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math: Optimize fma call on acospif 

The fma is required only for inputs less than 0x1.0fd288p-127.  Also
only add the extra check for !__FP_FAST_FMA targets.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>
This commit is contained in:
Adhemerval Zanella 2025-10-10 14:49:20 -03:00
parent c9d9336f50
commit c075ff00a6
1 changed files with 6 additions and 1 deletions
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7
sysdeps/ieee754/flt-32/s_acospif.c
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@ -67,7 +67,12 @@ __acospif (float x)
/* For |x| <= 0x1.0fd288p-127, c0 += c4*(z4*z4) would raise a spurious
underflow exception, we use an FMA instead, where c4 * z4 does not
underflow. */
c0 = fma (c4 * z4, z4, c0);
#ifndef __FP_FAST_FMA
if (__glibc_likely (ax > 0x1.0fd288p-127))
c0 = (c4 * z4) * z4 + c0;
else
#endif
c0 = fma (c4 * z4, z4, c0);
return 0.5 - z * c0;
}
else