-fPIC bug on sparc

[Brad Lucier]

I'm using (without any special configure options) the mainline

peano-36% gcc -v
Reading specs from /opt/egcs-mainline/lib/gcc-lib/sparc-sun-solaris2.5.1/egcs-2.92.11/specs
gcc version egcs-2.92.11 19980924 (gcc2 ss-980609 experimental)

with the extra patches from

CVSROOT:        /egcs/carton/cvsfiles
Module name:    egcs
Changes by:     davem@egcs.cygnus.com   98/09/24 02:44:57

When the following routine

int ___isnan(double x)
{
    unsigned long tmp = (*((unsigned long *) (&x) + (0)) ^ 0x7ff00000) & 0x7fffffff;
    return (tmp < 0x100000) && ((tmp | *((unsigned long *) (&x) + (1))) != 0);
}

is compiled with

gcc -fPIC -O2 -S setupE.c

the assembly code is:

___isnan:
	!#PROLOGUE# 0
	add	%sp, -120, %sp
	ld	[%sp+96], %g3          <= loads first word from stack before storing!!
	sethi	%hi(2146435072), %g2
	xor	%g3, %g2, %g3
	sethi	%hi(-2147483648), %o2
	sethi	%hi(1047552), %g2
	andn	%g3, %o2, %g3
	or	%g2, 1023, %g2
	std	%o0, [%sp+96]          <= stores double arg in %o0-%o1 on stack
	cmp	%g3, %g2
	bgu	.LL330
	mov	0, %o0
	ld	[%sp+100], %g2         <= loads second word from stack
	or	%g3, %g2, %g2
	subcc	%g0, %g2, %g0
	addx	%g0, 0, %o0
.LL330:
	retl
	sub	%sp, -120, %sp
.LLfe30:
	.size	 ___isnan,.LLfe30-___isnan

So this routine returns a random value, depending on what's on the stack
when it's called.

There is no problem with -fPIC -O1

Brad Lucier      lucier@math.purdue.edu