arm: precise float64 software floating point
Adds softfloat64 to generic runtime
(will be discarded by linker when unused)
and adds test for it. I used the test to check
the software code against amd64 hardware
and then check the software code against
the arm and its simulation of hardware.
The latter should have been a no-op (testing
against itself) but turned up a bug in 5c causing
the vlrt.c routines to miscompile.
These changes make the cmath, math,
and strconv tests pass without any special
accommodations for arm.
R=ken2
CC=golang-dev
https://golang.org/cl/2713042
diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index 34bd834..0bd56764 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -149,7 +149,6 @@
image/jpeg\
net/dict\
rand\
- runtime\
runtime/pprof\
syscall\
testing/iotest\
@@ -201,14 +200,6 @@
NOTEST+=time # no syscall.Kill, syscall.SIGCHLD for sleep tests
endif
-ifeq ($(GOARCH),arm)
-# Tests that fail, probably 5g bugs.
-# Disable so that dashboard all.bash can catch regressions.
-NOTEST+=cmath # software floating point (lack of) accuracy
-NOTEST+=math # software floating point (lack of) accuracy
-NOTEST+=strconv # software floating point (lack of) accuracy
-endif
-
TEST=\
$(filter-out $(NOTEST),$(DIRS))
diff --git a/src/pkg/runtime/Makefile b/src/pkg/runtime/Makefile
index 4c8d549..58e0e76 100644
--- a/src/pkg/runtime/Makefile
+++ b/src/pkg/runtime/Makefile
@@ -25,6 +25,7 @@
error.go\
extern.go\
sig.go\
+ softfloat64.go\
type.go\
version.go\
diff --git a/src/pkg/runtime/arm/softfloat.c b/src/pkg/runtime/arm/softfloat.c
index 396072f..a5a6ba1 100644
--- a/src/pkg/runtime/arm/softfloat.c
+++ b/src/pkg/runtime/arm/softfloat.c
@@ -2,6 +2,10 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
+// Software floating point interpretaton of ARM 7500 FP instructions.
+// The interpretation is not bit compatible with the 7500.
+// It uses true little-endian doubles, while the 7500 used mixed-endian.
+
#include "runtime.h"
void abort(void);
@@ -18,22 +22,6 @@
static uint32 doabort = 0;
static uint32 trace = 0;
-#define DOUBLE_EXPBIAS 1023
-#define DOUBLE_MANT_MASK 0xfffffffffffffull
-#define DOUBLE_MANT_TOP_BIT 0x10000000000000ull
-#define DZERO 0x0000000000000000ull
-#define DNZERO 0x8000000000000000ull
-#define DONE 0x3ff0000000000000ull
-#define DINF 0x7ff0000000000000ull
-#define DNINF 0xfff0000000000000ull
-#define DNAN 0x7FF0000000000001ull
-
-#define SINGLE_EXPBIAS 127
-#define FINF 0x7f800000ul
-#define FNINF 0xff800000ul
-#define FNAN 0x7f800000ul
-
-
static const int8* opnames[] = {
// binary
"adf",
@@ -115,24 +103,6 @@
}
}
-static int32
-fexp(uint64 f)
-{
- return (int32)((uint32)(f >> 52) & 0x7ff) - DOUBLE_EXPBIAS;
-}
-
-static uint32
-fsign(uint64 f)
-{
- return (uint32)(f >> 63) & 0x1;
-}
-
-static uint64
-fmantissa(uint64 f)
-{
- return f &0x000fffffffffffffll;
-}
-
static void
fprint(void)
{
@@ -145,42 +115,19 @@
static uint32
d2s(uint64 d)
{
- if ((d & ~(1ull << 63)) == 0)
- return (uint32)(d>>32);
- if (d == DINF)
- return FINF;
- if (d == DNINF)
- return FNINF;
- if ((d & ~(1ull << 63)) == DNAN)
- return FNAN;
- return (d>>32 & 0x80000000) | //sign
- ((uint32)(fexp(d) + SINGLE_EXPBIAS) & 0xff) << 23 | // exponent
- (d >> 29 & 0x7fffff); // mantissa
+ uint32 x;
+
+ ·f64to32c(d, &x);
+ return x;
}
static uint64
s2d(uint32 s)
{
- if ((s & ~(1ul << 31)) == 0)
- return (uint64)(s) << 32;
- if (s == FINF)
- return DINF;
- if (s == FNINF)
- return DNINF;
- if ((s & ~(1ul << 31)) == FNAN)
- return DNAN;
- return (uint64)(s & 0x80000000) << 32 | // sign
- (uint64)((s >> 23 &0xff) + (DOUBLE_EXPBIAS - SINGLE_EXPBIAS)) << 52 | // exponent
- (uint64)(s & 0x7fffff) << 29; // mantissa
-}
-
-static int64
-rsh(int64 f, int32 s)
-{
- if (s >= 0)
- return f>>s;
- else
- return f<<-s;
+ uint64 x;
+
+ ·f32to64c(s, &x);
+ return x;
}
// cdp, data processing instructions
@@ -188,12 +135,8 @@
dataprocess(uint32* pc)
{
uint32 i, opcode, unary, dest, lhs, rhs, prec;
- uint32 high;
- int32 expd, exp0, exp1;
- uint64 fraw0, fraw1, exp, sign;
- uint64 fd, f0, f1;
- int64 fsd, fs0, fs1;
-
+ uint64 l, r;
+ uint64 fd;
i = *pc;
// data processing
@@ -220,129 +163,25 @@
goto undef;
}
} else {
- fraw0 = m->freg[lhs];
- fraw1 = frhs(rhs);
- if (isNaN(float64frombits(fraw0)) || isNaN(float64frombits(fraw1))) {
- m->freg[dest] = DNAN;
- goto ret;
- }
+ l = m->freg[lhs];
+ r = frhs(rhs);
switch (opcode) {
- case 2: // suf
- fraw1 ^= 0x1ll << 63;
- // fallthrough
- case 0: // adf
- if (fraw0 == DZERO || fraw0 == DNZERO) {
- m->freg[dest] = fraw1;
- goto ret;
- }
- if (fraw1 == DZERO || fraw1 == DNZERO) {
- m->freg[dest] = fraw0;
- goto ret;
- }
- fs0 = fraw0 & DOUBLE_MANT_MASK | DOUBLE_MANT_TOP_BIT;
- fs1 = fraw1 & DOUBLE_MANT_MASK | DOUBLE_MANT_TOP_BIT;
- exp0 = fexp(fraw0);
- exp1 = fexp(fraw1);
- if (exp0 > exp1)
- fs1 = rsh(fs1, exp0-exp1);
- else
- fs0 = rsh(fs0, exp1-exp0);
- if (fraw0 & 0x1ll<<63)
- fs0 = -fs0;
- if (fraw1 & 0x1ll<<63)
- fs1 = -fs1;
- fsd = fs0 + fs1;
- if (fsd == 0) {
- m->freg[dest] = DZERO;
- goto ret;
- }
- sign = (uint64)fsd & 0x1ll<<63;
- if (fsd < 0)
- fsd = -fsd;
- for (expd = 55; expd > 0; expd--) {
- if (0x1ll<<expd & fsd)
- break;
- }
- if (expd - 52 < 0)
- fsd <<= -(expd - 52);
- else
- fsd >>= expd - 52;
- if (exp0 > exp1)
- exp = expd + exp0 - 52;
- else
- exp = expd + exp1 - 52;
- // too small value, can't represent
- if (1<<31 & expd) {
- m->freg[dest] = DZERO;
- goto ret;
- }
- // infinity
- if (expd > 1<<12) {
- m->freg[dest] = DINF;
- goto ret;
- }
- fd = sign | (exp + DOUBLE_EXPBIAS)<<52 | (uint64)fsd & DOUBLE_MANT_MASK;
- m->freg[dest] = fd;
- goto ret;
-
- case 4: //dvf
- if ((fraw1 & ~(1ull<<63)) == 0) {
- if ((fraw0 & ~(1ull<<63)) == 0) {
- m->freg[dest] = DNAN;
- } else {
- sign = fraw0 & 1ull<<63 ^ fraw1 & 1ull<<63;
- m->freg[dest] = sign | DINF;
- }
- goto ret;
- }
- // reciprocal for fraw1
- if (fraw1 == DONE)
- goto muf;
- f0 = 0x1ll << 63;
- f1 = fraw1 & DOUBLE_MANT_MASK | DOUBLE_MANT_TOP_BIT;
- f1 >>= 21;
- fd = f0/f1;
- fd <<= 21;
- fd &= DOUBLE_MANT_MASK;
- exp1 = -fexp(fraw1) - 1;
- sign = fraw1 & 0x1ll<<63;
- fraw1 = sign | (uint64)(exp1 + DOUBLE_EXPBIAS)<<52 | fd;
- // fallthrough
- case 1: // muf
-muf:
- if (fraw0 == DNZERO || fraw1 == DNZERO) {
- m->freg[dest] = DNZERO;
- goto ret;
- }
- if (fraw0 == DZERO || fraw1 == DZERO) {
- m->freg[dest] = DZERO;
- goto ret;
- }
- if (fraw0 == DONE) {
- m->freg[dest] = fraw1;
- goto ret;
- }
- if (fraw1 == DONE) {
- m->freg[dest] = fraw0;
- goto ret;
- }
- f0 = fraw0>>21 & 0x7fffffff | 0x1ll<<31;
- f1 = fraw1>>21 & 0x7fffffff | 0x1ll<<31;
- fd = f0*f1;
- high = fd >> 63;
- if (high)
- fd = fd >> 11 & DOUBLE_MANT_MASK;
- else
- fd = fd >> 10 & DOUBLE_MANT_MASK;
- exp = (uint64)(fexp(fraw0) + fexp(fraw1) + !!high + DOUBLE_EXPBIAS) & 0x7ff;
- sign = fraw0 >> 63 ^ fraw1 >> 63;
- fd = sign<<63 | exp<<52 | fd;
- m->freg[dest] = fd;
- goto ret;
-
default:
goto undef;
+ case 0:
+ ·fadd64c(l, r, &m->freg[dest]);
+ break;
+ case 1:
+ ·fmul64c(l, r, &m->freg[dest]);
+ break;
+ case 2:
+ ·fsub64c(l, r, &m->freg[dest]);
+ break;
+ case 4:
+ ·fdiv64c(l, r, &m->freg[dest]);
+ break;
}
+ goto ret;
}
@@ -375,61 +214,28 @@
static void
compare(uint32 *pc, uint32 *regs)
{
- uint32 i, flags, lhs, rhs, sign0, sign1;
- uint64 f0, f1, mant0, mant1;
- int32 exp0, exp1;
+ uint32 i, flags, lhs, rhs;
+ uint64 l, r;
+ int32 cmp;
+ bool nan;
i = *pc;
flags = 0;
lhs = i>>16 & 0x7;
rhs = i & 0xf;
- f0 = m->freg[lhs];
- f1 = frhs(rhs);
- if (isNaN(float64frombits(f0)) || isNaN(float64frombits(f1))) {
+ l = m->freg[lhs];
+ r = frhs(rhs);
+ ·fcmp64c(l, r, &cmp, &nan);
+ if (nan)
flags = FLAGS_C | FLAGS_V;
- goto ret;
- }
- if (f0 == f1) {
+ else if (cmp == 0)
flags = FLAGS_Z | FLAGS_C;
- goto ret;
- }
-
- sign0 = fsign(f0);
- sign1 = fsign(f1);
- if (sign0 == 1 && sign1 == 0) {
+ else if (cmp < 0)
flags = FLAGS_N;
- goto ret;
- }
- if (sign0 == 0 && sign1 == 1) {
+ else
flags = FLAGS_C;
- goto ret;
- }
- if (sign0 == 0) {
- exp0 = fexp(f0);
- exp1 = fexp(f1);
- mant0 = fmantissa(f0);
- mant1 = fmantissa(f1);
- } else {
- exp0 = fexp(f1);
- exp1 = fexp(f0);
- mant0 = fmantissa(f1);
- mant1 = fmantissa(f0);
- }
-
- if (exp0 > exp1) {
- flags = FLAGS_C;
- } else if (exp0 < exp1) {
- flags = FLAGS_N;
- } else {
- if (mant0 > mant1)
- flags = FLAGS_C;
- else
- flags = FLAGS_N;
- }
-
-ret:
if (trace) {
printf(" %p %x\tcmf\tf%d, ", pc, *pc, lhs);
if (rhs & 0x8)
@@ -503,9 +309,10 @@
static void
fltfix(uint32 *pc, uint32 *regs)
{
- uint32 i, toarm, freg, reg, sign, val, prec;
- int32 rd, exp;
- uint64 fd, f0;
+ uint32 i, toarm, freg, reg, prec;
+ int64 val;
+ uint64 f0;
+ bool ok;
i = *pc;
toarm = i>>20 & 0x1;
@@ -513,33 +320,15 @@
reg = i>>12 & 0xf;
prec = precision(i);
- if (toarm) { //fix
+ if (toarm) { // fix
f0 = m->freg[freg];
- fd = f0 & DOUBLE_MANT_MASK | DOUBLE_MANT_TOP_BIT;
- exp = fexp(f0) - 52;
- if (exp < 0)
- fd = fd>>(-exp);
- else
- fd = fd<<exp;
- rd = ((int32)fd & 0x7fffffff);
- if (f0 & 0x1ll<<63)
- rd = -rd;
- regs[reg] = (uint32)rd;
+ ·f64tointc(f0, &val, &ok);
+ if (!ok || (int32)val != val)
+ val = 0;
+ regs[reg] = val;
} else { // flt
- if (regs[reg] == 0) {
- m->freg[freg] = DZERO;
- goto ret;
- }
- sign = regs[reg] >> 31 & 0x1;
- val = regs[reg];
- if (sign) val = -val;
- for (exp = 31; exp >= 0; exp--) {
- if (1<<(exp) & val)
- break;
- }
- fd = (uint64)val<<(52-exp) & DOUBLE_MANT_MASK;
- m->freg[freg] = (uint64)(sign) << 63 |
- (uint64)(exp + DOUBLE_EXPBIAS) << 52 | fd;
+ ·fintto64c((int32)regs[reg], &f0);
+ m->freg[freg] = f0;
}
goto ret;
@@ -581,7 +370,8 @@
loadstore(pc, regs);
return 1;
case 7: // 111
- if (i>>24 & 1) return 0; // ignore swi
+ if (i>>24 & 1)
+ return 0; // ignore swi
if (i>>4 & 1) { //data transfer
if ((i&0x00f0ff00) == 0x0090f100) {
@@ -606,6 +396,14 @@
regs[11] = *(uint32*)((uint8*)pc + (i&0xfff) + 8);
return 1;
}
+
+ if(i == 0xe08bb00d) {
+ // add sp to 11.
+ // might be part of a large stack offset address
+ // (or might not, but again no harm done).
+ regs[11] += regs[13];
+ return 1;
+ }
return 0;
}
@@ -615,11 +413,9 @@
_sfloat2(uint32 *lr, uint32 r0)
{
uint32 skip;
-// uint32 cpsr;
- while(skip = stepflt(lr, &r0)) {
+ while(skip = stepflt(lr, &r0))
lr += skip;
- }
return lr;
}
diff --git a/src/pkg/runtime/export_test.go b/src/pkg/runtime/export_test.go
new file mode 100644
index 0000000..58631c7
--- /dev/null
+++ b/src/pkg/runtime/export_test.go
@@ -0,0 +1,17 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Export guts for testing.
+
+package runtime
+
+var Fadd64 = fadd64
+var Fsub64 = fsub64
+var Fmul64 = fmul64
+var Fdiv64 = fdiv64
+var F64to32 = f64to32
+var F32to64 = f32to64
+var Fcmp64 = fcmp64
+var Fintto64 = fintto64
+var F64toint = f64toint
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 92da669..0a36d27 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -558,6 +558,7 @@
void ·panic(Eface);
void ·panicindex(void);
void ·panicslice(void);
+
/*
* runtime c-called (but written in Go)
*/
@@ -565,6 +566,16 @@
void ·printany(Eface);
void ·newTypeAssertionError(Type*, Type*, Type*, String*, String*, String*, String*, Eface*);
void ·newErrorString(String, Eface*);
+void ·fadd64c(uint64, uint64, uint64*);
+void ·fsub64c(uint64, uint64, uint64*);
+void ·fmul64c(uint64, uint64, uint64*);
+void ·fdiv64c(uint64, uint64, uint64*);
+void ·fneg64c(uint64, uint64*);
+void ·f32to64c(uint32, uint64*);
+void ·f64to32c(uint64, uint32*);
+void ·fcmp64c(uint64, uint64, int32*, bool*);
+void ·fintto64c(int64, uint64*);
+void ·f64tointc(uint64, int64*, bool*);
/*
* wrapped for go users
diff --git a/src/pkg/runtime/softfloat64.go b/src/pkg/runtime/softfloat64.go
new file mode 100644
index 0000000..d9bbe5d
--- /dev/null
+++ b/src/pkg/runtime/softfloat64.go
@@ -0,0 +1,498 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Software IEEE754 64-bit floating point.
+// Only referred to (and thus linked in) by arm port
+// and by gotest in this directory.
+
+package runtime
+
+const (
+ mantbits64 uint = 52
+ expbits64 uint = 11
+ bias64 = -1<<(expbits64-1) + 1
+
+ nan64 uint64 = (1<<expbits64-1)<<mantbits64 + 1
+ inf64 uint64 = (1<<expbits64 - 1) << mantbits64
+ neg64 uint64 = 1 << (expbits64 + mantbits64)
+
+ mantbits32 uint = 23
+ expbits32 uint = 8
+ bias32 = -1<<(expbits32-1) + 1
+
+ nan32 uint32 = (1<<expbits32-1)<<mantbits32 + 1
+ inf32 uint32 = (1<<expbits32 - 1) << mantbits32
+ neg32 uint32 = 1 << (expbits32 + mantbits32)
+)
+
+func funpack64(f uint64) (sign, mant uint64, exp int, inf, nan bool) {
+ sign = f & (1 << (mantbits64 + expbits64))
+ mant = f & (1<<mantbits64 - 1)
+ exp = int(f>>mantbits64) & (1<<expbits64 - 1)
+
+ switch exp {
+ case 1<<expbits64 - 1:
+ if mant != 0 {
+ nan = true
+ return
+ }
+ inf = true
+ return
+
+ case 0:
+ // denormalized
+ if mant != 0 {
+ exp += bias64 + 1
+ for mant < 1<<mantbits64 {
+ mant <<= 1
+ exp--
+ }
+ }
+
+ default:
+ // add implicit top bit
+ mant |= 1 << mantbits64
+ exp += bias64
+ }
+ return
+}
+
+func funpack32(f uint32) (sign, mant uint32, exp int, inf, nan bool) {
+ sign = f & (1 << (mantbits32 + expbits32))
+ mant = f & (1<<mantbits32 - 1)
+ exp = int(f>>mantbits32) & (1<<expbits32 - 1)
+
+ switch exp {
+ case 1<<expbits32 - 1:
+ if mant != 0 {
+ nan = true
+ return
+ }
+ inf = true
+ return
+
+ case 0:
+ // denormalized
+ if mant != 0 {
+ exp += bias32 + 1
+ for mant < 1<<mantbits32 {
+ mant <<= 1
+ exp--
+ }
+ }
+
+ default:
+ // add implicit top bit
+ mant |= 1 << mantbits32
+ exp += bias32
+ }
+ return
+}
+
+func fpack64(sign, mant uint64, exp int, trunc uint64) uint64 {
+ mant0, exp0, trunc0 := mant, exp, trunc
+ if mant == 0 {
+ return sign
+ }
+ for mant < 1<<mantbits64 {
+ mant <<= 1
+ exp--
+ }
+ for mant >= 4<<mantbits64 {
+ trunc |= mant & 1
+ mant >>= 1
+ exp++
+ }
+ if mant >= 2<<mantbits64 {
+ if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
+ mant++
+ if mant >= 4<<mantbits64 {
+ mant >>= 1
+ exp++
+ }
+ }
+ mant >>= 1
+ exp++
+ }
+ if exp >= 1<<expbits64-1+bias64 {
+ return sign ^ inf64
+ }
+ if exp < bias64+1 {
+ if exp < bias64-int(mantbits64) {
+ return sign | 0
+ }
+ // repeat expecting denormal
+ mant, exp, trunc = mant0, exp0, trunc0
+ for exp < bias64 {
+ trunc |= mant & 1
+ mant >>= 1
+ exp++
+ }
+ if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
+ mant++
+ }
+ mant >>= 1
+ exp++
+ if mant < 1<<mantbits64 {
+ return sign | mant
+ }
+ }
+ return sign | uint64(exp-bias64)<<mantbits64 | mant&(1<<mantbits64-1)
+}
+
+func fpack32(sign, mant uint32, exp int, trunc uint32) uint32 {
+ mant0, exp0, trunc0 := mant, exp, trunc
+ if mant == 0 {
+ return sign
+ }
+ for mant < 1<<mantbits32 {
+ mant <<= 1
+ exp--
+ }
+ for mant >= 4<<mantbits32 {
+ trunc |= mant & 1
+ mant >>= 1
+ exp++
+ }
+ if mant >= 2<<mantbits32 {
+ if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
+ mant++
+ if mant >= 4<<mantbits32 {
+ mant >>= 1
+ exp++
+ }
+ }
+ mant >>= 1
+ exp++
+ }
+ if exp >= 1<<expbits32-1+bias32 {
+ return sign ^ inf32
+ }
+ if exp < bias32+1 {
+ if exp < bias32-int(mantbits32) {
+ return sign | 0
+ }
+ // repeat expecting denormal
+ mant, exp, trunc = mant0, exp0, trunc0
+ for exp < bias32 {
+ trunc |= mant & 1
+ mant >>= 1
+ exp++
+ }
+ if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
+ mant++
+ }
+ mant >>= 1
+ exp++
+ if mant < 1<<mantbits32 {
+ return sign | mant
+ }
+ }
+ return sign | uint32(exp-bias32)<<mantbits32 | mant&(1<<mantbits32-1)
+}
+
+func fadd64(f, g uint64) uint64 {
+ fs, fm, fe, fi, fn := funpack64(f)
+ gs, gm, ge, gi, gn := funpack64(g)
+
+ // Special cases.
+ switch {
+ case fn || gn: // NaN + x or x + NaN = NaN
+ return nan64
+
+ case fi && gi && fs != gs: // +Inf + -Inf or -Inf + +Inf = NaN
+ return nan64
+
+ case fi: // ±Inf + g = ±Inf
+ return f
+
+ case gi: // f + ±Inf = ±Inf
+ return g
+
+ case fm == 0 && gm == 0 && fs != 0 && gs != 0: // -0 + -0 = -0
+ return f
+
+ case fm == 0: // 0 + g = g but 0 + -0 = +0
+ if gm == 0 {
+ g ^= gs
+ }
+ return g
+
+ case gm == 0: // f + 0 = f
+ return f
+
+ }
+
+ if fe < ge || fe == ge && fm < gm {
+ f, g, fs, fm, fe, gs, gm, ge = g, f, gs, gm, ge, fs, fm, fe
+ }
+
+ shift := uint(fe - ge)
+ fm <<= 2
+ gm <<= 2
+ trunc := gm & (1<<shift - 1)
+ gm >>= shift
+ if fs == gs {
+ fm += gm
+ } else {
+ fm -= gm
+ if trunc != 0 {
+ fm--
+ }
+ }
+ if fm == 0 {
+ fs = 0
+ }
+ return fpack64(fs, fm, fe-2, trunc)
+}
+
+func fsub64(f, g uint64) uint64 {
+ return fadd64(f, fneg64(g))
+}
+
+func fneg64(f uint64) uint64 {
+ return f ^ (1 << (mantbits64 + expbits64))
+}
+
+func fmul64(f, g uint64) uint64 {
+ fs, fm, fe, fi, fn := funpack64(f)
+ gs, gm, ge, gi, gn := funpack64(g)
+
+ // Special cases.
+ switch {
+ case fn || gn: // NaN * g or f * NaN = NaN
+ return nan64
+
+ case fi && gi: // Inf * Inf = Inf (with sign adjusted)
+ return f ^ gs
+
+ case fi && gm == 0, fm == 0 && gi: // 0 * Inf = Inf * 0 = NaN
+ return nan64
+
+ case fm == 0: // 0 * x = 0 (with sign adjusted)
+ return f ^ gs
+
+ case gm == 0: // x * 0 = 0 (with sign adjusted)
+ return g ^ fs
+ }
+
+ // 53-bit * 53-bit = 107- or 108-bit
+ lo, hi := mullu(fm, gm)
+ shift := mantbits64 - 1
+ trunc := lo & (1<<shift - 1)
+ mant := hi<<(64-shift) | lo>>shift
+ return fpack64(fs^gs, mant, fe+ge-1, trunc)
+}
+
+func fdiv64(f, g uint64) uint64 {
+ fs, fm, fe, fi, fn := funpack64(f)
+ gs, gm, ge, gi, gn := funpack64(g)
+
+ // Special cases.
+ switch {
+ case fn || gn: // NaN / g = f / NaN = NaN
+ return nan64
+
+ case fi && gi: // ±Inf / ±Inf = NaN
+ return nan64
+
+ case !fi && !gi && fm == 0 && gm == 0: // 0 / 0 = NaN
+ return nan64
+
+ case fi, !gi && gm == 0: // Inf / g = f / 0 = Inf
+ return fs ^ gs ^ inf64
+
+ case gi, fm == 0: // f / Inf = 0 / g = Inf
+ return fs ^ gs ^ 0
+ }
+ _, _, _, _ = fi, fn, gi, gn
+
+ // 53-bit<<54 / 53-bit = 53- or 54-bit.
+ shift := mantbits64 + 2
+ q, r := divlu(fm>>(64-shift), fm<<shift, gm)
+ return fpack64(fs^gs, q, fe-ge-2, r)
+}
+
+func f64to32(f uint64) uint32 {
+ fs, fm, fe, fi, fn := funpack64(f)
+ if fn {
+ return nan32
+ }
+ fs32 := uint32(fs >> 32)
+ if fi {
+ return fs32 ^ inf32
+ }
+ const d = mantbits64 - mantbits32 - 1
+ return fpack32(fs32, uint32(fm>>d), fe-1, uint32(fm&(1<<d-1)))
+}
+
+func f32to64(f uint32) uint64 {
+ const d = mantbits64 - mantbits32
+ fs, fm, fe, fi, fn := funpack32(f)
+ if fn {
+ return nan64
+ }
+ fs64 := uint64(fs) << 32
+ if fi {
+ return fs64 ^ inf64
+ }
+ return fpack64(fs64, uint64(fm)<<d, fe, 0)
+}
+
+func fcmp64(f, g uint64) (cmp int, isnan bool) {
+ fs, fm, _, fi, fn := funpack64(f)
+ gs, gm, _, gi, gn := funpack64(g)
+
+ switch {
+ case fn, gn: // flag NaN
+ return 0, true
+
+ case !fi && !gi && fm == 0 && gm == 0: // ±0 == ±0
+ return 0, false
+
+ case fs > gs: // f < 0, g > 0
+ return -1, false
+
+ case fs < gs: // f > 0, g < 0
+ return +1, false
+
+ // Same sign, not NaN.
+ // Can compare encodings directly now.
+ // Reverse for sign.
+ case fs == 0 && f < g, fs != 0 && f > g:
+ return -1, false
+
+ case fs == 0 && f > g, fs != 0 && f < g:
+ return +1, false
+ }
+
+ // f == g
+ return 0, false
+}
+
+func f64toint(f uint64) (val int64, ok bool) {
+ fs, fm, fe, fi, fn := funpack64(f)
+
+ switch {
+ case fi, fn: // NaN
+ return 0, false
+
+ case fe < -1: // f < 0.5
+ return 0, false
+
+ case fe > 63: // f >= 2^63
+ if fs != 0 && fm == 0 { // f == -2^63
+ return -1 << 63, true
+ }
+ if fs != 0 {
+ return 0, false
+ }
+ return 0, false
+ }
+
+ for fe > int(mantbits64) {
+ fe--
+ fm <<= 1
+ }
+ for fe < int(mantbits64) {
+ fe++
+ fm >>= 1
+ }
+ val = int64(fm)
+ if fs != 0 {
+ val = -val
+ }
+ return val, true
+}
+
+func fintto64(val int64) (f uint64) {
+ fs := uint64(val) & (1 << 63)
+ mant := uint64(val)
+ if fs != 0 {
+ mant = -mant
+ }
+ return fpack64(fs, mant, int(mantbits64), 0)
+}
+
+// 64x64 -> 128 multiply.
+// adapted from hacker's delight.
+func mullu(u, v uint64) (lo, hi uint64) {
+ const (
+ s = 32
+ mask = 1<<s - 1
+ )
+ u0 := u & mask
+ u1 := u >> s
+ v0 := v & mask
+ v1 := v >> s
+ w0 := u0 * v0
+ t := u1*v0 + w0>>s
+ w1 := t & mask
+ w2 := t >> s
+ w1 += u0 * v1
+ return u * v, u1*v1 + w2 + w1>>s
+}
+
+// 128/64 -> 64 quotient, 64 remainder.
+// adapted from hacker's delight
+func divlu(u1, u0, v uint64) (q, r uint64) {
+ const b = 1 << 32
+
+ if u1 >= v {
+ return 1<<64 - 1, 1<<64 - 1
+ }
+
+ // s = nlz(v); v <<= s
+ s := uint(0)
+ for v&(1<<63) == 0 {
+ s++
+ v <<= 1
+ }
+
+ vn1 := v >> 32
+ vn0 := v & (1<<32 - 1)
+ un32 := u1<<s | u0>>(64-s)
+ un10 := u0 << s
+ un1 := un10 >> 32
+ un0 := un10 & (1<<32 - 1)
+ q1 := un32 / vn1
+ rhat := un32 - q1*vn1
+
+again1:
+ if q1 >= b || q1*vn0 > b*rhat+un1 {
+ q1--
+ rhat += vn1
+ if rhat < b {
+ goto again1
+ }
+ }
+
+ un21 := un32*b + un1 - q1*v
+ q0 := un21 / vn1
+ rhat = un21 - q0*vn1
+
+again2:
+ if q0 >= b || q0*vn0 > b*rhat+un0 {
+ q0--
+ rhat += vn1
+ if rhat < b {
+ goto again2
+ }
+ }
+
+ return q1*b + q0, (un21*b + un0 - q0*v) >> s
+}
+
+// callable from C
+
+func fadd64c(f, g uint64, ret *uint64) { *ret = fadd64(f, g) }
+func fsub64c(f, g uint64, ret *uint64) { *ret = fsub64(f, g) }
+func fmul64c(f, g uint64, ret *uint64) { *ret = fmul64(f, g) }
+func fdiv64c(f, g uint64, ret *uint64) { *ret = fdiv64(f, g) }
+func fneg64c(f uint64, ret *uint64) { *ret = fneg64(f) }
+func f32to64c(f uint32, ret *uint64) { *ret = f32to64(f) }
+func f64to32c(f uint64, ret *uint32) { *ret = f64to32(f) }
+func fcmp64c(f, g uint64, ret *int, retnan *bool) { *ret, *retnan = fcmp64(f, g) }
+func fintto64c(val int64, ret *uint64) { *ret = fintto64(val) }
+func f64tointc(f uint64, ret *int64, retok *bool) { *ret, *retok = f64toint(f) }
diff --git a/src/pkg/runtime/softfloat64_test.go b/src/pkg/runtime/softfloat64_test.go
new file mode 100644
index 0000000..fb7f3d3
--- /dev/null
+++ b/src/pkg/runtime/softfloat64_test.go
@@ -0,0 +1,198 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+ "math"
+ "rand"
+ . "runtime"
+ "testing"
+)
+
+// turn uint64 op into float64 op
+func fop(f func(x, y uint64) uint64) func(x, y float64) float64 {
+ return func(x, y float64) float64 {
+ bx := math.Float64bits(x)
+ by := math.Float64bits(y)
+ return math.Float64frombits(f(bx, by))
+ }
+}
+
+func add(x, y float64) float64 { return x + y }
+func sub(x, y float64) float64 { return x - y }
+func mul(x, y float64) float64 { return x * y }
+func div(x, y float64) float64 { return x / y }
+
+func TestFloat64(t *testing.T) {
+ base := []float64{
+ 0,
+ math.Copysign(0, -1),
+ -1,
+ 1,
+ math.NaN(),
+ math.Inf(+1),
+ math.Inf(-1),
+ 0.1,
+ 1.5,
+ 1.9999999999999998, // all 1s mantissa
+ 1.3333333333333333, // 1.010101010101...
+ 1.1428571428571428, // 1.001001001001...
+ 1.112536929253601e-308, // first normal
+ 2,
+ 4,
+ 8,
+ 16,
+ 32,
+ 64,
+ 128,
+ 256,
+ 3,
+ 12,
+ 1234,
+ 123456,
+ -0.1,
+ -1.5,
+ -1.9999999999999998,
+ -1.3333333333333333,
+ -1.1428571428571428,
+ -2,
+ -3,
+ 1e-200,
+ 1e-300,
+ 1e-310,
+ 5e-324,
+ 1e-105,
+ 1e-305,
+ 1e+200,
+ 1e+306,
+ 1e+307,
+ 1e+308,
+ }
+ all := make([]float64, 200)
+ copy(all, base)
+ for i := len(base); i < len(all); i++ {
+ all[i] = rand.NormFloat64()
+ }
+
+ test(t, "+", add, fop(Fadd64), all)
+ test(t, "-", sub, fop(Fsub64), all)
+ if GOARCH != "386" { // 386 is not precise!
+ test(t, "*", mul, fop(Fmul64), all)
+ test(t, "/", div, fop(Fdiv64), all)
+ }
+}
+
+// 64 -hw-> 32 -hw-> 64
+func trunc32(f float64) float64 {
+ return float64(float32(f))
+}
+
+// 64 -sw->32 -hw-> 64
+func to32sw(f float64) float64 {
+ return float64(math.Float32frombits(F64to32(math.Float64bits(f))))
+}
+
+// 64 -hw->32 -sw-> 64
+func to64sw(f float64) float64 {
+ return math.Float64frombits(F32to64(math.Float32bits(float32(f))))
+}
+
+// float64 -hw-> int64 -hw-> float64
+func hwint64(f float64) float64 {
+ return float64(int64(f))
+}
+
+// float64 -hw-> int32 -hw-> float64
+func hwint32(f float64) float64 {
+ return float64(int32(f))
+}
+
+// float64 -sw-> int64 -hw-> float64
+func toint64sw(f float64) float64 {
+ i, ok := F64toint(math.Float64bits(f))
+ if !ok {
+ // There's no right answer for out of range.
+ // Match the hardware to pass the test.
+ i = int64(f)
+ }
+ return float64(i)
+}
+
+// float64 -hw-> int64 -sw-> float64
+func fromint64sw(f float64) float64 {
+ return math.Float64frombits(Fintto64(int64(f)))
+}
+
+var nerr int
+
+func err(t *testing.T, format string, args ...interface{}) {
+ t.Errorf(format, args...)
+
+ // cut errors off after a while.
+ // otherwise we spend all our time
+ // allocating memory to hold the
+ // formatted output.
+ if nerr++; nerr >= 10 {
+ t.Fatal("too many errors")
+ }
+}
+
+func test(t *testing.T, op string, hw, sw func(float64, float64) float64, all []float64) {
+ for _, f := range all {
+ for _, g := range all {
+ h := hw(f, g)
+ s := sw(f, g)
+ if !same(h, s) {
+ err(t, "%g %s %g = sw %g, hw %g\n", f, op, g, s, h)
+ }
+ testu(t, "to32", trunc32, to32sw, h)
+ testu(t, "to64", trunc32, to64sw, h)
+ testu(t, "toint64", hwint64, toint64sw, h)
+ testu(t, "fromint64", hwint64, fromint64sw, h)
+ testcmp(t, f, h)
+ testcmp(t, h, f)
+ testcmp(t, g, h)
+ testcmp(t, h, g)
+ }
+ }
+}
+
+func testu(t *testing.T, op string, hw, sw func(float64) float64, v float64) {
+ h := hw(v)
+ s := sw(v)
+ if !same(h, s) {
+ err(t, "%s %g = sw %g, hw %g\n", op, v, s, h)
+ }
+}
+
+func hwcmp(f, g float64) (cmp int, isnan bool) {
+ switch {
+ case f < g:
+ return -1, false
+ case f > g:
+ return +1, false
+ case f == g:
+ return 0, false
+ }
+ return 0, true // must be NaN
+}
+
+func testcmp(t *testing.T, f, g float64) {
+ hcmp, hisnan := hwcmp(f, g)
+ scmp, sisnan := Fcmp64(math.Float64bits(f), math.Float64bits(g))
+ if hcmp != scmp || hisnan != sisnan {
+ err(t, "cmp(%g, %g) = sw %v, %v, hw %v, %v\n", f, g, scmp, sisnan, hcmp, hisnan)
+ }
+}
+
+func same(f, g float64) bool {
+ if math.IsNaN(f) && math.IsNaN(g) {
+ return true
+ }
+ if math.Copysign(1, f) != math.Copysign(1, g) {
+ return false
+ }
+ return f == g
+}
