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alpha: fix trunc for big input values

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The alpha specific version of trunc and truncf always add and subtract
0x1.0p23 or 0x1.0p52 even for big values. This causes this kind of
errors in the testsuite:

  Failure: Test: trunc_towardzero (0x1p107)
  Result:
   is:          1.6225927682921334e+32   0x1.fffffffffffffp+106
   should be:   1.6225927682921336e+32   0x1.0000000000000p+107
   difference:  1.8014398509481984e+16   0x1.0000000000000p+54
   ulp       :  0.5000
   max.ulp   :  0.0000

Change this by returning the input value when its absolute value is
greater than 0x1.0p23 or 0x1.0p52. NaN have to go through the add and
subtract operations to get possibly silenced.

Finally remove the code to handle inexact exception, trunc should never
generate such an exception.

Changelog:
	* sysdeps/alpha/fpu/s_trunc.c (__trunc): Return the input value
	when its absolute value is greater than 0x1.0p52.
	[_IEEE_FP_INEXACT] Remove.
	* sysdeps/alpha/fpu/s_truncf.c (__truncf): Return the input value
	when its absolute value is greater than 0x1.0p23.
	[_IEEE_FP_INEXACT] Remove.
This commit is contained in:
Aurelien Jarno 2016-08-02 09:18:59 +02:00
parent cb7f9d63b9
commit b74d259fe7
3 changed files with 12 additions and 8 deletions
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6
ChangeLog
View File

@ -11,6 +11,12 @@
* sysdeps/alpha/fpu/s_rint.c (__rint): Add argument with itself
when it is a NaN.
* sysdeps/alpha/fpu/s_rintf.c (__rintf): Likewise.
* sysdeps/alpha/fpu/s_trunc.c (__trunc): Return the input value
when its absolute value is greater than 0x1.0p52.
[_IEEE_FP_INEXACT] Remove.
* sysdeps/alpha/fpu/s_truncf.c (__truncf): Return the input value
when its absolute value is greater than 0x1.0p23.
[_IEEE_FP_INEXACT] Remove.
2016-08-01 Carlos O'Donell <carlos@redhat.com>

7
sysdeps/alpha/fpu/s_trunc.c
View File

@ -28,12 +28,11 @@ __trunc (double x)
double two52 = copysign (0x1.0p52, x);
double r, tmp;
if (isgreaterequal (fabs (x), 0x1.0p52))
return x;
__asm (
#ifdef _IEEE_FP_INEXACT
"addt/suic %2, %3, %1\n\tsubt/suic %1, %3, %0"
#else
"addt/suc %2, %3, %1\n\tsubt/suc %1, %3, %0"
#endif
: "=&f"(r), "=&f"(tmp)
: "f"(x), "f"(two52));

7
sysdeps/alpha/fpu/s_truncf.c
View File

@ -27,12 +27,11 @@ __truncf (float x)
float two23 = copysignf (0x1.0p23, x);
float r, tmp;
if (isgreaterequal (fabsf (x), 0x1.0p23))
return x;
__asm (
#ifdef _IEEE_FP_INEXACT
"adds/suic %2, %3, %1\n\tsubs/suic %1, %3, %0"
#else
"adds/suc %2, %3, %1\n\tsubs/suc %1, %3, %0"
#endif
: "=&f"(r), "=&f"(tmp)
: "f"(x), "f"(two23));