diff options
| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2018-12-07 14:58:51 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2018-12-07 14:58:51 +0000 |
| commit | 04884bd04eac4b251da4026900010ea7d8850edc (patch) | |
| tree | 33c966ee96c845a40dc64ecf3bac969e76c69bc1 /math/powf.c | |
| parent | 75b8d8c6c12b37a38211defcc5b941adb7de121f (diff) | |
| download | arm-optimized-routines-04884bd04eac4b251da4026900010ea7d8850edc.tar.gz | |
More consistent excess precision handling
The current code aims to support FLT_EVAL_METHOD!=0 targets (such as
i386 with x87 fpu or m68k) assuming appropriate narrowing eval functions
are defined for them. But the narrowing eval functions were not used
consistently: the return statement may not guarantee narrowing (e.g.
that was the C99 behaviour which got changed in C11 annex F) so we
should use the narrowing eval_as_ functions at return statements too.
Results should be correct if narrowing only happens at eval_as_ calls.
On most targets this change has no effect because eval_as_ is a noop.
Most math implementations that care about excess precision already
compile in a mode that narrows at returns so this change is not
necessary for them, just better documents the assumptions.
Diffstat (limited to 'math/powf.c')
| -rw-r--r-- | math/powf.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/math/powf.c b/math/powf.c index 06116f0..385719b 100644 --- a/math/powf.c +++ b/math/powf.c @@ -74,7 +74,7 @@ log2_inline (uint32_t ix) /* The output of log2 and thus the input of exp2 is either scaled by N (in case of fast toint intrinsics) or not. The unscaled xd must be in [-1021,1023], sign_bias sets the sign of the result. */ -static inline double_t +static inline float exp2_inline (double_t xd, uint32_t sign_bias) { uint64_t ki, ski, t; @@ -106,7 +106,7 @@ exp2_inline (double_t xd, uint32_t sign_bias) y = C[2] * r + 1; y = z * r2 + y; y = y * s; - return y; + return eval_as_float (y); } /* Returns 0 if not int, 1 if odd int, 2 if even int. The argument is @@ -214,7 +214,7 @@ powf (float x, float y) return __math_may_uflowf (sign_bias); #endif } - return (float) exp2_inline (ylogx, sign_bias); + return exp2_inline (ylogx, sign_bias); } #if USE_GLIBC_ABI strong_alias (powf, __powf_finite) |