github.com/lzhfromustc/gofuzz@v0.0.0-20211116160056-151b3108bbd1/runtime/memclr_386.s (about) 1 // Copyright 2014 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // +build !plan9 6 7 #include "go_asm.h" 8 #include "textflag.h" 9 10 // NOTE: Windows externalthreadhandler expects memclr to preserve DX. 11 12 // See memclrNoHeapPointers Go doc for important implementation constraints. 13 14 // func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) 15 TEXT runtime·memclrNoHeapPointers(SB), NOSPLIT, $0-8 16 MOVL ptr+0(FP), DI 17 MOVL n+4(FP), BX 18 XORL AX, AX 19 20 // MOVOU seems always faster than REP STOSL. 21 tail: 22 // BSR+branch table make almost all memmove/memclr benchmarks worse. Not worth doing. 23 TESTL BX, BX 24 JEQ _0 25 CMPL BX, $2 26 JBE _1or2 27 CMPL BX, $4 28 JB _3 29 JE _4 30 CMPL BX, $8 31 JBE _5through8 32 CMPL BX, $16 33 JBE _9through16 34 CMPB internal∕cpu·X86+const_offsetX86HasSSE2(SB), $1 35 JNE nosse2 36 PXOR X0, X0 37 CMPL BX, $32 38 JBE _17through32 39 CMPL BX, $64 40 JBE _33through64 41 CMPL BX, $128 42 JBE _65through128 43 CMPL BX, $256 44 JBE _129through256 45 46 loop: 47 MOVOU X0, 0(DI) 48 MOVOU X0, 16(DI) 49 MOVOU X0, 32(DI) 50 MOVOU X0, 48(DI) 51 MOVOU X0, 64(DI) 52 MOVOU X0, 80(DI) 53 MOVOU X0, 96(DI) 54 MOVOU X0, 112(DI) 55 MOVOU X0, 128(DI) 56 MOVOU X0, 144(DI) 57 MOVOU X0, 160(DI) 58 MOVOU X0, 176(DI) 59 MOVOU X0, 192(DI) 60 MOVOU X0, 208(DI) 61 MOVOU X0, 224(DI) 62 MOVOU X0, 240(DI) 63 SUBL $256, BX 64 ADDL $256, DI 65 CMPL BX, $256 66 JAE loop 67 JMP tail 68 69 _1or2: 70 MOVB AX, (DI) 71 MOVB AX, -1(DI)(BX*1) 72 RET 73 _0: 74 RET 75 _3: 76 MOVW AX, (DI) 77 MOVB AX, 2(DI) 78 RET 79 _4: 80 // We need a separate case for 4 to make sure we clear pointers atomically. 81 MOVL AX, (DI) 82 RET 83 _5through8: 84 MOVL AX, (DI) 85 MOVL AX, -4(DI)(BX*1) 86 RET 87 _9through16: 88 MOVL AX, (DI) 89 MOVL AX, 4(DI) 90 MOVL AX, -8(DI)(BX*1) 91 MOVL AX, -4(DI)(BX*1) 92 RET 93 _17through32: 94 MOVOU X0, (DI) 95 MOVOU X0, -16(DI)(BX*1) 96 RET 97 _33through64: 98 MOVOU X0, (DI) 99 MOVOU X0, 16(DI) 100 MOVOU X0, -32(DI)(BX*1) 101 MOVOU X0, -16(DI)(BX*1) 102 RET 103 _65through128: 104 MOVOU X0, (DI) 105 MOVOU X0, 16(DI) 106 MOVOU X0, 32(DI) 107 MOVOU X0, 48(DI) 108 MOVOU X0, -64(DI)(BX*1) 109 MOVOU X0, -48(DI)(BX*1) 110 MOVOU X0, -32(DI)(BX*1) 111 MOVOU X0, -16(DI)(BX*1) 112 RET 113 _129through256: 114 MOVOU X0, (DI) 115 MOVOU X0, 16(DI) 116 MOVOU X0, 32(DI) 117 MOVOU X0, 48(DI) 118 MOVOU X0, 64(DI) 119 MOVOU X0, 80(DI) 120 MOVOU X0, 96(DI) 121 MOVOU X0, 112(DI) 122 MOVOU X0, -128(DI)(BX*1) 123 MOVOU X0, -112(DI)(BX*1) 124 MOVOU X0, -96(DI)(BX*1) 125 MOVOU X0, -80(DI)(BX*1) 126 MOVOU X0, -64(DI)(BX*1) 127 MOVOU X0, -48(DI)(BX*1) 128 MOVOU X0, -32(DI)(BX*1) 129 MOVOU X0, -16(DI)(BX*1) 130 RET 131 nosse2: 132 MOVL BX, CX 133 SHRL $2, CX 134 REP 135 STOSL 136 ANDL $3, BX 137 JNE tail 138 RET