[Bug target/113738] New: [14 Regression] ICE: in df_reg_chain_verify_unmarked, at df-scan.cc:4001 with -O2 -march=rv64gcv

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113738

            Bug ID: 113738
           Summary: [14 Regression] ICE: in df_reg_chain_verify_unmarked,
                    at df-scan.cc:4001 with -O2 -march=rv64gcv
           Product: gcc
           Version: 14.0
            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 57305
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57305&action=edit
reduced testcase (from gcc.dg/torture/pr45764.c)

Compiler output:
$ riscv64-unknown-linux-gnu-gcc -O2 -march=rv64gcv testcase.c 
during RTL pass: rtl_dce
testcase.c: In function 'foo':
testcase.c:7:1: internal compiler error: in df_reg_chain_verify_unmarked, at
df-scan.cc:4001
    7 | }
      | ^
0xa138ee df_reg_chain_verify_unmarked
        /repo/gcc-trunk/gcc/df-scan.cc:4001
0xa15111 df_reg_chain_verify_unmarked
        /repo/gcc-trunk/gcc/df-scan.cc:4218
0xa15111 df_scan_verify()
        /repo/gcc-trunk/gcc/df-scan.cc:4264
0x11f06d1 df_verify()
        /repo/gcc-trunk/gcc/df-core.cc:1834
0x11f06d1 df_analyze_1
        /repo/gcc-trunk/gcc/df-core.cc:1221
0x29de3d5 init_dce
        /repo/gcc-trunk/gcc/dce.cc:763
0x29e103d rest_of_handle_fast_dce
        /repo/gcc-trunk/gcc/dce.cc:1193
0x29e103d execute
        /repo/gcc-trunk/gcc/dce.cc:1290
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-r14-8771-20240203001826-g4b7d4d8a4af-checking-yes-rtl-df-extra-riscv64/bin/../libexec/gcc/riscv64-unknown-linux-gnu/14.0.1/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-cloog --with-ppl --with-isl --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
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r14-8771-20240203001826-g4b7d4d8a4af-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.1 20240203 (experimental) (GCC)