alpha: fix trunc for big input values

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.

(cherry picked from commit b74d259fe793499134eb743222cd8dd7c74a31ce)
(cherry picked from commit e6eab16cc302e6c42f79e1af02ce98ebb9a783bc)

diff --git a/sysdeps/alpha/fpu/s_trunc.c b/sysdeps/alpha/fpu/s_trunc.c
index 16cb114a72f5f13f780e21bf71d89a39e2986eaa..4b986a6926ebc323e89747dcfe201d13a15634e5 100644 (file)
--- a/sysdeps/alpha/fpu/s_trunc.c
+++ b/sysdeps/alpha/fpu/s_trunc.c
@@ -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));
 

diff --git a/sysdeps/alpha/fpu/s_truncf.c b/sysdeps/alpha/fpu/s_truncf.c
index 2290f282954ddb0fa3bcf5b8aa771c6947075f04..3e933561663bea13423fe335d7c76e32d6e83804 100644 (file)
--- a/sysdeps/alpha/fpu/s_truncf.c
+++ b/sysdeps/alpha/fpu/s_truncf.c
@@ -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));