| Message ID | 20211228101422.GO2646553@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | optabs: Fix up checking for CALLs in newly added code by double-word divmod [PR103838] | expand |
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 <jakub@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
--- gcc/optabs.c.jj 2021-09-06 14:47:43.212049793 +0200 +++ gcc/optabs.c 2021-12-27 11:03:11.575586585 +0100 @@ -1135,6 +1135,10 @@ expand_doubleword_mod (machine_mode mode remainder = convert_modes (mode, word_mode, remainder, unsignedp); /* Punt if we need any library calls. */ + if (last) + last = NEXT_INSN (last); + else + last = get_insns (); for (; last; last = NEXT_INSN (last)) if (CALL_P (last)) return NULL_RTX; @@ -1228,6 +1232,10 @@ expand_doubleword_divmod (machine_mode m } /* Punt if we need any library calls. */ + if (last) + last = NEXT_INSN (last); + else + last = get_insns (); for (; last; last = NEXT_INSN (last)) if (CALL_P (last)) return NULL_RTX; --- gcc/testsuite/gcc.dg/pr103838.c.jj 2021-12-27 11:07:08.920225699 +0100 +++ gcc/testsuite/gcc.dg/pr103838.c 2021-12-27 11:06:57.555386630 +0100 @@ -0,0 +1,28 @@ +/* PR debug/103838 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fcompare-debug" } */ + +#ifdef __SIZEOF_INT128__ +__int128 m; +#else +long long m; +#endif +int n; + +__attribute__((noinline)) void +bar (void) +{ + n += !!m; +} + +void +foo (void) +{ + int i; + + for (i = 0; i < 2; ++i) + { + bar (); + m /= 3; + } +}