There are 3 possible problems:
1) bootstrap with BOOT_CFLAGS="-O2 -fstack-protector" fails when compiling
i386.o
2) warning in testcase.c
3) warning about x.0 in testcase2.c, crashing output binary
I don't know if any of these problems is a real bug.
All testcases were tested with recent builds of gcc trunk and 4.4 branch.
ad 1)
Bootstrap fails with BOOT_CFLAGS="-O2 -fstack-protector"
$ gcc-4.4.3 -fstack-check -Wuninitialized -Wno-format -Werror -O2 i386.i -c
cc1: warnings being treated as errors
/mnt/svn/gcc-trunk/gcc/config/i386/i386.c: In function
‘ix86_expand_vector_init_duplicate’:
/mnt/svn/gcc-trunk/gcc/config/i386/i386.c:26684: error:
‘dperm.4211’ may be used uninitialized in this function
/mnt/svn/gcc-trunk/gcc/config/i386/i386.c:26706: error:
‘saved_stack.4216’ may be used uninitialized in this function
ad 2)
This file, testcase.c, was reduced from gcc/config/i386/i386.c
---------- testcase.c ----------
void foo(void)
{
goto lab;
{
int x[64];
lab:;
}
}
--------------------------------
$ gcc-4.4.3 -Wuninitialized -c testcase.c
$ gcc-4.4.3 -fstack-check -Wuninitialized -c testcase.c
testcase.c: In function ‘foo’:
testcase.c:7: warning: ‘saved_stack.1’ is used uninitialized in
this function
(behaviour is the same with -O1, -O2, -O3)
ad 3)
Second testcase crashes when compiled with -fstack-protector:
---------- testcase2.c ----------
__attribute__((noinline)) int foo(void)
{
goto lab;
{
int x[64];
lab:;
x[63] = 0;
return x[63];
}
}
int main()
{
return foo();
}
--------------------------------
$ gcc-4.4.3 -Wuninitialized testcase2.c && ./a.out
$ gcc-4.4.3 -fstack-check -Wuninitialized testcase2.c && ./a.out
testcase2.c: In function ‘foo’:
testcase2.c:7: warning: ‘x.0’ is used uninitialized in this
function
testcase2.c:9: warning: ‘saved_stack.1’ is used uninitialized in
this function
Segmentation fault (SIGSEGV)
(behaviour is the same with -O1, -O2, -O3)
--
Summary: "warning: 'saved_stack.1' is used uninitialized in this
function" with -fstack-protector
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: zsojka at seznam dot cz
GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43013
