Source file src/cmd/compile/internal/test/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  //go:noinline
   174  func cvt9(a float64) int {
   175  	return int(a)
   176  }
   177  
   178  //go:noinline
   179  func cvt10(a float64) uint {
   180  	return uint(a)
   181  }
   182  
   183  //go:noinline
   184  func cvt11(a float32) int {
   185  	return int(a)
   186  }
   187  
   188  //go:noinline
   189  func cvt12(a float32) uint {
   190  	return uint(a)
   191  }
   192  
   193  //go:noinline
   194  func f2i64p(v float64) *int64 {
   195  	return ip64(int64(v / 0.1))
   196  }
   197  
   198  //go:noinline
   199  func ip64(v int64) *int64 {
   200  	return &v
   201  }
   202  
   203  func TestFloatConvert(t *testing.T) {
   204  	if got := cvt1(3.5); got != 3 {
   205  		t.Errorf("cvt1 got %d, wanted 3", got)
   206  	}
   207  	if got := cvt2(3.5); got != 3 {
   208  		t.Errorf("cvt2 got %d, wanted 3", got)
   209  	}
   210  	if got := cvt3(3.5); got != 3 {
   211  		t.Errorf("cvt3 got %d, wanted 3", got)
   212  	}
   213  	if got := cvt4(3.5); got != 3 {
   214  		t.Errorf("cvt4 got %d, wanted 3", got)
   215  	}
   216  	if got := cvt5(3.5); got != 3 {
   217  		t.Errorf("cvt5 got %d, wanted 3", got)
   218  	}
   219  	if got := cvt6(3.5); got != 3 {
   220  		t.Errorf("cvt6 got %d, wanted 3", got)
   221  	}
   222  	if got := cvt7(3.5); got != 3 {
   223  		t.Errorf("cvt7 got %d, wanted 3", got)
   224  	}
   225  	if got := cvt8(3.5); got != 3 {
   226  		t.Errorf("cvt8 got %d, wanted 3", got)
   227  	}
   228  	if got := cvt9(3.5); got != 3 {
   229  		t.Errorf("cvt9 got %d, wanted 3", got)
   230  	}
   231  	if got := cvt10(3.5); got != 3 {
   232  		t.Errorf("cvt10 got %d, wanted 3", got)
   233  	}
   234  	if got := cvt11(3.5); got != 3 {
   235  		t.Errorf("cvt11 got %d, wanted 3", got)
   236  	}
   237  	if got := cvt12(3.5); got != 3 {
   238  		t.Errorf("cvt12 got %d, wanted 3", got)
   239  	}
   240  	if got := *f2i64p(10); got != 100 {
   241  		t.Errorf("f2i64p got %d, wanted 100", got)
   242  	}
   243  }
   244  
   245  func TestFloatConvertFolded(t *testing.T) {
   246  	// Assign constants to variables so that they are (hopefully) constant folded
   247  	// by the SSA backend rather than the frontend.
   248  	u64, u32, u16, u8 := uint64(1<<63), uint32(1<<31), uint16(1<<15), uint8(1<<7)
   249  	i64, i32, i16, i8 := int64(-1<<63), int32(-1<<31), int16(-1<<15), int8(-1<<7)
   250  	du64, du32, du16, du8 := float64(1<<63), float64(1<<31), float64(1<<15), float64(1<<7)
   251  	di64, di32, di16, di8 := float64(-1<<63), float64(-1<<31), float64(-1<<15), float64(-1<<7)
   252  	su64, su32, su16, su8 := float32(1<<63), float32(1<<31), float32(1<<15), float32(1<<7)
   253  	si64, si32, si16, si8 := float32(-1<<63), float32(-1<<31), float32(-1<<15), float32(-1<<7)
   254  
   255  	// integer to float
   256  	if float64(u64) != du64 {
   257  		t.Errorf("float64(u64) != du64")
   258  	}
   259  	if float64(u32) != du32 {
   260  		t.Errorf("float64(u32) != du32")
   261  	}
   262  	if float64(u16) != du16 {
   263  		t.Errorf("float64(u16) != du16")
   264  	}
   265  	if float64(u8) != du8 {
   266  		t.Errorf("float64(u8) != du8")
   267  	}
   268  	if float64(i64) != di64 {
   269  		t.Errorf("float64(i64) != di64")
   270  	}
   271  	if float64(i32) != di32 {
   272  		t.Errorf("float64(i32) != di32")
   273  	}
   274  	if float64(i16) != di16 {
   275  		t.Errorf("float64(i16) != di16")
   276  	}
   277  	if float64(i8) != di8 {
   278  		t.Errorf("float64(i8) != di8")
   279  	}
   280  	if float32(u64) != su64 {
   281  		t.Errorf("float32(u64) != su64")
   282  	}
   283  	if float32(u32) != su32 {
   284  		t.Errorf("float32(u32) != su32")
   285  	}
   286  	if float32(u16) != su16 {
   287  		t.Errorf("float32(u16) != su16")
   288  	}
   289  	if float32(u8) != su8 {
   290  		t.Errorf("float32(u8) != su8")
   291  	}
   292  	if float32(i64) != si64 {
   293  		t.Errorf("float32(i64) != si64")
   294  	}
   295  	if float32(i32) != si32 {
   296  		t.Errorf("float32(i32) != si32")
   297  	}
   298  	if float32(i16) != si16 {
   299  		t.Errorf("float32(i16) != si16")
   300  	}
   301  	if float32(i8) != si8 {
   302  		t.Errorf("float32(i8) != si8")
   303  	}
   304  
   305  	// float to integer
   306  	if uint64(du64) != u64 {
   307  		t.Errorf("uint64(du64) != u64")
   308  	}
   309  	if uint32(du32) != u32 {
   310  		t.Errorf("uint32(du32) != u32")
   311  	}
   312  	if uint16(du16) != u16 {
   313  		t.Errorf("uint16(du16) != u16")
   314  	}
   315  	if uint8(du8) != u8 {
   316  		t.Errorf("uint8(du8) != u8")
   317  	}
   318  	if int64(di64) != i64 {
   319  		t.Errorf("int64(di64) != i64")
   320  	}
   321  	if int32(di32) != i32 {
   322  		t.Errorf("int32(di32) != i32")
   323  	}
   324  	if int16(di16) != i16 {
   325  		t.Errorf("int16(di16) != i16")
   326  	}
   327  	if int8(di8) != i8 {
   328  		t.Errorf("int8(di8) != i8")
   329  	}
   330  	if uint64(su64) != u64 {
   331  		t.Errorf("uint64(su64) != u64")
   332  	}
   333  	if uint32(su32) != u32 {
   334  		t.Errorf("uint32(su32) != u32")
   335  	}
   336  	if uint16(su16) != u16 {
   337  		t.Errorf("uint16(su16) != u16")
   338  	}
   339  	if uint8(su8) != u8 {
   340  		t.Errorf("uint8(su8) != u8")
   341  	}
   342  	if int64(si64) != i64 {
   343  		t.Errorf("int64(si64) != i64")
   344  	}
   345  	if int32(si32) != i32 {
   346  		t.Errorf("int32(si32) != i32")
   347  	}
   348  	if int16(si16) != i16 {
   349  		t.Errorf("int16(si16) != i16")
   350  	}
   351  	if int8(si8) != i8 {
   352  		t.Errorf("int8(si8) != i8")
   353  	}
   354  }
   355  
   356  func TestFloat32StoreToLoadConstantFold(t *testing.T) {
   357  	// Test that math.Float32{,from}bits constant fold correctly.
   358  	// In particular we need to be careful that signaling NaN (sNaN) values
   359  	// are not converted to quiet NaN (qNaN) values during compilation.
   360  	// See issue #27193 for more information.
   361  
   362  	// signaling NaNs
   363  	{
   364  		const nan = uint32(0x7f800001) // sNaN
   365  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   366  			t.Errorf("got %#x, want %#x", x, nan)
   367  		}
   368  	}
   369  	{
   370  		const nan = uint32(0x7fbfffff) // sNaN
   371  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   372  			t.Errorf("got %#x, want %#x", x, nan)
   373  		}
   374  	}
   375  	{
   376  		const nan = uint32(0xff800001) // sNaN
   377  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   378  			t.Errorf("got %#x, want %#x", x, nan)
   379  		}
   380  	}
   381  	{
   382  		const nan = uint32(0xffbfffff) // sNaN
   383  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   384  			t.Errorf("got %#x, want %#x", x, nan)
   385  		}
   386  	}
   387  
   388  	// quiet NaNs
   389  	{
   390  		const nan = uint32(0x7fc00000) // qNaN
   391  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   392  			t.Errorf("got %#x, want %#x", x, nan)
   393  		}
   394  	}
   395  	{
   396  		const nan = uint32(0x7fffffff) // qNaN
   397  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   398  			t.Errorf("got %#x, want %#x", x, nan)
   399  		}
   400  	}
   401  	{
   402  		const nan = uint32(0x8fc00000) // qNaN
   403  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   404  			t.Errorf("got %#x, want %#x", x, nan)
   405  		}
   406  	}
   407  	{
   408  		const nan = uint32(0x8fffffff) // qNaN
   409  		if x := math.Float32bits(math.Float32frombits(nan)); x != nan {
   410  			t.Errorf("got %#x, want %#x", x, nan)
   411  		}
   412  	}
   413  
   414  	// infinities
   415  	{
   416  		const inf = uint32(0x7f800000) // +∞
   417  		if x := math.Float32bits(math.Float32frombits(inf)); x != inf {
   418  			t.Errorf("got %#x, want %#x", x, inf)
   419  		}
   420  	}
   421  	{
   422  		const negInf = uint32(0xff800000) // -∞
   423  		if x := math.Float32bits(math.Float32frombits(negInf)); x != negInf {
   424  			t.Errorf("got %#x, want %#x", x, negInf)
   425  		}
   426  	}
   427  
   428  	// numbers
   429  	{
   430  		const zero = uint32(0) // +0.0
   431  		if x := math.Float32bits(math.Float32frombits(zero)); x != zero {
   432  			t.Errorf("got %#x, want %#x", x, zero)
   433  		}
   434  	}
   435  	{
   436  		const negZero = uint32(1 << 31) // -0.0
   437  		if x := math.Float32bits(math.Float32frombits(negZero)); x != negZero {
   438  			t.Errorf("got %#x, want %#x", x, negZero)
   439  		}
   440  	}
   441  	{
   442  		const one = uint32(0x3f800000) // 1.0
   443  		if x := math.Float32bits(math.Float32frombits(one)); x != one {
   444  			t.Errorf("got %#x, want %#x", x, one)
   445  		}
   446  	}
   447  	{
   448  		const negOne = uint32(0xbf800000) // -1.0
   449  		if x := math.Float32bits(math.Float32frombits(negOne)); x != negOne {
   450  			t.Errorf("got %#x, want %#x", x, negOne)
   451  		}
   452  	}
   453  	{
   454  		const frac = uint32(0x3fc00000) // +1.5
   455  		if x := math.Float32bits(math.Float32frombits(frac)); x != frac {
   456  			t.Errorf("got %#x, want %#x", x, frac)
   457  		}
   458  	}
   459  	{
   460  		const negFrac = uint32(0xbfc00000) // -1.5
   461  		if x := math.Float32bits(math.Float32frombits(negFrac)); x != negFrac {
   462  			t.Errorf("got %#x, want %#x", x, negFrac)
   463  		}
   464  	}
   465  }
   466  
   467  // Signaling NaN values as constants.
   468  const (
   469  	snan32bits uint32 = 0x7f800001
   470  	snan64bits uint64 = 0x7ff0000000000001
   471  )
   472  
   473  // Signaling NaNs as variables.
   474  var snan32bitsVar uint32 = snan32bits
   475  var snan64bitsVar uint64 = snan64bits
   476  
   477  func TestFloatSignalingNaN(t *testing.T) {
   478  	// Make sure we generate a signaling NaN from a constant properly.
   479  	// See issue 36400.
   480  	f32 := math.Float32frombits(snan32bits)
   481  	g32 := math.Float32frombits(snan32bitsVar)
   482  	x32 := math.Float32bits(f32)
   483  	y32 := math.Float32bits(g32)
   484  	if x32 != y32 {
   485  		t.Errorf("got %x, want %x (diff=%x)", x32, y32, x32^y32)
   486  	}
   487  
   488  	f64 := math.Float64frombits(snan64bits)
   489  	g64 := math.Float64frombits(snan64bitsVar)
   490  	x64 := math.Float64bits(f64)
   491  	y64 := math.Float64bits(g64)
   492  	if x64 != y64 {
   493  		t.Errorf("got %x, want %x (diff=%x)", x64, y64, x64^y64)
   494  	}
   495  }
   496  
   497  func TestFloatSignalingNaNConversion(t *testing.T) {
   498  	// Test to make sure when we convert a signaling NaN, we get a NaN.
   499  	// (Ideally we want a quiet NaN, but some platforms don't agree.)
   500  	// See issue 36399.
   501  	s32 := math.Float32frombits(snan32bitsVar)
   502  	if s32 == s32 {
   503  		t.Errorf("converting a NaN did not result in a NaN")
   504  	}
   505  	s64 := math.Float64frombits(snan64bitsVar)
   506  	if s64 == s64 {
   507  		t.Errorf("converting a NaN did not result in a NaN")
   508  	}
   509  }
   510  
   511  func TestFloatSignalingNaNConversionConst(t *testing.T) {
   512  	// Test to make sure when we convert a signaling NaN, it converts to a NaN.
   513  	// (Ideally we want a quiet NaN, but some platforms don't agree.)
   514  	// See issue 36399 and 36400.
   515  	s32 := math.Float32frombits(snan32bits)
   516  	if s32 == s32 {
   517  		t.Errorf("converting a NaN did not result in a NaN")
   518  	}
   519  	s64 := math.Float64frombits(snan64bits)
   520  	if s64 == s64 {
   521  		t.Errorf("converting a NaN did not result in a NaN")
   522  	}
   523  }
   524  
   525  var sinkFloat float64
   526  
   527  func BenchmarkMul2(b *testing.B) {
   528  	for i := 0; i < b.N; i++ {
   529  		var m float64 = 1
   530  		for j := 0; j < 500; j++ {
   531  			m *= 2
   532  		}
   533  		sinkFloat = m
   534  	}
   535  }
   536  func BenchmarkMulNeg2(b *testing.B) {
   537  	for i := 0; i < b.N; i++ {
   538  		var m float64 = 1
   539  		for j := 0; j < 500; j++ {
   540  			m *= -2
   541  		}
   542  		sinkFloat = m
   543  	}
   544  }
   545  

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