[PATCH 2/3] powerpc: POWER8 fmod optimization

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

This patch adds a POWER8 fmod optimization.  The implementation uses
floating point operations instead of default one which uses integers.
Inputs are handled for finite mode (since the symbol is meant to be used
with -ffinite-math-only) and inexact exceptions are disabled in FP
calculation.

Using GLIBC fmod benchmark:

* Default fmod:

  "fmod": {
   "": {
    "duration": 5.1043e+09,
    "iterations": 2.67654e+08,
    "max": 106.892,
    "min": 5.939,
    "mean": 19.0705
   }

* Patched version:

  "fmod": {
   "": {
    "duration": 5.08466e+09,
    "iterations": 6.35088e+08,
    "max": 92.284,
    "min": 6.849,
    "mean": 8.00623
   }

Tested on powerpc64 and powerpc64le.

--

	* sysdeps/powerpc/powerpc64/power8/fpu/e_fmod.S: New file: POWER8 fmod
	optimization.
	* sysdeps/powerpc/powerpc64/power8/fpu/e_fmodf.S: New file: POWER8
	fmodf optimization.

---

diff --git a/sysdeps/powerpc/powerpc64/power8/fpu/e_fmod.S b/sysdeps/powerpc/powerpc64/power8/fpu/e_fmod.S
new file mode 100644
index 0000000..e9b35a2
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power8/fpu/e_fmod.S
@@ -0,0 +1,46 @@
+/* Finite fmod optimization - PowerPC64/POWER8 version.
+   Copyright (C) 2014 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 <sysdep.h>
+#include <math_ldbl_opt.h>
+
+#define MFVSRD_R3_V2  .long 0x7c430066     /* mfvsrd  r3,vs1  */
+
+/* double [fp1] __ieee754_fmod (double [fp1] x, double [fp2] y)  */
+
+        .machine power8
+ENTRY(__ieee754_fmod)
+	/* First check if 'y' is InF and return 'x' if it is the case.  */
+	MFVSRD_R3_V2
+	lis     r9,0x7ff0       /* r9 = 0x7ff0  */
+	rldicl  r10,r3,0,1      /* r10 = r3 & (0x8000000000000000)  */
+	sldi    r9,r9,32	/* r9 = r9 << 52  */
+	cmpd    cr7,r10,r9      /* fp1 & 0x7ff0000000000000 ?  */
+	beqlr   cr7
+
+	mtfsb0  4*cr7+lt	/* Disable FE_INEXACT exception  */
+	fdiv    fp0,fp1,fp2	/* fp0 = -trunc (fp1 / fp2)  */
+	fneg    fp0,fp0
+	friz    fp0,fp0
+	fmadd   fp2,fp0,fp2,fp1 /* fp2 = x - (fp0) * y  */
+	fcpsgn  fp1,fp1,fp2
+	mtfsb0  4*cr1+eq	/* Clear any FE_INEXACT exception  */
+	blr
+END (__ieee754_fmod)
+
+strong_alias (__ieee754_fmod, __fmod_finite)
diff --git a/sysdeps/powerpc/powerpc64/power8/fpu/e_fmodf.S b/sysdeps/powerpc/powerpc64/power8/fpu/e_fmodf.S
new file mode 100644
index 0000000..7e16374
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power8/fpu/e_fmodf.S
@@ -0,0 +1,46 @@
+/* Finite fmodf optimization - PowerPC64/POWER8 version.
+   Copyright (C) 2014 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 <sysdep.h>
+#include <math_ldbl_opt.h>
+
+#define MFVSRD_R3_V2  .long 0x7c430066     /* mfvsrd  r3,vs1  */
+
+/* double [fp1] __ieee754_fmod (double [fp1] x, double [fp2] y)  */
+
+	.machine power8
+ENTRY(__ieee754_fmodf)
+	/* First check if 'y' is InF and return 'x' if it is the case.  */
+	MFVSRD_R3_V2
+	lis     r9,0x7ff0       /* r9 = 0x7ff0  */
+	rldicl  r10,r3,0,1      /* r10 = r3 & (0x8000000000000000)  */
+	sldi    r9,r9,32	/* r9 = r9 << 52  */
+	cmpd    cr7,r10,r9      /* fp1 & 0x7ff0000000000000 ?  */
+	beqlr   cr7
+
+	mtfsb0  4*cr7+lt	/* Disable FE_INEXACT exception  */
+	fdivs   fp0,fp1,fp2	/* fp0 = -trunc (fp1 / fp2)  */
+	fneg    fp0,fp0
+	friz    fp0,fp0
+	fmadds  fp2,fp0,fp2,fp1 /* fp2 = x - (fp0) * y  */
+	fcpsgn  fp1,fp1,fp2
+	mtfsb0  4*cr1+eq	/* Clear any FE_INEXACT exception  */
+	blr
+END (__ieee754_fmodf)
+
+strong_alias (__ieee754_fmodf, __fmodf_finite)