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a1550d3ca3
This changes the code generated for variable length shift counts to use isel instead of instructions that set and read the carry flag. This reduces the generated code for shifts like this by 1 instruction and avoids the use of instructions to set and read the carry flag. This sequence can be found in strconv with these results on power9: Atof64Decimal 71.6ns ± 0% 68.3ns ± 0% -4.61% Atof64Float 95.3ns ± 0% 90.9ns ± 0% -4.62% Atof64FloatExp 153ns ± 0% 149ns ± 0% -2.61% Atof64Big 234ns ± 0% 232ns ± 0% -0.85% Atof64RandomBits 348ns ± 0% 369ns ± 0% +6.03% Atof64RandomFloats 262ns ± 0% 262ns ± 0% ~ Atof32Decimal 72.0ns ± 0% 68.2ns ± 0% -5.28% Atof32Float 92.1ns ± 0% 87.1ns ± 0% -5.43% Atof32FloatExp 159ns ± 0% 158ns ± 0% -0.63% Atof32Random 194ns ± 0% 191ns ± 0% -1.55% Some tests in codegen/shift.go are enabled to verify the expected instructions are generated. Change-Id: I968715d10ada405a8c46132bf19b8ed9b85796d1 Reviewed-on: https://go-review.googlesource.com/c/go/+/227337 Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
175 lines
3.8 KiB
Go
175 lines
3.8 KiB
Go
// asmcheck
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// Copyright 2018 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 codegen
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// ------------------ //
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// masked shifts //
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// ------------------ //
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func lshMask64x64(v int64, s uint64) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v << (s & 63)
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}
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func rshMask64Ux64(v uint64, s uint64) uint64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v >> (s & 63)
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}
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func rshMask64x64(v int64, s uint64) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v >> (s & 63)
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}
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func lshMask32x64(v int32, s uint64) int32 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ISEL",-"ORN"
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// ppc64:"ISEL",-"ORN"
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return v << (s & 63)
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}
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func rshMask32Ux64(v uint32, s uint64) uint32 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ISEL",-"ORN"
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// ppc64:"ISEL",-"ORN"
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return v >> (s & 63)
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}
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func rshMask32x64(v int32, s uint64) int32 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ISEL",-"ORN"
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// ppc64:"ISEL",-"ORN"
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return v >> (s & 63)
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}
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func lshMask64x32(v int64, s uint32) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN"
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// ppc64:"ANDCC",-"ORN"
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return v << (s & 63)
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}
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func rshMask64Ux32(v uint64, s uint32) uint64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN"
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// ppc64:"ANDCC",-"ORN"
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return v >> (s & 63)
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}
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func rshMask64x32(v int64, s uint32) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v >> (s & 63)
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}
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func lshMask64x32Ext(v int64, s int32) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v << uint(s&63)
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}
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func rshMask64Ux32Ext(v uint64, s int32) uint64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v >> uint(s&63)
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}
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func rshMask64x32Ext(v int64, s int32) int64 {
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// s390x:-".*AND",-".*MOVDGE"
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// ppc64le:"ANDCC",-"ORN",-"ISEL"
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// ppc64:"ANDCC",-"ORN",-"ISEL"
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return v >> uint(s&63)
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}
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// --------------- //
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// signed shifts //
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// --------------- //
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// We do want to generate a test + panicshift for these cases.
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func lshSigned(v8 int8, v16 int16, v32 int32, v64 int64, x int) {
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// amd64:"TESTB"
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_ = x << v8
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// amd64:"TESTW"
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_ = x << v16
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// amd64:"TESTL"
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_ = x << v32
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// amd64:"TESTQ"
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_ = x << v64
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}
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// We want to avoid generating a test + panicshift for these cases.
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func lshSignedMasked(v8 int8, v16 int16, v32 int32, v64 int64, x int) {
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// amd64:-"TESTB"
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_ = x << (v8 & 7)
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// amd64:-"TESTW"
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_ = x << (v16 & 15)
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// amd64:-"TESTL"
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_ = x << (v32 & 31)
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// amd64:-"TESTQ"
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_ = x << (v64 & 63)
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}
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// ------------------ //
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// bounded shifts //
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// ------------------ //
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func rshGuarded64(v int64, s uint) int64 {
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if s < 64 {
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// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
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return v >> s
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}
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panic("shift too large")
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}
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func rshGuarded64U(v uint64, s uint) uint64 {
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if s < 64 {
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// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
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return v >> s
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}
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panic("shift too large")
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}
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func lshGuarded64(v int64, s uint) int64 {
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if s < 64 {
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// s390x:-".*AND",-".*MOVDGE" wasm:-"Select",-".*LtU"
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return v << s
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}
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panic("shift too large")
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}
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func checkWidenAfterShift(v int64, u uint64) (int64, uint64) {
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// ppc64le:-".*MOVW"
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f := int32(v>>32)
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// ppc64le:".*MOVW"
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f += int32(v>>31)
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// ppc64le:-".*MOVH"
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g := int16(v>>48)
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// ppc64le:".*MOVH"
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g += int16(v>>30)
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// ppc64le:-".*MOVH"
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g += int16(f>>16)
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// ppc64le:-".*MOVB"
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h := int8(v>>56)
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// ppc64le:".*MOVB"
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h += int8(v>>28)
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// ppc64le:-".*MOVB"
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h += int8(f>>24)
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// ppc64le:".*MOVB"
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h += int8(f>>16)
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return int64(h),uint64(g)
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}
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