110 lines
2.2 KiB
Go
110 lines
2.2 KiB
Go
package asm
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import (
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"testing"
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"unsafe"
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qt "github.com/frankban/quicktest"
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)
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func TestMetadata(t *testing.T) {
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var m Metadata
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// Metadata should be the size of a pointer.
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qt.Assert(t, unsafe.Sizeof(m), qt.Equals, unsafe.Sizeof(uintptr(0)))
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// A lookup in a nil meta should return nil.
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qt.Assert(t, m.Get(bool(false)), qt.IsNil)
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// We can look up anything we inserted.
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m.Set(bool(false), int(0))
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m.Set(int(1), int(1))
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qt.Assert(t, m.Get(bool(false)), qt.Equals, int(0))
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qt.Assert(t, m.Get(int(1)), qt.Equals, int(1))
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// We have copy on write semantics
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old := m
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m.Set(bool(false), int(1))
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qt.Assert(t, m.Get(bool(false)), qt.Equals, int(1))
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qt.Assert(t, m.Get(int(1)), qt.Equals, int(1))
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qt.Assert(t, old.Get(bool(false)), qt.Equals, int(0))
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qt.Assert(t, old.Get(int(1)), qt.Equals, int(1))
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// Newtypes are handled distinctly.
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type b bool
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m.Set(b(false), int(42))
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qt.Assert(t, m.Get(bool(false)), qt.Equals, int(1))
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qt.Assert(t, m.Get(int(1)), qt.Equals, int(1))
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qt.Assert(t, m.Get(b(false)), qt.Equals, int(42))
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// Setting nil removes a key.
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m.Set(bool(false), nil)
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qt.Assert(t, m.Get(bool(false)), qt.IsNil)
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qt.Assert(t, m.Get(int(1)), qt.Equals, int(1))
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qt.Assert(t, m.Get(b(false)), qt.Equals, int(42))
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}
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func BenchmarkMetadata(b *testing.B) {
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// Assume that three bits of metadata on a single instruction is
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// our worst case.
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const worstCaseItems = 3
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type t struct{}
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b.Run("add first", func(b *testing.B) {
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b.ReportAllocs()
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for i := 0; i < b.N; i++ {
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var v Metadata
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v.Set(t{}, 0)
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}
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})
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b.Run("add last", func(b *testing.B) {
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var m Metadata
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for i := 0; i < worstCaseItems-1; i++ {
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m.Set(i, i)
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}
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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v := m
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v.Set(t{}, 0)
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}
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})
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b.Run("add existing", func(b *testing.B) {
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var m Metadata
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for i := 0; i < worstCaseItems-1; i++ {
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m.Set(i, i)
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}
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m.Set(t{}, 0)
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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v := m
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v.Set(t{}, 0)
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}
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})
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b.Run("get miss", func(b *testing.B) {
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var m Metadata
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for i := 0; i < worstCaseItems; i++ {
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m.Set(i, i)
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}
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b.ReportAllocs()
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b.ResetTimer()
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for i := 0; i < b.N; i++ {
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if m.Get(t{}) != nil {
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b.Fatal("got result from miss")
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}
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}
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})
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}
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