| // Copyright 2015 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 amd64,!appengine,!gccgo | |
| #include "textflag.h" | |
| // func havePOPCNT() bool | |
| TEXT ·havePOPCNT(SB),4,$0 | |
| MOVQ $1, AX | |
| CPUID | |
| SHRQ $23, CX | |
| ANDQ $1, CX | |
| MOVB CX, ret+0(FP) | |
| RET | |
| // func popcnt(word) int | |
| TEXT ·popcnt(SB),NOSPLIT,$0-8 | |
| XORQ AX, AX | |
| MOVQ x+0(FP), SI | |
| // POPCNT (SI), AX is not recognized by Go assembler, | |
| // so we assemble it ourselves. | |
| BYTE $0xf3 | |
| BYTE $0x48 | |
| BYTE $0x0f | |
| BYTE $0xb8 | |
| BYTE $0xc6 | |
| MOVQ AX, ret+8(FP) | |
| RET |