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cmd/compile: remove nlz function

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Use nlzX variants instead. While at it, also remove tests involve
nlz/nlo/nto/log2, since when we are calling directly "math/bits"
functions.

Passes toolstash-check.

Change-Id: I83899741a29e05bc2c19d73652961ac795001781
Reviewed-on: https://go-review.googlesource.com/c/go/+/229138
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Cuong Manh Le 2020-04-21 13:04:59 +07:00
parent a95bf77e1a
commit 65c9b57566
3 changed files with 1 additions and 101 deletions
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1
src/cmd/compile/fmtmap_test.go
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@ -157,7 +157,6 @@ var knownFormats = map[string]string{
"int64 %+d": "",
"int64 %-10d": "",
"int64 %.5d": "",
"int64 %X": "",
"int64 %d": "",
"int64 %v": "",
"int64 %x": "",

3
src/cmd/compile/internal/ssa/rewrite.go
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@ -386,7 +386,6 @@ func isSameSym(sym interface{}, name string) bool {
}
// nlz returns the number of leading zeros.
func nlz(x int64) int64 { return int64(bits.LeadingZeros64(uint64(x))) } // TODO: remove when no longer used
func nlz64(x int64) int { return bits.LeadingZeros64(uint64(x)) }
func nlz32(x int32) int { return bits.LeadingZeros32(uint32(x)) }
func nlz16(x int16) int { return bits.LeadingZeros16(uint16(x)) }
@ -407,7 +406,7 @@ func oneBit64(x int64) bool { return x&(x-1) == 0 && x != 0 }
// nlo returns the number of leading ones.
func nlo(x int64) int64 {
return nlz(^x)
return int64(nlz64(^x))
}
// nto returns the number of trailing ones.

98
src/cmd/compile/internal/ssa/rewrite_test.go
View File

@ -6,104 +6,6 @@ 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)
}
}
}
// We generate memmove for copy(x[1:], x[:]), however we may change it to OpMove,
// because size is known. Check that OpMove is alias-safe, or we did call memmove.
func TestMove(t *testing.T) {