[Bug ipa/63664] New: ipa-icf pass fails with segfault

["enkovich.gnu at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63664

            Bug ID: 63664
           Summary: ipa-icf pass fails with segfault
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: enkovich.gnu at gmail dot com

Created attachment 33825
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33825&action=edit
Reproducer

There is a segfault in ipa-icf pass.

>g++ test.cpp -O2 -c

test.cpp:40:1: internal compiler error: Segmentation fault
 }
 ^
0xe87262 crash_signal
        ../../gcc-pl-ref/gcc/toplev.c:349
0x17000ad ipa_icf_gimple::func_checker::compatible_types_p(tree_node*,
tree_node*, bool, bool)
        ../../gcc-pl-ref/gcc/ipa-icf-gimple.c:172
0x170035c ipa_icf_gimple::func_checker::compare_operand(tree_node*, tree_node*)
        ../../gcc-pl-ref/gcc/ipa-icf-gimple.c:220
0x17020a2 ipa_icf_gimple::func_checker::compare_tree_ssa_label(tree_node*,
tree_node*)
        ../../gcc-pl-ref/gcc/ipa-icf-gimple.c:737
0x1702187
ipa_icf_gimple::func_checker::compare_gimple_label(gimple_statement_base*,
gimple_statement_base*)
        ../../gcc-pl-ref/gcc/ipa-icf-gimple.c:755
0x1701c29 ipa_icf_gimple::func_checker::compare_bb(ipa_icf_gimple::sem_bb*,
ipa_icf_gimple::sem_bb*)
        ../../gcc-pl-ref/gcc/ipa-icf-gimple.c:604
0x16f463b ipa_icf::sem_function::equals_private(ipa_icf::sem_item*,
hash_map<symtab_node*, ipa_icf::sem_item*, default_hashmap_traits>&)
        ../../gcc-pl-ref/gcc/ipa-icf.c:455
0x16f3e74 ipa_icf::sem_function::equals(ipa_icf::sem_item*,
hash_map<symtab_node*, ipa_icf::sem_item*, default_hashmap_traits>&)
        ../../gcc-pl-ref/gcc/ipa-icf.c:355
0x16f8687 ipa_icf::sem_item_optimizer::subdivide_classes_by_equality(bool)
        ../../gcc-pl-ref/gcc/ipa-icf.c:1771
0x16f7d93 ipa_icf::sem_item_optimizer::execute()
        ../../gcc-pl-ref/gcc/ipa-icf.c:1590
0x16fa221 ipa_icf_driver
        ../../gcc-pl-ref/gcc/ipa-icf.c:2320
0x16fa736 ipa_icf::pass_ipa_icf::execute(function*)
        ../../gcc-pl-ref/gcc/ipa-icf.c:2368
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

>g++ -v
Using built-in specs.
COLLECT_GCC=../../../gcc-ref-build/bin/g++
COLLECT_LTO_WRAPPER=/export/users/ienkovic/gcc-ref-build/libexec/gcc/x86_64-unknown-linux-gnu/5.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-ref/configure
--prefix=/export/users/ienkovic/gcc-ref-build --enable-languages=c,c++,fortran
--disable-bootstrap
Thread model: posix
gcc version 5.0.0 20141024 (experimental) (GCC)


The problem is that compared labels have null types and
ipa_icf_gimple::func_checker::compatible_types_p doesn't check for null types. 
Possible patch:

diff --git a/gcc/ipa-icf-gimple.c b/gcc/ipa-icf-gimple.c
index 1369b74..afc0eeb 100644
--- a/gcc/ipa-icf-gimple.c
+++ b/gcc/ipa-icf-gimple.c
@@ -169,6 +169,11 @@ bool func_checker::compatible_types_p (tree t1, tree t2,
                                       bool compare_polymorphic,
                                       bool first_argument)
 {
+  if (!t1 && !t2)
+    return true;
+  else if (!t1 || !t2)
+    return false;
+
   if (TREE_CODE (t1) != TREE_CODE (t2))
     return return_false_with_msg ("different tree types");



If we don't want labels to have null type then start_preparsed_function
(decl.c:13607) has to be fixed.