| Message ID | 20200513082716.GN8462@tucnak |
|---|---|
| State | New |
| Headers | show |
| Series | Fix -fcompare-debug issue in purge_dead_edges [PR95080] | expand |
On Wed, 13 May 2020, Jakub Jelinek wrote: > Hi! > > The following testcase fails with -fcompare-debug, the bug used to be latent > since introduction of -fcompare-debug. > The loop at the start of purge_dead_edges behaves differently between -g0 > and -g - if the last insn is a DEBUG_INSN, then it skips not just > DEBUG_INSNs but also NOTEs until it finds some other real insn (or bb head), > while with -g0 it will not skip any NOTEs, so if we have > real_insn > note > debug_insn // not present with -g0 > then with -g it might remove useless REG_EH_REGION from real_insn, while > with -g0 it will not. > > Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for > trunk? OK. Thanks, Richard. > Yet another option would be not skipping NOTE_P in the loop; I couldn't find > in history rationale for why it is done. > > 2020-05-13 Jakub Jelinek <jakub@redhat.com> > > PR debug/95080 > * cfgrtl.c (purge_dead_edges): Skip over debug and note insns even > if the last insn is a note. > > * g++.dg/opt/pr95080.C: New test. > > --- gcc/cfgrtl.c.jj 2020-04-17 10:32:58.589780140 +0200 > +++ gcc/cfgrtl.c 2020-05-12 21:02:09.808395583 +0200 > @@ -3100,7 +3100,7 @@ purge_dead_edges (basic_block bb) > bool found; > edge_iterator ei; > > - if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) > + if ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)) > do > insn = PREV_INSN (insn); > while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)); > --- gcc/testsuite/g++.dg/opt/pr95080.C.jj 2020-05-12 21:01:09.804295824 +0200 > +++ gcc/testsuite/g++.dg/opt/pr95080.C 2020-05-12 21:00:52.738551862 +0200 > @@ -0,0 +1,41 @@ > +// PR debug/95080 > +// { dg-do compile } > +// { dg-options "-Og -fcse-follow-jumps -fnon-call-exceptions -fcompare-debug" } > + > +char *a; > + > +void baz (); > + > +static inline bool > +bar () > +{ > + int j = a[0] - 1; > + switch (j) > + { > + case 0: > + case 2: > + return true; > + default: > + return false; > + } > +} > + > +static inline bool > +foo () > +{ > + if (bar ()) > + baz (); > + return 0; > +} > + > +struct S > +{ > + int h; > + ~S (); > +}; > + > +S::~S () > +{ > + if (a[0] == 0) > + foo () != h; > +} > > Jakub > >
--- gcc/cfgrtl.c.jj 2020-04-17 10:32:58.589780140 +0200 +++ gcc/cfgrtl.c 2020-05-12 21:02:09.808395583 +0200 @@ -3100,7 +3100,7 @@ purge_dead_edges (basic_block bb) bool found; edge_iterator ei; - if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) + if ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)) do insn = PREV_INSN (insn); while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)); --- gcc/testsuite/g++.dg/opt/pr95080.C.jj 2020-05-12 21:01:09.804295824 +0200 +++ gcc/testsuite/g++.dg/opt/pr95080.C 2020-05-12 21:00:52.738551862 +0200 @@ -0,0 +1,41 @@ +// PR debug/95080 +// { dg-do compile } +// { dg-options "-Og -fcse-follow-jumps -fnon-call-exceptions -fcompare-debug" } + +char *a; + +void baz (); + +static inline bool +bar () +{ + int j = a[0] - 1; + switch (j) + { + case 0: + case 2: + return true; + default: + return false; + } +} + +static inline bool +foo () +{ + if (bar ()) + baz (); + return 0; +} + +struct S +{ + int h; + ~S (); +}; + +S::~S () +{ + if (a[0] == 0) + foo () != h; +}