github.com/gagliardetto/golang-go@v0.0.0-20201020153340-53909ea70814/cmd/compile/internal/ssa/rewrite_test.go (about)

     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 ssa
     6  
     7  import "testing"
     8  
     9  // TestNlzNto tests nlz/nto of the same number which is used in some of
    10  // the rewrite rules.
    11  func TestNlzNto(t *testing.T) {
    12  	// construct the bit pattern 000...111, nlz(x) + nto(0) = 64
    13  	var x int64
    14  	for i := int64(0); i < 64; i++ {
    15  		if got := nto(x); got != i {
    16  			t.Errorf("expected nto(0x%X) = %d, got %d", x, i, got)
    17  		}
    18  		if got := nlz(x); got != 64-i {
    19  			t.Errorf("expected nlz(0x%X) = %d, got %d", x, 64-i, got)
    20  		}
    21  		x = (x << 1) | 1
    22  	}
    23  
    24  	x = 0
    25  	// construct the bit pattern 000...111, with bit 33 set as well.
    26  	for i := int64(0); i < 64; i++ {
    27  		tx := x | (1 << 32)
    28  		// nto should be the number of bits we've shifted on, with an extra bit
    29  		// at iter 32
    30  		ntoExp := i
    31  		if ntoExp == 32 {
    32  			ntoExp = 33
    33  		}
    34  		if got := nto(tx); got != ntoExp {
    35  			t.Errorf("expected nto(0x%X) = %d, got %d", tx, ntoExp, got)
    36  		}
    37  
    38  		// sinec bit 33 is set, nlz can be no greater than 31
    39  		nlzExp := 64 - i
    40  		if nlzExp > 31 {
    41  			nlzExp = 31
    42  		}
    43  		if got := nlz(tx); got != nlzExp {
    44  			t.Errorf("expected nlz(0x%X) = %d, got %d", tx, nlzExp, got)
    45  		}
    46  		x = (x << 1) | 1
    47  	}
    48  
    49  }
    50  
    51  func TestNlz(t *testing.T) {
    52  	var nlzTests = []struct {
    53  		v   int64
    54  		exp int64
    55  	}{{0x00, 64},
    56  		{0x01, 63},
    57  		{0x0F, 60},
    58  		{0xFF, 56},
    59  		{0xffffFFFF, 32},
    60  		{-0x01, 0}}
    61  
    62  	for _, tc := range nlzTests {
    63  		if got := nlz(tc.v); got != tc.exp {
    64  			t.Errorf("expected nlz(0x%X) = %d, got %d", tc.v, tc.exp, got)
    65  		}
    66  	}
    67  }
    68  
    69  func TestNto(t *testing.T) {
    70  	var ntoTests = []struct {
    71  		v   int64
    72  		exp int64
    73  	}{{0x00, 0},
    74  		{0x01, 1},
    75  		{0x0F, 4},
    76  		{0xFF, 8},
    77  		{0xffffFFFF, 32},
    78  		{-0x01, 64}}
    79  
    80  	for _, tc := range ntoTests {
    81  		if got := nto(tc.v); got != tc.exp {
    82  			t.Errorf("expected nto(0x%X) = %d, got %d", tc.v, tc.exp, got)
    83  		}
    84  	}
    85  }
    86  
    87  func TestLog2(t *testing.T) {
    88  	var log2Tests = []struct {
    89  		v   int64
    90  		exp int64
    91  	}{{0, -1}, // nlz expects log2(0) == -1
    92  		{1, 0},
    93  		{2, 1},
    94  		{4, 2},
    95  		{7, 2},
    96  		{8, 3},
    97  		{9, 3},
    98  		{1024, 10}}
    99  
   100  	for _, tc := range log2Tests {
   101  		if got := log2(tc.v); got != tc.exp {
   102  			t.Errorf("expected log2(%d) = %d, got %d", tc.v, tc.exp, got)
   103  		}
   104  	}
   105  }
   106  
   107  // We generate memmove for copy(x[1:], x[:]), however we may change it to OpMove,
   108  // because size is known. Check that OpMove is alias-safe, or we did call memmove.
   109  func TestMove(t *testing.T) {
   110  	x := [...]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40}
   111  	copy(x[1:], x[:])
   112  	for i := 1; i < len(x); i++ {
   113  		if int(x[i]) != i {
   114  			t.Errorf("Memmove got converted to OpMove in alias-unsafe way. Got %d insted of %d in position %d", int(x[i]), i, i+1)
   115  		}
   116  	}
   117  }
   118  
   119  func TestMoveSmall(t *testing.T) {
   120  	x := [...]byte{1, 2, 3, 4, 5, 6, 7}
   121  	copy(x[1:], x[:])
   122  	for i := 1; i < len(x); i++ {
   123  		if int(x[i]) != i {
   124  			t.Errorf("Memmove got converted to OpMove in alias-unsafe way. Got %d instead of %d in position %d", int(x[i]), i, i+1)
   125  		}
   126  	}
   127  }