| Message ID | orei9s7vsn.fsf@livre.localdomain |
|---|---|
| State | New |
| Headers | show |
On Wed, Dec 8, 2010 at 5:06 AM, Alexandre Oliva <aoliva@redhat.com> wrote: > At -O0, we merge blocks or not depending on locus information present at > the last insn in a block and the entry locus of the subsequent block. > We shouldn't use the locus of a debug insn for this compare, lest we may > end up not merging blocks that, with -g0, we would. > > This seldom occurs in practice, since this patch is only active at -O0, > and -fvar-tracking is disabled by default at -O0, even if -g is enabled. > However, since it's possible to explicitly activate -fvar-tracking (and > -fvar-tracking-assignments), even at -O0, we shouldn't generate > different executable code if the user does this. > > The patch below was regstrapped on x86_64-linux-gnu. Ok to install? Ok. Thanks, Richard. > > > > -- > Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ > You must be the change you wish to see in the world. -- Gandhi > Be Free! -- http://FSFLA.org/ FSF Latin America board member > Free Software Evangelist Red Hat Brazil Compiler Engineer > >
for gcc/ChangeLog from Alexandre Oliva <aoliva@redhat.com> PR debug/46782 * cfgcleanup.c (try_forward_edges): Skip debug insns. for gcc/testsuite/ChangeLog from Alexandre Oliva <aoliva@redhat.com> PR debug/46782 * gcc.dg/debug/pr46782.c: New. Index: gcc/cfgcleanup.c =================================================================== --- gcc/cfgcleanup.c.orig 2010-12-06 12:34:03.311495403 -0200 +++ gcc/cfgcleanup.c 2010-12-06 12:34:04.925493962 -0200 @@ -487,11 +487,17 @@ try_forward_edges (int mode, basic_block new_target = NULL; else { + rtx last; + if (new_locus) locus = new_locus; - new_locus = INSN_P (BB_END (target)) - ? INSN_LOCATOR (BB_END (target)) : 0; + last = BB_END (target); + if (DEBUG_INSN_P (last)) + last = prev_nondebug_insn (last); + + new_locus = last && INSN_P (last) + ? INSN_LOCATOR (last) : 0; if (new_locus && locus && !locator_eq (new_locus, locus)) new_target = NULL; Index: gcc/testsuite/gcc.dg/debug/pr46782.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ gcc/testsuite/gcc.dg/debug/pr46782.c 2010-12-06 12:34:43.712495319 -0200 @@ -0,0 +1,11 @@ +/* PR debug/46782 */ +/* { dg-do compile } */ +/* { dg-options "-w -O0 -fvar-tracking -fcompare-debug" } */ + +void foo (int i) +{ + if (i) + i++; + while (i) + ; +}