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bytes: add asm implementation for index on ppc64x

This adds an asm implementation of index on ppc64le and
ppc64. It results in a significant improvement in some
of the benchmarks that use bytes.Index.

The implementation is based on a port of the s390x asm
implementation. Comments on the design are found
with the code.

The following improvements occurred on power8:

Index/10       70.7ns ± 0%    18.8ns ± 0%   -73.4
Index/32        165ns ± 0%      95ns ± 0%   -42.6
Index/4K       9.23µs ± 0%    4.91µs ± 0%   -46
Index/4M       9.52ms ± 0%    5.10ms ± 0%   -46.4
Index/64M       155ms ± 0%      85ms ± 0%   -45.1

Count/10       83.0ns ± 0%    32.1ns ± 0%   -61.3
Count/32        178ns ± 0%     109ns ± 0%   -38.8
Count/4K       9.24µs ± 0%    4.93µs ± 0%   -46
Count/4M       9.52ms ± 0%    5.10ms ± 0%   -46.4
Count/64M       155ms ± 0%      85ms ± 0%   -45.1

IndexHard1     2.36ms ± 0%    0.13ms ± 0%   -94.4
IndexHard2     2.36ms ± 0%    1.28ms ± 0%   -45.8
IndexHard3     2.36ms ± 0%    1.19ms ± 0%   -49.4
IndexHard4     2.36ms ± 0%    2.35ms ± 0%    -0.1

CountHard1     2.36ms ± 0%    0.13ms ± 0%   -94.4
CountHard2     2.36ms ± 0%    1.28ms ± 0%   -45.8
CountHard3     2.36ms ± 0%    1.19ms ± 0%   -49.4

IndexPeriodic/IndexPeriodic2  146µs ± 0%       8µs ± 0%   -94
IndexPeriodic/IndexPeriodic4  146µs ± 0%       8µs ± 0%   -94

Change-Id: I7dd2bb7e278726e27f51825ca8b2f8317d460e60
Reviewed-on: https://go-review.googlesource.com/c/go/+/309730
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Reviewed-by: Carlos Eduardo Seo <carlos.seo@linaro.org>
Trust: Carlos Eduardo Seo <carlos.seo@linaro.org>
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>
This commit is contained in:
Lynn Boger 2021-03-15 16:36:47 -05:00
parent 5631c4b3bf
commit 8009a81f7a
4 changed files with 452 additions and 4 deletions

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@ -2,8 +2,9 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build !amd64 && !arm64 && !s390x
// +build !amd64,!arm64,!s390x
// go:build !amd64 && !arm64 && !s390x && !ppc64le && !ppc64
//go:build !amd64 && !arm64 && !s390x && !ppc64le && !ppc64
// +build !amd64,!arm64,!s390x,!ppc64le,!ppc64
package bytealg

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@ -2,8 +2,9 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build amd64 || arm64 || s390x
// +build amd64 arm64 s390x
// go:build amd64 || arm64 || s390x || ppc64le || ppc64
//go:build amd64 || arm64 || s390x || ppc64le || ppc64
// +build amd64 arm64 s390x ppc64le ppc64
package bytealg

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// Copyright 2021 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.
//go:build (aix || linux) && (ppc64 || ppc64le)
// +build aix linux
// +build ppc64 ppc64le
package bytealg
const MaxBruteForce = 16
func init() {
MaxLen = 32
}
// Cutover reports the number of failures of IndexByte we should tolerate
// before switching over to Index.
// n is the number of bytes processed so far.
// See the bytes.Index implementation for details.
func Cutover(n int) int {
// 1 error per 8 characters, plus a few slop to start.
return (n + 16) / 8
}

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// Copyright 2021 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.
// This is an implementation based on the s390x
// implementation.
// Find a separator with 2 <= len <= 32 within a string.
// Separators with lengths of 2, 3 or 4 are handled
// specially.
// This works on power8 and above. The loads and
// compares are done in big endian order
// since that allows the used of VCLZD, and allows
// the same implementation to work on big and little
// endian platforms with minimal conditional changes.
// NOTE: There is a power9 implementation that
// improves performance by 10-15% on little
// endian for some of the benchmarks, but
// work is still needed for a big endian
// implementation on power9.
// +build ppc64 ppc64le
#include "go_asm.h"
#include "textflag.h"
// Needed to swap LXVD2X loads to the correct
// byte order to work on POWER8.
#ifdef GOARCH_ppc64
DATA byteswap<>+0(SB)/8, $0x0001020304050607
DATA byteswap<>+8(SB)/8, $0x08090a0b0c0d0e0f
#else
DATA byteswap<>+0(SB)/8, $0x0706050403020100
DATA byteswap<>+8(SB)/8, $0x0f0e0d0c0b0a0908
#endif
// Load bytes in big endian order. Address
// alignment does not need checking.
#define VLOADSWAP(base, index, vreg, vsreg) \
LXVD2X (base)(index), vsreg; \
VPERM vreg, vreg, SWAP, vreg
GLOBL byteswap<>+0(SB), RODATA, $16
TEXT ·Index(SB), NOSPLIT|NOFRAME, $0-56
MOVD a_base+0(FP), R3 // R3 = byte array pointer
MOVD a_len+8(FP), R4 // R4 = length
MOVD b_base+24(FP), R5 // R5 = separator pointer
MOVD b_len+32(FP), R6 // R6 = separator length
MOVD $ret+48(FP), R14 // R14 = &ret
BR indexbody<>(SB)
TEXT ·IndexString(SB), NOSPLIT|NOFRAME, $0-40
MOVD a_base+0(FP), R3 // R3 = string
MOVD a_len+8(FP), R4 // R4 = length
MOVD b_base+16(FP), R5 // R5 = separator pointer
MOVD b_len+24(FP), R6 // R6 = separator length
MOVD $ret+32(FP), R14 // R14 = &ret
BR indexbody<>(SB)
// s: string we are searching
// sep: string to search for
// R3=&s[0], R4=len(s)
// R5=&sep[0], R6=len(sep)
// R14=&ret (index where sep found)
// R7=working addr of string
// R16=index value 16
// R17=index value 17
// R18=index value 18
// R19=index value 1
// R26=LASTBYTE of string
// R27=LASTSTR last start byte to compare with sep
// R8, R9 scratch
// V0=sep left justified zero fill
// CR4=sep length >= 16
#define SEPMASK V17
#define LASTBYTE R26
#define LASTSTR R27
#define ONES V20
#define SWAP V21
#define V0_ VS32
#define V1_ VS33
#define V2_ VS34
#define V3_ VS35
#define V4_ VS36
#define V5_ VS37
#define V6_ VS38
#define V7_ VS39
#define V8_ VS40
#define V9_ VS41
#define SWAP_ VS53
TEXT indexbody<>(SB), NOSPLIT|NOFRAME, $0
CMP R6, R4 // Compare lengths
BGT notfound // If sep len is > string, notfound
ADD R4, R3, LASTBYTE // find last byte addr
SUB R6, LASTBYTE, LASTSTR // LAST=&s[len(s)-len(sep)] (last valid start index)
CMP R6, $0 // Check sep len
BEQ notfound // sep len 0 -- not found
MOVD R3, R7 // Copy of string addr
MOVD $16, R16 // Index value 16
MOVD $17, R17 // Index value 17
MOVD $18, R18 // Index value 18
MOVD $1, R19 // Index value 1
MOVD $byteswap<>+00(SB), R8
VSPLTISB $0xFF, ONES // splat all 1s
LXVD2X (R8)(R0), SWAP_ // Set up swap string
CMP R6, $16, CR4 // CR4 for len(sep) >= 16
VOR ONES, ONES, SEPMASK // Set up full SEPMASK
BGE CR4, loadge16 // Load for len(sep) >= 16
SUB R6, R16, R9 // 16-len of sep
SLD $3, R9 // Set up for VSLO
MTVSRD R9, V9_ // Set up for VSLO
VSLDOI $8, V9, V9, V9 // Set up for VSLO
VSLO ONES, V9, SEPMASK // Mask for separator len(sep) < 16
loadge16:
ANDCC $15, R5, R9 // Find byte offset of sep
ADD R9, R6, R10 // Add sep len
CMP R10, $16 // Check if sep len+offset > 16
BGE sepcross16 // Sep crosses 16 byte boundary
RLDICR $0, R5, $59, R8 // Adjust addr to 16 byte container
VLOADSWAP(R8, R0, V0, V0_)// Load 16 bytes @R8 into V0
SLD $3, R9 // Set up shift count for VSLO
MTVSRD R9, V8_ // Set up shift count for VSLO
VSLDOI $8, V8, V8, V8
VSLO V0, V8, V0 // Shift by start byte
VAND V0, SEPMASK, V0 // Mask separator (< 16)
BR index2plus
sepcross16:
VLOADSWAP(R5, R0, V0, V0_) // Load 16 bytes @R5 into V0
VAND V0, SEPMASK, V0 // mask out separator
BLE CR4, index2to16
BR index17plus // Handle sep > 16
index2plus:
CMP R6, $2 // Check length of sep
BNE index3plus // If not 2, check for 3
ADD $16, R7, R9 // Check if next 16 bytes past last
CMP R9, LASTBYTE // compare with last
BGE index2to16 // 2 <= len(string) <= 16
MOVD $0xff00, R21 // Mask for later
MTVSRD R21, V25 // Move to Vreg
VSPLTH $3, V25, V31 // Splat mask
VSPLTH $0, V0, V1 // Splat 1st 2 bytes of sep
VSPLTISB $0, V10 // Clear V10
// First case: 2 byte separator
// V1: 2 byte separator splatted
// V2: 16 bytes at addr
// V4: 16 bytes at addr+1
// Compare 2 byte separator at start
// and at start+1. Use VSEL to combine
// those results to find the first
// matching start byte, returning
// that value when found. Loop as
// long as len(string) > 16
index2loop2:
VLOADSWAP(R7, R19, V3, V3_) // Load 16 bytes @R7+1 into V3
index2loop:
VLOADSWAP(R7, R0, V2, V2_) // Load 16 bytes @R7 into V2
VCMPEQUH V1, V2, V5 // Search for sep
VCMPEQUH V1, V3, V6 // Search for sep offset by 1
VSEL V6, V5, V31, V7 // merge even and odd indices
VCLZD V7, V18 // find index of first match
MFVSRD V18, R25 // get first value
CMP R25, $64 // Found if < 64
BLT foundR25 // Return byte index where found
VSLDOI $8, V18, V18, V18 // Adjust 2nd value
MFVSRD V18, R25 // get second value
CMP R25, $64 // Found if < 64
ADD $64, R25 // Update byte offset
BLT foundR25 // Return value
ADD $16, R7 // R7+=16 Update string pointer
ADD $17, R7, R9 // R9=F7+17 since loop unrolled
CMP R9, LASTBYTE // Compare addr+17 against last byte
BLT index2loop2 // If < last, continue loop
CMP R7, LASTBYTE // Compare addr+16 against last byte
BLT index2to16 // If < 16 handle specially
VLOADSWAP(R7, R0, V3, V3_) // Load 16 bytes @R7 into V3
VSLDOI $1, V3, V10, V3 // Shift left by 1 byte
BR index2loop
index3plus:
CMP R6, $3 // Check if sep == 3
BNE index4plus // If not check larger
ADD $19, R7, R9 // Find bytes for use in this loop
CMP R9, LASTBYTE // Compare against last byte
BGE index2to16 // Remaining string 2<=len<=16
MOVD $0xff00, R21 // Set up mask for upcoming loop
MTVSRD R21, V25 // Move mask to Vreg
VSPLTH $3, V25, V31 // Splat mask
VSPLTH $0, V0, V1 // Splat 1st two bytes of sep
VSPLTB $2, V0, V8 // Splat 3rd byte of sep
// Loop to process 3 byte separator.
// string[0:16] is in V2
// string[2:18] is in V3
// sep[0:2] splatted in V1
// sec[3] splatted in v8
// Load vectors at string, string+1
// and string+2. Compare string, string+1
// against first 2 bytes of separator
// splatted, and string+2 against 3rd
// byte splatted. Merge the results with
// VSEL to find the first byte of a match.
// Special handling for last 16 bytes if the
// string fits in 16 byte multiple.
index3loop2:
MOVD $2, R21 // Set up index for 2
VSPLTISB $0, V10 // Clear V10
VLOADSWAP(R7, R21, V3, V3_)// Load 16 bytes @R7+2 into V3
VSLDOI $14, V3, V10, V3 // Left justify next 2 bytes
index3loop:
VLOADSWAP(R7, R0, V2, V2_) // Load with correct order
VSLDOI $1, V2, V3, V4 // string[1:17]
VSLDOI $2, V2, V3, V9 // string[2:18]
VCMPEQUH V1, V2, V5 // compare hw even indices
VCMPEQUH V1, V4, V6 // compare hw odd indices
VCMPEQUB V8, V9, V10 // compare 3rd to last byte
VSEL V6, V5, V31, V7 // Find 1st matching byte using mask
VAND V7, V10, V7 // AND matched bytes with matched 3rd byte
VCLZD V7, V18 // Find first nonzero indexes
MFVSRD V18, R25 // Move 1st doubleword
CMP R25, $64 // If < 64 found
BLT foundR25 // Return matching index
VSLDOI $8, V18, V18, V18 // Move value
MFVSRD V18, R25 // Move 2nd doubleword
CMP R25, $64 // If < 64 found
ADD $64, R25 // Update byte index
BLT foundR25 // Return matching index
ADD $16, R7 // R7+=16 string ptr
ADD $19, R7, R9 // Number of string bytes for loop
CMP R9, LASTBYTE // Compare against last byte of string
BLT index3loop2 // If within, continue this loop
CMP R7, LASTSTR // Compare against last start byte
BLT index2to16 // Process remainder
VSPLTISB $0, V3 // Special case for last 16 bytes
BR index3loop // Continue this loop
// Loop to process 4 byte separator
// string[0:16] in V2
// string[3:16] in V3
// sep[0:4] splatted in V1
// Set up vectors with strings at offsets
// 0, 1, 2, 3 and compare against the 4 byte
// separator also splatted. Use VSEL with the
// compare results to find the first byte where
// a separator match is found.
index4plus:
CMP R6, $4 // Check if 4 byte separator
BNE index5plus // If not next higher
ADD $20, R7, R9 // Check string size to load
CMP R9, LASTBYTE // Verify string length
BGE index2to16 // If not large enough, process remaining
MOVD $2, R15 // Set up index
// Set up masks for use with VSEL
MOVD $0xff, R21 // Set up mask 0xff000000ff000000...
SLD $24, R21
MTVSRD R21, V10
VSPLTW $1, V10, V29
VSLDOI $2, V29, V29, V30 // Mask 0x0000ff000000ff00...
MOVD $0xffff, R21
SLD $16, R21
MTVSRD R21, V10
VSPLTW $1, V10, V31 // Mask 0xffff0000ffff0000...
VSPLTW $0, V0, V1 // Splat 1st word of separator
index4loop:
VLOADSWAP(R7, R0, V2, V2_) // Load 16 bytes @R7 into V2
next4:
VSPLTISB $0, V10 // Clear
MOVD $3, R9 // Number of bytes beyond 16
VLOADSWAP(R7, R9, V3, V3_) // Load 16 bytes @R7+3 into V3
VSLDOI $13, V3, V10, V3 // Shift left last 3 bytes
VSLDOI $1, V2, V3, V4 // V4=(V2:V3)<<1
VSLDOI $2, V2, V3, V9 // V9=(V2:V3)<<2
VSLDOI $3, V2, V3, V10 // V10=(V2:v3)<<3
VCMPEQUW V1, V2, V5 // compare index 0, 4, ... with sep
VCMPEQUW V1, V4, V6 // compare index 1, 5, ... with sep
VCMPEQUW V1, V9, V11 // compare index 2, 6, ... with sep
VCMPEQUW V1, V10, V12 // compare index 3, 7, ... with sep
VSEL V6, V5, V29, V13 // merge index 0, 1, 4, 5, using mask
VSEL V12, V11, V30, V14 // merge index 2, 3, 6, 7, using mask
VSEL V14, V13, V31, V7 // final merge
VCLZD V7, V18 // Find first index for each half
MFVSRD V18, R25 // Isolate value
CMP R25, $64 // If < 64, found
BLT foundR25 // Return found index
VSLDOI $8, V18, V18, V18 // Move for MFVSRD
MFVSRD V18, R25 // Isolate other value
CMP R25, $64 // If < 64, found
ADD $64, R25 // Update index for high doubleword
BLT foundR25 // Return found index
ADD $16, R7 // R7+=16 for next string
ADD $20, R7, R9 // R+20 for all bytes to load
CMP R9, LASTBYTE // Past end? Maybe check for extra?
BLT index4loop // If not, continue loop
CMP R7, LASTSTR // Check remainder
BLE index2to16 // Process remainder
BR notfound // Not found
index5plus:
CMP R6, $16 // Check for sep > 16
BGT index17plus // Handle large sep
// Assumption is that the separator is smaller than the string at this point
index2to16:
CMP R7, LASTSTR // Compare last start byte
BGT notfound // last takes len(sep) into account
ADD $16, R7, R9 // Check for last byte of string
CMP R9, LASTBYTE
BGT index2to16tail
// At least 16 bytes of string left
// Mask the number of bytes in sep
index2to16loop:
VLOADSWAP(R7, R0, V1, V1_) // Load 16 bytes @R7 into V1
compare:
VAND V1, SEPMASK, V2 // Mask out sep size
VCMPEQUBCC V0, V2, V3 // Compare masked string
BLT CR6, found // All equal
ADD $1, R7 // Update ptr to next byte
CMP R7, LASTSTR // Still less than last start byte
BGT notfound // Not found
ADD $16, R7, R9 // Verify remaining bytes
CMP R9, LASTBYTE // At least 16
BLT index2to16loop // Try again
// Less than 16 bytes remaining in string
// Separator >= 2
index2to16tail:
ADD R3, R4, R9 // End of string
SUB R7, R9, R9 // Number of bytes left
ANDCC $15, R7, R10 // 16 byte offset
ADD R10, R9, R11 // offset + len
CMP R11, $16 // >= 16?
BLE short // Does not cross 16 bytes
VLOADSWAP(R7, R0, V1, V1_)// Load 16 bytes @R7 into V1
BR index2to16next // Continue on
short:
RLDICR $0, R7, $59, R9 // Adjust addr to 16 byte container
VLOADSWAP(R9, R0, V1, V1_)// Load 16 bytes @R9 into V1
SLD $3, R10 // Set up shift
MTVSRD R10, V8_ // Set up shift
VSLDOI $8, V8, V8, V8
VSLO V1, V8, V1 // Shift by start byte
VSPLTISB $0, V25 // Clear for later use
index2to16next:
VAND V1, SEPMASK, V2 // Just compare size of sep
VCMPEQUBCC V0, V2, V3 // Compare sep and partial string
BLT CR6, found // Found
ADD $1, R7 // Not found, try next partial string
CMP R7, LASTSTR // Check for end of string
BGT notfound // If at end, then not found
VSLDOI $1, V1, V25, V1 // Shift string left by 1 byte
BR index2to16next // Check the next partial string
index17plus:
CMP R6, $32 // Check if 17 < len(sep) <= 32
BGT index33plus
SUB $16, R6, R9 // Extra > 16
SLD $56, R9, R10 // Shift to use in VSLO
MTVSRD R10, V9_ // Set up for VSLO
VLOADSWAP(R5, R9, V1, V1_)// Load 16 bytes @R5+R9 into V1
VSLO V1, V9, V1 // Shift left
VSPLTISB $0xff, V7 // Splat 1s
VSPLTISB $0, V27 // Splat 0
index17to32loop:
VLOADSWAP(R7, R0, V2, V2_) // Load 16 bytes @R7 into V2
next17:
VLOADSWAP(R7, R9, V3, V3_) // Load 16 bytes @R7+R9 into V3
VSLO V3, V9, V3 // Shift left
VCMPEQUB V0, V2, V4 // Compare first 16 bytes
VCMPEQUB V1, V3, V5 // Compare extra over 16 bytes
VAND V4, V5, V6 // Check if both equal
VCMPEQUBCC V6, V7, V8 // All equal?
BLT CR6, found // Yes
ADD $1, R7 // On to next byte
CMP R7, LASTSTR // Check if last start byte
BGT notfound // If too high, not found
BR index17to32loop // Continue
notfound:
MOVD $-1, R8 // Return -1 if not found
MOVD R8, (R14)
RET
index33plus:
MOVD $0, (R0) // Case not implemented
RET // Crash before return
foundR25:
SRD $3, R25 // Convert from bits to bytes
ADD R25, R7 // Add to current string address
SUB R3, R7 // Subtract from start of string
MOVD R7, (R14) // Return byte where found
RET
found:
SUB R3, R7 // Return byte where found
MOVD R7, (R14)
RET