float_test.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package test
     6  
     7  import (
     8  	"math"
     9  	"testing"
    10  )
    11  
    12  //go:noinline
    13  func compare1(a, b float64) bool {
    14  	return a < b
    15  }
    16  
    17  //go:noinline
    18  func compare2(a, b float32) bool {
    19  	return a < b
    20  }
    21  
    22  func TestFloatCompare(t *testing.T) {
    23  	if !compare1(3, 5) {
    24  		t.Errorf("compare1 returned false")
    25  	}
    26  	if !compare2(3, 5) {
    27  		t.Errorf("compare2 returned false")
    28  	}
    29  }
    30  
    31  func TestFloatCompareFolded(t *testing.T) {
    32  	// float64 comparisons
    33  	d1, d3, d5, d9 := float64(1), float64(3), float64(5), float64(9)
    34  	if d3 == d5 {
    35  		t.Errorf("d3 == d5 returned true")
    36  	}
    37  	if d3 != d3 {
    38  		t.Errorf("d3 != d3 returned true")
    39  	}
    40  	if d3 > d5 {
    41  		t.Errorf("d3 > d5 returned true")
    42  	}
    43  	if d3 >= d9 {
    44  		t.Errorf("d3 >= d9 returned true")
    45  	}
    46  	if d5 < d1 {
    47  		t.Errorf("d5 < d1 returned true")
    48  	}
    49  	if d9 <= d1 {
    50  		t.Errorf("d9 <= d1 returned true")
    51  	}
    52  	if math.NaN() == math.NaN() {
    53  		t.Errorf("math.NaN() == math.NaN() returned true")
    54  	}
    55  	if math.NaN() >= math.NaN() {
    56  		t.Errorf("math.NaN() >= math.NaN() returned true")
    57  	}
    58  	if math.NaN() <= math.NaN() {
    59  		t.Errorf("math.NaN() <= math.NaN() returned true")
    60  	}
    61  	if math.Copysign(math.NaN(), -1) < math.NaN() {
    62  		t.Errorf("math.Copysign(math.NaN(), -1) < math.NaN() returned true")
    63  	}
    64  	if math.Inf(1) != math.Inf(1) {
    65  		t.Errorf("math.Inf(1) != math.Inf(1) returned true")
    66  	}
    67  	if math.Inf(-1) != math.Inf(-1) {
    68  		t.Errorf("math.Inf(-1) != math.Inf(-1) returned true")
    69  	}
    70  	if math.Copysign(0, -1) != 0 {
    71  		t.Errorf("math.Copysign(0, -1) != 0 returned true")
    72  	}
    73  	if math.Copysign(0, -1) < 0 {
    74  		t.Errorf("math.Copysign(0, -1) < 0 returned true")
    75  	}
    76  	if 0 > math.Copysign(0, -1) {
    77  		t.Errorf("0 > math.Copysign(0, -1) returned true")
    78  	}
    79  
    80  	// float32 comparisons
    81  	s1, s3, s5, s9 := float32(1), float32(3), float32(5), float32(9)
    82  	if s3 == s5 {
    83  		t.Errorf("s3 == s5 returned true")
    84  	}
    85  	if s3 != s3 {
    86  		t.Errorf("s3 != s3 returned true")
    87  	}
    88  	if s3 > s5 {
    89  		t.Errorf("s3 > s5 returned true")
    90  	}
    91  	if s3 >= s9 {
    92  		t.Errorf("s3 >= s9 returned true")
    93  	}
    94  	if s5 < s1 {
    95  		t.Errorf("s5 < s1 returned true")
    96  	}
    97  	if s9 <= s1 {
    98  		t.Errorf("s9 <= s1 returned true")
    99  	}
   100  	sPosNaN, sNegNaN := float32(math.NaN()), float32(math.Copysign(math.NaN(), -1))
   101  	if sPosNaN == sPosNaN {
   102  		t.Errorf("sPosNaN == sPosNaN returned true")
   103  	}
   104  	if sPosNaN >= sPosNaN {
   105  		t.Errorf("sPosNaN >= sPosNaN returned true")
   106  	}
   107  	if sPosNaN <= sPosNaN {
   108  		t.Errorf("sPosNaN <= sPosNaN returned true")
   109  	}
   110  	if sNegNaN < sPosNaN {
   111  		t.Errorf("sNegNaN < sPosNaN returned true")
   112  	}
   113  	sPosInf, sNegInf := float32(math.Inf(1)), float32(math.Inf(-1))
   114  	if sPosInf != sPosInf {
   115  		t.Errorf("sPosInf != sPosInf returned true")
   116  	}
   117  	if sNegInf != sNegInf {
   118  		t.Errorf("sNegInf != sNegInf returned true")
   119  	}
   120  	sNegZero := float32(math.Copysign(0, -1))
   121  	if sNegZero != 0 {
   122  		t.Errorf("sNegZero != 0 returned true")
   123  	}
   124  	if sNegZero < 0 {
   125  		t.Errorf("sNegZero < 0 returned true")
   126  	}
   127  	if 0 > sNegZero {
   128  		t.Errorf("0 > sNegZero returned true")
   129  	}
   130  }
   131  
   132  //go:noinline
   133  func cvt1(a float64) uint64 {
   134  	return uint64(a)
   135  }
   136  
   137  //go:noinline
   138  func cvt2(a float64) uint32 {
   139  	return uint32(a)
   140  }
   141  
   142  //go:noinline
   143  func cvt3(a float32) uint64 {
   144  	return uint64(a)
   145  }
   146  
   147  //go:noinline
   148  func cvt4(a float32) uint32 {
   149  	return uint32(a)
   150  }
   151  
   152  //go:noinline
   153  func cvt5(a float64) int64 {
   154  	return int64(a)
   155  }
   156  
   157  //go:noinline
   158  func cvt6(a float64) int32 {
   159  	return int32(a)
   160  }
   161  
   162  //go:noinline
   163  func cvt7(a float32) int64 {
   164  	return int64(a)
   165  }
   166  
   167  //go:noinline
   168  func cvt8(a float32) int32 {
   169  	return int32(a)
   170  }
   171  
   172  // make sure to cover int, uint cases (issue #16738)
   173  //
   174  //go:noinline
   175  func cvt9(a float64) int {
   176  	return int(a)
   177  }
   178  
   179  //go:noinline
   180  func cvt10(a float64) uint {
   181  	return uint(a)
   182  }
   183  
   184  //go:noinline
   185  func cvt11(a float32) int {
   186  	return int(a)
   187  }
   188  
   189  //go:noinline
   190  func cvt12(a float32) uint {
   191  	return uint(a)
   192  }
   193  
   194  //go:noinline
   195  func f2i64p(v float64) *int64 {
   196  	return ip64(int64(v / 0.1))
   197  }
   198  
   199  //go:noinline
   200  func ip64(v int64) *int64 {
   201  	return &v
   202  }
   203  
   204  func TestFloatConvert(t *testing.T) {
   205  	if got := cvt1(3.5); got != 3 {
   206  		t.Errorf("cvt1 got %d, wanted 3", got)
   207  	}
   208  	if got := cvt2(3.5); got != 3 {
   209  		t.Errorf("cvt2 got %d, wanted 3", got)
   210  	}
   211  	if got := cvt3(3.5); got != 3 {
   212  		t.Errorf("cvt3 got %d, wanted 3", got)
   213  	}
   214  	if got := cvt4(3.5); got != 3 {
   215  		t.Errorf("cvt4 got %d, wanted 3", got)
   216  	}
   217  	if got := cvt5(3.5); got != 3 {
   218  		t.Errorf("cvt5 got %d, wanted 3", got)
   219  	}
   220  	if got := cvt6(3.5); got != 3 {
   221  		t.Errorf("cvt6 got %d, wanted 3", got)
   222  	}
   223  	if got := cvt7(3.5); got != 3 {
   224  		t.Errorf("cvt7 got %d, wanted 3", got)
   225  	}
   226  	if got := cvt8(3.5); got != 3 {
   227  		t.Errorf("cvt8 got %d, wanted 3", got)
   228  	}
   229  	if got := cvt9(3.5); got != 3 {
   230  		t.Errorf("cvt9 got %d, wanted 3", got)
   231  	}
   232  	if got := cvt10(3.5); got != 3 {
   233  		t.Errorf("cvt10 got %d, wanted 3", got)
   234  	}
   235  	if got := cvt11(3.5); got != 3 {
   236  		t.Errorf("cvt11 got %d, wanted 3", got)
   237  	}
   238  	if got := cvt12(3.5); got != 3 {
   239  		t.Errorf("cvt12 got %d, wanted 3", got)
   240  	}
   241  	if got := *f2i64p(10); got != 100 {
   242  		t.Errorf("f2i64p got %d, wanted 100", got)
   243  	}
   244  }
   245  
   246  func TestFloatConvertFolded(t *testing.T) {
   247  	// Assign constants to variables so that they are (hopefully) constant folded
   248  	// by the SSA backend rather than the frontend.
   249  	u64, u32, u16, u8 := uint64(1<<63), uint32(1<<31), uint16(1<<15), uint8(1<<7)
   250  	i64, i32, i16, i8 := int64(-1<<63), int32(-1<<31), int16(-1<<15), int8(-1<<7)
   251  	du64, du32, du16, du8 := float64(1<<63), float64(1<<31), float64(1<<15), float64(1<<7)
   252  	di64, di32, di16, di8 := float64(-1<<63), float64(-1<<31), float64(-1<<15), float64(-1<<7)
   253  	su64, su32, su16, su8 := float32(1<<63), float32(1<<31), float32(1<<15), float32(1<<7)
   254  	si64, si32, si16, si8 := float32(-1<<63), float32(-1<<31), float32(-1<<15), float32(-1<<7)
   255  
   256  	// integer to float
   257  	if float64(u64) != du64 {
   258  		t.Errorf("float64(u64) != du64")
   259  	}
   260  	if float64(u32) != du32 {
   261  		t.Errorf("float64(u32) != du32")
   262  	}
   263  	if float64(u16) != du16 {
   264  		t.Errorf("float64(u16) != du16")
   265  	}
   266  	if float64(u8) != du8 {
   267  		t.Errorf("float64(u8) != du8")
   268  	}
   269  	if float64(i64) != di64 {
   270  		t.Errorf("float64(i64) != di64")
   271  	}
   272  	if float64(i32) != di32 {
   273  		t.Errorf("float64(i32) != di32")
   274  	}
   275  	if float64(i16) != di16 {
   276  		t.Errorf("float64(i16) != di16")
   277  	}
   278  	if float64(i8) != di8 {
   279  		t.Errorf("float64(i8) != di8")
   280  	}
   281  	if float32(u64) != su64 {
   282  		t.Errorf("float32(u64) != su64")
   283  	}
   284  	if float32(u32) != su32 {
   285  		t.Errorf("float32(u32) != su32")
   286  	}
   287  	if float32(u16) != su16 {
   288  		t.Errorf("float32(u16) != su16")
   289  	}
   290  	if float32(u8) != su8 {
   291  		t.Errorf("float32(u8) != su8")
   292  	}
   293  	if float32(i64) != si64 {
   294  		t.Errorf("float32(i64) != si64")
   295  	}
   296  	if float32(i32) != si32 {
   297  		t.Errorf("float32(i32) != si32")
   298  	}
   299  	if float32(i16) != si16 {
   300  		t.Errorf("float32(i16) != si16")
   301  	}
   302  	if float32(i8) != si8 {
   303  		t.Errorf("float32(i8) != si8")
   304  	}
   305  
   306  	// float to integer
   307  	if uint64(du64) != u64 {
   308  		t.Errorf("uint64(du64) != u64")
   309  	}
   310  	if uint32(du32) != u32 {
   311  		t.Errorf("uint32(du32) != u32")
   312  	}
   313  	if uint16(du16) != u16 {
   314  		t.Errorf("uint16(du16) != u16")
   315  	}
   316  	if uint8(du8) != u8 {
   317  		t.Errorf("uint8(du8) != u8")
   318  	}
   319  	if int64(di64) != i64 {
   320  		t.Errorf("int64(di64) != i64")
   321  	}
   322  	if int32(di32) != i32 {
   323  		t.Errorf("int32(di32) != i32")
   324  	}
   325  	if int16(di16) != i16 {
   326  		t.Errorf("int16(di16) != i16")
   327  	}
   328  	if int8(di8) != i8 {
   329  		t.Errorf("int8(di8) != i8")
   330  	}
   331  	if uint64(su64) != u64 {
   332  		t.Errorf("uint64(su64) != u64")
   333  	}
   334  	if uint32(su32) != u32 {
   335  		t.Errorf("uint32(su32) != u32")
   336  	}
   337  	if uint16(su16) != u16 {
   338  		t.Errorf("uint16(su16) != u16")
   339  	}
   340  	if uint8(su8) != u8 {
   341  		t.Errorf("uint8(su8) != u8")
   342  	}
   343  	if int64(si64) != i64 {
   344  		t.Errorf("int64(si64) != i64")
   345  	}
   346  	if int32(si32) != i32 {
   347  		t.Errorf("int32(si32) != i32")
   348  	}
   349  	if int16(si16) != i16 {
   350  		t.Errorf("int16(si16) != i16")
   351  	}
   352  	if int8(si8) != i8 {
   353  		t.Errorf("int8(si8) != i8")
   354  	}
   355  }
   356  
   357  func TestFloat32StoreToLoadConstantFold(t *testing.T) {
   358  	// Test that math.Float32{,from}bits constant fold correctly.
   359  	// In particular we need to be careful that signaling NaN (sNaN) values
   360  	// are not converted to quiet NaN (qNaN) values during compilation.
   361  	// See issue #27193 for more information.
   362  
   363  	// signaling NaNs
   364  	{
   365  		const nan = uint32(0x7f800001) // sNaN
   366  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   367  			t.Errorf("got %#x, want %#x", x, nan)
   368  		}
   369  	}
   370  	{
   371  		const nan = uint32(0x7fbfffff) // sNaN
   372  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   373  			t.Errorf("got %#x, want %#x", x, nan)
   374  		}
   375  	}
   376  	{
   377  		const nan = uint32(0xff800001) // sNaN
   378  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   379  			t.Errorf("got %#x, want %#x", x, nan)
   380  		}
   381  	}
   382  	{
   383  		const nan = uint32(0xffbfffff) // sNaN
   384  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   385  			t.Errorf("got %#x, want %#x", x, nan)
   386  		}
   387  	}
   388  
   389  	// quiet NaNs
   390  	{
   391  		const nan = uint32(0x7fc00000) // qNaN
   392  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   393  			t.Errorf("got %#x, want %#x", x, nan)
   394  		}
   395  	}
   396  	{
   397  		const nan = uint32(0x7fffffff) // qNaN
   398  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   399  			t.Errorf("got %#x, want %#x", x, nan)
   400  		}
   401  	}
   402  	{
   403  		const nan = uint32(0x8fc00000) // qNaN
   404  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   405  			t.Errorf("got %#x, want %#x", x, nan)
   406  		}
   407  	}
   408  	{
   409  		const nan = uint32(0x8fffffff) // qNaN
   410  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   411  			t.Errorf("got %#x, want %#x", x, nan)
   412  		}
   413  	}
   414  
   415  	// infinities
   416  	{
   417  		const inf = uint32(0x7f800000) // +∞
   418  		if x := math.Float32bits(math.Float32frombits(inf)); x != inf {
   419  			t.Errorf("got %#x, want %#x", x, inf)
   420  		}
   421  	}
   422  	{
   423  		const negInf = uint32(0xff800000) // -∞
   424  		if x := math.Float32bits(math.Float32frombits(negInf)); x != negInf {
   425  			t.Errorf("got %#x, want %#x", x, negInf)
   426  		}
   427  	}
   428  
   429  	// numbers
   430  	{
   431  		const zero = uint32(0) // +0.0
   432  		if x := math.Float32bits(math.Float32frombits(zero)); x != zero {
   433  			t.Errorf("got %#x, want %#x", x, zero)
   434  		}
   435  	}
   436  	{
   437  		const negZero = uint32(1 << 31) // -0.0
   438  		if x := math.Float32bits(math.Float32frombits(negZero)); x != negZero {
   439  			t.Errorf("got %#x, want %#x", x, negZero)
   440  		}
   441  	}
   442  	{
   443  		const one = uint32(0x3f800000) // 1.0
   444  		if x := math.Float32bits(math.Float32frombits(one)); x != one {
   445  			t.Errorf("got %#x, want %#x", x, one)
   446  		}
   447  	}
   448  	{
   449  		const negOne = uint32(0xbf800000) // -1.0
   450  		if x := math.Float32bits(math.Float32frombits(negOne)); x != negOne {
   451  			t.Errorf("got %#x, want %#x", x, negOne)
   452  		}
   453  	}
   454  	{
   455  		const frac = uint32(0x3fc00000) // +1.5
   456  		if x := math.Float32bits(math.Float32frombits(frac)); x != frac {
   457  			t.Errorf("got %#x, want %#x", x, frac)
   458  		}
   459  	}
   460  	{
   461  		const negFrac = uint32(0xbfc00000) // -1.5
   462  		if x := math.Float32bits(math.Float32frombits(negFrac)); x != negFrac {
   463  			t.Errorf("got %#x, want %#x", x, negFrac)
   464  		}
   465  	}
   466  }
   467  
   468  // Signaling NaN values as constants.
   469  const (
   470  	snan32bits uint32 = 0x7f800001
   471  	snan64bits uint64 = 0x7ff0000000000001
   472  )
   473  
   474  // Signaling NaNs as variables.
   475  var snan32bitsVar uint32 = snan32bits
   476  var snan64bitsVar uint64 = snan64bits
   477  
   478  func TestFloatSignalingNaN(t *testing.T) {
   479  	// Make sure we generate a signaling NaN from a constant properly.
   480  	// See issue 36400.
   481  	f32 := math.Float32frombits(snan32bits)
   482  	g32 := math.Float32frombits(snan32bitsVar)
   483  	x32 := math.Float32bits(f32)
   484  	y32 := math.Float32bits(g32)
   485  	if x32 != y32 {
   486  		t.Errorf("got %x, want %x (diff=%x)", x32, y32, x32^y32)
   487  	}
   488  
   489  	f64 := math.Float64frombits(snan64bits)
   490  	g64 := math.Float64frombits(snan64bitsVar)
   491  	x64 := math.Float64bits(f64)
   492  	y64 := math.Float64bits(g64)
   493  	if x64 != y64 {
   494  		t.Errorf("got %x, want %x (diff=%x)", x64, y64, x64^y64)
   495  	}
   496  }
   497  
   498  func TestFloatSignalingNaNConversion(t *testing.T) {
   499  	// Test to make sure when we convert a signaling NaN, we get a NaN.
   500  	// (Ideally we want a quiet NaN, but some platforms don't agree.)
   501  	// See issue 36399.
   502  	s32 := math.Float32frombits(snan32bitsVar)
   503  	if s32 == s32 {
   504  		t.Errorf("converting a NaN did not result in a NaN")
   505  	}
   506  	s64 := math.Float64frombits(snan64bitsVar)
   507  	if s64 == s64 {
   508  		t.Errorf("converting a NaN did not result in a NaN")
   509  	}
   510  }
   511  
   512  func TestFloatSignalingNaNConversionConst(t *testing.T) {
   513  	// Test to make sure when we convert a signaling NaN, it converts to a NaN.
   514  	// (Ideally we want a quiet NaN, but some platforms don't agree.)
   515  	// See issue 36399 and 36400.
   516  	s32 := math.Float32frombits(snan32bits)
   517  	if s32 == s32 {
   518  		t.Errorf("converting a NaN did not result in a NaN")
   519  	}
   520  	s64 := math.Float64frombits(snan64bits)
   521  	if s64 == s64 {
   522  		t.Errorf("converting a NaN did not result in a NaN")
   523  	}
   524  }
   525  
   526  var sinkFloat float64
   527  
   528  func BenchmarkMul2(b *testing.B) {
   529  	for i := 0; i < b.N; i++ {
   530  		var m float64 = 1
   531  		for j := 0; j < 500; j++ {
   532  			m *= 2
   533  		}
   534  		sinkFloat = m
   535  	}
   536  }
   537  func BenchmarkMulNeg2(b *testing.B) {
   538  	for i := 0; i < b.N; i++ {
   539  		var m float64 = 1
   540  		for j := 0; j < 500; j++ {
   541  			m *= -2
   542  		}
   543  		sinkFloat = m
   544  	}
   545  }
   546
View as plain text