1 // Copyright 2009 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 package x86 6 7 import ( 8 "cmd/compile/internal/gc" 9 "cmd/internal/obj" 10 "cmd/internal/obj/x86" 11 ) 12 13 func defframe(ptxt *obj.Prog) { 14 // fill in argument size, stack size 15 ptxt.To.Type = obj.TYPE_TEXTSIZE 16 17 ptxt.To.Val = int32(gc.Rnd(gc.Curfn.Type.ArgWidth(), int64(gc.Widthptr))) 18 frame := uint32(gc.Rnd(gc.Stksize+gc.Maxarg, int64(gc.Widthreg))) 19 ptxt.To.Offset = int64(frame) 20 21 // insert code to zero ambiguously live variables 22 // so that the garbage collector only sees initialized values 23 // when it looks for pointers. 24 p := ptxt 25 26 hi := int64(0) 27 lo := hi 28 ax := uint32(0) 29 for _, n := range gc.Curfn.Func.Dcl { 30 if !n.Name.Needzero { 31 continue 32 } 33 if n.Class != gc.PAUTO { 34 gc.Fatalf("needzero class %d", n.Class) 35 } 36 if n.Type.Width%int64(gc.Widthptr) != 0 || n.Xoffset%int64(gc.Widthptr) != 0 || n.Type.Width == 0 { 37 gc.Fatalf("var %L has size %d offset %d", n, int(n.Type.Width), int(n.Xoffset)) 38 } 39 if lo != hi && n.Xoffset+n.Type.Width >= lo-int64(2*gc.Widthptr) { 40 // merge with range we already have 41 lo = n.Xoffset 42 43 continue 44 } 45 46 // zero old range 47 p = zerorange(p, int64(frame), lo, hi, &ax) 48 49 // set new range 50 hi = n.Xoffset + n.Type.Width 51 52 lo = n.Xoffset 53 } 54 55 // zero final range 56 zerorange(p, int64(frame), lo, hi, &ax) 57 } 58 59 func zerorange(p *obj.Prog, frame int64, lo int64, hi int64, ax *uint32) *obj.Prog { 60 cnt := hi - lo 61 if cnt == 0 { 62 return p 63 } 64 if *ax == 0 { 65 p = gc.Appendpp(p, x86.AMOVL, obj.TYPE_CONST, 0, 0, obj.TYPE_REG, x86.REG_AX, 0) 66 *ax = 1 67 } 68 69 if cnt <= int64(4*gc.Widthreg) { 70 for i := int64(0); i < cnt; i += int64(gc.Widthreg) { 71 p = gc.Appendpp(p, x86.AMOVL, obj.TYPE_REG, x86.REG_AX, 0, obj.TYPE_MEM, x86.REG_SP, frame+lo+i) 72 } 73 } else if !gc.Nacl && cnt <= int64(128*gc.Widthreg) { 74 p = gc.Appendpp(p, x86.ALEAL, obj.TYPE_MEM, x86.REG_SP, frame+lo, obj.TYPE_REG, x86.REG_DI, 0) 75 p = gc.Appendpp(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_ADDR, 0, 1*(128-cnt/int64(gc.Widthreg))) 76 p.To.Sym = gc.Linksym(gc.Pkglookup("duffzero", gc.Runtimepkg)) 77 } else { 78 p = gc.Appendpp(p, x86.AMOVL, obj.TYPE_CONST, 0, cnt/int64(gc.Widthreg), obj.TYPE_REG, x86.REG_CX, 0) 79 p = gc.Appendpp(p, x86.ALEAL, obj.TYPE_MEM, x86.REG_SP, frame+lo, obj.TYPE_REG, x86.REG_DI, 0) 80 p = gc.Appendpp(p, x86.AREP, obj.TYPE_NONE, 0, 0, obj.TYPE_NONE, 0, 0) 81 p = gc.Appendpp(p, x86.ASTOSL, obj.TYPE_NONE, 0, 0, obj.TYPE_NONE, 0, 0) 82 } 83 84 return p 85 } 86 87 func ginsnop() { 88 p := gc.Prog(x86.AXCHGL) 89 p.From.Type = obj.TYPE_REG 90 p.From.Reg = x86.REG_AX 91 p.To.Type = obj.TYPE_REG 92 p.To.Reg = x86.REG_AX 93 } 94
