* [committed] Fix segfault in free_growth_caches (PR jit/80954)
[not found] <20170522153754.GE21448@kam.mff.cuni.cz>
@ 2017-01-01 0:00 ` David Malcolm
0 siblings, 0 replies; only message in thread
From: David Malcolm @ 2017-01-01 0:00 UTC (permalink / raw)
To: gcc-patches; +Cc: Jan Hubicka, jit, David Malcolm
r248336 added these lines to free_growth_caches
if (edge_removal_hook_holder)
symtab->remove_edge_removal_hook (edge_removal_hook_holder);
which broke the JIT; attempts to compile more than one time
within a single process segfault here:
305 symbol_table::remove_edge_removal_hook (cgraph_edge_hook_list *entry)
306 {
307 cgraph_edge_hook_list **ptr = &m_first_edge_removal_hook;
308
309 while (*ptr != entry)
>>310 ptr = &(*ptr)->next;
311 *ptr = entry->next;
312 free (entry);
313 }
(gdb) p ptr
$3 = (cgraph_edge_hook_list **) 0x10
(gdb) bt
#0 symbol_table::remove_edge_removal_hook (this=0x7fffeef83200, entry=0x664c90) at ../../src/gcc/cgraph.c:310
#1 0x00007ffff6a03e2c in free_growth_caches () at ../../src/gcc/ipa-inline-analysis.c:113
#2 0x00007ffff73e7bd9 in inline_small_functions () at ../../src/gcc/ipa-inline.c:2059
#3 ipa_inline () at ../../src/gcc/ipa-inline.c:2417
[...]
The root cause is that initialize_growth_caches lazily adds
edge_removal_hook_holder to the symtab:
99 if (!edge_removal_hook_holder)
100 edge_removal_hook_holder =
101 symtab->add_edge_removal_hook (&inline_edge_removal_hook, NULL);
but free_growth_caches removes it without NULL-ing it:
112 if (edge_removal_hook_holder)
113 symtab->remove_edge_removal_hook (edge_removal_hook_holder);
Hence on the second call to free_growth_caches, it attempts to remove
the edge_removal_hook_holder from the 1st iteration's
initialize_growth_caches, which isn't present in the 2nd iteration's
symtab.
Hence the edge_removal_hook_holder isn't present, and
symtab::remove_edge_removal_hook, relying on it as a sentinel value,
reads through ((cgraph_edge_hook_list *)NULL)->next.
This patch fixes the segfault by resetting it to NULL when removing it.
Successfully bootstrapped®rtested on x86_64-pc-linux-gnu.
Restores jit.sum from:
# of expected passes 2892
# of unexpected failures 61
# of unresolved testcases 1
to:
# of expected passes 3202
Committed to trunk as r248841, under the "obvious" rule.
gcc/ChangeLog:
PR jit/80954
* ipa-inline-analysis.c (free_growth_caches): Set
edge_removal_hook_holder to NULL after removing it.
---
gcc/ipa-inline-analysis.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gcc/ipa-inline-analysis.c b/gcc/ipa-inline-analysis.c
index f562ca5..9f7b2a1 100644
--- a/gcc/ipa-inline-analysis.c
+++ b/gcc/ipa-inline-analysis.c
@@ -110,7 +110,10 @@ void
free_growth_caches (void)
{
if (edge_removal_hook_holder)
- symtab->remove_edge_removal_hook (edge_removal_hook_holder);
+ {
+ symtab->remove_edge_removal_hook (edge_removal_hook_holder);
+ edge_removal_hook_holder = NULL;
+ }
edge_growth_cache.release ();
}
--
1.8.5.3
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2017-01-01 0:00 ` [committed] Fix segfault in free_growth_caches (PR jit/80954) David Malcolm
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