problems with -O2 and sparc-solaris 2.51

["Anthony J Heading" <heading_anthony at jpmorgan dot com>]

Hi,
      With 19980824 (and at least a few snapshots earlier), -O2 on sparc
Solaris still appears to have problems.  The following results from a
compilation of jwz's xscreensaver-2.27 - there's a bus error seemingly
in the middle of some innocuous looking floating-point calcs.  Dropping
the -O2 causes the problem to go away.

If there's anything useful I could do to help isolate the problem, please
let me know.

Regards
Anthony

% gdb hacks/xroger
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This GDB was configured as "sparc-sun-solaris2.5.1"...
(gdb) run
Starting program: /opt/research/build/xscreensaver-2.27/hacks/xroger

Program received signal SIGBUS, Bus error.
0x1558c in add_bezier_arc (s=0xeffff1e8, x0=135.16666666666669,
y0=292.16666666666669,
    x1=136.33333333333334, y1=288.66666666666669, x2=138.66666666666666,
y2=286.33333333333331,
    x3=149.16666666666666, y3=285.16666666666663) at spline.c:162
162       if (can_approx_with_line (cx, cy, midx23, midy23, x3, y3))
(gdb) where
#0  0x1558c in add_bezier_arc (s=0xeffff1e8, x0=135.16666666666669,
y0=292.16666666666669,
    x1=136.33333333333334, y1=288.66666666666669, x2=138.66666666666666,
y2=286.33333333333331,
    x3=149.16666666666666, y3=285.16666666666663) at spline.c:162
#1  0x15878 in calc_section (s=0xeffff1e8, cminus1x=134,
cminus1y=-3.0985570937468609e+231, cx=134, cy=291,
    cplus1x=141, cplus1y=284, cplus2x=197, cplus2y=284) at spline.c:185
#2  0x15b14 in compute_closed_spline (s=0xeffff1e8) at spline.c:229
#3  0x1487c in skull (dpy=0x2d930, window=96468993, draw_gc=0x31e58,
erase_gc=0x31de0, x=134, y=255, w=117,
    h=117) at xroger.c:84
#4  0x13d14 in screenhack (dpy=0x2d930, window=96468993) at
xroger-hack.c:75
#5  0x12604 in main (argc=1, argv=0x21) at screenhack.c:378
(gdb) list
157         add_line (s, x0, y0, cx, cy);
158       else if ((midx01 != x1) || (midy01 != y1) || (midlsegx != x2)
159                || (midlsegy != y2) || (cx != x3) || (cy != y3))
160         add_bezier_arc (s, x0, y0, midx01, midy01, midlsegx, midlsegy,
cx, cy);
161
162       if (can_approx_with_line (cx, cy, midx23, midy23, x3, y3))
163         add_line (s, cx, cy, x3, y3);
164       else if ((cx != x0) || (cy != y0) || (midrsegx != x1) ||
(midrsegy != y1)
165                || (midx23 != x2) || (midy23 != y2))
166         add_bezier_arc (s, cx, cy, midrsegx, midrsegy, midx23, midy23,
x3, y3);