http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53541
Bug #: 53541
Summary: gcc-4.6.2 segfaults on dumping tree information
Classification: Unclassified
Product: gcc
Version: 4.6.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c
AssignedTo: [email protected]
ReportedBy: [email protected]
consider simple reproduction:
{code}
struct atexit {
struct atexit *next;
};
struct atexit *__atexit;
void *
test(void *dso)
{
struct atexit *p = 0, *q = 0;
if (dso == (void *)0)
{
for (p = __atexit; p != ((void *)0); )
{
q = p;
p = p->next;
}
}
return (void *)p;
}
{code}
We will use gcc-4.6.2 on x86:
tilir@kivladimirov ~/research/5368 $ ~/4.6-toolset/bin/gcc --version
gcc (GCC) 4.6.2
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Compiling with appropriate command line and see segfault:
$ gcc -m32 -O2 -fomit-frame-pointer -fdump-tree-all-lineno-details -flto
repro.c -S
repro.c: In function ‘test’:
repro.c:20:1: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
Lets look some deeper:
run cc1 with
{noformat}
$ /home/tilir/4.6-toolset/libexec/gcc/x86_64-unknown-linux-gnu/4.6.2/cc1 -m32
-march=x86-64 -O2 -fomit-frame-pointer -fdump-tree-all-lineno-details -flto
repro.c
Analyzing compilation unit
Performing interprocedural optimizations
<*free_lang_data> <visibility> <early_local_cleanups>
repro.c: In function ‘test’:
repro.c:20:1: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
{noformat}
using GDB it is easy to see, that segfault is on line tree-pretty-print.c:1176
When GCC trying to calculate TREE_TYPE (TREE_TYPE (TREE_OPERAND (op0, 0)) it
segfaults because TREE_CODE( TREE_OPERAND (op0, 0)) is SSA_NAME, thus TREE_TYPE
(TREE_OPERAND (op0, 0) is 0, thus double TREE_TYPE is segfault.
I not sure how to correct it better -- may be add explicit check of SSA_NAME
case? But what is reason of SSA_NAME node arising here?
