| // Copyright 2009 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 "runtime.h" |
| |
| #pragma textflag 7 |
| // func closure(siz int32, |
| // fn func(arg0, arg1, arg2 *ptr, callerpc uintptr, xxx) yyy, |
| // arg0, arg1, arg2 *ptr) (func(xxx) yyy) |
| void |
| sysยทclosure(int32 siz, byte *fn, byte *arg0) |
| { |
| byte *p, *q, **ret; |
| int32 i, n; |
| int64 pcrel; |
| |
| if(siz < 0 || siz%8 != 0) |
| throw("bad closure size"); |
| |
| ret = (byte**)((byte*)&arg0 + siz); |
| |
| if(siz > 100) { |
| // TODO(rsc): implement stack growth preamble? |
| throw("closure too big"); |
| } |
| |
| // compute size of new fn. |
| // must match code laid out below. |
| n = 7+10+3; // SUBQ MOVQ MOVQ |
| if(siz <= 4*8) |
| n += 2*siz/8; // MOVSQ MOVSQ... |
| else |
| n += 7+3; // MOVQ REP MOVSQ |
| n += 12; // CALL worst case; sometimes only 5 |
| n += 7+1; // ADDQ RET |
| |
| // store args aligned after code, so gc can find them. |
| n += siz; |
| if(n%8) |
| n += 8 - n%8; |
| |
| p = mal(n); |
| *ret = p; |
| q = p + n - siz; |
| |
| if(siz > 0) { |
| mcpy(q, (byte*)&arg0, siz); |
| |
| // SUBQ $siz, SP |
| *p++ = 0x48; |
| *p++ = 0x81; |
| *p++ = 0xec; |
| *(uint32*)p = siz; |
| p += 4; |
| |
| // MOVQ $q, SI |
| *p++ = 0x48; |
| *p++ = 0xbe; |
| *(byte**)p = q; |
| p += 8; |
| |
| // MOVQ SP, DI |
| *p++ = 0x48; |
| *p++ = 0x89; |
| *p++ = 0xe7; |
| |
| if(siz <= 4*8) { |
| for(i=0; i<siz; i+=8) { |
| // MOVSQ |
| *p++ = 0x48; |
| *p++ = 0xa5; |
| } |
| } else { |
| // MOVQ $(siz/8), CX [32-bit immediate siz/8] |
| *p++ = 0x48; |
| *p++ = 0xc7; |
| *p++ = 0xc1; |
| *(uint32*)p = siz/8; |
| p += 4; |
| |
| // REP; MOVSQ |
| *p++ = 0xf3; |
| *p++ = 0x48; |
| *p++ = 0xa5; |
| } |
| } |
| |
| // call fn |
| pcrel = fn - (p+5); |
| if((int32)pcrel == pcrel) { |
| // can use direct call with pc-relative offset |
| // CALL fn |
| *p++ = 0xe8; |
| *(int32*)p = pcrel; |
| p += 4; |
| } else { |
| // MOVQ $fn, CX [64-bit immediate fn] |
| *p++ = 0x48; |
| *p++ = 0xb9; |
| *(byte**)p = fn; |
| p += 8; |
| |
| // CALL *CX |
| *p++ = 0xff; |
| *p++ = 0xd1; |
| } |
| |
| // ADDQ $siz, SP |
| *p++ = 0x48; |
| *p++ = 0x81; |
| *p++ = 0xc4; |
| *(uint32*)p = siz; |
| p += 4; |
| |
| // RET |
| *p++ = 0xc3; |
| |
| if(p > q) |
| throw("bad math in sys.closure"); |
| } |
| |
| |