diff mbox

alpha: fix truncf and trunc for big input values

Message ID 1467449920-2372-1-git-send-email-aurelien@aurel32.net
State New
Headers show

Commit Message

Aurelien Jarno July 2, 2016, 8:58 a.m. UTC 
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_truncf.c (__truncf): Return the input value
	when its absolute value is greater than 0x1.0p23.
	[_IEEE_FP_INEXACT] Remove.
	* sysdeps/alpha/fpu/s_trunc.c (__trunc): Return the input value
	when its absolute value is greater than 0x1.0p52.
	[_IEEE_FP_INEXACT] Remove.
---
 ChangeLog                    | 9 +++++++++
 sysdeps/alpha/fpu/s_trunc.c  | 7 +++----
 sysdeps/alpha/fpu/s_truncf.c | 7 +++----
 3 files changed, 15 insertions(+), 8 deletions(-)
diff mbox

Patch

diff --git a/ChangeLog b/ChangeLog
index a7ca1ff..eda80f8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@ 
+2016-07-02  Aurelien Jarno  <aurelien@aurel32.net>
+
+	* sysdeps/alpha/fpu/s_truncf.c (__truncf): Return the input value
+	when its absolute value is greater than 0x1.0p23.
+	[_IEEE_FP_INEXACT] Remove.
+	* sysdeps/alpha/fpu/s_trunc.c (__trunc): Return the input value
+	when its absolute value is greater than 0x1.0p52.
+	[_IEEE_FP_INEXACT] Remove.
+
 2016-07-01  Aurelien Jarno  <aurelien@aurel32.net>
 
 	* sparc/sparc32/sparcv9/fpu/s_nearbyint.S (__nearbyint): Trigger an
diff --git a/sysdeps/alpha/fpu/s_trunc.c b/sysdeps/alpha/fpu/s_trunc.c
index 16cb114..c072c26 100644
--- 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 (!isnan(x) && 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 2290f28..3dbe2ad 100644
--- 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 (!isnan(x) && fabs(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));