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Diffstat (limited to 'src/cmd/compile/internal/dwarfgen/dwarf.go')
-rw-r--r--src/cmd/compile/internal/dwarfgen/dwarf.go600
1 files changed, 600 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/dwarfgen/dwarf.go b/src/cmd/compile/internal/dwarfgen/dwarf.go
new file mode 100644
index 0000000..90c331f
--- /dev/null
+++ b/src/cmd/compile/internal/dwarfgen/dwarf.go
@@ -0,0 +1,600 @@
+// Copyright 2011 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 dwarfgen
+
+import (
+ "bytes"
+ "flag"
+ "fmt"
+ "internal/buildcfg"
+ "sort"
+
+ "cmd/compile/internal/base"
+ "cmd/compile/internal/ir"
+ "cmd/compile/internal/reflectdata"
+ "cmd/compile/internal/ssa"
+ "cmd/compile/internal/ssagen"
+ "cmd/compile/internal/types"
+ "cmd/internal/dwarf"
+ "cmd/internal/obj"
+ "cmd/internal/objabi"
+ "cmd/internal/src"
+)
+
+func Info(fnsym *obj.LSym, infosym *obj.LSym, curfn interface{}) ([]dwarf.Scope, dwarf.InlCalls) {
+ fn := curfn.(*ir.Func)
+
+ if fn.Nname != nil {
+ expect := fn.Linksym()
+ if fnsym.ABI() == obj.ABI0 {
+ expect = fn.LinksymABI(obj.ABI0)
+ }
+ if fnsym != expect {
+ base.Fatalf("unexpected fnsym: %v != %v", fnsym, expect)
+ }
+ }
+
+ // Back when there were two different *Funcs for a function, this code
+ // was not consistent about whether a particular *Node being processed
+ // was an ODCLFUNC or ONAME node. Partly this is because inlined function
+ // bodies have no ODCLFUNC node, which was it's own inconsistency.
+ // In any event, the handling of the two different nodes for DWARF purposes
+ // was subtly different, likely in unintended ways. CL 272253 merged the
+ // two nodes' Func fields, so that code sees the same *Func whether it is
+ // holding the ODCLFUNC or the ONAME. This resulted in changes in the
+ // DWARF output. To preserve the existing DWARF output and leave an
+ // intentional change for a future CL, this code does the following when
+ // fn.Op == ONAME:
+ //
+ // 1. Disallow use of createComplexVars in createDwarfVars.
+ // It was not possible to reach that code for an ONAME before,
+ // because the DebugInfo was set only on the ODCLFUNC Func.
+ // Calling into it in the ONAME case causes an index out of bounds panic.
+ //
+ // 2. Do not populate apdecls. fn.Func.Dcl was in the ODCLFUNC Func,
+ // not the ONAME Func. Populating apdecls for the ONAME case results
+ // in selected being populated after createSimpleVars is called in
+ // createDwarfVars, and then that causes the loop to skip all the entries
+ // in dcl, meaning that the RecordAutoType calls don't happen.
+ //
+ // These two adjustments keep toolstash -cmp working for now.
+ // Deciding the right answer is, as they say, future work.
+ //
+ // We can tell the difference between the old ODCLFUNC and ONAME
+ // cases by looking at the infosym.Name. If it's empty, DebugInfo is
+ // being called from (*obj.Link).populateDWARF, which used to use
+ // the ODCLFUNC. If it's non-empty (the name will end in $abstract),
+ // DebugInfo is being called from (*obj.Link).DwarfAbstractFunc,
+ // which used to use the ONAME form.
+ isODCLFUNC := infosym.Name == ""
+
+ var apdecls []*ir.Name
+ // Populate decls for fn.
+ if isODCLFUNC {
+ for _, n := range fn.Dcl {
+ if n.Op() != ir.ONAME { // might be OTYPE or OLITERAL
+ continue
+ }
+ switch n.Class {
+ case ir.PAUTO:
+ if !n.Used() {
+ // Text == nil -> generating abstract function
+ if fnsym.Func().Text != nil {
+ base.Fatalf("debuginfo unused node (AllocFrame should truncate fn.Func.Dcl)")
+ }
+ continue
+ }
+ case ir.PPARAM, ir.PPARAMOUT:
+ default:
+ continue
+ }
+ apdecls = append(apdecls, n)
+ if n.Type().Kind() == types.TSSA {
+ // Can happen for TypeInt128 types. This only happens for
+ // spill locations, so not a huge deal.
+ continue
+ }
+ fnsym.Func().RecordAutoType(reflectdata.TypeLinksym(n.Type()))
+ }
+ }
+
+ decls, dwarfVars := createDwarfVars(fnsym, isODCLFUNC, fn, apdecls)
+
+ // For each type referenced by the functions auto vars but not
+ // already referenced by a dwarf var, attach an R_USETYPE relocation to
+ // the function symbol to insure that the type included in DWARF
+ // processing during linking.
+ typesyms := []*obj.LSym{}
+ for t := range fnsym.Func().Autot {
+ typesyms = append(typesyms, t)
+ }
+ sort.Sort(obj.BySymName(typesyms))
+ for _, sym := range typesyms {
+ r := obj.Addrel(infosym)
+ r.Sym = sym
+ r.Type = objabi.R_USETYPE
+ }
+ fnsym.Func().Autot = nil
+
+ var varScopes []ir.ScopeID
+ for _, decl := range decls {
+ pos := declPos(decl)
+ varScopes = append(varScopes, findScope(fn.Marks, pos))
+ }
+
+ scopes := assembleScopes(fnsym, fn, dwarfVars, varScopes)
+ var inlcalls dwarf.InlCalls
+ if base.Flag.GenDwarfInl > 0 {
+ inlcalls = assembleInlines(fnsym, dwarfVars)
+ }
+ return scopes, inlcalls
+}
+
+func declPos(decl *ir.Name) src.XPos {
+ return decl.Canonical().Pos()
+}
+
+// createDwarfVars process fn, returning a list of DWARF variables and the
+// Nodes they represent.
+func createDwarfVars(fnsym *obj.LSym, complexOK bool, fn *ir.Func, apDecls []*ir.Name) ([]*ir.Name, []*dwarf.Var) {
+ // Collect a raw list of DWARF vars.
+ var vars []*dwarf.Var
+ var decls []*ir.Name
+ var selected ir.NameSet
+
+ if base.Ctxt.Flag_locationlists && base.Ctxt.Flag_optimize && fn.DebugInfo != nil && complexOK {
+ decls, vars, selected = createComplexVars(fnsym, fn)
+ } else if fn.ABI == obj.ABIInternal && base.Flag.N != 0 && complexOK {
+ decls, vars, selected = createABIVars(fnsym, fn, apDecls)
+ } else {
+ decls, vars, selected = createSimpleVars(fnsym, apDecls)
+ }
+ if fn.DebugInfo != nil {
+ // Recover zero sized variables eliminated by the stackframe pass
+ for _, n := range fn.DebugInfo.(*ssa.FuncDebug).OptDcl {
+ if n.Class != ir.PAUTO {
+ continue
+ }
+ types.CalcSize(n.Type())
+ if n.Type().Size() == 0 {
+ decls = append(decls, n)
+ vars = append(vars, createSimpleVar(fnsym, n))
+ vars[len(vars)-1].StackOffset = 0
+ fnsym.Func().RecordAutoType(reflectdata.TypeLinksym(n.Type()))
+ }
+ }
+ }
+
+ dcl := apDecls
+ if fnsym.WasInlined() {
+ dcl = preInliningDcls(fnsym)
+ } else {
+ // The backend's stackframe pass prunes away entries from the
+ // fn's Dcl list, including PARAMOUT nodes that correspond to
+ // output params passed in registers. Add back in these
+ // entries here so that we can process them properly during
+ // DWARF-gen. See issue 48573 for more details.
+ debugInfo := fn.DebugInfo.(*ssa.FuncDebug)
+ for _, n := range debugInfo.RegOutputParams {
+ if n.Class != ir.PPARAMOUT || !n.IsOutputParamInRegisters() {
+ panic("invalid ir.Name on debugInfo.RegOutputParams list")
+ }
+ dcl = append(dcl, n)
+ }
+ }
+
+ // If optimization is enabled, the list above will typically be
+ // missing some of the original pre-optimization variables in the
+ // function (they may have been promoted to registers, folded into
+ // constants, dead-coded away, etc). Input arguments not eligible
+ // for SSA optimization are also missing. Here we add back in entries
+ // for selected missing vars. Note that the recipe below creates a
+ // conservative location. The idea here is that we want to
+ // communicate to the user that "yes, there is a variable named X
+ // in this function, but no, I don't have enough information to
+ // reliably report its contents."
+ // For non-SSA-able arguments, however, the correct information
+ // is known -- they have a single home on the stack.
+ for _, n := range dcl {
+ if selected.Has(n) {
+ continue
+ }
+ c := n.Sym().Name[0]
+ if c == '.' || n.Type().IsUntyped() {
+ continue
+ }
+ if n.Class == ir.PPARAM && !ssagen.TypeOK(n.Type()) {
+ // SSA-able args get location lists, and may move in and
+ // out of registers, so those are handled elsewhere.
+ // Autos and named output params seem to get handled
+ // with VARDEF, which creates location lists.
+ // Args not of SSA-able type are treated here; they
+ // are homed on the stack in a single place for the
+ // entire call.
+ vars = append(vars, createSimpleVar(fnsym, n))
+ decls = append(decls, n)
+ continue
+ }
+ typename := dwarf.InfoPrefix + types.TypeSymName(n.Type())
+ decls = append(decls, n)
+ abbrev := dwarf.DW_ABRV_AUTO_LOCLIST
+ isReturnValue := (n.Class == ir.PPARAMOUT)
+ if n.Class == ir.PPARAM || n.Class == ir.PPARAMOUT {
+ abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
+ }
+ if n.Esc() == ir.EscHeap {
+ // The variable in question has been promoted to the heap.
+ // Its address is in n.Heapaddr.
+ // TODO(thanm): generate a better location expression
+ }
+ inlIndex := 0
+ if base.Flag.GenDwarfInl > 1 {
+ if n.InlFormal() || n.InlLocal() {
+ inlIndex = posInlIndex(n.Pos()) + 1
+ if n.InlFormal() {
+ abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
+ }
+ }
+ }
+ declpos := base.Ctxt.InnermostPos(n.Pos())
+ vars = append(vars, &dwarf.Var{
+ Name: n.Sym().Name,
+ IsReturnValue: isReturnValue,
+ Abbrev: abbrev,
+ StackOffset: int32(n.FrameOffset()),
+ Type: base.Ctxt.Lookup(typename),
+ DeclFile: declpos.RelFilename(),
+ DeclLine: declpos.RelLine(),
+ DeclCol: declpos.RelCol(),
+ InlIndex: int32(inlIndex),
+ ChildIndex: -1,
+ DictIndex: n.DictIndex,
+ })
+ // Record go type of to insure that it gets emitted by the linker.
+ fnsym.Func().RecordAutoType(reflectdata.TypeLinksym(n.Type()))
+ }
+
+ // Sort decls and vars.
+ sortDeclsAndVars(fn, decls, vars)
+
+ return decls, vars
+}
+
+// sortDeclsAndVars sorts the decl and dwarf var lists according to
+// parameter declaration order, so as to insure that when a subprogram
+// DIE is emitted, its parameter children appear in declaration order.
+// Prior to the advent of the register ABI, sorting by frame offset
+// would achieve this; with the register we now need to go back to the
+// original function signature.
+func sortDeclsAndVars(fn *ir.Func, decls []*ir.Name, vars []*dwarf.Var) {
+ paramOrder := make(map[*ir.Name]int)
+ idx := 1
+ for _, selfn := range types.RecvsParamsResults {
+ fsl := selfn(fn.Type()).FieldSlice()
+ for _, f := range fsl {
+ if n, ok := f.Nname.(*ir.Name); ok {
+ paramOrder[n] = idx
+ idx++
+ }
+ }
+ }
+ sort.Stable(varsAndDecls{decls, vars, paramOrder})
+}
+
+type varsAndDecls struct {
+ decls []*ir.Name
+ vars []*dwarf.Var
+ paramOrder map[*ir.Name]int
+}
+
+func (v varsAndDecls) Len() int {
+ return len(v.decls)
+}
+
+func (v varsAndDecls) Less(i, j int) bool {
+ nameLT := func(ni, nj *ir.Name) bool {
+ oi, foundi := v.paramOrder[ni]
+ oj, foundj := v.paramOrder[nj]
+ if foundi {
+ if foundj {
+ return oi < oj
+ } else {
+ return true
+ }
+ }
+ return false
+ }
+ return nameLT(v.decls[i], v.decls[j])
+}
+
+func (v varsAndDecls) Swap(i, j int) {
+ v.vars[i], v.vars[j] = v.vars[j], v.vars[i]
+ v.decls[i], v.decls[j] = v.decls[j], v.decls[i]
+}
+
+// Given a function that was inlined at some point during the
+// compilation, return a sorted list of nodes corresponding to the
+// autos/locals in that function prior to inlining. If this is a
+// function that is not local to the package being compiled, then the
+// names of the variables may have been "versioned" to avoid conflicts
+// with local vars; disregard this versioning when sorting.
+func preInliningDcls(fnsym *obj.LSym) []*ir.Name {
+ fn := base.Ctxt.DwFixups.GetPrecursorFunc(fnsym).(*ir.Func)
+ var rdcl []*ir.Name
+ for _, n := range fn.Inl.Dcl {
+ c := n.Sym().Name[0]
+ // Avoid reporting "_" parameters, since if there are more than
+ // one, it can result in a collision later on, as in #23179.
+ if unversion(n.Sym().Name) == "_" || c == '.' || n.Type().IsUntyped() {
+ continue
+ }
+ rdcl = append(rdcl, n)
+ }
+ return rdcl
+}
+
+// createSimpleVars creates a DWARF entry for every variable declared in the
+// function, claiming that they are permanently on the stack.
+func createSimpleVars(fnsym *obj.LSym, apDecls []*ir.Name) ([]*ir.Name, []*dwarf.Var, ir.NameSet) {
+ var vars []*dwarf.Var
+ var decls []*ir.Name
+ var selected ir.NameSet
+ for _, n := range apDecls {
+ if ir.IsAutoTmp(n) {
+ continue
+ }
+
+ decls = append(decls, n)
+ vars = append(vars, createSimpleVar(fnsym, n))
+ selected.Add(n)
+ }
+ return decls, vars, selected
+}
+
+func createSimpleVar(fnsym *obj.LSym, n *ir.Name) *dwarf.Var {
+ var abbrev int
+ var offs int64
+
+ localAutoOffset := func() int64 {
+ offs = n.FrameOffset()
+ if base.Ctxt.Arch.FixedFrameSize == 0 {
+ offs -= int64(types.PtrSize)
+ }
+ if buildcfg.FramePointerEnabled {
+ offs -= int64(types.PtrSize)
+ }
+ return offs
+ }
+
+ switch n.Class {
+ case ir.PAUTO:
+ offs = localAutoOffset()
+ abbrev = dwarf.DW_ABRV_AUTO
+ case ir.PPARAM, ir.PPARAMOUT:
+ abbrev = dwarf.DW_ABRV_PARAM
+ if n.IsOutputParamInRegisters() {
+ offs = localAutoOffset()
+ } else {
+ offs = n.FrameOffset() + base.Ctxt.Arch.FixedFrameSize
+ }
+
+ default:
+ base.Fatalf("createSimpleVar unexpected class %v for node %v", n.Class, n)
+ }
+
+ typename := dwarf.InfoPrefix + types.TypeSymName(n.Type())
+ delete(fnsym.Func().Autot, reflectdata.TypeLinksym(n.Type()))
+ inlIndex := 0
+ if base.Flag.GenDwarfInl > 1 {
+ if n.InlFormal() || n.InlLocal() {
+ inlIndex = posInlIndex(n.Pos()) + 1
+ if n.InlFormal() {
+ abbrev = dwarf.DW_ABRV_PARAM
+ }
+ }
+ }
+ declpos := base.Ctxt.InnermostPos(declPos(n))
+ return &dwarf.Var{
+ Name: n.Sym().Name,
+ IsReturnValue: n.Class == ir.PPARAMOUT,
+ IsInlFormal: n.InlFormal(),
+ Abbrev: abbrev,
+ StackOffset: int32(offs),
+ Type: base.Ctxt.Lookup(typename),
+ DeclFile: declpos.RelFilename(),
+ DeclLine: declpos.RelLine(),
+ DeclCol: declpos.RelCol(),
+ InlIndex: int32(inlIndex),
+ ChildIndex: -1,
+ DictIndex: n.DictIndex,
+ }
+}
+
+// createABIVars creates DWARF variables for functions in which the
+// register ABI is enabled but optimization is turned off. It uses a
+// hybrid approach in which register-resident input params are
+// captured with location lists, and all other vars use the "simple"
+// strategy.
+func createABIVars(fnsym *obj.LSym, fn *ir.Func, apDecls []*ir.Name) ([]*ir.Name, []*dwarf.Var, ir.NameSet) {
+
+ // Invoke createComplexVars to generate dwarf vars for input parameters
+ // that are register-allocated according to the ABI rules.
+ decls, vars, selected := createComplexVars(fnsym, fn)
+
+ // Now fill in the remainder of the variables: input parameters
+ // that are not register-resident, output parameters, and local
+ // variables.
+ for _, n := range apDecls {
+ if ir.IsAutoTmp(n) {
+ continue
+ }
+ if _, ok := selected[n]; ok {
+ // already handled
+ continue
+ }
+
+ decls = append(decls, n)
+ vars = append(vars, createSimpleVar(fnsym, n))
+ selected.Add(n)
+ }
+
+ return decls, vars, selected
+}
+
+// createComplexVars creates recomposed DWARF vars with location lists,
+// suitable for describing optimized code.
+func createComplexVars(fnsym *obj.LSym, fn *ir.Func) ([]*ir.Name, []*dwarf.Var, ir.NameSet) {
+ debugInfo := fn.DebugInfo.(*ssa.FuncDebug)
+
+ // Produce a DWARF variable entry for each user variable.
+ var decls []*ir.Name
+ var vars []*dwarf.Var
+ var ssaVars ir.NameSet
+
+ for varID, dvar := range debugInfo.Vars {
+ n := dvar
+ ssaVars.Add(n)
+ for _, slot := range debugInfo.VarSlots[varID] {
+ ssaVars.Add(debugInfo.Slots[slot].N)
+ }
+
+ if dvar := createComplexVar(fnsym, fn, ssa.VarID(varID)); dvar != nil {
+ decls = append(decls, n)
+ vars = append(vars, dvar)
+ }
+ }
+
+ return decls, vars, ssaVars
+}
+
+// createComplexVar builds a single DWARF variable entry and location list.
+func createComplexVar(fnsym *obj.LSym, fn *ir.Func, varID ssa.VarID) *dwarf.Var {
+ debug := fn.DebugInfo.(*ssa.FuncDebug)
+ n := debug.Vars[varID]
+
+ var abbrev int
+ switch n.Class {
+ case ir.PAUTO:
+ abbrev = dwarf.DW_ABRV_AUTO_LOCLIST
+ case ir.PPARAM, ir.PPARAMOUT:
+ abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
+ default:
+ return nil
+ }
+
+ gotype := reflectdata.TypeLinksym(n.Type())
+ delete(fnsym.Func().Autot, gotype)
+ typename := dwarf.InfoPrefix + gotype.Name[len("type:"):]
+ inlIndex := 0
+ if base.Flag.GenDwarfInl > 1 {
+ if n.InlFormal() || n.InlLocal() {
+ inlIndex = posInlIndex(n.Pos()) + 1
+ if n.InlFormal() {
+ abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
+ }
+ }
+ }
+ declpos := base.Ctxt.InnermostPos(n.Pos())
+ dvar := &dwarf.Var{
+ Name: n.Sym().Name,
+ IsReturnValue: n.Class == ir.PPARAMOUT,
+ IsInlFormal: n.InlFormal(),
+ Abbrev: abbrev,
+ Type: base.Ctxt.Lookup(typename),
+ // The stack offset is used as a sorting key, so for decomposed
+ // variables just give it the first one. It's not used otherwise.
+ // This won't work well if the first slot hasn't been assigned a stack
+ // location, but it's not obvious how to do better.
+ StackOffset: ssagen.StackOffset(debug.Slots[debug.VarSlots[varID][0]]),
+ DeclFile: declpos.RelFilename(),
+ DeclLine: declpos.RelLine(),
+ DeclCol: declpos.RelCol(),
+ InlIndex: int32(inlIndex),
+ ChildIndex: -1,
+ DictIndex: n.DictIndex,
+ }
+ list := debug.LocationLists[varID]
+ if len(list) != 0 {
+ dvar.PutLocationList = func(listSym, startPC dwarf.Sym) {
+ debug.PutLocationList(list, base.Ctxt, listSym.(*obj.LSym), startPC.(*obj.LSym))
+ }
+ }
+ return dvar
+}
+
+// RecordFlags records the specified command-line flags to be placed
+// in the DWARF info.
+func RecordFlags(flags ...string) {
+ if base.Ctxt.Pkgpath == "" {
+ // We can't record the flags if we don't know what the
+ // package name is.
+ return
+ }
+
+ type BoolFlag interface {
+ IsBoolFlag() bool
+ }
+ type CountFlag interface {
+ IsCountFlag() bool
+ }
+ var cmd bytes.Buffer
+ for _, name := range flags {
+ f := flag.Lookup(name)
+ if f == nil {
+ continue
+ }
+ getter := f.Value.(flag.Getter)
+ if getter.String() == f.DefValue {
+ // Flag has default value, so omit it.
+ continue
+ }
+ if bf, ok := f.Value.(BoolFlag); ok && bf.IsBoolFlag() {
+ val, ok := getter.Get().(bool)
+ if ok && val {
+ fmt.Fprintf(&cmd, " -%s", f.Name)
+ continue
+ }
+ }
+ if cf, ok := f.Value.(CountFlag); ok && cf.IsCountFlag() {
+ val, ok := getter.Get().(int)
+ if ok && val == 1 {
+ fmt.Fprintf(&cmd, " -%s", f.Name)
+ continue
+ }
+ }
+ fmt.Fprintf(&cmd, " -%s=%v", f.Name, getter.Get())
+ }
+
+ // Adds flag to producer string signaling whether regabi is turned on or
+ // off.
+ // Once regabi is turned on across the board and the relative GOEXPERIMENT
+ // knobs no longer exist this code should be removed.
+ if buildcfg.Experiment.RegabiArgs {
+ cmd.Write([]byte(" regabi"))
+ }
+
+ if cmd.Len() == 0 {
+ return
+ }
+ s := base.Ctxt.Lookup(dwarf.CUInfoPrefix + "producer." + base.Ctxt.Pkgpath)
+ s.Type = objabi.SDWARFCUINFO
+ // Sometimes (for example when building tests) we can link
+ // together two package main archives. So allow dups.
+ s.Set(obj.AttrDuplicateOK, true)
+ base.Ctxt.Data = append(base.Ctxt.Data, s)
+ s.P = cmd.Bytes()[1:]
+}
+
+// RecordPackageName records the name of the package being
+// compiled, so that the linker can save it in the compile unit's DIE.
+func RecordPackageName() {
+ s := base.Ctxt.Lookup(dwarf.CUInfoPrefix + "packagename." + base.Ctxt.Pkgpath)
+ s.Type = objabi.SDWARFCUINFO
+ // Sometimes (for example when building tests) we can link
+ // together two package main archives. So allow dups.
+ s.Set(obj.AttrDuplicateOK, true)
+ base.Ctxt.Data = append(base.Ctxt.Data, s)
+ s.P = []byte(types.LocalPkg.Name)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-01-01 18:22:28 +0000