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This patch implements a fast copysign for PPC but only for -flag_unsafe_math_optimizations as it does not handle signed zeros correctly. This uses the optable which RTH added a couple of days ago to do this expansion.
With this patch copysign is expanded to: fabs f0,f1 fnabs f1,f1 fsel f1,f2,f0,f1
Which is faster and smaller than storing and doing bitfield operations on the sign bit.
Thanks, Andrew Pinski
ChangeLog: * config/rs6000/rs6000.md (copysignsf3): New expand. (copysigndf3): Likewise.
Attachment:
fastcopysign.diff.txt
Description: Text document
Testcase: /* { dg-do run } */ /* { dg-options "-O2 -ffast-math" } */
float copysignf(float,float); double copysign(double, double);
float fs(float a,float b) { return copysignf(a,b); }
double f(double a,double b) { return copysign(a,b); } float a = __builtin_inf(); float b = 1.0; void abort(void);
int main(void) { if (fs (a,a)!=__builtin_fabs(a)) abort(); if (fs (a,-a)!=-__builtin_fabs(a)) abort(); if (fs (-a,a)!=__builtin_fabs(a)) abort(); if (fs (-a,-a)!=-__builtin_fabs(a)) abort();
if (f (a,a)!=__builtin_fabs(a)) abort(); if (f (a,-a)!=-__builtin_fabs(a)) abort(); if (f (-a,a)!=__builtin_fabs(a)) abort(); if (f (-a,-a)!=-__builtin_fabs(a)) abort();
if (fs (b,b)!=__builtin_fabs(b)) abort(); if (fs (b,-b)!=-__builtin_fabs(b)) abort(); if (fs (-b,b)!=__builtin_fabs(b)) abort(); if (fs (-b,-b)!=-__builtin_fabs(b)) abort();
if (f (b,b)!=__builtin_fabs(b)) abort(); if (f (b,-b)!=-__builtin_fabs(b)) abort(); if (f (-b,b)!=__builtin_fabs(b)) abort(); if (f (-b,-b)!=-__builtin_fabs(b)) abort(); }
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