| // 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 |
