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Commit 0e23ca41 authored by Ilya Tocar's avatar Ilya Tocar Committed by Keith Randall
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bytes: speed up Compare() on amd64 

Use AVX2 if available.
Results (haswell), below:

name                           old time/op    new time/op     delta
BytesCompare1-6                  11.4ns ± 0%     11.4ns ± 0%     ~     (all samples are equal)
BytesCompare2-6                  11.4ns ± 0%     11.4ns ± 0%     ~     (all samples are equal)
BytesCompare4-6                  11.4ns ± 0%     11.4ns ± 0%     ~     (all samples are equal)
BytesCompare8-6                  9.29ns ± 2%     8.76ns ± 0%   -5.72%        (p=0.000 n=16+17)
BytesCompare16-6                 9.29ns ± 2%     9.20ns ± 0%   -1.02%        (p=0.000 n=20+16)
BytesCompare32-6                 11.4ns ± 1%     11.4ns ± 0%     ~           (p=0.191 n=20+20)
BytesCompare64-6                 14.4ns ± 0%     13.1ns ± 0%   -8.68%        (p=0.000 n=20+20)
BytesCompare128-6                20.2ns ± 0%     18.5ns ± 0%   -8.27%        (p=0.000 n=16+20)
BytesCompare256-6                29.3ns ± 0%     24.5ns ± 0%  -16.38%        (p=0.000 n=16+16)
BytesCompare512-6                46.8ns ± 0%     37.1ns ± 0%  -20.78%        (p=0.000 n=18+16)
BytesCompare1024-6               82.9ns ± 0%     62.3ns ± 0%  -24.86%        (p=0.000 n=20+14)
BytesCompare2048-6                155ns ± 0%      112ns ± 0%  -27.74%        (p=0.000 n=20+20)
CompareBytesEqual-6              10.1ns ± 1%     10.0ns ± 1%     ~           (p=0.527 n=20+20)
CompareBytesToNil-6              10.0ns ± 2%      9.4ns ± 0%   -6.57%        (p=0.000 n=20+17)
CompareBytesEmpty-6              8.76ns ± 0%     8.76ns ± 0%     ~     (all samples are equal)
CompareBytesIdentical-6          8.76ns ± 0%     8.76ns ± 0%     ~     (all samples are equal)
CompareBytesSameLength-6         10.6ns ± 1%     10.6ns ± 1%     ~           (p=0.240 n=20+20)
CompareBytesDifferentLength-6    10.6ns ± 0%     10.6ns ± 1%     ~           (p=1.000 n=20+20)
CompareBytesBigUnaligned-6        132±s ± 1%      105±s ± 1%  -20.61%        (p=0.000 n=20+18)
CompareBytesBig-6                 125±s ± 1%      105±s ± 1%  -16.31%        (p=0.000 n=20+20)
CompareBytesBigIdentical-6       8.13ns ± 0%     8.13ns ± 0%     ~     (all samples are equal)

name                           old speed      new speed       delta
CompareBytesBigUnaligned-6     7.94GB/s ± 1%  10.01GB/s ± 1%  +25.96%        (p=0.000 n=20+18)
CompareBytesBig-6              8.38GB/s ± 1%  10.01GB/s ± 1%  +19.48%        (p=0.000 n=20+20)
CompareBytesBigIdentical-6      129TB/s ± 0%    129TB/s ± 0%   +0.01%        (p=0.003 n=17+19)

Change-Id: I820f31bab4582dd4204b146bb077c0d2f24cd8f5
Reviewed-on: https://go-review.googlesource.com/16434
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: default avatarKlaus Post <klauspost@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: default avatarKeith Randall <khr@golang.org>
parent cf73357e
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Inline Side-by-side
Showing with 126 additions and 8 deletions
src/cmd/internal/obj/x86/a.out.go
View file @ 0e23ca41
......@@ -746,6 +746,8 @@ const (
AMOVHDU
AMOVNTHD
AMOVHDA
AVPCMPEQB
AVPMOVMSKB
// from 386
AJCXZW
......
src/cmd/internal/obj/x86/anames.go
View file @ 0e23ca41
......@@ -687,6 +687,8 @@ var Anames = []string{
"MOVHDU",
"MOVNTHD",
"MOVHDA",
"VPCMPEQB",
"VPMOVMSKB",
"JCXZW",
"FCMOVCC",
"FCMOVCS",
......
src/cmd/internal/obj/x86/asm6.go
View file @ 0e23ca41
......@@ -195,6 +195,7 @@ const (
Zr_m
Zr_m_xm
Zr_m_xm_vex
Zr_r_r_vex
Zrp_
Z_ib
Z_il
......@@ -630,6 +631,11 @@ var yxr_ml_vex = []ytab{
{Yxr, Ynone, Yml, Zr_m_xm_vex, 1},
}
var yxm_xm_xm = []ytab{
{Yxr, Yxr, Yxr, Zr_r_r_vex, 1},
{Yxm, Yxr, Yxr, Zr_r_r_vex, 1},
}
var ymr = []ytab{
{Ymr, Ynone, Ymr, Zm_r, 1},
}
......@@ -725,6 +731,10 @@ var ymskb = []ytab{
{Ymr, Ynone, Yrl, Zm_r_xm, 1},
}
var ymskb_vex = []ytab{
{Yxr, Ynone, Yrl, Zm_r_xm_vex, 2},
}
var ycrc32l = []ytab{
{Yml, Ynone, Yrl, Zlitm_r, 0},
}
......@@ -1497,6 +1507,8 @@ var optab =
{AMOVHDU, yxmov_vex, Pvex2, [23]uint8{0x6f, 0x7f}},
{AMOVNTHD, yxr_ml_vex, Pvex1, [23]uint8{0xe7}},
{AMOVHDA, yxmov_vex, Pvex1, [23]uint8{0x6f, 0x7f}},
{AVPCMPEQB, yxm_xm_xm, Pvex1, [23]uint8{0x74, 0x74}},
{AVPMOVMSKB, ymskb_vex, Pvex1, [23]uint8{0xd7}},
{obj.AUSEFIELD, ynop, Px, [23]uint8{0, 0}},
{obj.ATYPE, nil, 0, [23]uint8{}},
{obj.AFUNCDATA, yfuncdata, Px, [23]uint8{0, 0}},
......@@ -2943,11 +2955,15 @@ var bpduff2 = []byte{
0x48, 0x8b, 0x6d, 0x00, // MOVQ 0(BP), BP
}
func vexprefix(ctxt *obj.Link, to *obj.Addr, from *obj.Addr, pref uint8) {
// Assemble vex prefix, from 3 operands and prefix.
// For details about vex prefix see:
// https://en.wikipedia.org/wiki/VEX_prefix#Technical_description
func vexprefix(ctxt *obj.Link, to *obj.Addr, from *obj.Addr, from3 *obj.Addr, pref uint8) {
rexR := regrex[to.Reg]
rexB := regrex[from.Reg]
rexX := regrex[from.Index]
var prefBit uint8
// This will go into VEX.PP field.
if pref == Pvex1 {
prefBit = 1
} else if pref == Pvex2 {
......@@ -2955,21 +2971,36 @@ func vexprefix(ctxt *obj.Link, to *obj.Addr, from *obj.Addr, pref uint8) {
} // TODO add Pvex0,Pvex3
if rexX == 0 && rexB == 0 { // 2-byte vex prefix
// In 2-byte case, first byte is always C5
ctxt.Andptr[0] = 0xc5
ctxt.Andptr = ctxt.Andptr[1:]
if rexR != 0 {
if from3 == nil {
// If this is a 2-operand instruction fill VEX.VVVV with 1111
// We are also interested only in 256-bit version, so VEX.L=1
ctxt.Andptr[0] = 0x7c
} else {
ctxt.Andptr[0] = 0xfc
// VEX.L=1
ctxt.Andptr[0] = 0x4
// VEX.VVVV (bits 3:6) is a inversed register number
ctxt.Andptr[0] |= byte((^(from3.Reg - REG_X0))<<3) & 0x78
}
// VEX encodes REX.R as inversed upper bit
if rexR == 0 {
ctxt.Andptr[0] |= 0x80
}
ctxt.Andptr[0] |= prefBit
ctxt.Andptr = ctxt.Andptr[1:]
} else {
} else { // 3-byte case
// First byte is always C$
ctxt.Andptr[0] = 0xc4
ctxt.Andptr = ctxt.Andptr[1:]
// Encode VEX.mmmmm with prefix value, for now assume 0F 38,
// which encodes as 1.
ctxt.Andptr[0] = 0x1 // TODO handle different prefix
// REX.[RXB] are inverted and encoded in 3 upper bits
if rexR == 0 {
ctxt.Andptr[0] |= 0x80
}
......@@ -2981,7 +3012,13 @@ func vexprefix(ctxt *obj.Link, to *obj.Addr, from *obj.Addr, pref uint8) {
}
ctxt.Andptr = ctxt.Andptr[1:]
// Fill VEX.VVVV, same as 2-operand VEX instruction.
if from3 == nil {
ctxt.Andptr[0] = 0x7c
} else {
ctxt.Andptr[0] = 0x4
ctxt.Andptr[0] |= byte((^(from3.Reg - REG_X0))<<3) & 0x78
}
ctxt.Andptr[0] |= prefBit
ctxt.Andptr = ctxt.Andptr[1:]
}
......@@ -3222,7 +3259,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
case Zm_r_xm_vex:
ctxt.Vexflag = 1
vexprefix(ctxt, &p.To, &p.From, o.prefix)
vexprefix(ctxt, &p.To, &p.From, nil, o.prefix)
ctxt.Andptr[0] = byte(op)
ctxt.Andptr = ctxt.Andptr[1:]
asmand(ctxt, p, &p.From, &p.To)
......@@ -3284,11 +3321,18 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
case Zr_m_xm_vex:
ctxt.Vexflag = 1
vexprefix(ctxt, &p.From, &p.To, o.prefix)
vexprefix(ctxt, &p.From, &p.To, nil, o.prefix)
ctxt.Andptr[0] = byte(op)
ctxt.Andptr = ctxt.Andptr[1:]
asmand(ctxt, p, &p.To, &p.From)
case Zr_r_r_vex:
ctxt.Vexflag = 1
vexprefix(ctxt, &p.To, &p.From, p.From3, o.prefix)
ctxt.Andptr[0] = byte(op)
ctxt.Andptr = ctxt.Andptr[1:]
asmand(ctxt, p, &p.From, &p.To)
case Zr_m_xm:
mediaop(ctxt, o, op, int(yt.zoffset), z)
asmand(ctxt, p, &p.To, &p.From)
......
src/runtime/asm_amd64.s
View file @ 0e23ca41
......@@ -42,11 +42,37 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
JNE notintel
MOVB $1, runtime·lfenceBeforeRdtsc(SB)
notintel:
// Do nothing.
MOVQ $1, AX
CPUID
MOVL CX, runtime·cpuid_ecx(SB)
MOVL DX, runtime·cpuid_edx(SB)
// Detect AVX and AVX2 as per 14.7.1 Detection of AVX2 chapter of [1]
// [1] 64-ia-32-architectures-software-developer-manual-325462.pdf
// http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf
ANDL $0x18000000, CX // check for OSXSAVE and AVX bits
CMPL CX, $0x18000000
JNE noavx
MOVL $0, CX
// For XGETBV, OSXSAVE bit is required and sufficient
BYTE $0x0F; BYTE $0x01; BYTE $0xD0
ANDL $6, AX
CMPL AX, $6 // Check for OS support of YMM registers
JNE noavx
MOVB $1, runtime·support_avx(SB)
MOVL $7, AX
MOVL $0, CX
CPUID
ANDL $0x20, BX // check for AVX2 bit
CMPL BX, $0x20
JNE noavx2
MOVB $1, runtime·support_avx2(SB)
JMP nocpuinfo
noavx:
MOVB $0, runtime·support_avx(SB)
noavx2:
MOVB $0, runtime·support_avx2(SB)
nocpuinfo:
// if there is an _cgo_init, call it.
......@@ -1508,7 +1534,10 @@ TEXT runtime·cmpbody(SB),NOSPLIT,$0-0
JB small
CMPQ R8, $63
JA big_loop
JBE loop
CMPB runtime·support_avx2(SB), $1
JEQ big_loop_avx2
JMP big_loop
loop:
CMPQ R8, $16
JBE _0through16
......@@ -1657,6 +1686,45 @@ big_loop:
JBE loop
JMP big_loop
// Compare 64-bytes per loop iteration.
// Loop is unrolled and uses AVX2.
big_loop_avx2:
MOVHDU (SI), X2
MOVHDU (DI), X3
MOVHDU 32(SI), X4
MOVHDU 32(DI), X5
VPCMPEQB X2, X3, X0
VPMOVMSKB X0, AX
XORL $0xffffffff, AX
JNE diff32_avx2
VPCMPEQB X4, X5, X6
VPMOVMSKB X6, AX
XORL $0xffffffff, AX
JNE diff64_avx2
ADDQ $64, SI
ADDQ $64, DI
SUBQ $64, R8
CMPQ R8, $64
JB big_loop_avx2_exit
JMP big_loop_avx2
// Avoid AVX->SSE transition penalty and search first 32 bytes of 64 byte chunk.
diff32_avx2:
VZEROUPPER
JMP diff16
// Same as diff32_avx2, but for last 32 bytes.
diff64_avx2:
VZEROUPPER
JMP diff48
// For <64 bytes remainder jump to normal loop.
big_loop_avx2_exit:
VZEROUPPER
JMP loop
TEXT bytes·IndexByte(SB),NOSPLIT,$0-40
MOVQ s+0(FP), SI
MOVQ s_len+8(FP), BX
......
src/runtime/runtime2.go
View file @ 0e23ca41
......@@ -627,6 +627,8 @@ var (
cpuid_ecx uint32
cpuid_edx uint32
lfenceBeforeRdtsc bool
support_avx bool
support_avx2 bool
goarm uint8 // set by cmd/link on arm systems
)
......
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