc/sched-rgn.cc:3854
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-20251223062311-r16-6349-gdbe8e0efb7b029-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-20251223062311-r16-6349-gdbe8e0efb7b029-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.0 20251223 (experimental) (GCC)