MIPS: math-emu: Unify ieee754dp_m{add,sub}f

The code for emulating MIPSr6 madd.d & msub.d instructions has
previously been implemented as 2 different functions, namely
ieee754dp_maddf & ieee754dp_msubf. The difference in behaviour of these
2 instructions is merely the sign of the product, so we can easily share
the code implementing them. Do this for the double precision variant,
removing the original ieee754dp_msubf in favor of reusing the code from
ieee754dp_maddf.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13155/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/math-emu/Makefile b/arch/mips/math-emu/Makefile
index 3389aff..e9bbc2a 100644 (file)
--- a/arch/mips/math-emu/Makefile
+++ b/arch/mips/math-emu/Makefile
@@ -4,7 +4,7 @@
 
 obj-y  += cp1emu.o ieee754dp.o ieee754sp.o ieee754.o \
           dp_div.o dp_mul.o dp_sub.o dp_add.o dp_fsp.o dp_cmp.o dp_simple.o \
-          dp_tint.o dp_fint.o dp_maddf.o dp_msubf.o dp_2008class.o dp_fmin.o dp_fmax.o \
+          dp_tint.o dp_fint.o dp_maddf.o dp_2008class.o dp_fmin.o dp_fmax.o \
           sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_simple.o \
           sp_tint.o sp_fint.o sp_maddf.o sp_2008class.o sp_fmin.o sp_fmax.o \
           dsemul.o

diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index 119eda9..d5e0fb1 100644 (file)
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -14,8 +14,12 @@
 
 #include "ieee754dp.h"
 
-union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
-                               union ieee754dp y)
+enum maddf_flags {
+       maddf_negate_product    = 1 << 0,
+};
+
+static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
+                                union ieee754dp y, enum maddf_flags flags)
 {
        int re;
        int rs;
@@ -154,6 +158,8 @@ union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
 
        re = xe + ye;
        rs = xs ^ ys;
+       if (flags & maddf_negate_product)
+               rs ^= 1;
 
        /* shunt to top of word */
        xm <<= 64 - (DP_FBITS + 1);
@@ -263,3 +269,15 @@ union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
 
        return ieee754dp_format(zs, ze, zm);
 }
+
+union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
+                               union ieee754dp y)
+{
+       return _dp_maddf(z, x, y, 0);
+}
+
+union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
+                               union ieee754dp y)
+{
+       return _dp_maddf(z, x, y, maddf_negate_product);
+}

diff --git a/arch/mips/math-emu/dp_msubf.c b/arch/mips/math-emu/dp_msubf.c
deleted file mode 100644 (file)
index 1224126..0000000
--- a/arch/mips/math-emu/dp_msubf.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/*
- * IEEE754 floating point arithmetic
- * double precision: MSUB.f (Fused Multiply Subtract)
- * MSUBF.fmt: FPR[fd] = FPR[fd] - (FPR[fs] x FPR[ft])
- *
- * MIPS floating point support
- * Copyright (C) 2015 Imagination Technologies, Ltd.
- * Author: Markos Chandras <markos.chandras@imgtec.com>
- *
- *  This program is free software; you can distribute it and/or modify it
- *  under the terms of the GNU General Public License as published by the
- *  Free Software Foundation; version 2 of the License.
- */
-
-#include "ieee754dp.h"
-
-union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
-                               union ieee754dp y)
-{
-       int re;
-       int rs;
-       u64 rm;
-       unsigned lxm;
-       unsigned hxm;
-       unsigned lym;
-       unsigned hym;
-       u64 lrm;
-       u64 hrm;
-       u64 t;
-       u64 at;
-       int s;
-
-       COMPXDP;
-       COMPYDP;
-
-       u64 zm; int ze; int zs __maybe_unused; int zc;
-
-       EXPLODEXDP;
-       EXPLODEYDP;
-       EXPLODEDP(z, zc, zs, ze, zm)
-
-       FLUSHXDP;
-       FLUSHYDP;
-       FLUSHDP(z, zc, zs, ze, zm);
-
-       ieee754_clearcx();
-
-       switch (zc) {
-       case IEEE754_CLASS_SNAN:
-               ieee754_setcx(IEEE754_INVALID_OPERATION);
-               return ieee754dp_nanxcpt(z);
-       case IEEE754_CLASS_DNORM:
-               DPDNORMx(zm, ze);
-       /* QNAN is handled separately below */
-       }
-
-       switch (CLPAIR(xc, yc)) {
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
-               return ieee754dp_nanxcpt(y);
-
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
-       case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
-               return ieee754dp_nanxcpt(x);
-
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
-               return y;
-
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
-               return x;
-
-
-       /*
-        * Infinity handling
-        */
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
-               if (zc == IEEE754_CLASS_QNAN)
-                       return z;
-               ieee754_setcx(IEEE754_INVALID_OPERATION);
-               return ieee754dp_indef();
-
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
-       case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
-               if (zc == IEEE754_CLASS_QNAN)
-                       return z;
-               return ieee754dp_inf(xs ^ ys);
-
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
-       case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
-               if (zc == IEEE754_CLASS_INF)
-                       return ieee754dp_inf(zs);
-               /* Multiplication is 0 so just return z */
-               return z;
-
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
-               DPDNORMX;
-
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
-               if (zc == IEEE754_CLASS_QNAN)
-                       return z;
-               else if (zc == IEEE754_CLASS_INF)
-                       return ieee754dp_inf(zs);
-               DPDNORMY;
-               break;
-
-       case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
-               if (zc == IEEE754_CLASS_QNAN)
-                       return z;
-               else if (zc == IEEE754_CLASS_INF)
-                       return ieee754dp_inf(zs);
-               DPDNORMX;
-               break;
-
-       case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
-               if (zc == IEEE754_CLASS_QNAN)
-                       return z;
-               else if (zc == IEEE754_CLASS_INF)
-                       return ieee754dp_inf(zs);
-               /* fall through to real computations */
-       }
-
-       /* Finally get to do some computation */
-
-       /*
-        * Do the multiplication bit first
-        *
-        * rm = xm * ym, re = xe + ye basically
-        *
-        * At this point xm and ym should have been normalized.
-        */
-       assert(xm & DP_HIDDEN_BIT);
-       assert(ym & DP_HIDDEN_BIT);
-
-       re = xe + ye;
-       rs = xs ^ ys;
-
-       /* shunt to top of word */
-       xm <<= 64 - (DP_FBITS + 1);
-       ym <<= 64 - (DP_FBITS + 1);
-
-       /*
-        * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
-        */
-
-       /* 32 * 32 => 64 */
-#define DPXMULT(x, y)  ((u64)(x) * (u64)y)
-
-       lxm = xm;
-       hxm = xm >> 32;
-       lym = ym;
-       hym = ym >> 32;
-
-       lrm = DPXMULT(lxm, lym);
-       hrm = DPXMULT(hxm, hym);
-
-       t = DPXMULT(lxm, hym);
-
-       at = lrm + (t << 32);
-       hrm += at < lrm;
-       lrm = at;
-
-       hrm = hrm + (t >> 32);
-
-       t = DPXMULT(hxm, lym);
-
-       at = lrm + (t << 32);
-       hrm += at < lrm;
-       lrm = at;
-
-       hrm = hrm + (t >> 32);
-
-       rm = hrm | (lrm != 0);
-
-       /*
-        * Sticky shift down to normal rounding precision.
-        */
-       if ((s64) rm < 0) {
-               rm = (rm >> (64 - (DP_FBITS + 1 + 3))) |
-                    ((rm << (DP_FBITS + 1 + 3)) != 0);
-                       re++;
-       } else {
-               rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
-                    ((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
-       }
-       assert(rm & (DP_HIDDEN_BIT << 3));
-
-       /* And now the subtraction */
-
-       /* flip sign of r and handle as add */
-       rs ^= 1;
-
-       assert(zm & DP_HIDDEN_BIT);
-
-       /*
-        * Provide guard,round and stick bit space.
-        */
-       zm <<= 3;
-
-       if (ze > re) {
-               /*
-                * Have to shift y fraction right to align.
-                */
-               s = ze - re;
-               rm = XDPSRS(rm, s);
-               re += s;
-       } else if (re > ze) {
-               /*
-                * Have to shift x fraction right to align.
-                */
-               s = re - ze;
-               zm = XDPSRS(zm, s);
-               ze += s;
-       }
-       assert(ze == re);
-       assert(ze <= DP_EMAX);
-
-       if (zs == rs) {
-               /*
-                * Generate 28 bit result of adding two 27 bit numbers
-                * leaving result in xm, xs and xe.
-                */
-               zm = zm + rm;
-
-               if (zm >> (DP_FBITS + 1 + 3)) { /* carry out */
-                       zm = XDPSRS1(zm);
-                       ze++;
-               }
-       } else {
-               if (zm >= rm) {
-                       zm = zm - rm;
-               } else {
-                       zm = rm - zm;
-                       zs = rs;
-               }
-               if (zm == 0)
-                       return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
-
-               /*
-                * Normalize to rounding precision.
-                */
-               while ((zm >> (DP_FBITS + 3)) == 0) {
-                       zm <<= 1;
-                       ze--;
-               }
-       }
-
-       return ieee754dp_format(zs, ze, zm);
-}