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[PATCH 4/4] alpha: fix trunc for big input values [committed/2.24]
- From: Mike Frysinger <vapier at gentoo dot org>
- To: libc-alpha at sourceware dot org
- Date: Thu, 8 Dec 2016 13:52:29 -0500
- Subject: [PATCH 4/4] alpha: fix trunc for big input values [committed/2.24]
- Authentication-results: sourceware.org; auth=none
- References: <20161208185229.22804-1-vapier@gentoo.org>
From: Aurelien Jarno <aurelien@aurel32.net>
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)
---
ChangeLog | 6 ++++++
sysdeps/alpha/fpu/s_trunc.c | 7 +++----
sysdeps/alpha/fpu/s_truncf.c | 7 +++----
3 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 66cfa3d420c8..06360aa83662 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,12 @@
* 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.
2016-11-30 H.J. Lu <hongjiu.lu@intel.com>
diff --git a/sysdeps/alpha/fpu/s_trunc.c b/sysdeps/alpha/fpu/s_trunc.c
index 16cb114a72f5..4b986a6926eb 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 (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 2290f282954d..3e933561663b 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 (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));
--
2.11.0.rc2