| // Copyright 2013 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. |
| |
| package obj |
| |
| import ( |
| "fmt" |
| "log" |
| ) |
| |
| func addvarint(ctxt *Link, d *Pcdata, val uint32) { |
| var v uint32 |
| for v = val; v >= 0x80; v >>= 7 { |
| d.P = append(d.P, uint8(v|0x80)) |
| } |
| d.P = append(d.P, uint8(v)) |
| } |
| |
| // funcpctab writes to dst a pc-value table mapping the code in func to the values |
| // returned by valfunc parameterized by arg. The invocation of valfunc to update the |
| // current value is, for each p, |
| // |
| // val = valfunc(func, val, p, 0, arg); |
| // record val as value at p->pc; |
| // val = valfunc(func, val, p, 1, arg); |
| // |
| // where func is the function, val is the current value, p is the instruction being |
| // considered, and arg can be used to further parameterize valfunc. |
| func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*Link, *LSym, int32, *Prog, int32, interface{}) int32, arg interface{}) { |
| // To debug a specific function, uncomment second line and change name. |
| dbg := 0 |
| |
| //dbg = strcmp(func->name, "main.main") == 0; |
| //dbg = strcmp(desc, "pctofile") == 0; |
| |
| ctxt.Debugpcln += int32(dbg) |
| |
| dst.P = dst.P[:0] |
| |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "funcpctab %s [valfunc=%s]\n", func_.Name, desc) |
| } |
| |
| val := int32(-1) |
| oldval := val |
| if func_.Text == nil { |
| ctxt.Debugpcln -= int32(dbg) |
| return |
| } |
| |
| pc := func_.Text.Pc |
| |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "%6x %6d %v\n", uint64(pc), val, func_.Text) |
| } |
| |
| started := int32(0) |
| var delta uint32 |
| for p := func_.Text; p != nil; p = p.Link { |
| // Update val. If it's not changing, keep going. |
| val = valfunc(ctxt, func_, val, p, 0, arg) |
| |
| if val == oldval && started != 0 { |
| val = valfunc(ctxt, func_, val, p, 1, arg) |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "%6x %6s %v\n", uint64(int64(p.Pc)), "", p) |
| } |
| continue |
| } |
| |
| // If the pc of the next instruction is the same as the |
| // pc of this instruction, this instruction is not a real |
| // instruction. Keep going, so that we only emit a delta |
| // for a true instruction boundary in the program. |
| if p.Link != nil && p.Link.Pc == p.Pc { |
| val = valfunc(ctxt, func_, val, p, 1, arg) |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "%6x %6s %v\n", uint64(int64(p.Pc)), "", p) |
| } |
| continue |
| } |
| |
| // The table is a sequence of (value, pc) pairs, where each |
| // pair states that the given value is in effect from the current position |
| // up to the given pc, which becomes the new current position. |
| // To generate the table as we scan over the program instructions, |
| // we emit a "(value" when pc == func->value, and then |
| // each time we observe a change in value we emit ", pc) (value". |
| // When the scan is over, we emit the closing ", pc)". |
| // |
| // The table is delta-encoded. The value deltas are signed and |
| // transmitted in zig-zag form, where a complement bit is placed in bit 0, |
| // and the pc deltas are unsigned. Both kinds of deltas are sent |
| // as variable-length little-endian base-128 integers, |
| // where the 0x80 bit indicates that the integer continues. |
| |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "%6x %6d %v\n", uint64(int64(p.Pc)), val, p) |
| } |
| |
| if started != 0 { |
| addvarint(ctxt, dst, uint32((p.Pc-pc)/int64(ctxt.Arch.Minlc))) |
| pc = p.Pc |
| } |
| |
| delta = uint32(val) - uint32(oldval) |
| if delta>>31 != 0 { |
| delta = 1 | ^(delta << 1) |
| } else { |
| delta <<= 1 |
| } |
| addvarint(ctxt, dst, delta) |
| oldval = val |
| started = 1 |
| val = valfunc(ctxt, func_, val, p, 1, arg) |
| } |
| |
| if started != 0 { |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "%6x done\n", uint64(int64(func_.Text.Pc)+func_.Size)) |
| } |
| addvarint(ctxt, dst, uint32((func_.Value+func_.Size-pc)/int64(ctxt.Arch.Minlc))) |
| addvarint(ctxt, dst, 0) // terminator |
| } |
| |
| if ctxt.Debugpcln != 0 { |
| fmt.Fprintf(ctxt.Bso, "wrote %d bytes to %p\n", len(dst.P), dst) |
| for i := 0; i < len(dst.P); i++ { |
| fmt.Fprintf(ctxt.Bso, " %02x", dst.P[i]) |
| } |
| fmt.Fprintf(ctxt.Bso, "\n") |
| } |
| |
| ctxt.Debugpcln -= int32(dbg) |
| } |
| |
| // pctofileline computes either the file number (arg == 0) |
| // or the line number (arg == 1) to use at p. |
| // Because p->lineno applies to p, phase == 0 (before p) |
| // takes care of the update. |
| func pctofileline(ctxt *Link, sym *LSym, oldval int32, p *Prog, phase int32, arg interface{}) int32 { |
| if p.As == ATEXT || p.As == ANOP || p.As == AUSEFIELD || p.Lineno == 0 || phase == 1 { |
| return oldval |
| } |
| var l int32 |
| var f *LSym |
| linkgetline(ctxt, p.Lineno, &f, &l) |
| if f == nil { |
| // print("getline failed for %s %P\n", ctxt->cursym->name, p); |
| return oldval |
| } |
| |
| if arg == nil { |
| return l |
| } |
| pcln := arg.(*Pcln) |
| |
| if f == pcln.Lastfile { |
| return int32(pcln.Lastindex) |
| } |
| |
| var i int32 |
| for i = 0; i < int32(len(pcln.File)); i++ { |
| file := pcln.File[i] |
| if file == f { |
| pcln.Lastfile = f |
| pcln.Lastindex = int(i) |
| return int32(i) |
| } |
| } |
| pcln.File = append(pcln.File, f) |
| pcln.Lastfile = f |
| pcln.Lastindex = int(i) |
| return i |
| } |
| |
| // pctospadj computes the sp adjustment in effect. |
| // It is oldval plus any adjustment made by p itself. |
| // The adjustment by p takes effect only after p, so we |
| // apply the change during phase == 1. |
| func pctospadj(ctxt *Link, sym *LSym, oldval int32, p *Prog, phase int32, arg interface{}) int32 { |
| if oldval == -1 { // starting |
| oldval = 0 |
| } |
| if phase == 0 { |
| return oldval |
| } |
| if oldval+p.Spadj < -10000 || oldval+p.Spadj > 1100000000 { |
| ctxt.Diag("overflow in spadj: %d + %d = %d", oldval, p.Spadj, oldval+p.Spadj) |
| log.Fatalf("bad code") |
| } |
| |
| return oldval + p.Spadj |
| } |
| |
| // pctopcdata computes the pcdata value in effect at p. |
| // A PCDATA instruction sets the value in effect at future |
| // non-PCDATA instructions. |
| // Since PCDATA instructions have no width in the final code, |
| // it does not matter which phase we use for the update. |
| func pctopcdata(ctxt *Link, sym *LSym, oldval int32, p *Prog, phase int32, arg interface{}) int32 { |
| if phase == 0 || p.As != APCDATA || p.From.Offset != int64(arg.(uint32)) { |
| return oldval |
| } |
| if int64(int32(p.To.Offset)) != p.To.Offset { |
| ctxt.Diag("overflow in PCDATA instruction: %v", p) |
| log.Fatalf("bad code") |
| } |
| |
| return int32(p.To.Offset) |
| } |
| |
| func linkpcln(ctxt *Link, cursym *LSym) { |
| ctxt.Cursym = cursym |
| |
| pcln := new(Pcln) |
| cursym.Pcln = pcln |
| |
| npcdata := 0 |
| nfuncdata := 0 |
| for p := cursym.Text; p != nil; p = p.Link { |
| if p.As == APCDATA && p.From.Offset >= int64(npcdata) { |
| npcdata = int(p.From.Offset + 1) |
| } |
| if p.As == AFUNCDATA && p.From.Offset >= int64(nfuncdata) { |
| nfuncdata = int(p.From.Offset + 1) |
| } |
| } |
| |
| pcln.Pcdata = make([]Pcdata, npcdata) |
| pcln.Pcdata = pcln.Pcdata[:npcdata] |
| pcln.Funcdata = make([]*LSym, nfuncdata) |
| pcln.Funcdataoff = make([]int64, nfuncdata) |
| pcln.Funcdataoff = pcln.Funcdataoff[:nfuncdata] |
| |
| funcpctab(ctxt, &pcln.Pcsp, cursym, "pctospadj", pctospadj, nil) |
| funcpctab(ctxt, &pcln.Pcfile, cursym, "pctofile", pctofileline, pcln) |
| funcpctab(ctxt, &pcln.Pcline, cursym, "pctoline", pctofileline, nil) |
| |
| // tabulate which pc and func data we have. |
| havepc := make([]uint32, (npcdata+31)/32) |
| havefunc := make([]uint32, (nfuncdata+31)/32) |
| for p := cursym.Text; p != nil; p = p.Link { |
| if p.As == AFUNCDATA { |
| if (havefunc[p.From.Offset/32]>>uint64(p.From.Offset%32))&1 != 0 { |
| ctxt.Diag("multiple definitions for FUNCDATA $%d", p.From.Offset) |
| } |
| havefunc[p.From.Offset/32] |= 1 << uint64(p.From.Offset%32) |
| } |
| |
| if p.As == APCDATA { |
| havepc[p.From.Offset/32] |= 1 << uint64(p.From.Offset%32) |
| } |
| } |
| |
| // pcdata. |
| for i := 0; i < npcdata; i++ { |
| if (havepc[i/32]>>uint(i%32))&1 == 0 { |
| continue |
| } |
| funcpctab(ctxt, &pcln.Pcdata[i], cursym, "pctopcdata", pctopcdata, interface{}(uint32(i))) |
| } |
| |
| // funcdata |
| if nfuncdata > 0 { |
| var i int |
| for p := cursym.Text; p != nil; p = p.Link { |
| if p.As == AFUNCDATA { |
| i = int(p.From.Offset) |
| pcln.Funcdataoff[i] = p.To.Offset |
| if p.To.Type != TYPE_CONST { |
| // TODO: Dedup. |
| //funcdata_bytes += p->to.sym->size; |
| pcln.Funcdata[i] = p.To.Sym |
| } |
| } |
| } |
| } |
| } |
| |
| // iteration over encoded pcdata tables. |
| |
| func getvarint(pp *[]byte) uint32 { |
| v := uint32(0) |
| p := *pp |
| for shift := 0; ; shift += 7 { |
| v |= uint32(p[0]&0x7F) << uint(shift) |
| tmp7 := p |
| p = p[1:] |
| if tmp7[0]&0x80 == 0 { |
| break |
| } |
| } |
| |
| *pp = p |
| return v |
| } |
| |
| func pciternext(it *Pciter) { |
| it.pc = it.nextpc |
| if it.done != 0 { |
| return |
| } |
| if -cap(it.p) >= -cap(it.d.P[len(it.d.P):]) { |
| it.done = 1 |
| return |
| } |
| |
| // value delta |
| v := getvarint(&it.p) |
| |
| if v == 0 && it.start == 0 { |
| it.done = 1 |
| return |
| } |
| |
| it.start = 0 |
| dv := int32(v>>1) ^ (int32(v<<31) >> 31) |
| it.value += dv |
| |
| // pc delta |
| v = getvarint(&it.p) |
| |
| it.nextpc = it.pc + v*it.pcscale |
| } |
| |
| func pciterinit(ctxt *Link, it *Pciter, d *Pcdata) { |
| it.d = *d |
| it.p = it.d.P |
| it.pc = 0 |
| it.nextpc = 0 |
| it.value = -1 |
| it.start = 1 |
| it.done = 0 |
| it.pcscale = uint32(ctxt.Arch.Minlc) |
| pciternext(it) |
| } |