github.com/tidwall/go@v0.0.0-20170415222209-6694a6888b7d/src/cmd/compile/internal/ppc64/ggen.go (about) 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 ppc64 6 7 import ( 8 "cmd/compile/internal/gc" 9 "cmd/internal/obj" 10 "cmd/internal/obj/ppc64" 11 ) 12 13 func defframe(pp *gc.Progs, fn *gc.Node, sz int64) { 14 // fill in argument size, stack size 15 pp.Text.To.Type = obj.TYPE_TEXTSIZE 16 17 pp.Text.To.Val = int32(gc.Rnd(fn.Type.ArgWidth(), int64(gc.Widthptr))) 18 frame := uint32(gc.Rnd(sz, int64(gc.Widthreg))) 19 pp.Text.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 := pp.Text 25 26 hi := int64(0) 27 lo := hi 28 29 // iterate through declarations - they are sorted in decreasing xoffset order. 30 for _, n := range fn.Func.Dcl { 31 if !n.Name.Needzero() { 32 continue 33 } 34 if n.Class != gc.PAUTO { 35 gc.Fatalf("needzero class %d", n.Class) 36 } 37 if n.Type.Width%int64(gc.Widthptr) != 0 || n.Xoffset%int64(gc.Widthptr) != 0 || n.Type.Width == 0 { 38 gc.Fatalf("var %L has size %d offset %d", n, int(n.Type.Width), int(n.Xoffset)) 39 } 40 41 if lo != hi && n.Xoffset+n.Type.Width >= lo-int64(2*gc.Widthreg) { 42 // merge with range we already have 43 lo = n.Xoffset 44 45 continue 46 } 47 48 // zero old range 49 p = zerorange(pp, p, int64(frame), lo, hi) 50 51 // set new range 52 hi = n.Xoffset + n.Type.Width 53 54 lo = n.Xoffset 55 } 56 57 // zero final range 58 zerorange(pp, p, int64(frame), lo, hi) 59 } 60 61 func zerorange(pp *gc.Progs, p *obj.Prog, frame int64, lo int64, hi int64) *obj.Prog { 62 cnt := hi - lo 63 if cnt == 0 { 64 return p 65 } 66 if cnt < int64(4*gc.Widthptr) { 67 for i := int64(0); i < cnt; i += int64(gc.Widthptr) { 68 p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_REG, ppc64.REGZERO, 0, obj.TYPE_MEM, ppc64.REGSP, gc.Ctxt.FixedFrameSize()+frame+lo+i) 69 } 70 } else if cnt <= int64(128*gc.Widthptr) { 71 p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_CONST, 0, gc.Ctxt.FixedFrameSize()+frame+lo-8, obj.TYPE_REG, ppc64.REGRT1, 0) 72 p.Reg = ppc64.REGSP 73 p = pp.Appendpp(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_MEM, 0, 0) 74 p.To.Name = obj.NAME_EXTERN 75 p.To.Sym = gc.Duffzero 76 p.To.Offset = 4 * (128 - cnt/int64(gc.Widthptr)) 77 } else { 78 p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_CONST, 0, gc.Ctxt.FixedFrameSize()+frame+lo-8, obj.TYPE_REG, ppc64.REGTMP, 0) 79 p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_REG, ppc64.REGTMP, 0, obj.TYPE_REG, ppc64.REGRT1, 0) 80 p.Reg = ppc64.REGSP 81 p = pp.Appendpp(p, ppc64.AMOVD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, ppc64.REGTMP, 0) 82 p = pp.Appendpp(p, ppc64.AADD, obj.TYPE_REG, ppc64.REGTMP, 0, obj.TYPE_REG, ppc64.REGRT2, 0) 83 p.Reg = ppc64.REGRT1 84 p = pp.Appendpp(p, ppc64.AMOVDU, obj.TYPE_REG, ppc64.REGZERO, 0, obj.TYPE_MEM, ppc64.REGRT1, int64(gc.Widthptr)) 85 p1 := p 86 p = pp.Appendpp(p, ppc64.ACMP, obj.TYPE_REG, ppc64.REGRT1, 0, obj.TYPE_REG, ppc64.REGRT2, 0) 87 p = pp.Appendpp(p, ppc64.ABNE, obj.TYPE_NONE, 0, 0, obj.TYPE_BRANCH, 0, 0) 88 gc.Patch(p, p1) 89 } 90 91 return p 92 } 93 94 func ginsnop(pp *gc.Progs) { 95 p := pp.Prog(ppc64.AOR) 96 p.From.Type = obj.TYPE_REG 97 p.From.Reg = ppc64.REG_R0 98 p.To.Type = obj.TYPE_REG 99 p.To.Reg = ppc64.REG_R0 100 } 101 102 func ginsnop2(pp *gc.Progs) { 103 // PPC64 is unusual because TWO nops are required 104 // (see gc/cgen.go, gc/plive.go -- copy of comment below) 105 // 106 // On ppc64, when compiling Go into position 107 // independent code on ppc64le we insert an 108 // instruction to reload the TOC pointer from the 109 // stack as well. See the long comment near 110 // jmpdefer in runtime/asm_ppc64.s for why. 111 // If the MOVD is not needed, insert a hardware NOP 112 // so that the same number of instructions are used 113 // on ppc64 in both shared and non-shared modes. 114 115 ginsnop(pp) 116 if gc.Ctxt.Flag_shared { 117 p := pp.Prog(ppc64.AMOVD) 118 p.From.Type = obj.TYPE_MEM 119 p.From.Offset = 24 120 p.From.Reg = ppc64.REGSP 121 p.To.Type = obj.TYPE_REG 122 p.To.Reg = ppc64.REG_R2 123 } else { 124 ginsnop(pp) 125 } 126 }