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* Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
@ 2002-12-04 14:31 bangerth
0 siblings, 0 replies; 4+ messages in thread
From: bangerth @ 2002-12-04 14:31 UTC (permalink / raw)
To: duchier, gcc-bugs, gcc-prs, nobody
Old Synopsis: incorrect inlining of memcpy under -O2
New Synopsis: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Wed Dec 4 14:31:57 2002
State-Changed-Why:
Confirmed. This program
----------------------------
#include <stdio.h>
#include <string.h>
int main()
{
char* buffer = new char[8];
const char head[8] = {
'A', 'B', 'C', 'D',
'E', 'F', 'G', 'H'
};
memcpy(buffer,head,8);
for(int i=0;i<8;i++)
printf ("[%u] = %c, %c\n", i, head[i], buffer[i]);
return 0;
}
--------------------------------
yields with 3.2.2pre, 3.3pre, and 2.95 respectively:
tmp/g> /home/bangerth/bin/gcc-3.2.2-pre/bin/c++ -O2 bug.cc && ./a.out
[0] = A, A
[1] = B,
[2] = C,
[3] = D,
[4] = E, E
[5] = F, F
[6] = G, G
[7] = H, H
tmp/g> /home/bangerth/bin/gcc-3.3-pre/bin/c++ -O2 bug.cc && ./a.out
[0] = A, A
[1] = B,
[2] = C,
[3] = D,
[4] = E, E
[5] = F, F
[6] = G, G
[7] = H, H
tmp/g> c++ -O2 bug.cc && ./a.out
[0] = A, A
[1] = B, B
[2] = C, C
[3] = D, D
[4] = E, E
[5] = F, F
[6] = G, G
[7] = H, H
That seems like a regression.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8634
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
@ 2002-12-10 0:26 Glen Nakamura
0 siblings, 0 replies; 4+ messages in thread
From: Glen Nakamura @ 2002-12-10 0:26 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR optimization/8634; it has been noted by GNATS.
From: Glen Nakamura <glen@imodulo.com>
To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Cc:
Subject: Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
Date: Mon, 9 Dec 2002 22:20:00 -1000
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8634
Additional analysis of the problem and work-around patch posted at:
http://gcc.gnu.org/ml/gcc-patches/2002-12/msg00533.html
GCC developers with more experience should decide whether or not
const initializers should be flagged as RTX_UNCHANGING, and if so then
the cases that generate multiple sets need to be fixed...
- glen
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
@ 2002-12-23 16:36 Janis Johnson
0 siblings, 0 replies; 4+ messages in thread
From: Janis Johnson @ 2002-12-23 16:36 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR optimization/8634; it has been noted by GNATS.
From: Janis Johnson <janis187@us.ibm.com>
To: gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, duchier@ps.uni-sb.de,
gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org
Cc:
Subject: Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining
of memcpy under -O2
Date: Mon, 23 Dec 2002 16:37:21 -0800
The regression reported in PR optimization/8634 showed up
starting with this patch (strange but true):
Fri Dec 21 23:30:14 CET 2001 Jan Hubicka <jh@suse.cz>
* i386.h (TARGET_CPU_DEFAULT_pentium_mmx): New.
(TARGET_CPU_DEFAULT_*): Renumber.
I used this test case that Wolfgang provided. It aborts
when the wrong code is generated for -O2 on i686-linux:
--------------
/* incorrect code for inlining of memcpy under -O2 */
#include <string.h>
#include <stdlib.h>
int
main ()
{
int i;
char buffer[8];
const char head[8] =
{ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H' };
memcpy (buffer, head, 8);
for (i = 0; i < 8; i++)
if (head[i] != buffer[i])
abort ();
return 0;
}
--------------
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8634
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
@ 2003-03-23 18:21 Glen Nakamura
0 siblings, 0 replies; 4+ messages in thread
From: Glen Nakamura @ 2003-03-23 18:21 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR optimization/8634; it has been noted by GNATS.
From: Glen Nakamura <glen@imodulo.com>
To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Cc:
Subject: Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
Date: Sun, 23 Mar 2003 18:07:39 +0000
--wRRV7LY7NUeQGEoC
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8634
Attached is an extended test case for constant initializers.
--wRRV7LY7NUeQGEoC
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment; filename="pr8634.c"
/* PR optimization/8634 */
/* Contributed by Glen Nakamura <glen@imodulo.com> */
extern void abort (void);
struct foo {
char a, b, c, d, e, f, g, h, i, j;
};
int test1 ()
{
const char X[8] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H' };
char buffer[8];
__builtin_memcpy (buffer, X, 8);
if (buffer[0] != 'A' || buffer[1] != 'B'
|| buffer[2] != 'C' || buffer[3] != 'D'
|| buffer[4] != 'E' || buffer[5] != 'F'
|| buffer[6] != 'G' || buffer[7] != 'H')
abort ();
return 0;
}
int test2 ()
{
const char X[10] = { 'A', 'B', 'C', 'D', 'E' };
char buffer[10];
__builtin_memcpy (buffer, X, 10);
if (buffer[0] != 'A' || buffer[1] != 'B'
|| buffer[2] != 'C' || buffer[3] != 'D'
|| buffer[4] != 'E' || buffer[5] != '\0'
|| buffer[6] != '\0' || buffer[7] != '\0'
|| buffer[8] != '\0' || buffer[9] != '\0')
abort ();
return 0;
}
int test3 ()
{
const struct foo X = { a : 'A', c : 'C', e : 'E', g : 'G', i : 'I' };
char buffer[10];
__builtin_memcpy (buffer, &X, 10);
if (buffer[0] != 'A' || buffer[1] != '\0'
|| buffer[2] != 'C' || buffer[3] != '\0'
|| buffer[4] != 'E' || buffer[5] != '\0'
|| buffer[6] != 'G' || buffer[7] != '\0'
|| buffer[8] != 'I' || buffer[9] != '\0')
abort ();
return 0;
}
int test4 ()
{
const struct foo X = { .b = 'B', .d = 'D', .f = 'F', .h = 'H' , .j = 'J' };
char buffer[10];
__builtin_memcpy (buffer, &X, 10);
if (buffer[0] != '\0' || buffer[1] != 'B'
|| buffer[2] != '\0' || buffer[3] != 'D'
|| buffer[4] != '\0' || buffer[5] != 'F'
|| buffer[6] != '\0' || buffer[7] != 'H'
|| buffer[8] != '\0' || buffer[9] != 'J')
abort ();
return 0;
}
int main ()
{
test1 (); test2 (); test3 (); test4 ();
return 0;
}
--wRRV7LY7NUeQGEoC--
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2003-03-23 18:16 UTC | newest]
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2002-12-04 14:31 optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2 bangerth
2002-12-10 0:26 Glen Nakamura
2002-12-23 16:36 Janis Johnson
2003-03-23 18:21 Glen Nakamura
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