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[PATCH 6/7] [BZ #13848] alpha: Fix s_nearbyint implementation.
- From: Richard Henderson <rth at twiddle dot net>
- To: libc-ports at sourceware dot org
- Date: Fri, 15 Jun 2012 12:20:36 -0700
- Subject: [PATCH 6/7] [BZ #13848] alpha: Fix s_nearbyint implementation.
- References: <1339788037-29519-1-git-send-email-rth@twiddle.net>
---
sysdeps/alpha/fpu/s_nearbyint.c | 31 ++++++++++++++++---------------
sysdeps/alpha/fpu/s_nearbyintf.c | 35 +++++++++++++++++++++--------------
2 files changed, 37 insertions(+), 29 deletions(-)
diff --git a/sysdeps/alpha/fpu/s_nearbyint.c b/sysdeps/alpha/fpu/s_nearbyint.c
index 1f89260..4589bfc 100644
--- a/sysdeps/alpha/fpu/s_nearbyint.c
+++ b/sysdeps/alpha/fpu/s_nearbyint.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007 Free Software Foundation, Inc.
+/* Copyright (C) 2000-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson.
@@ -19,22 +19,23 @@
#include <math.h>
#include <math_ldbl_opt.h>
-#ifdef _IEEE_FP_INEXACT
-#error "Don't compile with -mieee-with-inexact"
-#endif
double
__nearbyint (double x)
{
- double two52 = copysign (0x1.0p52, x);
- double r;
-
- r = x + two52;
- r = r - two52;
-
- /* nearbyint(-0.1) == -0, and in general we'll always have the same sign
- as our input. */
- return copysign (r, x);
+ if (isless (fabs (x), 9007199254740992.0)) /* 1 << DBL_MANT_DIG */
+ {
+ double tmp1, new_x;
+ __asm ("cvttq/svd %2,%1\n\t"
+ "cvtqt/d %1,%0\n\t"
+ : "=f"(new_x), "=&f"(tmp1)
+ : "f"(x));
+
+ /* nearbyint(-0.1) == -0, and in general we'll always have the same
+ sign as our input. */
+ x = copysign(new_x, x);
+ }
+ return x;
}
weak_alias (__nearbyint, nearbyint)
@@ -42,6 +43,6 @@ weak_alias (__nearbyint, nearbyint)
strong_alias (__nearbyint, __nearbyintl)
weak_alias (__nearbyint, nearbyintl)
#endif
-#if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
-compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_1);
+#if LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)
+compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_0);
#endif
diff --git a/sysdeps/alpha/fpu/s_nearbyintf.c b/sysdeps/alpha/fpu/s_nearbyintf.c
index efea959..871b9f6 100644
--- a/sysdeps/alpha/fpu/s_nearbyintf.c
+++ b/sysdeps/alpha/fpu/s_nearbyintf.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007 Free Software Foundation, Inc.
+/* Copyright (C) 2007-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson.
@@ -18,22 +18,29 @@
#include <math.h>
-#ifdef _IEEE_FP_INEXACT
-#error "Don't compile with -mieee-with-inexact"
-#endif
-
float
__nearbyintf (float x)
{
- float two23 = copysignf (0x1.0p23, x);
- float r;
-
- r = x + two23;
- r = r - two23;
-
- /* nearbyint(-0.1) == -0, and in general we'll always have the same sign
- as our input. */
- return copysign (r, x);
+ if (isless (fabsf (x), 16777216.0f)) /* 1 << FLT_MANT_DIG */
+ {
+ /* Note that Alpha S_Floating is stored in registers in a
+ restricted T_Floating format, so we don't even need to
+ convert back to S_Floating in the end. The initial
+ conversion to T_Floating is needed to handle denormals. */
+
+ float tmp1, tmp2, new_x;
+
+ __asm ("cvtst/s %3,%2\n\t"
+ "cvttq/svd %2,%1\n\t"
+ "cvtqt/d %1,%0\n\t"
+ : "=f"(new_x), "=&f"(tmp1), "=&f"(tmp2)
+ : "f"(x));
+
+ /* nearbyintf(-0.1) == -0, and in general we'll always have the same
+ sign as our input. */
+ x = copysignf(new_x, x);
+ }
+ return x;
}
weak_alias (__nearbyintf, nearbyintf)
--
1.7.7.6