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