HEADS-UP: gcc-4.2 import appears to miscompile libm.
shoesoft at gmx.net
Sun May 27 08:53:15 UTC 2007
On Sunday 27 May 2007 01:31:16 Steve Kargl wrote:
> On Sat, May 26, 2007 at 07:09:16PM -0400, Wes Morgan wrote:
> > Working from -O towards -O2 based on the info pages, I can "reproduce"
> > the problem with "-O -fstrict-aliasing -fgcse"... However, -O2 with
> > -fno-strict-aliasing by itself seems to work around the issue. At first
> > glance it looks like a possible interaction between several
> > optimizations.
> Ths patch fixes the problem.
> --- s_frexpf.c.orig Sat May 26 16:26:50 2007
> +++ s_frexpf.c Sat May 26 16:28:03 2007
> @@ -39,6 +39,9 @@
> *eptr += (ix>>23)-126;
> hx = (hx&0x807fffff)|0x3f000000;
> +#if 0
> *(int*)&x = hx;
> + SET_FLOAT_WORD(x,hx);
> return x;
-fno-strict-aliasing is used by default for me (i386). Also, if you use -Wall
the compiler outputs a warning.
[root at something /usr/src/lib/msun/src]# cc -O2 -Wall -pipe -c s_frexpf.c
s_frexpf.c: In function 'frexpf':
s_frexpf.c:42: warning: dereferencing type-punned pointer will break
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