libgo: update to Go1.16beta1 release

This does not yet include support for the //go:embed directive added
in this release.

	* Makefile.am (check-runtime): Don't create check-runtime-dir.
	(mostlyclean-local): Don't remove check-runtime-dir.
	(check-go-tool, check-vet): Copy in go.mod and modules.txt.
	(check-cgo-test, check-carchive-test): Add go.mod file.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/280172

1 files changed, 0 insertions, 143 deletions

diff --git a/libgo/go/strconv/extfloat.go b/libgo/go/strconv/extfloat.go
index 793a34d..e7bfe51 100644
--- a/libgo/go/strconv/extfloat.go
+++ b/libgo/go/strconv/extfloat.go
@@ -126,53 +126,6 @@ var powersOfTen = [...]extFloat{
 	{0xaf87023b9bf0ee6b, 1066, false},  // 10^340
 }
 
-// floatBits returns the bits of the float64 that best approximates
-// the extFloat passed as receiver. Overflow is set to true if
-// the resulting float64 is ±Inf.
-func (f *extFloat) floatBits(flt *floatInfo) (bits uint64, overflow bool) {
-	f.Normalize()
-
-	exp := f.exp + 63
-
-	// Exponent too small.
-	if exp < flt.bias+1 {
-		n := flt.bias + 1 - exp
-		f.mant >>= uint(n)
-		exp += n
-	}
-
-	// Extract 1+flt.mantbits bits from the 64-bit mantissa.
-	mant := f.mant >> (63 - flt.mantbits)
-	if f.mant&(1<<(62-flt.mantbits)) != 0 {
-		// Round up.
-		mant += 1
-	}
-
-	// Rounding might have added a bit; shift down.
-	if mant == 2<<flt.mantbits {
-		mant >>= 1
-		exp++
-	}
-
-	// Infinities.
-	if exp-flt.bias >= 1<<flt.expbits-1 {
-		// ±Inf
-		mant = 0
-		exp = 1<<flt.expbits - 1 + flt.bias
-		overflow = true
-	} else if mant&(1<<flt.mantbits) == 0 {
-		// Denormalized?
-		exp = flt.bias
-	}
-	// Assemble bits.
-	bits = mant & (uint64(1)<<flt.mantbits - 1)
-	bits |= uint64((exp-flt.bias)&(1<<flt.expbits-1)) << flt.mantbits
-	if f.neg {
-		bits |= 1 << (flt.mantbits + flt.expbits)
-	}
-	return
-}
-
 // AssignComputeBounds sets f to the floating point value
 // defined by mant, exp and precision given by flt. It returns
 // lower, upper such that any number in the closed interval
@@ -225,102 +178,6 @@ var uint64pow10 = [...]uint64{
 	1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
 }
 
-// AssignDecimal sets f to an approximate value mantissa*10^exp. It
-// reports whether the value represented by f is guaranteed to be the
-// best approximation of d after being rounded to a float64 or
-// float32 depending on flt.
-func (f *extFloat) AssignDecimal(mantissa uint64, exp10 int, neg bool, trunc bool, flt *floatInfo) (ok bool) {
-	const uint64digits = 19
-
-	// Errors (in the "numerical approximation" sense, not the "Go's error
-	// type" sense) in this function are measured as multiples of 1/8 of a ULP,
-	// so that "1/2 of a ULP" can be represented in integer arithmetic.
-	//
-	// The C++ double-conversion library also uses this 8x scaling factor:
-	// https://github.com/google/double-conversion/blob/f4cb2384/double-conversion/strtod.cc#L291
-	// but this Go implementation has a bug, where it forgets to scale other
-	// calculations (further below in this function) by the same number. The
-	// C++ implementation does not forget:
-	// https://github.com/google/double-conversion/blob/f4cb2384/double-conversion/strtod.cc#L366
-	//
-	// Scaling the "errors" in the "is mant_extra in the range (halfway ±
-	// errors)" check, but not scaling the other values, means that we return
-	// ok=false (and fall back to a slower atof code path) more often than we
-	// could. This affects performance but not correctness.
-	//
-	// Longer term, we could fix the forgot-to-scale bug (and look carefully
-	// for correctness regressions; https://codereview.appspot.com/5494068
-	// landed in 2011), or replace this atof algorithm with a faster one (e.g.
-	// Ryu). Shorter term, this comment will suffice.
-	const errorscale = 8
-
-	errors := 0 // An upper bound for error, computed in ULP/errorscale.
-	if trunc {
-		// the decimal number was truncated.
-		errors += errorscale / 2
-	}
-
-	f.mant = mantissa
-	f.exp = 0
-	f.neg = neg
-
-	// Multiply by powers of ten.
-	i := (exp10 - firstPowerOfTen) / stepPowerOfTen
-	if exp10 < firstPowerOfTen || i >= len(powersOfTen) {
-		return false
-	}
-	adjExp := (exp10 - firstPowerOfTen) % stepPowerOfTen
-
-	// We multiply by exp%step
-	if adjExp < uint64digits && mantissa < uint64pow10[uint64digits-adjExp] {
-		// We can multiply the mantissa exactly.
-		f.mant *= uint64pow10[adjExp]
-		f.Normalize()
-	} else {
-		f.Normalize()
-		f.Multiply(smallPowersOfTen[adjExp])
-		errors += errorscale / 2
-	}
-
-	// We multiply by 10 to the exp - exp%step.
-	f.Multiply(powersOfTen[i])
-	if errors > 0 {
-		errors += 1
-	}
-	errors += errorscale / 2
-
-	// Normalize
-	shift := f.Normalize()
-	errors <<= shift
-
-	// Now f is a good approximation of the decimal.
-	// Check whether the error is too large: that is, if the mantissa
-	// is perturbated by the error, the resulting float64 will change.
-	// The 64 bits mantissa is 1 + 52 bits for float64 + 11 extra bits.
-	//
-	// In many cases the approximation will be good enough.
-	denormalExp := flt.bias - 63
-	var extrabits uint
-	if f.exp <= denormalExp {
-		// f.mant * 2^f.exp is smaller than 2^(flt.bias+1).
-		extrabits = 63 - flt.mantbits + 1 + uint(denormalExp-f.exp)
-	} else {
-		extrabits = 63 - flt.mantbits
-	}
-
-	halfway := uint64(1) << (extrabits - 1)
-	mant_extra := f.mant & (1<<extrabits - 1)
-
-	// Do a signed comparison here! If the error estimate could make
-	// the mantissa round differently for the conversion to double,
-	// then we can't give a definite answer.
-	if int64(halfway)-int64(errors) < int64(mant_extra) &&
-		int64(mant_extra) < int64(halfway)+int64(errors) {
-		return false
-	}
-	return true
-}
-
 // Frexp10 is an analogue of math.Frexp for decimal powers. It scales
 // f by an approximate power of ten 10^-exp, and returns exp10, so
 // that f*10^exp10 has the same value as the old f, up to an ulp,