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diff --git a/src/internal/bytealg/equal_386.s b/src/internal/bytealg/equal_386.s
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+// 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.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+// memequal(a, b unsafe.Pointer, size uintptr) bool
+TEXT runtime·memequal(SB),NOSPLIT,$0-13
+ MOVL a+0(FP), SI
+ MOVL b+4(FP), DI
+ CMPL SI, DI
+ JEQ eq
+ MOVL size+8(FP), BX
+ LEAL ret+12(FP), AX
+ JMP memeqbody<>(SB)
+eq:
+ MOVB $1, ret+12(FP)
+ RET
+
+// memequal_varlen(a, b unsafe.Pointer) bool
+TEXT runtime·memequal_varlen(SB),NOSPLIT,$0-9
+ MOVL a+0(FP), SI
+ MOVL b+4(FP), DI
+ CMPL SI, DI
+ JEQ eq
+ MOVL 4(DX), BX // compiler stores size at offset 4 in the closure
+ LEAL ret+8(FP), AX
+ JMP memeqbody<>(SB)
+eq:
+ MOVB $1, ret+8(FP)
+ RET
+
+// a in SI
+// b in DI
+// count in BX
+// address of result byte in AX
+TEXT memeqbody<>(SB),NOSPLIT,$0-0
+ CMPL BX, $4
+ JB small
+
+ // 64 bytes at a time using xmm registers
+hugeloop:
+ CMPL BX, $64
+ JB bigloop
+#ifdef GO386_softfloat
+ JMP bigloop
+#endif
+ MOVOU (SI), X0
+ MOVOU (DI), X1
+ MOVOU 16(SI), X2
+ MOVOU 16(DI), X3
+ MOVOU 32(SI), X4
+ MOVOU 32(DI), X5
+ MOVOU 48(SI), X6
+ MOVOU 48(DI), X7
+ PCMPEQB X1, X0
+ PCMPEQB X3, X2
+ PCMPEQB X5, X4
+ PCMPEQB X7, X6
+ PAND X2, X0
+ PAND X6, X4
+ PAND X4, X0
+ PMOVMSKB X0, DX
+ ADDL $64, SI
+ ADDL $64, DI
+ SUBL $64, BX
+ CMPL DX, $0xffff
+ JEQ hugeloop
+ MOVB $0, (AX)
+ RET
+
+ // 4 bytes at a time using 32-bit register
+bigloop:
+ CMPL BX, $4
+ JBE leftover
+ MOVL (SI), CX
+ MOVL (DI), DX
+ ADDL $4, SI
+ ADDL $4, DI
+ SUBL $4, BX
+ CMPL CX, DX
+ JEQ bigloop
+ MOVB $0, (AX)
+ RET
+
+ // remaining 0-4 bytes
+leftover:
+ MOVL -4(SI)(BX*1), CX
+ MOVL -4(DI)(BX*1), DX
+ CMPL CX, DX
+ SETEQ (AX)
+ RET
+
+small:
+ CMPL BX, $0
+ JEQ equal
+
+ LEAL 0(BX*8), CX
+ NEGL CX
+
+ MOVL SI, DX
+ CMPB DX, $0xfc
+ JA si_high
+
+ // load at SI won't cross a page boundary.
+ MOVL (SI), SI
+ JMP si_finish
+si_high:
+ // address ends in 111111xx. Load up to bytes we want, move to correct position.
+ MOVL -4(SI)(BX*1), SI
+ SHRL CX, SI
+si_finish:
+
+ // same for DI.
+ MOVL DI, DX
+ CMPB DX, $0xfc
+ JA di_high
+ MOVL (DI), DI
+ JMP di_finish
+di_high:
+ MOVL -4(DI)(BX*1), DI
+ SHRL CX, DI
+di_finish:
+
+ SUBL SI, DI
+ SHLL CX, DI
+equal:
+ SETEQ (AX)
+ RET