[PATCH 03/28] powerpc: Remove power4 mpa optimization

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

This patch removes the POWER4 optimized mpa optimization used for power4+
build.  For newer chips, GCC generates *worse* code than generic
implementation as benchmaks result below.  One possibilty would to add
IFUNC variants for the mpa routines (as x86_64), but it will add complexity
only for older chips (and one would need to check if power5, power5+, and
power6 do benefict from this optimization), and only for specific
implementation (since most used ones such as sin, cos, exp, pow already
avoid calling the slow multiprecision path).

  * POWER9 patched
    "atan": {
     "": {
      "duration": 5.12565e+09,
      "iterations": 1.552e+08,
      "max": 100.552,
      "min": 7.799,
      "mean": 33.0261
     },
     "144bits": {
      "duration": 5.12745e+09,
      "iterations": 825000,
      "max": 7517.17,
      "min": 6186.3,
      "mean": 6215.09
     }
    }
    "acos": {
     "": {
      "duration": 5.21741e+09,
      "iterations": 1.269e+08,
      "max": 191.738,
      "min": 7.931,
      "mean": 41.1144
     },
     "slow": {
      "duration": 5.25999e+09,
      "iterations": 198000,
      "max": 26681.7,
      "min": 26463.6,
      "mean": 26565.6
     }
    }

  * POWER9 master
    "atan": {
     "": {
      "duration": 5.12815e+09,
      "iterations": 1.552e+08,
      "max": 134.788,
      "min": 7.803,
      "mean": 33.0422
     },
     "144bits": {
      "duration": 5.1209e+09,
      "iterations": 447000,
      "max": 11615.8,
      "min": 11301.8,
      "mean": 11456.2
     }
    }
    "acos": {
     "": {
      "duration": 5.22272e+09,
      "iterations": 1.269e+08,
      "max": 115.981,
      "min": 7.931,
      "mean": 41.1562
     },
     "slow": {
      "duration": 5.28723e+09,
      "iterations": 96000,
      "max": 55434.1,
      "min": 54820.6,
      "mean": 55075.3
     }
    }

  * POWER8 patched
    "acos": {
     "": {
      "duration": 5.16398e+09,
      "iterations": 9.99e+07,
      "max": 174.408,
      "min": 8.645,
      "mean": 51.6915
     },
     "slow": {
      "duration": 5.16982e+09,
      "iterations": 96000,
      "max": 54830.5,
      "min": 53703.8,
      "mean": 53852.3
     }
    }
  * POWER8 master
    "acos": {
     "": {
      "duration": 5.17019e+09,
      "iterations": 9.99e+07,
      "max": 186.127,
      "min": 8.633,
      "mean": 51.7537
     },
     "slow": {
      "duration": 5.34225e+09,
      "iterations": 90000,
      "max": 60353.2,
      "min": 59155.3,
      "mean": 59358.4
     }
    }

  * POWER7 patched
    "asin": {
     "": {
      "duration": 5.15559e+09,
      "iterations": 6.5e+07,
      "max": 193.335,
      "min": 12.227,
      "mean": 79.3168
     },
     "slow": {
      "duration": 5.20538e+09,
      "iterations": 80000,
      "max": 65705.2,
      "min": 64299.4,
      "mean": 65067.3
     }
    }
  * POWER7 master
    "asin": {
     "": {
      "duration": 5.15446e+09,
      "iterations": 6.5e+07,
      "max": 184.575,
      "min": 12.226,
      "mean": 79.2994
     },
     "slow": {
      "duration": 5.20616e+09,
      "iterations": 80000,
      "max": 65705.1,
      "min": 64336.6,
      "mean": 65076.9
     }
    }

Checked on powerpc-linux-gnu (built without --with-cpu, with
--with-cpu=power4 and with --with-cpu=power5+ and --disable-multi-arch),
powerpc64-linux-gnu (built without --with-cp and with --with-cpu=power5+
and --disable-multi-arch).

	* sysdeps/powerpc/power4/fpu/Makefile: Remove file.
	* sysdeps/powerpc/power4/fpu/mpa-arch.h: Likewise.
	* sysdeps/powerpc/power4/fpu/mpa.c: Likewise.
---
 sysdeps/powerpc/power4/fpu/Makefile   |   5 -
 sysdeps/powerpc/power4/fpu/mpa-arch.h |  56 -------
 sysdeps/powerpc/power4/fpu/mpa.c      | 214 --------------------------
 3 files changed, 275 deletions(-)
 delete mode 100644 sysdeps/powerpc/power4/fpu/Makefile
 delete mode 100644 sysdeps/powerpc/power4/fpu/mpa-arch.h
 delete mode 100644 sysdeps/powerpc/power4/fpu/mpa.c

diff --git a/sysdeps/powerpc/power4/fpu/Makefile b/sysdeps/powerpc/power4/fpu/Makefile
deleted file mode 100644
index f487ed6014..0000000000
--- a/sysdeps/powerpc/power4/fpu/Makefile
+++ /dev/null
@@ -1,5 +0,0 @@
-# Makefile fragment for POWER4/5/5+ with FPU.
-
-ifeq ($(subdir),math)
-CFLAGS-mpa.c += --param max-unroll-times=4 -funroll-loops -fpeel-loops
-endif
diff --git a/sysdeps/powerpc/power4/fpu/mpa-arch.h b/sysdeps/powerpc/power4/fpu/mpa-arch.h
deleted file mode 100644
index 929c60b314..0000000000
--- a/sysdeps/powerpc/power4/fpu/mpa-arch.h
+++ /dev/null
@@ -1,56 +0,0 @@
-/* Overridable constants and operations.
-   Copyright (C) 2013-2019 Free Software Foundation, Inc.
-
-   This program 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.
-
-   This program 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 this program; if not, see <http://www.gnu.org/licenses/>.  */
-
-typedef double mantissa_t;
-typedef double mantissa_store_t;
-
-#define TWOPOW(i) (0x1.0p##i)
-
-#define RADIX TWOPOW (24)		/* 2^24    */
-#define CUTTER TWOPOW (76)		/* 2^76    */
-#define RADIXI 0x1.0p-24		/* 2^-24 */
-#define TWO52 TWOPOW (52)		/* 2^52 */
-
-/* Divide D by RADIX and put the remainder in R.  */
-#define DIV_RADIX(d,r) \
-  ({									      \
-    double u = ((d) + CUTTER) - CUTTER;					      \
-    if (u > (d))							      \
-      u -= RADIX;							      \
-    r = (d) - u;							      \
-    (d) = u * RADIXI;							      \
-  })
-
-/* Put the integer component of a double X in R and retain the fraction in
-   X.  */
-#define INTEGER_OF(x, r) \
-  ({									      \
-    double u = ((x) + TWO52) - TWO52;					      \
-    if (u > (x))							      \
-      u -= 1;								      \
-    (r) = u;								      \
-    (x) -= u;								      \
-  })
-
-/* Align IN down to a multiple of F, where F is a power of two.  */
-#define ALIGN_DOWN_TO(in, f) \
-  ({									      \
-    double factor = f * TWO52;						      \
-    double u = (in + factor) - factor;					      \
-    if (u > in)								      \
-      u -= f;								      \
-    u;									      \
-  })
diff --git a/sysdeps/powerpc/power4/fpu/mpa.c b/sysdeps/powerpc/power4/fpu/mpa.c
deleted file mode 100644
index 1be2e93cb7..0000000000
--- a/sysdeps/powerpc/power4/fpu/mpa.c
+++ /dev/null
@@ -1,214 +0,0 @@
-
-/*
- * IBM Accurate Mathematical Library
- * written by International Business Machines Corp.
- * Copyright (C) 2001-2019 Free Software Foundation, Inc.
- *
- * This program 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.
- *
- * This program 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 this program; if not, see <http://www.gnu.org/licenses/>.
- */
-
-/* Define __mul and __sqr and use the rest from generic code.  */
-#define NO__MUL
-#define NO__SQR
-
-#include <sysdeps/ieee754/dbl-64/mpa.c>
-
-/* Multiply *X and *Y and store result in *Z.  X and Y may overlap but not X
-   and Z or Y and Z.  For P in [1, 2, 3], the exact result is truncated to P
-   digits.  In case P > 3 the error is bounded by 1.001 ULP.  */
-void
-__mul (const mp_no *x, const mp_no *y, mp_no *z, int p)
-{
-  long i, i1, i2, j, k, k2;
-  long p2 = p;
-  double u, zk, zk2;
-
-  /* Is z=0?  */
-  if (__glibc_unlikely (X[0] * Y[0] == 0))
-    {
-      Z[0] = 0;
-      return;
-    }
-
-  /* Multiply, add and carry */
-  k2 = (p2 < 3) ? p2 + p2 : p2 + 3;
-  zk = Z[k2] = 0;
-  for (k = k2; k > 1;)
-    {
-      if (k > p2)
-	{
-	  i1 = k - p2;
-	  i2 = p2 + 1;
-	}
-      else
-	{
-	  i1 = 1;
-	  i2 = k;
-	}
-#if 1
-      /* Rearrange this inner loop to allow the fmadd instructions to be
-         independent and execute in parallel on processors that have
-         dual symmetrical FP pipelines.  */
-      if (i1 < (i2 - 1))
-	{
-	  /* Make sure we have at least 2 iterations.  */
-	  if (((i2 - i1) & 1L) == 1L)
-	    {
-	      /* Handle the odd iterations case.  */
-	      zk2 = x->d[i2 - 1] * y->d[i1];
-	    }
-	  else
-	    zk2 = 0.0;
-	  /* Do two multiply/adds per loop iteration, using independent
-	     accumulators; zk and zk2.  */
-	  for (i = i1, j = i2 - 1; i < i2 - 1; i += 2, j -= 2)
-	    {
-	      zk += x->d[i] * y->d[j];
-	      zk2 += x->d[i + 1] * y->d[j - 1];
-	    }
-	  zk += zk2;		/* Final sum.  */
-	}
-      else
-	{
-	  /* Special case when iterations is 1.  */
-	  zk += x->d[i1] * y->d[i1];
-	}
-#else
-      /* The original code.  */
-      for (i = i1, j = i2 - 1; i < i2; i++, j--)
-	zk += X[i] * Y[j];
-#endif
-
-      u = (zk + CUTTER) - CUTTER;
-      if (u > zk)
-	u -= RADIX;
-      Z[k] = zk - u;
-      zk = u * RADIXI;
-      --k;
-    }
-  Z[k] = zk;
-
-  int e = EX + EY;
-  /* Is there a carry beyond the most significant digit?  */
-  if (Z[1] == 0)
-    {
-      for (i = 1; i <= p2; i++)
-	Z[i] = Z[i + 1];
-      e--;
-    }
-
-  EZ = e;
-  Z[0] = X[0] * Y[0];
-}
-
-/* Square *X and store result in *Y.  X and Y may not overlap.  For P in
-   [1, 2, 3], the exact result is truncated to P digits.  In case P > 3 the
-   error is bounded by 1.001 ULP.  This is a faster special case of
-   multiplication.  */
-void
-__sqr (const mp_no *x, mp_no *y, int p)
-{
-  long i, j, k, ip;
-  double u, yk;
-
-  /* Is z=0?  */
-  if (__glibc_unlikely (X[0] == 0))
-    {
-      Y[0] = 0;
-      return;
-    }
-
-  /* We need not iterate through all X's since it's pointless to
-     multiply zeroes.  */
-  for (ip = p; ip > 0; ip--)
-    if (X[ip] != 0)
-      break;
-
-  k = (__glibc_unlikely (p < 3)) ? p + p : p + 3;
-
-  while (k > 2 * ip + 1)
-    Y[k--] = 0;
-
-  yk = 0;
-
-  while (k > p)
-    {
-      double yk2 = 0.0;
-      long lim = k / 2;
-
-      if (k % 2 == 0)
-        {
-	  yk += X[lim] * X[lim];
-	  lim--;
-	}
-
-      /* In __mul, this loop (and the one within the next while loop) run
-         between a range to calculate the mantissa as follows:
-
-         Z[k] = X[k] * Y[n] + X[k+1] * Y[n-1] ... + X[n-1] * Y[k+1]
-		+ X[n] * Y[k]
-
-         For X == Y, we can get away with summing halfway and doubling the
-	 result.  For cases where the range size is even, the mid-point needs
-	 to be added separately (above).  */
-      for (i = k - p, j = p; i <= lim; i++, j--)
-	yk2 += X[i] * X[j];
-
-      yk += 2.0 * yk2;
-
-      u = (yk + CUTTER) - CUTTER;
-      if (u > yk)
-	u -= RADIX;
-      Y[k--] = yk - u;
-      yk = u * RADIXI;
-    }
-
-  while (k > 1)
-    {
-      double yk2 = 0.0;
-      long lim = k / 2;
-
-      if (k % 2 == 0)
-        {
-	  yk += X[lim] * X[lim];
-	  lim--;
-	}
-
-      /* Likewise for this loop.  */
-      for (i = 1, j = k - 1; i <= lim; i++, j--)
-	yk2 += X[i] * X[j];
-
-      yk += 2.0 * yk2;
-
-      u = (yk + CUTTER) - CUTTER;
-      if (u > yk)
-	u -= RADIX;
-      Y[k--] = yk - u;
-      yk = u * RADIXI;
-    }
-  Y[k] = yk;
-
-  /* Squares are always positive.  */
-  Y[0] = 1.0;
-
-  int e = EX * 2;
-  /* Is there a carry beyond the most significant digit?  */
-  if (__glibc_unlikely (Y[1] == 0))
-    {
-      for (i = 1; i <= p; i++)
-	Y[i] = Y[i + 1];
-      e--;
-    }
-  EY = e;
-}
-- 
2.17.1