On 12/28/2021 3:14 AM, Jakub Jelinek wrote:
Hi!

These two spots are meant to punt if the newly added code contains
any CALL_INSNs, because in that case having a large sequence of insns
that also calls something is undesirable, better have one call that
is optimized in itself well.
The functions do last = get_last_insn (); before emitting any insns
(and expand_binop as the ultimate caller uses delete_insns_since if
the expansion fails), but the checks were incorrect for 2 reasons:
1) it checked not just what follows after that last insn, but also
    the last insn itself; so, if the division or modulo is immediately
    preceded by a CALL_INSN, then we punt; this also causes -fcompare-debug
    failures if the CALL_INSN is with -g followed by one or more DEBUG_INSNs
2) if get_last_insn () is NULL (i.e. emitting into a new sequence), then
    we didn't check anything

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2021-12-28  Jakub Jelinek  <ja...@redhat.com>

        PR debug/103838
        * optabs.c (expand_doubleword_mod, expand_doubleword_divmod): Only
        check newly added insns for CALL_P, not the last insn of previous
        code.

        * gcc.dg/pr103838.c: New test.
OK
jeff

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