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// Copyright ©2016 The Gonum 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 !noasm,!gccgo,!safe
#include "textflag.h"
// func AxpyUnitary(alpha float32, x, y []float32)
TEXT ·AxpyUnitary(SB), NOSPLIT, $0
MOVQ x_base+8(FP), SI // SI = &x
MOVQ y_base+32(FP), DI // DI = &y
MOVQ x_len+16(FP), BX // BX = min( len(x), len(y) )
CMPQ y_len+40(FP), BX
CMOVQLE y_len+40(FP), BX
CMPQ BX, $0 // if BX == 0 { return }
JE axpy_end
MOVSS alpha+0(FP), X0
SHUFPS $0, X0, X0 // X0 = { a, a, a, a }
XORQ AX, AX // i = 0
PXOR X2, X2 // 2 NOP instructions (PXOR) to align
PXOR X3, X3 // loop to cache line
MOVQ DI, CX
ANDQ $0xF, CX // Align on 16-byte boundary for ADDPS
JZ axpy_no_trim // if CX == 0 { goto axpy_no_trim }
XORQ $0xF, CX // CX = 4 - floor( BX % 16 / 4 )
INCQ CX
SHRQ $2, CX
axpy_align: // Trim first value(s) in unaligned buffer do {
MOVSS (SI)(AX*4), X2 // X2 = x[i]
MULSS X0, X2 // X2 *= a
ADDSS (DI)(AX*4), X2 // X2 += y[i]
MOVSS X2, (DI)(AX*4) // y[i] = X2
INCQ AX // i++
DECQ BX
JZ axpy_end // if --BX == 0 { return }
LOOP axpy_align // } while --CX > 0
axpy_no_trim:
MOVUPS X0, X1 // Copy X0 to X1 for pipelining
MOVQ BX, CX
ANDQ $0xF, BX // BX = len % 16
SHRQ $4, CX // CX = int( len / 16 )
JZ axpy_tail4_start // if CX == 0 { return }
axpy_loop: // Loop unrolled 16x do {
MOVUPS (SI)(AX*4), X2 // X2 = x[i:i+4]
MOVUPS 16(SI)(AX*4), X3
MOVUPS 32(SI)(AX*4), X4
MOVUPS 48(SI)(AX*4), X5
MULPS X0, X2 // X2 *= a
MULPS X1, X3
MULPS X0, X4
MULPS X1, X5
ADDPS (DI)(AX*4), X2 // X2 += y[i:i+4]
ADDPS 16(DI)(AX*4), X3
ADDPS 32(DI)(AX*4), X4
ADDPS 48(DI)(AX*4), X5
MOVUPS X2, (DI)(AX*4) // dst[i:i+4] = X2
MOVUPS X3, 16(DI)(AX*4)
MOVUPS X4, 32(DI)(AX*4)
MOVUPS X5, 48(DI)(AX*4)
ADDQ $16, AX // i += 16
LOOP axpy_loop // while (--CX) > 0
CMPQ BX, $0 // if BX == 0 { return }
JE axpy_end
axpy_tail4_start: // Reset loop counter for 4-wide tail loop
MOVQ BX, CX // CX = floor( BX / 4 )
SHRQ $2, CX
JZ axpy_tail_start // if CX == 0 { goto axpy_tail_start }
axpy_tail4: // Loop unrolled 4x do {
MOVUPS (SI)(AX*4), X2 // X2 = x[i]
MULPS X0, X2 // X2 *= a
ADDPS (DI)(AX*4), X2 // X2 += y[i]
MOVUPS X2, (DI)(AX*4) // y[i] = X2
ADDQ $4, AX // i += 4
LOOP axpy_tail4 // } while --CX > 0
axpy_tail_start: // Reset loop counter for 1-wide tail loop
MOVQ BX, CX // CX = BX % 4
ANDQ $3, CX
JZ axpy_end // if CX == 0 { return }
axpy_tail:
MOVSS (SI)(AX*4), X1 // X1 = x[i]
MULSS X0, X1 // X1 *= a
ADDSS (DI)(AX*4), X1 // X1 += y[i]
MOVSS X1, (DI)(AX*4) // y[i] = X1
INCQ AX // i++
LOOP axpy_tail // } while --CX > 0
axpy_end:
RET
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