Patch for 3.4.4. Infinite memory allocation on -O3.

[Grigory Tolstolytkin <gtolstolytkin at ru dot mvista dot com>]

Compilation of the following testcase leads to inifite memory allocation:

test.c:
int rd(int *p) {

 if (p<((int*)4)) return 0;
 return *p;
}

void wr(int *p) {
 if (p<((int*)4)) return;
 *p = 0;
}

void test(void *p)
{
 int i;
 int a[2];

 for(i=0;i<2;i++)
 {
   wr(p);
   a[i]=rd(p);
 }
}

How to reproduce:
/home/gt/fsf/inst/arm-3.4-20050429-2.3.2/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2/bin/arm-unknown-linux-gnu-gcc 
-c -O3 test.c

gcc info:
[root@devzero root]# 
/home/gt/fsf/inst/arm-csl-arm-20050504-2.3.2/arm-unknown-linux-gnu/gcc-csl-arm-20050504-glibc-2.3.2/bin/arm-unknown-linux-gnu-gcc 
-v
-bash: 
/home/gt/fsf/inst/arm-csl-arm-20050504-2.3.2/arm-unknown-linux-gnu/gcc-csl-arm-20050504-glibc-2.3.2/bin/arm-unknown-linux-gnu-gcc: 
No such file or directory
[root@devzero root]# 
/home/gt/fsf/inst/arm-3.4-20050429-2.3.2/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2/bin/arm-unknown-linux-gnu-gcc 
-v
Reading specs from 
/home/gt/fsf/inst/arm-3.4-20050429-2.3.2/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2/lib/gcc/arm-unknown-linux-gnu/3.4.4/specs
Configured with: 
/home/gt/work/distr/fsf/crosstool-0.31/build/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2/gcc-3.4-20050429/configure 
--target=arm-unknown-linux-gnu --host=i686-host_pc-linux-gnu 
--prefix=/home/gt/fsf/inst/arm-3.4-20050429-2.3.2/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2 
--with-local-prefix=/home/gt/fsf/inst/arm-3.4-20050429-2.3.2/arm-unknown-linux-gnu/gcc-3.4-20050429-glibc-2.3.2/arm-unknown-linux-gnu 
--disable-multilib --with-newlib --without-headers --disable-nls 
--enable-threads=no --enable-symvers=gnu --enable-__cxa_atexit 
--enable-languages=c --disable-shared
Thread model: single
gcc version 3.4.4 20050429 (prerelease)

Fix the problem (was done by Richard Kenner (kenner@vlsi1.ultra.nyu.edu 
<mailto:kenner@vlsi1.ultra.nyu.edu>) on 2004-02-12 for gcc 3.5:
        * emit-rtl.c (set_mem_attributes_minus_bitpos): Don't kill 
previous MEM_VOLATILE in REF)

diff -urN gcc-3.4.3/gcc/emit-rtl.c gcc-3.4.3-fix18081/gcc/emit-rtl.c
--- gcc-3.4.3/gcc/emit-rtl.c	2004-03-25 19:44:40.000000000 +0300
+++ gcc-3.4.3-fix18081/gcc/emit-rtl.c	2005-05-02 11:50:26.328539084 +0400
@@ -1592,7 +1592,7 @@
     front-end routine) and use it.  */
  alias = get_alias_set (t);

-  MEM_VOLATILE_P (ref) = TYPE_VOLATILE (type);
+  MEM_VOLATILE_P (ref) |= TYPE_VOLATILE (type);
  MEM_IN_STRUCT_P (ref) = AGGREGATE_TYPE_P (type);
  RTX_UNCHANGING_P (ref)
    |= ((lang_hooks.honor_readonly


There was opened a bug against this problem: 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18081

Thanks,
Grigory.