mirror of
https://github.com/golang/go
synced 2024-11-25 03:07:56 -07:00
c6ce44822c
* Eliminate bounds check on known small shifts. * Rewrite x<<s | x>>(32-s) as a rotate (constant s). * More aggressive (but still minimal) range analysis. R=ken, dave, iant CC=golang-dev https://golang.org/cl/6209077
142 lines
2.8 KiB
Go
142 lines
2.8 KiB
Go
// $G $D/$F.go && $L $F.$A &&
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// ./$A.out >tmp.go && $G tmp.go && $L -o $A.out1 tmp.$A && ./$A.out1
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// rm -f tmp.go $A.out1
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// Copyright 2012 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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// Generate test of shift and rotate by constants.
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// The output is compiled and run.
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//
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// The output takes around a minute to compile, link, and run
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// but it is only done during ./run, not in normal builds using run.go.
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package main
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import (
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"bufio"
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"flag"
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"fmt"
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"os"
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)
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func main() {
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flag.Parse()
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b := bufio.NewWriter(os.Stdout)
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defer b.Flush()
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fmt.Fprintf(b, "%s\n", prolog)
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for logBits := uint(3); logBits <= 6; logBits++ {
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for mode := 0; mode < 1<<2; mode++ {
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gentest(b, 1<<logBits, mode&1 != 0, mode&2 != 0)
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}
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}
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}
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const prolog = `
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package main
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import (
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"fmt"
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"os"
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)
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var (
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i8 int8 = 0x12
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i16 int16 = 0x1234
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i32 int32 = 0x12345678
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i64 int64 = 0x123456789abcdef0
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ui8 uint8 = 0x12
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ui16 uint16 = 0x1234
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ui32 uint32 = 0x12345678
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ui64 uint64 = 0x123456789abcdef0
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ni8 = ^i8
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ni16 = ^i16
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ni32 = ^i32
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ni64 = ^i64
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nui8 = ^ui8
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nui16 = ^ui16
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nui32 = ^ui32
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nui64 = ^ui64
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)
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var nfail = 0
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func check(desc string, have, want interface{}) {
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if have != want {
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nfail++
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fmt.Printf("%s = %T(%#x), want %T(%#x)\n", desc, have, have, want, want)
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if nfail >= 100 {
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fmt.Printf("BUG: stopping after 100 failures\n")
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os.Exit(0)
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}
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}
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}
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func main() {
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if nfail > 0 {
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fmt.Printf("BUG\n")
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}
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}
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`
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func gentest(b *bufio.Writer, bits uint, unsigned, inverted bool) {
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fmt.Fprintf(b, "func init() {\n")
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defer fmt.Fprintf(b, "}\n")
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n := 0
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// Generate tests for left/right and right/left.
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for l := uint(0); l <= bits; l++ {
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for r := uint(0); r <= bits; r++ {
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typ := fmt.Sprintf("int%d", bits)
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v := fmt.Sprintf("i%d", bits)
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if unsigned {
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typ = "u" + typ
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v = "u" + v
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}
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v0 := int64(0x123456789abcdef0)
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if inverted {
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v = "n" + v
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v0 = ^v0
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}
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expr1 := fmt.Sprintf("%s<<%d | %s>>%d", v, l, v, r)
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expr2 := fmt.Sprintf("%s>>%d | %s<<%d", v, r, v, l)
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var result string
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if unsigned {
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v := uint64(v0) >> (64 - bits)
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v = v<<l | v>>r
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v <<= 64 - bits
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v >>= 64 - bits
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result = fmt.Sprintf("%#x", v)
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} else {
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v := int64(v0) >> (64 - bits)
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v = v<<l | v>>r
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v <<= 64 - bits
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v >>= 64 - bits
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result = fmt.Sprintf("%#x", v)
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}
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fmt.Fprintf(b, "\tcheck(%q, %s, %s(%s))\n", expr1, expr1, typ, result)
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fmt.Fprintf(b, "\tcheck(%q, %s, %s(%s))\n", expr2, expr2, typ, result)
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// Chop test into multiple functions so that there's not one
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// enormous function to compile/link.
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// All the functions are named init so we don't have to do
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// anything special to call them. ☺
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if n++; n >= 100 {
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fmt.Fprintf(b, "}\n")
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fmt.Fprintf(b, "func init() {\n")
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n = 0
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}
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}
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}
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}
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