[PD] Lost at compilig cyclone ;-((((

[Thomas Grill]

Hi all,
am i right suspecting that only the first half of the PD_BADFLOAT macro is
optimized away? (because otherwise the optimizer were buggy, weren't it?)
Then, there's another possibility to test for almost denormals, suggested on
the musicdsp site:

#define IS_ALMOST_DENORMAL(f) (fabs(f) < 3.e-34)

probably that's not much slower on modern cpus... should be profiled though

best,
Thomas

----- Original Message ----- 
From: "Krzysztof Czaja" <czaja at chopin.edu.pl>
To: "guenter geiger" <geiger at xdv.org>
Cc: <pd-list at iem.at>
Sent: Saturday, June 26, 2004 5:14 PM
Subject: Re: [PD] Lost at compilig cyclone ;-((((


> hi Guenter,
>
> this fails, though:
>
> int result[25];
>
> void pass1(void)
> {
>      int i;
>      float f = 0.0001, *fp = &f;
>
>      for (i=0;i<25;i++) {
>          *fp*=0.0001;
>          if (PD_BADFLOAT(*fp)) result[i] = 1;
>          else result[i] = 0;
>      }
> }
>
> void pass2(void)
> {
>      int i;
>      float f = 0.0001;
>      for (i=0;i<25;i++) {
>          f*=0.0001;
>          if (result[i]) printf("%d badfloat %g %08x\n",i,f,*(int*)&f);
>          else printf("%d goodfloat %g %08x\n",i,f,*(int*)&f);
>      }
> }
>
> If compiled with "gcc-3.3 -O6...", you will get:
>
> ...
> 8 goodfloat 9.99995e-41 000116c2
> 9 goodfloat 9.80909e-45 00000007
> ...
>
> while without "-O6" it works ok.  The bottom line is, that I do not
> know the rules (if there are any).
>
> Krzysztof
>
> guenter geiger wrote:
> ...
> > I just tested this with gcc 3.3.4 from Debian and it seems to work.
>
>
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