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ieee754: provide gcc builtins based generic sqrt functions

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Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Vineet Gupta
2020-05-29 15:21:39 -07:00
parent ba9f6ee9bb
commit 3374868668
4 changed files with 22 additions and 6 deletions
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3
sysdeps/generic/math-use-builtins.h
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@ -60,4 +60,7 @@
# define USE_COPYSIGNF128_BUILTIN 0 # define USE_COPYSIGNF128_BUILTIN 0
#endif #endif
#define USE_SQRT_BUILTIN 0
#define USE_SQRTF_BUILTIN 0
#endif /* math-use-builtins.h */ #endif /* math-use-builtins.h */

6
sysdeps/ieee754/dbl-64/e_sqrt.c
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@ -41,6 +41,7 @@
#include <math_private.h> #include <math_private.h>
#include <fenv_private.h> #include <fenv_private.h>
#include <libm-alias-finite.h> #include <libm-alias-finite.h>
#include <math-use-builtins.h>
/*********************************************************************/ /*********************************************************************/
/* An ultimate sqrt routine. Given an IEEE double machine number x */ /* An ultimate sqrt routine. Given an IEEE double machine number x */
@ -50,6 +51,10 @@
double double
__ieee754_sqrt (double x) __ieee754_sqrt (double x)
{ {
#if USE_SQRT_BUILTIN
return __builtin_sqrt (x);
#else
/* Use generic implementation. */
static const double static const double
rt0 = 9.99999999859990725855365213134618E-01, rt0 = 9.99999999859990725855365213134618E-01,
rt1 = 4.99999999495955425917856814202739E-01, rt1 = 4.99999999495955425917856814202739E-01,
@ -138,6 +143,7 @@ __ieee754_sqrt (double x)
return (x - x) / (x - x); /* sqrt(-ve)=sNaN */ return (x - x) / (x - x); /* sqrt(-ve)=sNaN */
return 0x1p-256 * __ieee754_sqrt (x * 0x1p512); return 0x1p-256 * __ieee754_sqrt (x * 0x1p512);
} }
#endif /* ! USE_SQRT_BUILTIN */
} }
#ifndef __ieee754_sqrt #ifndef __ieee754_sqrt
libm_alias_finite (__ieee754_sqrt, __sqrt) libm_alias_finite (__ieee754_sqrt, __sqrt)

16
sysdeps/ieee754/flt-32/e_sqrtf.c
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@ -16,12 +16,15 @@
#include <math.h> #include <math.h>
#include <math_private.h> #include <math_private.h>
#include <libm-alias-finite.h> #include <libm-alias-finite.h>
#include <math-use-builtins.h>
static const float one = 1.0, tiny=1.0e-30;
float float
__ieee754_sqrtf(float x) __ieee754_sqrtf(float x)
{ {
#if USE_SQRTF_BUILTIN
return __builtin_sqrtf (x);
#else
/* Use generic implementation. */
float z; float z;
int32_t sign = (int)0x80000000; int32_t sign = (int)0x80000000;
int32_t ix,s,q,m,t,i; int32_t ix,s,q,m,t,i;
@ -70,10 +73,10 @@ __ieee754_sqrtf(float x)
/* use floating add to find out rounding direction */ /* use floating add to find out rounding direction */
if(ix!=0) { if(ix!=0) {
z = one-tiny; /* trigger inexact flag */ z = 0x1p0 - 0x1.4484cp-100; /* trigger inexact flag. */
if (z>=one) { if (z >= 0x1p0) {
z = one+tiny; z = 0x1p0 + 0x1.4484cp-100;
if (z>one) if (z > 0x1p0)
q += 2; q += 2;
else else
q += (q&1); q += (q&1);
@ -83,6 +86,7 @@ __ieee754_sqrtf(float x)
ix += (m <<23); ix += (m <<23);
SET_FLOAT_WORD(z,ix); SET_FLOAT_WORD(z,ix);
return z; return z;
#endif /* ! USE_SQRTF_BUILTIN */
} }
#ifndef __ieee754_sqrtf #ifndef __ieee754_sqrtf
libm_alias_finite (__ieee754_sqrtf, __sqrtf) libm_alias_finite (__ieee754_sqrtf, __sqrtf)

3
sysdeps/s390/fpu/math-use-builtins.h
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@ -108,4 +108,7 @@
# define USE_COPYSIGNF128_BUILTIN 0 # define USE_COPYSIGNF128_BUILTIN 0
#endif #endif
#define USE_SQRT_BUILTIN 0
#define USE_SQRTF_BUILTIN 0
#endif /* math-use-builtins.h */ #endif /* math-use-builtins.h */