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

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@chopin.edu.pl To: "guenter geiger" geiger@xdv.org Cc: pd-list@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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