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That way we don't need to call into the runtime when the type being switched on has been seen many times before. The cache is just a hash table of a sample of all the concrete types that have been switched on at that source location. We record the matching case number and the resulting itab for each concrete input type. The caches seldom get large. The only two in a run of all.bash that get more than 100 entries, even with the sampling rate set to 1, are test/fixedbugs/issue29264.go, with 101 test/fixedbugs/issue29312.go, with 254 Both happen at the type switch in fmt.(*pp).handleMethods, perhaps unsurprisingly. name old time/op new time/op delta SwitchInterfaceTypePredictable-24 25.8ns ± 2% 2.5ns ± 3% -90.43% (p=0.000 n=10+10) SwitchInterfaceTypeUnpredictable-24 37.5ns ± 2% 11.2ns ± 1% -70.02% (p=0.000 n=10+10) Change-Id: I4961ac9547b7f15b03be6f55cdcb972d176955eb Reviewed-on: https://go-review.googlesource.com/c/go/+/526658 Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Keith Randall <khr@google.com>
142 lines
2.6 KiB
Go
142 lines
2.6 KiB
Go
// asmcheck
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// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// These tests check code generation of switch statements.
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package codegen
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// see issue 33934
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func f(x string) int {
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// amd64:-`cmpstring`
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switch x {
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case "":
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return -1
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case "1", "2", "3":
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return -2
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default:
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return -3
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}
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}
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// use jump tables for 8+ int cases
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func square(x int) int {
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// amd64:`JMP\s\(.*\)\(.*\)$`
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// arm64:`MOVD\s\(R.*\)\(R.*<<3\)`,`JMP\s\(R.*\)$`
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switch x {
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case 1:
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return 1
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case 2:
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return 4
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case 3:
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return 9
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case 4:
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return 16
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case 5:
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return 25
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case 6:
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return 36
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case 7:
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return 49
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case 8:
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return 64
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default:
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return x * x
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}
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}
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// use jump tables for 8+ string lengths
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func length(x string) int {
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// amd64:`JMP\s\(.*\)\(.*\)$`
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// arm64:`MOVD\s\(R.*\)\(R.*<<3\)`,`JMP\s\(R.*\)$`
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switch x {
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case "a":
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return 1
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case "bb":
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return 2
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case "ccc":
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return 3
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case "dddd":
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return 4
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case "eeeee":
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return 5
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case "ffffff":
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return 6
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case "ggggggg":
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return 7
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case "hhhhhhhh":
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return 8
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default:
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return len(x)
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}
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}
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// Use single-byte ordered comparisons for binary searching strings.
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// See issue 53333.
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func mimetype(ext string) string {
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// amd64: `CMPB\s1\(.*\), \$104$`,-`cmpstring`
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// arm64: `MOVB\s1\(R.*\), R.*$`, `CMPW\s\$104, R.*$`, -`cmpstring`
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switch ext {
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// amd64: `CMPL\s\(.*\), \$1836345390$`
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// arm64: `MOVD\s\$1836345390`, `CMPW\sR.*, R.*$`
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case ".htm":
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return "A"
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// amd64: `CMPL\s\(.*\), \$1953457454$`
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// arm64: `MOVD\s\$1953457454`, `CMPW\sR.*, R.*$`
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case ".eot":
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return "B"
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// amd64: `CMPL\s\(.*\), \$1735815982$`
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// arm64: `MOVD\s\$1735815982`, `CMPW\sR.*, R.*$`
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case ".svg":
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return "C"
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// amd64: `CMPL\s\(.*\), \$1718907950$`
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// arm64: `MOVD\s\$1718907950`, `CMPW\sR.*, R.*$`
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case ".ttf":
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return "D"
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default:
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return ""
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}
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}
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// use jump tables for type switches to concrete types.
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func typeSwitch(x any) int {
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// amd64:`JMP\s\(.*\)\(.*\)$`
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// arm64:`MOVD\s\(R.*\)\(R.*<<3\)`,`JMP\s\(R.*\)$`
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switch x.(type) {
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case int:
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return 0
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case int8:
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return 1
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case int16:
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return 2
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case int32:
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return 3
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case int64:
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return 4
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}
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return 7
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}
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type I interface {
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foo()
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}
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type J interface {
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bar()
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}
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// use a runtime call for type switches to interface types.
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func interfaceSwitch(x any) int {
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// amd64:`CALL\truntime.interfaceSwitch`,`MOVL\t16\(.*\)`,`MOVQ\t8\(.*\)(.*\*8)`
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// arm64:`CALL\truntime.interfaceSwitch`,`LDAR`,`MOVWU`,`MOVD\t\(R.*\)\(R.*\)`
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switch x.(type) {
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case I:
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return 1
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case J:
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return 2
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default:
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return 3
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}
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}
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