[Bug middle-end/110864] New: [14 Regression] ICE in combine.cc causes stage2 build failure on RISCV

[patrick at rivosinc dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110864

            Bug ID: 110864
           Summary: [14 Regression] ICE in combine.cc causes stage2 build
                    failure on RISCV
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: patrick at rivosinc dot com
  Target Milestone: ---

Created attachment 55667
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55667&action=edit
Full build log with the error

Using https://github.com/riscv-collab/riscv-gnu-toolchain with tip-of-tree GCC
fails to build rv32gc linux target.

Here's the error:
during RTL pass: combine
../../../../gcc/libitm/beginend.cc: In static member function 'static uint32_t
GTM::gtm_thread::begin_transaction(uint32_t, const GTM::gtm_jmpbuf*)':
../../../../gcc/libitm/beginend.cc:425:1: internal compiler error: in
decompose, at rtl.h:2297
  425 | }
      | ^

The full log with the traceback is attached.

Affects rv32gc linux. rv64gc linux and rv{32|64}gc Newlib/musl still build.

I haven't attempted to bootstrap other architectures so it may affect those as
well.

I've partially bisected it down to 5 possible commits:
Known to fail: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=75d62394
Known to succeed: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=05986af

I'll continue bisecting and keep this issue updated.