[Bug target/121007] New: [Regression 15] compiler hangs when building ffpmeg with -mcpu=power9 on ppc64le

[siddhesh at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121007

            Bug ID: 121007
           Summary: [Regression 15] compiler hangs when building ffpmeg
                    with -mcpu=power9 on ppc64le
           Product: gcc
           Version: 15.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: siddhesh at gcc dot gnu.org
  Target Milestone: ---

Created attachment 61822
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61822&action=edit
Unreduced preprocessed source

Attempt to build libavcodec/ppc/h264dsp.c on ppc64le with -mcpu=power9 results
in the build hanging in push_to_sequence in emit-rtl.cc:

      for (last = first; last && NEXT_INSN (last); last = NEXT_INSN (last))
        ;

The same code appears to build just fine with gcc 14.3.

Preprocessed source attached.  Reproducible with:

gcc/cc1 -quiet -mcpu=power9 -O2 -o /dev/null h264dsp.i

The command just hangs there and does not finish.  Works fine on
baseline/gcc-15, I'm trying to figure out which commit may have broken this.