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// Copyright 2016 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 ssa
import "testing"
// TestNlzNto tests nlz/nto of the same number which is used in some of
// the rewrite rules.
func TestNlzNto(t *testing.T) {
// construct the bit pattern 000...111, nlz(x) + nto(0) = 64
var x int64
for i := int64(0); i < 64; i++ {
if got := nto(x); got != i {
t.Errorf("expected nto(0x%X) = %d, got %d", x, i, got)
}
if got := nlz(x); got != 64-i {
t.Errorf("expected nlz(0x%X) = %d, got %d", x, 64-i, got)
}
x = (x << 1) | 1
}
x = 0
// construct the bit pattern 000...111, with bit 33 set as well.
for i := int64(0); i < 64; i++ {
tx := x | (1 << 32)
// nto should be the number of bits we've shifted on, with an extra bit
// at iter 32
ntoExp := i
if ntoExp == 32 {
ntoExp = 33
}
if got := nto(tx); got != ntoExp {
t.Errorf("expected nto(0x%X) = %d, got %d", tx, ntoExp, got)
}
// sinec bit 33 is set, nlz can be no greater than 31
nlzExp := 64 - i
if nlzExp > 31 {
nlzExp = 31
}
if got := nlz(tx); got != nlzExp {
t.Errorf("expected nlz(0x%X) = %d, got %d", tx, nlzExp, got)
}
x = (x << 1) | 1
}
}
func TestNlz(t *testing.T) {
var nlzTests = []struct {
v int64
exp int64
}{{0x00, 64},
{0x01, 63},
{0x0F, 60},
{0xFF, 56},
{0xffffFFFF, 32},
{-0x01, 0}}
for _, tc := range nlzTests {
if got := nlz(tc.v); got != tc.exp {
t.Errorf("expected nlz(0x%X) = %d, got %d", tc.v, tc.exp, got)
}
}
}
func TestNto(t *testing.T) {
var ntoTests = []struct {
v int64
exp int64
}{{0x00, 0},
{0x01, 1},
{0x0F, 4},
{0xFF, 8},
{0xffffFFFF, 32},
{-0x01, 64}}
for _, tc := range ntoTests {
if got := nto(tc.v); got != tc.exp {
t.Errorf("expected nto(0x%X) = %d, got %d", tc.v, tc.exp, got)
}
}
}
func TestLog2(t *testing.T) {
var log2Tests = []struct {
v int64
exp int64
}{{0, -1}, // nlz expects log2(0) == -1
{1, 0},
{2, 1},
{4, 2},
{7, 2},
{8, 3},
{9, 3},
{1024, 10}}
for _, tc := range log2Tests {
if got := log2(tc.v); got != tc.exp {
t.Errorf("expected log2(%d) = %d, got %d", tc.v, tc.exp, got)
}
}
}
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