mirror of
https://github.com/golang/go
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d5dc490519
Implement math/bits.TrailingZerosX using intrinsics.
Generally reorganize the intrinsic spec a bit.
The instrinsics data structure is now built at init time.
This will make doing the other functions in math/bits easier.
Update sys.CtzX to return int instead of uint{64,32} so it
matches math/bits.TrailingZerosX.
Improve the intrinsics a bit for amd64. We don't need the CMOV
for <64 bit versions.
Update #18616
Change-Id: Ic1c5339c943f961d830ae56f12674d7b29d4ff39
Reviewed-on: https://go-review.googlesource.com/38155
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
95 lines
2.4 KiB
Go
95 lines
2.4 KiB
Go
// Copyright 2016 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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package main
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import (
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"fmt"
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T "runtime/internal/sys"
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)
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var A = []uint64{0x0102030405060708, 0x1122334455667788}
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var B = []uint64{0x0807060504030201, 0x8877665544332211}
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var errors int
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func logf(f string, args ...interface{}) {
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errors++
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fmt.Printf(f, args...)
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if errors > 100 { // 100 is enough spewage
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panic("100 errors is plenty is enough")
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}
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}
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func test(i int, x uint64) {
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t := T.Ctz64(x) // ERROR "intrinsic substitution for Ctz64"
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if i != t {
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logf("Ctz64(0x%x) expected %d but got %d\n", x, i, t)
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}
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x = -x
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t = T.Ctz64(x) // ERROR "intrinsic substitution for Ctz64"
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if i != t {
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logf("Ctz64(0x%x) expected %d but got %d\n", x, i, t)
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}
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if i <= 32 {
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x32 := uint32(x)
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t32 := T.Ctz32(x32) // ERROR "intrinsic substitution for Ctz32"
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if i != t32 {
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logf("Ctz32(0x%x) expected %d but got %d\n", x32, i, t32)
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}
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x32 = -x32
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t32 = T.Ctz32(x32) // ERROR "intrinsic substitution for Ctz32"
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if i != t32 {
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logf("Ctz32(0x%x) expected %d but got %d\n", x32, i, t32)
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}
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}
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}
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func main() {
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// Test Bswap first because the other test relies on it
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// working correctly (to implement bit reversal).
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for i := range A {
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x := A[i]
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y := B[i]
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X := T.Bswap64(x) // ERROR "intrinsic substitution for Bswap64"
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Y := T.Bswap64(y) // ERROR "intrinsic substitution for Bswap64"
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if y != X {
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logf("Bswap64(0x%08x) expected 0x%08x but got 0x%08x\n", x, y, X)
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}
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if x != Y {
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logf("Bswap64(0x%08x) expected 0x%08x but got 0x%08x\n", y, x, Y)
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}
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x32 := uint32(X)
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y32 := uint32(Y >> 32)
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X32 := T.Bswap32(x32) // ERROR "intrinsic substitution for Bswap32"
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Y32 := T.Bswap32(y32) // ERROR "intrinsic substitution for Bswap32"
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if y32 != X32 {
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logf("Bswap32(0x%08x) expected 0x%08x but got 0x%08x\n", x32, y32, X32)
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}
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if x32 != Y32 {
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logf("Bswap32(0x%08x) expected 0x%08x but got 0x%08x\n", y32, x32, Y32)
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}
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}
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// Zero is a special case, be sure it is done right.
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if T.Ctz32(0) != 32 { // ERROR "intrinsic substitution for Ctz32"
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logf("ctz32(0) != 32")
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}
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if T.Ctz64(0) != 64 { // ERROR "intrinsic substitution for Ctz64"
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logf("ctz64(0) != 64")
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}
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for i := 0; i <= 64; i++ {
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for j := uint64(1); j <= 255; j += 2 {
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for k := uint64(1); k <= 65537; k += 128 {
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x := (j * k) << uint(i)
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test(i, x)
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}
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}
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}
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}
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