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* [Bug target/44575] [4.5 Regression] __builtin_va_arg overwrites into adjacent stack location
[not found] <bug-44575-4@http.gcc.gnu.org/bugzilla/>
@ 2010-09-30 9:25 ` eraman at google dot com
2010-10-01 13:13 ` jakub at gcc dot gnu.org
1 sibling, 0 replies; 5+ messages in thread
From: eraman at google dot com @ 2010-09-30 9:25 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44575
--- Comment #7 from Easwaran Raman <eraman at google dot com> 2010-09-30 00:21:17 UTC ---
This is a variation of the same problem where __builtin_va_arg overwrites into
adjacent stack location [Not sure if I should reopen this bug or file a new
one]:
$ cat vararg.cc
#include <stdarg.h>
#include <stdlib.h>
struct S933 { struct{struct{}b[6];union{}c[7];}a;char d;char e; };
struct S933 arg;
void check933va (int z, ...) {
char c;
va_list ap;
__builtin_va_start(ap,z);
c = 'a';
arg = __builtin_va_arg(ap,struct S933);
if (c != 'a')
abort();
}
int main() {
struct S933 s933;
check933va (1, s933);
}
$ ./trunk-g++ -O0 vararg.cc && ./a.out
Aborted
./trunk-g++ is GNU C++ version 4.6.0 20100924 (experimental)
(x86_64-unknown-linux-gnu)
The relevant portion of the gimple is below:
D.2773_4 = ap.reg_save_area;
D.2774_5 = ap.gp_offset;
D.2775_6 = (long unsigned int) D.2774_5;
int_addr.1_7 = D.2773_4 + D.2775_6;
addr.0_8 = &va_arg_tmp.3;
D.2777_9 = addr.0_8 + 8;
D.2778_10 = MEM[(long unsigned int *)int_addr.1_7];
*D.2777_9 = D.2778_10; <--- Bad move
The move to address D.2777_9 is the problem
For this struct type, construct_container returns the following:
(parallel:BLK [
(expr_list:REG_DEP_TRUE (reg:DI 0 ax)
(const_int 8 [0x8]))
])
The destination of the move is at offset 8 (INTVAL (XEXP (slot, 1))) of the
temporary created. The size of the temp (sizeof(S933)) is 15 bytes and the move
is in DI mode. I think the problem is the check if (prev_size + cur_size >
size) doesn't really check if the destination is overwritten.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/44575] [4.5 Regression] __builtin_va_arg overwrites into adjacent stack location
[not found] <bug-44575-4@http.gcc.gnu.org/bugzilla/>
2010-09-30 9:25 ` [Bug target/44575] [4.5 Regression] __builtin_va_arg overwrites into adjacent stack location eraman at google dot com
@ 2010-10-01 13:13 ` jakub at gcc dot gnu.org
1 sibling, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2010-10-01 13:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44575
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-10-01 13:13:36 UTC ---
Author: jakub
Date: Fri Oct 1 13:13:31 2010
New Revision: 164884
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164884
Log:
Backport from mainline
2010-09-30 Jakub Jelinek <jakub@redhat.com>
PR target/45843
* config/i386/i386.c (ix86_gimplify_va_arg): Use
INTVAL (XEXP (slot, 1)) as prev_size.
2010-06-21 Jakub Jelinek <jakub@redhat.com>
PR target/44575
* config/i386/i386.c (ix86_gimplify_va_arg): When copying
va_arg from a set of register save slots into a temporary,
if the container is bigger than type size, do the copying
using smaller mode or using memcpy.
Backport from mainline
2010-09-30 Jakub Jelinek <jakub@redhat.com>
* g++.dg/torture/pr45843.C: New test.
2010-06-21 Jakub Jelinek <jakub@redhat.com>
PR target/44575
* gcc.c-torture/execute/pr44575.c: New test.
Added:
branches/gcc-4_4-branch/gcc/testsuite/g++.dg/torture/pr45843.C
branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/execute/pr44575.c
Modified:
branches/gcc-4_4-branch/gcc/ChangeLog
branches/gcc-4_4-branch/gcc/config/i386/i386.c
branches/gcc-4_4-branch/gcc/testsuite/ChangeLog
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug target/44575] New: __builtin_va_arg overwrites into adjacent stack location
@ 2010-06-18 0:00 eraman at google dot com
2010-06-24 21:43 ` [Bug target/44575] [4.5 Regression] " rguenth at gcc dot gnu dot org
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: eraman at google dot com @ 2010-06-18 0:00 UTC (permalink / raw)
To: gcc-bugs
$ cat vararg.c
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
int fails = 0;
struct S116 { float a[3]; } ;
struct S116 a116[5];
void check116va (int z, ...)
{ struct S116 arg, *p;
va_list ap;
int j=0,k=0;
int i;
__builtin_va_start(ap,z);
for (i = 2; i < 4; ++i) {
p = NULL;
j++;
k+=2;
switch ((z << 4) | i) {
case 0x12: case 0x13: p = &a116[2]; arg = __builtin_va_arg(ap,struct
S116); break;
default: ++fails; break;
}
if (p && p->a[2] != arg.a[2]) {
++fails;
}
if (fails)
break;
}
__builtin_va_end(ap);
}
int main()
{
memset (a116, '\0', sizeof (a116));
a116[2].a[2] = -49026.625000;
check116va (1, a116[2], a116[2]);
if (fails)
abort();
}
$ ./trunk-gcc -O0 vararg.c && ./a.out
Aborted
./trunk-gcc is gcc 4.6.0 configured with --target=x86_64-unknown-linux-gnu
--disable-nls --enable-threads=posix --enable-symvers=gnu --enable-__cxa_atexit
--enable-c99 --enable-long-long --with-gnu-as --with-gnu-ld
--build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu
--enable-checking=release --enable-multilib --enable-targets=all
--with-arch-32=pentium3 --with-tune-32=pentium4
--enable-shared=libgcc,libmudflap,libssp,libstdc++,libgfortran
--with-pic=libgfortran --enable-languages=c,c++,fortran
--with-native-system-header-dir=/include --enable-linker-build-id
--with-host-libstdcxx=-lstdc++ FCFLAGS='-g -O2 '
The test cases passes with gcc 4.2.4 and 4.4.3.
The gimple for __builtin_va_arg (from vararg.c.004t.gimple ) contains
addr.1 = &va_arg_tmp.4;
addr.5 = (long unsigned int * {ref-all}) addr.1;
sse_addr.6 = (long unsigned int *) sse_addr.3;
D.3520 = *sse_addr.6;
*addr.5 = D.3520; ---> (1)
addr.7 = (long unsigned int * {ref-all}) addr.1;
D.3522 = addr.7 + 8;
sse_addr.8 = (long unsigned int *) sse_addr.3;
D.3524 = sse_addr.8 + 16;
D.3525 = *D.3524;
*D.3522 = D.3525; ---> (2)
The assignments (1) and (2) above are 8 byte moves, one at offset 0 and
another at offset 8, into va_arg_tmp.4. But the size of va_arg_tmp.4 is 12
bytes (sizeof (struct S116)) resulting in overwriting of adjacent stack
location ( variable i in this case) leading to the failure.
--
Summary: __builtin_va_arg overwrites into adjacent stack location
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: eraman at google dot com
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44575
^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <bug-44575-4@http.gcc.gnu.org/bugzilla/>
2010-09-30 9:25 ` [Bug target/44575] [4.5 Regression] __builtin_va_arg overwrites into adjacent stack location eraman at google dot com
2010-10-01 13:13 ` jakub at gcc dot gnu.org
2010-06-18 0:00 [Bug target/44575] New: " eraman at google dot com
2010-06-24 21:43 ` [Bug target/44575] [4.5 Regression] " rguenth at gcc dot gnu dot org
2010-07-01 11:02 ` jakub at gcc dot gnu dot org
2010-07-01 11:06 ` jakub at gcc dot gnu dot org
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