[PATCH] powerpc: Fix fsqrt build in libm

[Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>]

Some powerpc64 processors (e5500 core for instance) does not provide the
fsqrt instruction, however current check to use in math_private.h is
__WORDSIZE and _ARCH_PWR4 (ISA 2.02).  This is patch change it to use
the compiler flag _ARCH_PPCSQ (which is the same condition GCC uses to
decide whether to generate fsqrt instruction).

It fixes BZ#16576.

Tested on powerpc64/powerpc32 with -with-cpu=power4 and with -with-cpu=powerpc64.
The powerpc64 testcase showed some ULPs and exceptions issues when using
the software implementation and I will track them in other bug reports.

Carlos, I would like to push to 2.21.

--

	[BZ #16576]
	* sysdeps/powerpc/fpu/math_private.h [__CPU_HAS_FSQRT]: Remove define
	and use _ARCH_PPCSQ instead.
	(__ieee754_sqrt): Likewise.
	(__ieee754_sqrtf): Likewise.
	* sysdeps/powerpc/fpu/e_sqrt.c (__slow_ieee754_sqrt): Build only if
	_ARCH_PPCSQ is defined.
	(__ieee754_sqrt): Use _ARCH_PPCSQ to select wheter to use hardware
	fsqrt instruction.
	* sysdeps/powerpc/fpu/e_sqrtf.c (__ieee754_sqrtf): Build only if
	_ARCH_PPCSQ is defined.
	(__ieee754_sqrtf): Use _ARCH_PPCSQ to select wheter to use hardware
	fsqrts instruction.
	* sysdeps/powerpc/powerpc64/fpu/e_sqrt.c: Remove file.

--

diff --git a/NEWS b/NEWS
index 903d925..ed15176 100644
--- a/NEWS
+++ b/NEWS
@@ -10,15 +10,15 @@ Version 2.21
 * The following bugs are resolved with this release:
 
   6652, 10672, 12674, 12847, 12926, 13862, 14132, 14138, 14171, 14498,
-  15215, 15884, 16009, 16418, 16191, 16469, 16617, 16619, 16657, 16740,
-  16857, 17192, 17266, 17273, 17344, 17363, 17370, 17371, 17411, 17460,
-  17475, 17485, 17501, 17506, 17508, 17522, 17555, 17570, 17571, 17572,
-  17573, 17574, 17582, 17583, 17584, 17585, 17589, 17594, 17601, 17608,
-  17616, 17625, 17630, 17633, 17634, 17635, 17647, 17653, 17657, 17658,
-  17664, 17665, 17668, 17682, 17702, 17717, 17719, 17722, 17723, 17724,
-  17725, 17732, 17733, 17744, 17745, 17746, 17747, 17748, 17775, 17777,
-  17780, 17781, 17782, 17791, 17793, 17796, 17797, 17803, 17806, 17834,
-  17844, 17848.
+  15215, 15884, 16009, 16418, 16191, 16469, 16576, 16617, 16619, 16657,
+  16740, 16857, 17192, 17266, 17273, 17344, 17363, 17370, 17371, 17411,
+  17460, 17475, 17485, 17501, 17506, 17508, 17522, 17555, 17570, 17571,
+  17572, 17573, 17574, 17582, 17583, 17584, 17585, 17589, 17594, 17601,
+  17608, 17616, 17625, 17630, 17633, 17634, 17635, 17647, 17653, 17657,
+  17658, 17664, 17665, 17668, 17682, 17702, 17717, 17719, 17722, 17723,
+  17724, 17725, 17732, 17733, 17744, 17745, 17746, 17747, 17748, 17775,
+  17777, 17780, 17781, 17782, 17791, 17793, 17796, 17797, 17803, 17806,
+  17834, 17844, 17848.
 
 * A new semaphore algorithm has been implemented in generic C code for all
   machines. Previous custom assembly implementations of semaphore were
diff --git a/sysdeps/powerpc/fpu/e_sqrt.c b/sysdeps/powerpc/fpu/e_sqrt.c
index ba77ae5..4a854a1 100644
--- a/sysdeps/powerpc/fpu/e_sqrt.c
+++ b/sysdeps/powerpc/fpu/e_sqrt.c
@@ -24,6 +24,7 @@
 #include <sysdep.h>
 #include <ldsodefs.h>
 
+#ifndef _ARCH_PPCSQ
 static const double almost_half = 0.5000000000000001;	/* 0.5 + 2^-53 */
 static const ieee_float_shape_type a_nan = {.word = 0x7fc00000 };
 static const ieee_float_shape_type a_inf = {.word = 0x7f800000 };
@@ -152,6 +153,7 @@ __slow_ieee754_sqrt (double x)
     }
   return f_wash (x);
 }
+#endif /* _ARCH_PPCSQ  */
 
 #undef __ieee754_sqrt
 double
@@ -159,16 +161,11 @@ __ieee754_sqrt (double x)
 {
   double z;
 
-  /* If the CPU is 64-bit we can use the optional FP instructions.  */
-  if (__CPU_HAS_FSQRT)
-    {
-      /* Volatile is required to prevent the compiler from moving the
-	 fsqrt instruction above the branch.  */
-      __asm __volatile ("	fsqrt	%0,%1\n"
-				:"=f" (z):"f" (x));
-    }
-  else
-    z = __slow_ieee754_sqrt (x);
+#ifdef _ARCH_PPCSQ
+  asm ("fsqrt	%0,%1\n" :"=f" (z):"f" (x));
+#else
+  z = __slow_ieee754_sqrt (x);
+#endif
 
   return z;
 }
diff --git a/sysdeps/powerpc/fpu/e_sqrtf.c b/sysdeps/powerpc/fpu/e_sqrtf.c
index 5cf47f7..034b6f5 100644
--- a/sysdeps/powerpc/fpu/e_sqrtf.c
+++ b/sysdeps/powerpc/fpu/e_sqrtf.c
@@ -24,6 +24,7 @@
 #include <sysdep.h>
 #include <ldsodefs.h>
 
+#ifndef _ARCH_PPCSQ
 static const float almost_half = 0.50000006;	/* 0.5 + 2^-24 */
 static const ieee_float_shape_type a_nan = {.word = 0x7fc00000 };
 static const ieee_float_shape_type a_inf = {.word = 0x7f800000 };
@@ -128,6 +129,7 @@ __slow_ieee754_sqrtf (float x)
     }
   return f_washf (x);
 }
+#endif /* _ARCH_PPCSQ  */
 
 #undef __ieee754_sqrtf
 float
@@ -135,16 +137,11 @@ __ieee754_sqrtf (float x)
 {
   double z;
 
-  /* If the CPU is 64-bit we can use the optional FP instructions.  */
-  if (__CPU_HAS_FSQRT)
-    {
-      /* Volatile is required to prevent the compiler from moving the
-	 fsqrt instruction above the branch.  */
-      __asm __volatile ("	fsqrts	%0,%1\n"
-				:"=f" (z):"f" (x));
-    }
-  else
-    z = __slow_ieee754_sqrtf (x);
+#ifdef _ARCH_PPCSQ
+  asm ("fsqrts	%0,%1\n" :"=f" (z):"f" (x));
+#else
+  z = __slow_ieee754_sqrtf (x);
+#endif
 
   return z;
 }
diff --git a/sysdeps/powerpc/fpu/math_private.h b/sysdeps/powerpc/fpu/math_private.h
index 6631535..37e7456 100644
--- a/sysdeps/powerpc/fpu/math_private.h
+++ b/sysdeps/powerpc/fpu/math_private.h
@@ -25,26 +25,17 @@
 #include <fenv_private.h>
 #include_next <math_private.h>
 
-# if __WORDSIZE == 64 || defined _ARCH_PWR4
-#  define __CPU_HAS_FSQRT 1
-# else
-#  define __CPU_HAS_FSQRT ((GLRO(dl_hwcap) & PPC_FEATURE_64) != 0)
-# endif
-
 extern double __slow_ieee754_sqrt (double);
 extern __always_inline double
 __ieee754_sqrt (double __x)
 {
   double __z;
 
-  if (__CPU_HAS_FSQRT)
-    {
-      /* Volatile is required to prevent the compiler from moving the
-         fsqrt instruction above the branch.  */
-      __asm __volatile ("fsqrt	%0,%1" : "=f" (__z) : "f" (__x));
-    }
-  else
-     __z = __slow_ieee754_sqrt(__x);
+#ifdef _ARCH_PPCSQ
+   asm ("fsqrt	%0,%1" : "=f" (__z) : "f" (__x));
+#else
+   __z = __slow_ieee754_sqrt(__x);
+#endif
 
   return __z;
 }
@@ -55,14 +46,11 @@ __ieee754_sqrtf (float __x)
 {
   float __z;
 
-  if (__CPU_HAS_FSQRT)
-    {
-      /* Volatile is required to prevent the compiler from moving the
-         fsqrts instruction above the branch.  */
-      __asm __volatile ("fsqrts	%0,%1" : "=f" (__z) : "f" (__x));
-    }
-  else
-     __z = __slow_ieee754_sqrtf(__x);
+#ifdef _ARCH_PPCSQ
+  asm ("fsqrts	%0,%1" : "=f" (__z) : "f" (__x));
+#else
+   __z = __slow_ieee754_sqrtf(__x);
+#endif
 
   return __z;
 }
diff --git a/sysdeps/powerpc/powerpc64/fpu/e_sqrt.c b/sysdeps/powerpc/powerpc64/fpu/e_sqrt.c
deleted file mode 100644
index 796388e..0000000
--- a/sysdeps/powerpc/powerpc64/fpu/e_sqrt.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Double-precision floating point square root.
-   Copyright (C) 1997-2015 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <math.h>
-#include <math_private.h>
-
-#undef __ieee754_sqrt
-double
-__ieee754_sqrt (double x)
-{
-  double z;
-  __asm __volatile ("fsqrt %0,%1" : "=f" (z) : "f" (x));
-  return z;
-}
-strong_alias (__ieee754_sqrt, __sqrt_finite)
diff --git a/sysdeps/powerpc/powerpc64/fpu/e_sqrtf.c b/sysdeps/powerpc/powerpc64/fpu/e_sqrtf.c
deleted file mode 100644
index 5502525..0000000
--- a/sysdeps/powerpc/powerpc64/fpu/e_sqrtf.c
+++ /dev/null
@@ -1,30 +0,0 @@
-/* Single-precision floating point square root.
-   Copyright (C) 1997-2015 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <math.h>
-#include <math_private.h>
-
-#undef __ieee754_sqrtf
-float
-__ieee754_sqrtf (float x)
-{
-  double z;
-  __asm ("fsqrts %0,%1" : "=f" (z) : "f" (x));
-  return z;
-}
-strong_alias (__ieee754_sqrtf, __sqrtf_finite)