mirror of
https://github.com/golang/go
synced 2024-09-29 11:24:28 -06:00
e4a1cf8a56
This change to the rules removes some unnecessary signed shifts that appear in the math/rand functions. Existing rules did not cover some of the signed cases. A little improvement seen in math/rand due to removing 1 of 2 instructions generated for Int31n, which is inlined quite a bit. Intn1000 46.9ns ± 0% 45.5ns ± 0% -2.99% (p=1.000 n=1+1) Int63n1000 33.5ns ± 0% 32.8ns ± 0% -2.09% (p=1.000 n=1+1) Int31n1000 32.7ns ± 0% 32.6ns ± 0% -0.31% (p=1.000 n=1+1) Float32 32.7ns ± 0% 30.3ns ± 0% -7.34% (p=1.000 n=1+1) Float64 21.7ns ± 0% 20.9ns ± 0% -3.69% (p=1.000 n=1+1) Perm3 205ns ± 0% 202ns ± 0% -1.46% (p=1.000 n=1+1) Perm30 1.71µs ± 0% 1.68µs ± 0% -1.35% (p=1.000 n=1+1) Perm30ViaShuffle 1.65µs ± 0% 1.65µs ± 0% -0.30% (p=1.000 n=1+1) ShuffleOverhead 2.83µs ± 0% 2.83µs ± 0% -0.07% (p=1.000 n=1+1) Read3 18.7ns ± 0% 16.1ns ± 0% -13.90% (p=1.000 n=1+1) Read64 126ns ± 0% 124ns ± 0% -1.59% (p=1.000 n=1+1) Read1000 1.75µs ± 0% 1.63µs ± 0% -7.08% (p=1.000 n=1+1) Change-Id: I11502dfca7d65aafc76749a8d713e9e50c24a858 Reviewed-on: https://go-review.googlesource.com/c/go/+/225917 Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com> Reviewed-by: Cherry Zhang <cherryyz@google.com>
151 lines
3.1 KiB
Go
151 lines
3.1 KiB
Go
// asmcheck
|
|
|
|
// Copyright 2018 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package codegen
|
|
|
|
// ------------------ //
|
|
// masked shifts //
|
|
// ------------------ //
|
|
|
|
func lshMask64x64(v int64, s uint64) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v << (s & 63)
|
|
}
|
|
|
|
func rshMask64Ux64(v uint64, s uint64) uint64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func rshMask64x64(v int64, s uint64) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func lshMask32x64(v int32, s uint64) int32 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v << (s & 63)
|
|
}
|
|
|
|
func rshMask32Ux64(v uint32, s uint64) uint32 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func rshMask32x64(v int32, s uint64) int32 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func lshMask64x32(v int64, s uint32) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v << (s & 63)
|
|
}
|
|
|
|
func rshMask64Ux32(v uint64, s uint32) uint64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func rshMask64x32(v int64, s uint32) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> (s & 63)
|
|
}
|
|
|
|
func lshMask64x32Ext(v int64, s int32) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v << uint(s&63)
|
|
}
|
|
|
|
func rshMask64Ux32Ext(v uint64, s int32) uint64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> uint(s&63)
|
|
}
|
|
|
|
func rshMask64x32Ext(v int64, s int32) int64 {
|
|
// s390x:-".*AND",-".*MOVDGE"
|
|
return v >> uint(s&63)
|
|
}
|
|
|
|
// --------------- //
|
|
// signed shifts //
|
|
// --------------- //
|
|
|
|
// We do want to generate a test + panicshift for these cases.
|
|
func lshSigned(v8 int8, v16 int16, v32 int32, v64 int64, x int) {
|
|
// amd64:"TESTB"
|
|
_ = x << v8
|
|
// amd64:"TESTW"
|
|
_ = x << v16
|
|
// amd64:"TESTL"
|
|
_ = x << v32
|
|
// amd64:"TESTQ"
|
|
_ = x << v64
|
|
}
|
|
|
|
// We want to avoid generating a test + panicshift for these cases.
|
|
func lshSignedMasked(v8 int8, v16 int16, v32 int32, v64 int64, x int) {
|
|
// amd64:-"TESTB"
|
|
_ = x << (v8 & 7)
|
|
// amd64:-"TESTW"
|
|
_ = x << (v16 & 15)
|
|
// amd64:-"TESTL"
|
|
_ = x << (v32 & 31)
|
|
// amd64:-"TESTQ"
|
|
_ = x << (v64 & 63)
|
|
}
|
|
|
|
// ------------------ //
|
|
// bounded shifts //
|
|
// ------------------ //
|
|
|
|
func rshGuarded64(v int64, s uint) int64 {
|
|
if s < 64 {
|
|
// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
|
|
return v >> s
|
|
}
|
|
panic("shift too large")
|
|
}
|
|
|
|
func rshGuarded64U(v uint64, s uint) uint64 {
|
|
if s < 64 {
|
|
// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
|
|
return v >> s
|
|
}
|
|
panic("shift too large")
|
|
}
|
|
|
|
func lshGuarded64(v int64, s uint) int64 {
|
|
if s < 64 {
|
|
// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
|
|
return v << s
|
|
}
|
|
panic("shift too large")
|
|
}
|
|
|
|
func checkWidenAfterShift(v int64, u uint64) (int64, uint64) {
|
|
|
|
// ppc64le:-".*MOVW"
|
|
f := int32(v>>32)
|
|
// ppc64le:".*MOVW"
|
|
f += int32(v>>31)
|
|
// ppc64le:-".*MOVH"
|
|
g := int16(v>>48)
|
|
// ppc64le:".*MOVH"
|
|
g += int16(v>>30)
|
|
// ppc64le:-".*MOVH"
|
|
g += int16(f>>16)
|
|
// ppc64le:-".*MOVB"
|
|
h := int8(v>>56)
|
|
// ppc64le:".*MOVB"
|
|
h += int8(v>>28)
|
|
// ppc64le:-".*MOVB"
|
|
h += int8(f>>24)
|
|
// ppc64le:".*MOVB"
|
|
h += int8(f>>16)
|
|
return int64(h),uint64(g)
|
|
}
|