gtsocial-umbx

pcln.go (12020B)

---

 // 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 (
 	"github.com/twitchyliquid64/golang-asm/goobj"
 	"encoding/binary"
 	"log"
 )
 
 // 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{}) {
 	dbg := desc == ctxt.Debugpcln
 
 	dst.P = dst.P[:0]
 
 	if dbg {
 		ctxt.Logf("funcpctab %s [valfunc=%s]\n", func_.Name, desc)
 	}
 
 	val := int32(-1)
 	oldval := val
 	if func_.Func.Text == nil {
 		return
 	}
 
 	pc := func_.Func.Text.Pc
 
 	if dbg {
 		ctxt.Logf("%6x %6d %v\n", uint64(pc), val, func_.Func.Text)
 	}
 
 	buf := make([]byte, binary.MaxVarintLen32)
 	started := false
 	for p := func_.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 {
 			val = valfunc(ctxt, func_, val, p, 1, arg)
 			if dbg {
 				ctxt.Logf("%6x %6s %v\n", uint64(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 dbg {
 				ctxt.Logf("%6x %6s %v\n", uint64(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 dbg {
 			ctxt.Logf("%6x %6d %v\n", uint64(p.Pc), val, p)
 		}
 
 		if started {
 			pcdelta := (p.Pc - pc) / int64(ctxt.Arch.MinLC)
 			n := binary.PutUvarint(buf, uint64(pcdelta))
 			dst.P = append(dst.P, buf[:n]...)
 			pc = p.Pc
 		}
 
 		delta := val - oldval
 		n := binary.PutVarint(buf, int64(delta))
 		dst.P = append(dst.P, buf[:n]...)
 		oldval = val
 		started = true
 		val = valfunc(ctxt, func_, val, p, 1, arg)
 	}
 
 	if started {
 		if dbg {
 			ctxt.Logf("%6x done\n", uint64(func_.Func.Text.Pc+func_.Size))
 		}
 		v := (func_.Size - pc) / int64(ctxt.Arch.MinLC)
 		if v < 0 {
 			ctxt.Diag("negative pc offset: %v", v)
 		}
 		n := binary.PutUvarint(buf, uint64(v))
 		dst.P = append(dst.P, buf[:n]...)
 		// add terminating varint-encoded 0, which is just 0
 		dst.P = append(dst.P, 0)
 	}
 
 	if dbg {
 		ctxt.Logf("wrote %d bytes to %p\n", len(dst.P), dst)
 		for _, p := range dst.P {
 			ctxt.Logf(" %02x", p)
 		}
 		ctxt.Logf("\n")
 	}
 }
 
 // pctofileline computes either the file number (arg == 0)
 // or the line number (arg == 1) to use at p.
 // Because p.Pos 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.Pos.Line() == 0 || phase == 1 {
 		return oldval
 	}
 	f, l := getFileIndexAndLine(ctxt, p.Pos)
 	if arg == nil {
 		return l
 	}
 	pcln := arg.(*Pcln)
 	pcln.UsedFiles[goobj.CUFileIndex(f)] = struct{}{}
 	return int32(f)
 }
 
 // pcinlineState holds the state used to create a function's inlining
 // tree and the PC-value table that maps PCs to nodes in that tree.
 type pcinlineState struct {
 	globalToLocal map[int]int
 	localTree     InlTree
 }
 
 // addBranch adds a branch from the global inlining tree in ctxt to
 // the function's local inlining tree, returning the index in the local tree.
 func (s *pcinlineState) addBranch(ctxt *Link, globalIndex int) int {
 	if globalIndex < 0 {
 		return -1
 	}
 
 	localIndex, ok := s.globalToLocal[globalIndex]
 	if ok {
 		return localIndex
 	}
 
 	// Since tracebacks don't include column information, we could
 	// use one node for multiple calls of the same function on the
 	// same line (e.g., f(x) + f(y)). For now, we use one node for
 	// each inlined call.
 	call := ctxt.InlTree.nodes[globalIndex]
 	call.Parent = s.addBranch(ctxt, call.Parent)
 	localIndex = len(s.localTree.nodes)
 	s.localTree.nodes = append(s.localTree.nodes, call)
 	s.globalToLocal[globalIndex] = localIndex
 	return localIndex
 }
 
 func (s *pcinlineState) setParentPC(ctxt *Link, globalIndex int, pc int32) {
 	localIndex, ok := s.globalToLocal[globalIndex]
 	if !ok {
 		// We know where to unwind to when we need to unwind a body identified
 		// by globalIndex. But there may be no instructions generated by that
 		// body (it's empty, or its instructions were CSEd with other things, etc.).
 		// In that case, we don't need an unwind entry.
 		// TODO: is this really right? Seems to happen a whole lot...
 		return
 	}
 	s.localTree.setParentPC(localIndex, pc)
 }
 
 // pctoinline computes the index into the local inlining tree to use at p.
 // If p is not the result of inlining, pctoinline returns -1. Because p.Pos
 // applies to p, phase == 0 (before p) takes care of the update.
 func (s *pcinlineState) pctoinline(ctxt *Link, sym *LSym, oldval int32, p *Prog, phase int32, arg interface{}) int32 {
 	if phase == 1 {
 		return oldval
 	}
 
 	posBase := ctxt.PosTable.Pos(p.Pos).Base()
 	if posBase == nil {
 		return -1
 	}
 
 	globalIndex := posBase.InliningIndex()
 	if globalIndex < 0 {
 		return -1
 	}
 
 	if s.globalToLocal == nil {
 		s.globalToLocal = make(map[int]int)
 	}
 
 	return int32(s.addBranch(ctxt, globalIndex))
 }
 
 // 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)
 		ctxt.DiagFlush()
 		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)
 		ctxt.DiagFlush()
 		log.Fatalf("bad code")
 	}
 
 	return int32(p.To.Offset)
 }
 
 func linkpcln(ctxt *Link, cursym *LSym) {
 	pcln := &cursym.Func.Pcln
 	pcln.UsedFiles = make(map[goobj.CUFileIndex]struct{})
 
 	npcdata := 0
 	nfuncdata := 0
 	for p := cursym.Func.Text; p != nil; p = p.Link {
 		// Find the highest ID of any used PCDATA table. This ignores PCDATA table
 		// that consist entirely of "-1", since that's the assumed default value.
 		//   From.Offset is table ID
 		//   To.Offset is data
 		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
 			npcdata = int(p.From.Offset + 1)
 		}
 		// Find the highest ID of any FUNCDATA table.
 		//   From.Offset is table ID
 		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)
 
 	// Check that all the Progs used as inline markers are still reachable.
 	// See issue #40473.
 	inlMarkProgs := make(map[*Prog]struct{}, len(cursym.Func.InlMarks))
 	for _, inlMark := range cursym.Func.InlMarks {
 		inlMarkProgs[inlMark.p] = struct{}{}
 	}
 	for p := cursym.Func.Text; p != nil; p = p.Link {
 		if _, ok := inlMarkProgs[p]; ok {
 			delete(inlMarkProgs, p)
 		}
 	}
 	if len(inlMarkProgs) > 0 {
 		ctxt.Diag("one or more instructions used as inline markers are no longer reachable")
 	}
 
 	pcinlineState := new(pcinlineState)
 	funcpctab(ctxt, &pcln.Pcinline, cursym, "pctoinline", pcinlineState.pctoinline, nil)
 	for _, inlMark := range cursym.Func.InlMarks {
 		pcinlineState.setParentPC(ctxt, int(inlMark.id), int32(inlMark.p.Pc))
 	}
 	pcln.InlTree = pcinlineState.localTree
 	if ctxt.Debugpcln == "pctoinline" && len(pcln.InlTree.nodes) > 0 {
 		ctxt.Logf("-- inlining tree for %s:\n", cursym)
 		dumpInlTree(ctxt, pcln.InlTree)
 		ctxt.Logf("--\n")
 	}
 
 	// tabulate which pc and func data we have.
 	havepc := make([]uint32, (npcdata+31)/32)
 	havefunc := make([]uint32, (nfuncdata+31)/32)
 	for p := cursym.Func.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 && p.To.Offset != -1 {
 			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 {
 		for p := cursym.Func.Text; p != nil; p = p.Link {
 			if p.As != AFUNCDATA {
 				continue
 			}
 			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
 			}
 		}
 	}
 }
 
 // PCIter iterates over encoded pcdata tables.
 type PCIter struct {
 	p       []byte
 	PC      uint32
 	NextPC  uint32
 	PCScale uint32
 	Value   int32
 	start   bool
 	Done    bool
 }
 
 // newPCIter creates a PCIter with a scale factor for the PC step size.
 func NewPCIter(pcScale uint32) *PCIter {
 	it := new(PCIter)
 	it.PCScale = pcScale
 	return it
 }
 
 // Next advances it to the Next pc.
 func (it *PCIter) Next() {
 	it.PC = it.NextPC
 	if it.Done {
 		return
 	}
 	if len(it.p) == 0 {
 		it.Done = true
 		return
 	}
 
 	// Value delta
 	val, n := binary.Varint(it.p)
 	if n <= 0 {
 		log.Fatalf("bad Value varint in pciterNext: read %v", n)
 	}
 	it.p = it.p[n:]
 
 	if val == 0 && !it.start {
 		it.Done = true
 		return
 	}
 
 	it.start = false
 	it.Value += int32(val)
 
 	// pc delta
 	pc, n := binary.Uvarint(it.p)
 	if n <= 0 {
 		log.Fatalf("bad pc varint in pciterNext: read %v", n)
 	}
 	it.p = it.p[n:]
 
 	it.NextPC = it.PC + uint32(pc)*it.PCScale
 }
 
 // init prepares it to iterate over p,
 // and advances it to the first pc.
 func (it *PCIter) Init(p []byte) {
 	it.p = p
 	it.PC = 0
 	it.NextPC = 0
 	it.Value = -1
 	it.start = true
 	it.Done = false
 	it.Next()
 }