// 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.
// +build ppc64 ppc64le
#include "go_asm.h"
#include "textflag.h"
TEXT ·IndexByte(SB),NOSPLIT|NOFRAME,$0-40
MOVD b_base+0(FP), R3 // R3 = byte array pointer
MOVD b_len+8(FP), R4 // R4 = length
MOVBZ c+24(FP), R5 // R5 = byte
MOVD $ret+32(FP), R14 // R14 = &ret
BR indexbytebody<>(SB)
TEXT ·IndexByteString(SB),NOSPLIT|NOFRAME,$0-32
MOVD s_base+0(FP), R3 // R3 = string
MOVD s_len+8(FP), R4 // R4 = length
MOVBZ c+16(FP), R5 // R5 = byte
MOVD $ret+24(FP), R14 // R14 = &ret
BR indexbytebody<>(SB)
TEXT indexbytebody<>(SB),NOSPLIT|NOFRAME,$0-0
MOVD R3,R17 // Save base address for calculating the index later.
RLDICR $0,R3,$60,R8 // Align address to doubleword boundary in R8.
RLDIMI $8,R5,$48,R5 // Replicating the byte across the register.
ADD R4,R3,R7 // Last acceptable address in R7.
DCBT (R8) // Prepare cache line.
RLDIMI $16,R5,$32,R5
CMPU R4,$32 // Check if it's a small string (≤32 bytes). Those will be processed differently.
MOVD $-1,R9
WORD $0x54661EB8 // Calculate padding in R6 (rlwinm r6,r3,3,26,28).
RLDIMI $32,R5,$0,R5
MOVD R7,R10 // Save last acceptable address in R10 for later.
ADD $-1,R7,R7
#ifdef GOARCH_ppc64le
SLD R6,R9,R9 // Prepare mask for Little Endian
#else
SRD R6,R9,R9 // Same for Big Endian
#endif
BLE small_string // Jump to the small string case if it's ≤32 bytes.
// If we are 64-byte aligned, branch to qw_align just to get the auxiliary values
// in V0, V1 and V10, then branch to the preloop.
ANDCC $63,R3,R11
BEQ CR0,qw_align
RLDICL $0,R3,$61,R11
MOVD 0(R8),R12 // Load one doubleword from the aligned address in R8.
CMPB R12,R5,R3 // Check for a match.
AND R9,R3,R3 // Mask bytes below s_base
RLDICL $0,R7,$61,R6 // length-1
RLDICR $0,R7,$60,R7 // Last doubleword in R7
CMPU R3,$0,CR7 // If we have a match, jump to the final computation
BNE CR7,done
ADD $8,R8,R8
ADD $-8,R4,R4
ADD R4,R11,R4
// Check for quadword alignment
ANDCC $15,R8,R11
BEQ CR0,qw_align
// Not aligned, so handle the next doubleword
MOVD 0(R8),R12
CMPB R12,R5,R3
CMPU R3,$0,CR7
BNE CR7,done
ADD $8,R8,R8
ADD $-8,R4,R4
// Either quadword aligned or 64-byte at this point. We can use LVX.
qw_align:
// Set up auxiliary data for the vectorized algorithm.
VSPLTISB $0,V0 // Replicate 0 across V0
VSPLTISB $3,V10 // Use V10 as control for VBPERMQ
MTVRD R5,V1
LVSL (R0+R0),V11
VSLB V11,V10,V10
VSPLTB $7,V1,V1 // Replicate byte across V1
CMPU R4, $64 // If len ≤ 64, don't use the vectorized loop
BLE tail
// We will load 4 quardwords per iteration in the loop, so check for
// 64-byte alignment. If 64-byte aligned, then branch to the preloop.
ANDCC $63,R8,R11
BEQ CR0,preloop
// Not 64-byte aligned. Load one quadword at a time until aligned.
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6 // Check for byte in V4
BNE CR6,found_qw_align
ADD $16,R8,R8
ADD $-16,R4,R4
ANDCC $63,R8,R11
BEQ CR0,preloop
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6 // Check for byte in V4
BNE CR6,found_qw_align
ADD $16,R8,R8
ADD $-16,R4,R4
ANDCC $63,R8,R11
BEQ CR0,preloop
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6 // Check for byte in V4
BNE CR6,found_qw_align
ADD $-16,R4,R4
ADD $16,R8,R8
// 64-byte aligned. Prepare for the main loop.
preloop:
CMPU R4,$64
BLE tail // If len ≤ 64, don't use the vectorized loop
// We are now aligned to a 64-byte boundary. We will load 4 quadwords
// per loop iteration. The last doubleword is in R10, so our loop counter
// starts at (R10-R8)/64.
SUB R8,R10,R6
SRD $6,R6,R9 // Loop counter in R9
MOVD R9,CTR
ADD $-64,R8,R8 // Adjust index for loop entry
MOVD $16,R11 // Load offsets for the vector loads
MOVD $32,R9
MOVD $48,R7
// Main loop we will load 64 bytes per iteration
loop:
ADD $64,R8,R8 // Fuse addi+lvx for performance
LVX (R8+R0),V2 // Load 4 16-byte vectors
LVX (R8+R11),V3
VCMPEQUB V1,V2,V6 // Look for byte in each vector
VCMPEQUB V1,V3,V7
LVX (R8+R9),V4
LVX (R8+R7),V5
VCMPEQUB V1,V4,V8
VCMPEQUB V1,V5,V9
VOR V6,V7,V11 // Compress the result in a single vector
VOR V8,V9,V12
VOR V11,V12,V13
VCMPEQUBCC V0,V13,V14 // Check for byte
BGE CR6,found
BC 16,0,loop // bdnz loop
// Handle the tailing bytes or R4 ≤ 64
RLDICL $0,R6,$58,R4
ADD $64,R8,R8
tail:
CMPU R4,$0
BEQ notfound
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6
BNE CR6,found_qw_align
ADD $16,R8,R8
CMPU R4,$16,CR6
BLE CR6,notfound
ADD $-16,R4,R4
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6
BNE CR6,found_qw_align
ADD $16,R8,R8
CMPU R4,$16,CR6
BLE CR6,notfound
ADD $-16,R4,R4
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6
BNE CR6,found_qw_align
ADD $16,R8,R8
CMPU R4,$16,CR6
BLE CR6,notfound
ADD $-16,R4,R4
LVX (R8+R0),V4
VCMPEQUBCC V1,V4,V6
BNE CR6,found_qw_align
notfound:
MOVD $-1,R3
MOVD R3,(R14)
RET
found:
// We will now compress the results into a single doubleword,
// so it can be moved to a GPR for the final index calculation.
// The bytes in V6-V9 are either 0x00 or 0xFF. So, permute the
// first bit of each byte into bits 48-63.
VBPERMQ V6,V10,V6
VBPERMQ V7,V10,V7
VBPERMQ V8,V10,V8
VBPERMQ V9,V10,V9
// Shift each 16-bit component into its correct position for
// merging into a single doubleword.
#ifdef GOARCH_ppc64le
VSLDOI $2,V7,V7,V7
VSLDOI $4,V8,V8,V8
VSLDOI $6,V9,V9,V9
#else
VSLDOI $6,V6,V6,V6
VSLDOI $4,V7,V7,V7
VSLDOI $2,V8,V8,V8
#endif
// Merge V6-V9 into a single doubleword and move to a GPR.
VOR V6,V7,V11
VOR V8,V9,V4
VOR V4,V11,V4
MFVRD V4,R3
#ifdef GOARCH_ppc64le
ADD $-1,R3,R11
ANDN R3,R11,R11
POPCNTD R11,R11 // Count trailing zeros (Little Endian).
#else
CNTLZD R3,R11 // Count leading zeros (Big Endian).
#endif
ADD R8,R11,R3 // Calculate byte address
return:
SUB R17,R3
MOVD R3,(R14)
RET
found_qw_align:
// Use the same algorithm as above. Compress the result into
// a single doubleword and move it to a GPR for the final
// calculation.
VBPERMQ V6,V10,V6
#ifdef GOARCH_ppc64le
MFVRD V6,R3
ADD $-1,R3,R11
ANDN R3,R11,R11
POPCNTD R11,R11
#else
VSLDOI $6,V6,V6,V6
MFVRD V6,R3
CNTLZD R3,R11
#endif
ADD R8,R11,R3
CMPU R11,R4
BLT return
BR notfound
done:
// At this point, R3 has 0xFF in the same position as the byte we are
// looking for in the doubleword. Use that to calculate the exact index
// of the byte.
#ifdef GOARCH_ppc64le
ADD $-1,R3,R11
ANDN R3,R11,R11
POPCNTD R11,R11 // Count trailing zeros (Little Endian).
#else
CNTLZD R3,R11 // Count leading zeros (Big Endian).
#endif
CMPU R8,R7 // Check if we are at the last doubleword.
SRD $3,R11 // Convert trailing zeros to bytes.
ADD R11,R8,R3
CMPU R11,R6,CR7 // If at the last doubleword, check the byte offset.
BNE return
BLE CR7,return
BR notfound
small_string:
// We unroll this loop for better performance.
CMPU R4,$0 // Check for length=0
BEQ notfound
MOVD 0(R8),R12 // Load one doubleword from the aligned address in R8.
CMPB R12,R5,R3 // Check for a match.
AND R9,R3,R3 // Mask bytes below s_base.
CMPU R3,$0,CR7 // If we have a match, jump to the final computation.
RLDICL $0,R7,$61,R6 // length-1
RLDICR $0,R7,$60,R7 // Last doubleword in R7.
CMPU R8,R7
BNE CR7,done
BEQ notfound // Hit length.
MOVDU 8(R8),R12
CMPB R12,R5,R3
CMPU R3,$0,CR6
CMPU R8,R7
BNE CR6,done
BEQ notfound
MOVDU 8(R8),R12
CMPB R12,R5,R3
CMPU R3,$0,CR6
CMPU R8,R7
BNE CR6,done
BEQ notfound
MOVDU 8(R8),R12
CMPB R12,R5,R3
CMPU R3,$0,CR6
CMPU R8,R7
BNE CR6,done
BEQ notfound
MOVDU 8(R8),R12
CMPB R12,R5,R3
CMPU R3,$0,CR6
BNE CR6,done
BR notfound
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