Re: (fwd) K6 Issues

Re: (fwd) K6 Issues

[meissner]

| > We did so. AMD's Tech support _and_ one of our Linux customers report
| > that gcc and g++ use self-modifying code to optimize some functions, and
| > this is a definate no-no, according to the erratum. 
| 
| The only self-modifying code I am aware of is trampolines.  Do you know
| any more about this?

See the discussion in the Linux Kernel mailing list.  Basically signal delivery
also uses self modifying code (and I think gdb also), in addition to
trampolines.

Re: 970814: libU77/dtime_.c:73: #error Dont know clock tick length

[Jeffrey A Law]

  In message you write:
  > 
  > This is for i386-pc-solaris2.5.1.
  > 
  > % as -v
  > GNU assembler version 2.8.1 (i386-pc-solaris2.5.1), using BFD version 2.8.1
  > 
  > I saw this after running make with -j2:
  > 
  >   gcc -g -DSTDC_HEADERS=1 -D_POSIX_SOURCE=1 -DRETSIGTYPE=void -DNON_ANSI_RW
  > _MODES=1 -DNO_EOF_CHAR_CHECK=1 -DSkip_f2c_Undefs=1 -DPad_UDread=1 -DWANT_LE
  > AD_0=1   -c libU77/dtime_.c -o libU77/dtime_.o
  >   libU77/dtime_.c:73: #error Dont know clock tick length
  >   make[1]: *** [libU77/dtime_.o] Error 1
  >   make[1]: *** Waiting for unfinished jobs....
  > 
  > Surprisingly, if I run make again after that failure, I don't see
  > the error again.
We checked in some of HJ's patches to address some parallel make issues,
particularly in the g77 subdirs.

Are you still having this problem?

jeff

test results for egcs 970828 on alpha-dec-osf4.0

[scott snyder]

hi -

I just ran the testsuite using egcs 970828 on an alpha-dec-osf4.0 host.


Here's the gcc summary:

                === gcc Summary ===

# of expected passes            4857
# of unexpected failures        22
# of expected failures          4
# of unsupported tests          7

These are the tests which fail:


FAIL: gcc.c-torture/compile/961203-1.c,  -O0  
FAIL: gcc.c-torture/compile/961203-1.c,  -O1  
FAIL: gcc.c-torture/compile/961203-1.c,  -O2  
FAIL: gcc.c-torture/compile/961203-1.c,  -O2 -fomit-frame-pointer -finline-funct
FAIL: gcc.c-torture/execute/920411-1.c execution,  -O1
FAIL: gcc.c-torture/execute/920411-1.c execution,  -O2
FAIL: gcc.c-torture/execute/920411-1.c execution,  -O2 -fomit-frame-pointer -finline-functions 
FAIL: gcc.c-torture/execute/920411-1.c execution,  -O2 -fomit-frame-pointer -finline-functions -funroll-loops 
FAIL: gcc.c-torture/execute/920411-1.c execution,  -O2 -fomit-frame-pointer -finline-functions -funroll-all-loops 
FAIL: gcc.c-torture/execute/cbrt.c execution,  -O0 
FAIL: gcc.c-torture/execute/cbrt.c execution,  -O1 
FAIL: gcc.c-torture/execute/cbrt.c execution,  -O2 
FAIL: gcc.c-torture/execute/cbrt.c execution,  -O2 -fomit-frame-pointer -finline-functions 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O0 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O1 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O2 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O2 -fomit-frame-pointer -finline-functions 
FAIL: gcc.c-torture/execute/ieee/fp-cmp-1.c execution,  -O0 
FAIL: gcc.c-torture/execute/ieee/fp-cmp-1.c execution,  -O1 
FAIL: gcc.c-torture/execute/ieee/fp-cmp-1.c execution,  -O2 
FAIL: gcc.c-torture/execute/ieee/fp-cmp-1.c execution,  -O2 -fomit-frame-pointer -finline-functions 
FAIL: gcc.misc-tests/m-un-1.c (test for excess errors)



Here's the g++ summary:


                === g++ Summary ===

# of expected passes            3263
# of unexpected successes       5
# of expected failures          83
# of untested testcases         6

The unexpected successes are:

XPASS: g++.brendan/array1.C overflow in array dimension.* , (test for errors, line 6)
XPASS: g++.brendan/scope4.C (test for excess errors)
XPASS: g++.law/profile1.C (test for excess errors)
XPASS: g++.law/profile1.C  Execution test
XPASS: g++.mike/p7325.C *-*-* Execution test


Here's a brief analysis of the unexpected failures for the gcc check.


-- 961203-1.c ---------------------------------------------------------------
struct s {
  char a[0x32100000];
  int x:30, y:30;
};

int
main ()
{
  struct s* p;

  p = (struct s*) 0;
  if (p->x == p->y)
    exit (1);
}
-----------------------------------------------------------------------------

For these, i got an error:

Stack overflow: pid 22083, proc cc1, addr 0x11dffffe0, pc 0x12009e72c

and

xgcc: Internal compiler error: program cc1 got fatal signal 11



-- 920411-1.c ---------------------------------------------------------------
long f (w)
     char *w;
{
  long k, i, c = 0, x;
  char *p = (char*) &x;
  for (i = 0; i = 0;) a[i] = ' ';
  if (f (a) != ~0UL / (unsigned char) ~0 * ' ')
    abort ();
  exit (0);
}
-----------------------------------------------------------------------------

When this is compiled with -O1, f (a) returns 0.
It appears that gcc is not noticing the aliasing between
*p and x in f(): The store into p[k] is done directly into memory,
but the x used in c += x comes from a register.

Here's the generated code (with -O1):

	.verstamp 3 11
	.set noreorder
	.set volatile
	.set noat
	.arch ev4
	.file	1 "920411-1.c"
gcc2_compiled.:
__gnu_compiled_c:
.text
	.align 3
	.globl f
	.ent f
f:
f..ng:
	lda $30,-16($30)
	.frame $30,16,$26,0
	.prologue 0
	bis $31,$31,$0
	bis $30,$30,$6
	bis $0,$0,$5
	ldq $7,0($30)
	.align 5
$37:
	bis $31,$31,$4
	.align 5
$41:
	addq $6,$4,$3
	addq $16,$4,$2
	ldq_u $1,0($2)
	extbl $1,$2,$1
	ldq_u $2,0($3)
	mskbl $2,$3,$2
	insbl $1,$3,$1
	bis $1,$2,$1
	stq_u $1,0($3)
	addq $4,1,$4
	cmpule $4,7,$1
	bne $1,$41
	addq $0,$7,$0
	addq $5,1,$5
	ble $5,$37
	addq $30,16,$30
	ret $31,($26),1
	.end f
.rdata
	.quad 0
	.align 3
$C32:
	.quad 2314885530818453536
.text
	.align 3
	.globl main
	.ent main
main:
	ldgp $29,0($27)
main..ng:
	lda $30,-32($30)
	.frame $30,32,$26,0
	stq $26,0($30)
	.mask 0x4000000,-32
	.prologue 1
	bis $31,7,$4
	bis $31,32,$5
	.align 5
$48:
	addq $30,$4,$3
	addq $3,16,$3
	ldq_u $2,0($3)
	mskbl $2,$3,$2
	insbl $5,$3,$1
	bis $1,$2,$1
	stq_u $1,0($3)
	subl $4,1,$4
	bge $4,$48
	addq $30,16,$16
	bsr $26,f..ng
	lda $1,$C32
	ldq $1,0($1)
	subq $0,$1,$0
	beq $0,$50
	jsr $26,abort
	ldgp $29,0($26)
	.align 4
$50:
	bis $31,$31,$16
	jsr $26,exit
	ldgp $29,0($26)
	.align 4
	.end main



-- cbrt.c -------------------------------------------------------------------
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
*/

#ifndef __vax__
static const unsigned long
	B1 = 715094163, /* B1 = (682-0.03306235651)*2**20 */
	B2 = 696219795; /* B2 = (664-0.03306235651)*2**20 */

static const double
	C =  5.42857142857142815906e-01, /* 19/35     = 0x3FE15F15, 0xF15F15F1 */
	D = -7.05306122448979611050e-01, /* -864/1225 = 0xBFE691DE, 0x2532C834 */
	E =  1.41428571428571436819e+00, /* 99/70     = 0x3FF6A0EA, 0x0EA0EA0F */
	F =  1.60714285714285720630e+00, /* 45/28     = 0x3FF9B6DB, 0x6DB6DB6E */
	G =  3.57142857142857150787e-01; /* 5/14      = 0x3FD6DB6D, 0xB6DB6DB7 */

double
cbrtl (double x)
{
  long hx;
  double r,s,w;
  double lt;
  unsigned sign;
  union {
    double t;
    unsigned long pt[2];
  } ut, ux;
  int n0;

  ut.t = 1.0;
  n0 = (ut.pt[0] == 0);

  ut.t = 0.0;
  ux.t = x;

  hx = ux.pt[n0];			/* high word of x */
  sign=hx&0x80000000;			/* sign= sign(x) */
  hx  ^=sign;
  if(hx>=0x7ff00000) return(x+x);	/* cbrt(NaN,INF) is itself */
  if((hx| ux.pt[1-n0])==0)
    return(ux.t);			/* cbrt(0) is itself */

  ux.pt[n0] = hx;
  /* rough cbrt to 5 bits */
  if(hx

double nan = 1.0/0.0 - 1.0/0.0;
double x = 1.0;

void leave ()
{
  exit (0);
}

main ()
{
#if ! defined (__vax__) && ! defined (_CRAY)
  /* NaN is an IEEE unordered operand.  All these test should be false.  */
  if (nan == nan)
    abort ();
  if (nan != x)
    x = 1.0;
  else
    abort ();

#ifndef SIGNAL_SUPPRESS
  /* Some machines catches a SIGFPE when a NaN is compared.
     Let this test succeed o such machines.  */
  signal (SIGFPE, leave);
#endif

  if (nan  x)
    abort ();
  if (nan = x)
    abort ();
  if (nan == x)
    abort ();
#endif
  exit (0);
}
-----------------------------------------------------------------------------


On the alpha, the first test triggers a floating point exception.


-- m-un-1.c -----------------------------------------------------------------
/* m-un-1.c: "un" for "uninitialized" */

/*
From: Jim Wilson 
Date: Wed, 6 Jul 1994 13:11:47 -0700
To: dje@cygnus.com
Subject: Re: devo/gcc ChangeLog.fsf stmt.c
Cc: cvs-gcc@cygnus.com, tege@cygnus.com

	How about a test case?  :-)

Compile with -O -Wall and the broken compiler gives you:
tmp.c:6: warning: `k' might be used uninitialized in this function
The fixed compiler (and gcc 2.5.8) gives no warning.

This happens to fix a performance regression in the code generated for
while loops, but that is presumably much much harder to test for.
*/

/* { dg-do compile } */
/* { dg-options "-O -Wall" } */

int
sub ()
{
  int i = 0;
  int j = 0;
  int k;	/* { dg-bogus "`k' might be used uninitialized" "uninitialized warning regression" } */

  while (i == 0 && j == 0)
    {
      k = 10;
      i = sub ();
    }

  return k;
}
-----------------------------------------------------------------------------


This is compiled with the command

 /d0sgif/data1/snyder/egcs-build/ALPHA/gcc/xgcc -B/d0sgif/data1/snyder/egcs-build/ALPHA/gcc/ /d0sgif/data1/snyder/egcs/gcc/testsuite/gcc.misc-tests/m-un-1.c   -O -Wall -c  -o m-un-1.s

and gives the error

compiler exited with status 1
output is:
as: Error: -o m-un-1.s resembles the name of a source file, disallowed


.. this looks like a problem with the test harness.

Re: build on sparc-sun-sunos4.1.3

[Jeffrey A Law]

  In message you write:
  > Here's a fix for this problem.  The main reason is that libiberty is
  > not multilib'ed, so there's not a libiberty directory in each multilib
  > dir, only in the main build directory.
I think that's just papering over the problem.

libiberty is supposed to be multilib'd just like libio, libstdc++
and libgcc.  So what we need to do is figure out why it wasn't
multilib'd.

jeff

Re: test results for egcs 970828 on alpha-dec-osf4.0

[Richard Henderson]

> FAIL: gcc.c-torture/compile/961203-1.c,  -O0  
[...]
> For these, i got an error:
> Stack overflow: pid 22083, proc cc1, addr 0x11dffffe0, pc 0x12009e72c

Yep.  Everyone gets this one -- the fields are at a bit offset
above 2^31, which overflows the int used to hold it.


> -- complex-5.c -----
> It looks like the passing of complex values to functions 
> is all screwed up -- both arguments seem to be passed in the same registers!

Sure enough, the handling of complex arguments is completely bogus;
complex double will work, but only by accident.  I gave a stab at
solving this today, but slowly realized what I was doing wasn't going
to work.

What needs to happen is for the halves of a complex argument to be
treated as two separate arguments.  While I got the arguments in 
which both halves land in registers to come out right, it doesn't
fix the internal padding of those that land on the stack.

Ho hum.  Perhaps I'll try again tomorrow.  But if a good approach 
to this problem leaps to someone's mind, please let me know.


> -- fp-cmp-1.c  -------
> On the alpha, the first test triggers a floating point exception.

You don't get IEEE compliant arithmetic on the Alpha without -mieee.

The hardware doesn't handle non-finite operands, and special steps
must be taken to handle this, which imposes a significant performance
penalty.  Since most programs do not deal with non-finite operands,
it is not enabled by default.  Not surprisingly, Digital's compilers
operate the same way.

The test succeeds with -mieee.


r~