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re PR c++/55135 (Segfault of gcc on a big file)

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gcc/
	PR c++/55135
	* except.h (remove_unreachable_eh_regions): New prototype.
	* except.c (remove_eh_handler_splicer): New function, split out
	of remove_eh_handler.
	(remove_eh_handler): Use remove_eh_handler_splicer.  Add comment
	warning about running it on many EH regions one at a time.
	(remove_unreachable_eh_regions_worker): New function, walk the
	EH tree in depth-first order and remove non-marked regions.
	(remove_unreachable_eh_regions): New function.
	* tree-eh.c (mark_reachable_handlers): New function, split out
	from remove_unreachable_handlers.
	(remove_unreachable_handlers): Use mark_reachable_handlers and
	remove_unreachable_eh_regions.
	(remove_unreachable_handlers_no_lp): Use mark_reachable_handlers
	and remove_unreachable_eh_regions.

From-SVN: r196464
This commit is contained in:
Steven Bosscher 2013-03-05 14:45:23 +00:00
parent 574f9d7ecd
commit d273b17674
4 changed files with 171 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
gcc/ChangeLog
View File

@ -1,3 +1,21 @@
2013-03-05 Steven Bosscher <steven@gcc.gnu.org>
PR c++/55135
* except.h (remove_unreachable_eh_regions): New prototype.
* except.c (remove_eh_handler_splicer): New function, split out
of remove_eh_handler.
(remove_eh_handler): Use remove_eh_handler_splicer. Add comment
warning about running it on many EH regions one at a time.
(remove_unreachable_eh_regions_worker): New function, walk the
EH tree in depth-first order and remove non-marked regions.
(remove_unreachable_eh_regions): New function.
* tree-eh.c (mark_reachable_handlers): New function, split out
from remove_unreachable_handlers.
(remove_unreachable_handlers): Use mark_reachable_handlers and
remove_unreachable_eh_regions.
(remove_unreachable_handlers_no_lp): Use mark_reachable_handlers
and remove_unreachable_eh_regions.
2013-03-05 Richard Biener <rguenther@suse.de>
PR middle-end/56525

71
gcc/except.c
View File

@ -1505,12 +1505,12 @@ remove_eh_landing_pad (eh_landing_pad lp)
(*cfun->eh->lp_array)[lp->index] = NULL;
}
/* Splice REGION from the region tree. */
/* Splice the EH region at PP from the region tree. */
void
remove_eh_handler (eh_region region)
static void
remove_eh_handler_splicer (eh_region *pp)
{
eh_region *pp, *pp_start, p, outer;
eh_region region = *pp;
eh_landing_pad lp;
for (lp = region->landing_pads; lp ; lp = lp->next_lp)
@ -1520,15 +1520,11 @@ remove_eh_handler (eh_region region)
(*cfun->eh->lp_array)[lp->index] = NULL;
}
outer = region->outer;
if (outer)
pp_start = &outer->inner;
else
pp_start = &cfun->eh->region_tree;
for (pp = pp_start, p = *pp; p != region; pp = &p->next_peer, p = *pp)
continue;
if (region->inner)
{
eh_region p, outer;
outer = region->outer;
*pp = p = region->inner;
do
{
@ -1543,6 +1539,59 @@ remove_eh_handler (eh_region region)
(*cfun->eh->region_array)[region->index] = NULL;
}
/* Splice a single EH region REGION from the region tree.
To unlink REGION, we need to find the pointer to it with a relatively
expensive search in REGION's outer region. If you are going to
remove a number of handlers, using remove_unreachable_eh_regions may
be a better option. */
void
remove_eh_handler (eh_region region)
{
eh_region *pp, *pp_start, p, outer;
outer = region->outer;
if (outer)
pp_start = &outer->inner;
else
pp_start = &cfun->eh->region_tree;
for (pp = pp_start, p = *pp; p != region; pp = &p->next_peer, p = *pp)
continue;
remove_eh_handler_splicer (pp);
}
/* Worker for remove_unreachable_eh_regions.
PP is a pointer to the region to start a region tree depth-first
search from. R_REACHABLE is the set of regions that have to be
preserved. */
static void
remove_unreachable_eh_regions_worker (eh_region *pp, sbitmap r_reachable)
{
while (*pp)
{
eh_region region = *pp;
remove_unreachable_eh_regions_worker (&region->inner, r_reachable);
if (!bitmap_bit_p (r_reachable, region->index))
remove_eh_handler_splicer (pp);
else
pp = &region->next_peer;
}
}
/* Splice all EH regions *not* marked in R_REACHABLE from the region tree.
Do this by traversing the EH tree top-down and splice out regions that
are not marked. By removing regions from the leaves, we avoid costly
searches in the region tree. */
void
remove_unreachable_eh_regions (sbitmap r_reachable)
{
remove_unreachable_eh_regions_worker (&cfun->eh->region_tree, r_reachable);
}
/* Invokes CALLBACK for every exception handler landing pad label.
Only used by reload hackery; should not be used by new code. */

1
gcc/except.h
View File

@ -229,6 +229,7 @@ extern void init_eh_for_function (void);
extern void remove_eh_landing_pad (eh_landing_pad);
extern void remove_eh_handler (eh_region);
extern void remove_unreachable_eh_regions (sbitmap);
extern bool current_function_has_exception_handlers (void);
extern void output_function_exception_table (const char *);

156
gcc/tree-eh.c
View File

@ -3519,22 +3519,37 @@ struct gimple_opt_pass pass_lower_eh_dispatch =
}
};
/* Walk statements, see what regions are really referenced and remove
those that are unused. */
/* Walk statements, see what regions and, optionally, landing pads
are really referenced.
Returns in R_REACHABLEP an sbitmap with bits set for reachable regions,
and in LP_REACHABLE an sbitmap with bits set for reachable landing pads.
Passing NULL for LP_REACHABLE is valid, in this case only reachable
regions are marked.
The caller is responsible for freeing the returned sbitmaps. */
static void
remove_unreachable_handlers (void)
mark_reachable_handlers (sbitmap *r_reachablep, sbitmap *lp_reachablep)
{
sbitmap r_reachable, lp_reachable;
eh_region region;
eh_landing_pad lp;
basic_block bb;
int lp_nr, r_nr;
bool mark_landing_pads = (lp_reachablep != NULL);
gcc_checking_assert (r_reachablep != NULL);
r_reachable = sbitmap_alloc (cfun->eh->region_array->length ());
lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ());
bitmap_clear (r_reachable);
bitmap_clear (lp_reachable);
*r_reachablep = r_reachable;
if (mark_landing_pads)
{
lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ());
bitmap_clear (lp_reachable);
*lp_reachablep = lp_reachable;
}
else
lp_reachable = NULL;
FOR_EACH_BB (bb)
{
@ -3543,20 +3558,24 @@ remove_unreachable_handlers (void)
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple stmt = gsi_stmt (gsi);
lp_nr = lookup_stmt_eh_lp (stmt);
/* Negative LP numbers are MUST_NOT_THROW regions which
are not considered BB enders. */
if (lp_nr < 0)
bitmap_set_bit (r_reachable, -lp_nr);
/* Positive LP numbers are real landing pads, are are BB enders. */
else if (lp_nr > 0)
if (mark_landing_pads)
{
gcc_assert (gsi_one_before_end_p (gsi));
region = get_eh_region_from_lp_number (lp_nr);
bitmap_set_bit (r_reachable, region->index);
bitmap_set_bit (lp_reachable, lp_nr);
int lp_nr = lookup_stmt_eh_lp (stmt);
/* Negative LP numbers are MUST_NOT_THROW regions which
are not considered BB enders. */
if (lp_nr < 0)
bitmap_set_bit (r_reachable, -lp_nr);
/* Positive LP numbers are real landing pads, and BB enders. */
else if (lp_nr > 0)
{
gcc_assert (gsi_one_before_end_p (gsi));
eh_region region = get_eh_region_from_lp_number (lp_nr);
bitmap_set_bit (r_reachable, region->index);
bitmap_set_bit (lp_reachable, lp_nr);
}
}
/* Avoid removing regions referenced from RESX/EH_DISPATCH. */
@ -3573,6 +3592,19 @@ remove_unreachable_handlers (void)
}
}
}
}
/* Remove unreachable handlers and unreachable landing pads. */
static void
remove_unreachable_handlers (void)
{
sbitmap r_reachable, lp_reachable;
eh_region region;
eh_landing_pad lp;
unsigned i;
mark_reachable_handlers (&r_reachable, &lp_reachable);
if (dump_file)
{
@ -3584,21 +3616,24 @@ remove_unreachable_handlers (void)
dump_bitmap_file (dump_file, lp_reachable);
}
for (r_nr = 1;
vec_safe_iterate (cfun->eh->region_array, r_nr, &region); ++r_nr)
if (region && !bitmap_bit_p (r_reachable, r_nr))
{
if (dump_file)
fprintf (dump_file, "Removing unreachable region %d\n", r_nr);
remove_eh_handler (region);
}
if (dump_file)
{
FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
if (region && !bitmap_bit_p (r_reachable, region->index))
fprintf (dump_file,
"Removing unreachable region %d\n",
region->index);
}
for (lp_nr = 1;
vec_safe_iterate (cfun->eh->lp_array, lp_nr, &lp); ++lp_nr)
if (lp && !bitmap_bit_p (lp_reachable, lp_nr))
remove_unreachable_eh_regions (r_reachable);
FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
if (lp && !bitmap_bit_p (lp_reachable, lp->index))
{
if (dump_file)
fprintf (dump_file, "Removing unreachable landing pad %d\n", lp_nr);
fprintf (dump_file,
"Removing unreachable landing pad %d\n",
lp->index);
remove_eh_landing_pad (lp);
}
@ -3624,12 +3659,12 @@ void
maybe_remove_unreachable_handlers (void)
{
eh_landing_pad lp;
int i;
unsigned i;
if (cfun->eh == NULL)
return;
for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i)
FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
if (lp && lp->post_landing_pad)
{
if (label_to_block (lp->post_landing_pad) == NULL)
@ -3642,45 +3677,38 @@ maybe_remove_unreachable_handlers (void)
/* Remove regions that do not have landing pads. This assumes
that remove_unreachable_handlers has already been run, and
that we've just manipulated the landing pads since then. */
that we've just manipulated the landing pads since then.
Preserve regions with landing pads and regions that prevent
exceptions from propagating further, even if these regions
are not reachable. */
static void
remove_unreachable_handlers_no_lp (void)
{
eh_region r;
int i;
eh_region region;
sbitmap r_reachable;
basic_block bb;
unsigned i;
r_reachable = sbitmap_alloc (cfun->eh->region_array->length ());
bitmap_clear (r_reachable);
mark_reachable_handlers (&r_reachable, /*lp_reachablep=*/NULL);
FOR_EACH_BB (bb)
FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
{
gimple stmt = last_stmt (bb);
if (stmt)
/* Avoid removing regions referenced from RESX/EH_DISPATCH. */
switch (gimple_code (stmt))
{
case GIMPLE_RESX:
bitmap_set_bit (r_reachable, gimple_resx_region (stmt));
break;
case GIMPLE_EH_DISPATCH:
bitmap_set_bit (r_reachable, gimple_eh_dispatch_region (stmt));
break;
default:
break;
}
if (! region)
continue;
if (region->landing_pads != NULL
|| region->type == ERT_MUST_NOT_THROW)
bitmap_set_bit (r_reachable, region->index);
if (dump_file
&& !bitmap_bit_p (r_reachable, region->index))
fprintf (dump_file,
"Removing unreachable region %d\n",
region->index);
}
for (i = 1; cfun->eh->region_array->iterate (i, &r); ++i)
if (r && r->landing_pads == NULL && r->type != ERT_MUST_NOT_THROW
&& !bitmap_bit_p (r_reachable, i))
{
if (dump_file)
fprintf (dump_file, "Removing unreachable region %d\n", i);
remove_eh_handler (r);
}
remove_unreachable_eh_regions (r_reachable);
sbitmap_free (r_reachable);
}