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cmd/compile: fixes for bad DWARF abstract origin references

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Change the compiler's DWARF inline info generation to be more careful
about producing consistent instances of abstract function DIEs. The
new strategy is to insure that the only params/variables created in an
abstract subprogram DIE are those corresponding to declarations in the
original pre-inlining version of the code. If a concrete subprogram
winds up with other vars as part of the compilation process (return
temps, for example, or scalars generated by splitting a structure into
pieces) these are emitted as regular param/variable DIEs instead of
concrete DIEs.

The linker dwarf test now has a couple of new testpoints that include
checks to make sure that all abstract DIE references are
sane/resolvable; this will help catch similar problems in the future.

Fixes #23046.

Change-Id: I9b0030da8673fbb80b7ad50461fcf8c6ac823a37
Reviewed-on: https://go-review.googlesource.com/83675
Run-TryBot: Than McIntosh <thanm@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Than McIntosh 2017-12-11 15:53:31 -05:00
parent 44213336f0
commit fdecaa837c
5 changed files with 345 additions and 134 deletions
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74
src/cmd/compile/internal/gc/pgen.go
View file

@ -414,6 +414,9 @@ func createSimpleVars(automDecls []*Node) ([]*Node, []*dwarf.Var, map[*Node]bool
if genDwarfInline > 1 {
if n.InlFormal() || n.InlLocal() {
inlIndex = posInlIndex(n.Pos) + 1
if n.InlFormal() {
abbrev = dwarf.DW_ABRV_PARAM
}
}
}
declpos := Ctxt.InnermostPos(n.Pos)
@ -513,9 +516,8 @@ func createDwarfVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*No
}
var dcl []*Node
var chopVersion bool
if fnsym.WasInlined() {
dcl, chopVersion = preInliningDcls(fnsym)
dcl = preInliningDcls(fnsym)
} else {
dcl = automDecls
}
@ -534,7 +536,7 @@ func createDwarfVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*No
continue
}
c := n.Sym.Name[0]
if c == '~' || c == '.' || n.Type.IsUntyped() {
if c == '.' || n.Type.IsUntyped() {
continue
}
typename := dwarf.InfoPrefix + typesymname(n.Type)
@ -547,6 +549,9 @@ func createDwarfVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*No
if genDwarfInline > 1 {
if n.InlFormal() || n.InlLocal() {
inlIndex = posInlIndex(n.Pos) + 1
if n.InlFormal() {
abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
}
}
}
declpos := Ctxt.InnermostPos(n.Pos)
@ -575,49 +580,59 @@ func createDwarfVars(fnsym *obj.LSym, debugInfo *ssa.FuncDebug, automDecls []*No
}
// Parameter and local variable names are given middle dot
// version numbers as part of the writing them out to export
// data (see issue 4326). If DWARF inlined routine generation
// is turned on, undo this versioning, since DWARF variables
// in question will be parented by the inlined routine and
// not the top-level caller.
if genDwarfInline > 1 && chopVersion {
for _, v := range vars {
if v.InlIndex != -1 {
if i := strings.Index(v.Name, "·"); i > 0 {
v.Name = v.Name[:i] // cut off Vargen
}
}
}
}
return decls, vars
}
// Given a function that was inlined at some point during the compilation,
// return a list of nodes corresponding to the autos/locals in that
// function prior to inlining. Untyped and compiler-synthesized vars are
// stripped out along the way.
func preInliningDcls(fnsym *obj.LSym) ([]*Node, bool) {
// 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) []*Node {
fn := Ctxt.DwFixups.GetPrecursorFunc(fnsym).(*Node)
imported := false
var dcl, rdcl []*Node
if fn.Name.Defn != nil {
dcl = fn.Func.Inldcl.Slice() // local function
} else {
dcl = fn.Func.Dcl // imported function
imported = true
}
for _, n := range dcl {
c := n.Sym.Name[0]
if c == '~' || c == '.' || n.Type.IsUntyped() {
if c == '.' || n.Type.IsUntyped() {
continue
}
rdcl = append(rdcl, n)
}
return rdcl, imported
sort.Sort(byNodeName(rdcl))
return rdcl
}
func cmpNodeName(a, b *Node) bool {
aart := 0
if strings.HasPrefix(a.Sym.Name, "~") {
aart = 1
}
bart := 0
if strings.HasPrefix(b.Sym.Name, "~") {
bart = 1
}
if aart != bart {
return aart < bart
}
aname := unversion(a.Sym.Name)
bname := unversion(b.Sym.Name)
return aname < bname
}
// byNodeName implements sort.Interface for []*Node using cmpNodeName.
type byNodeName []*Node
func (s byNodeName) Len() int { return len(s) }
func (s byNodeName) Less(i, j int) bool { return cmpNodeName(s[i], s[j]) }
func (s byNodeName) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
// varOffset returns the offset of slot within the user variable it was
// decomposed from. This has nothing to do with its stack offset.
func varOffset(slot *ssa.LocalSlot) int64 {
@ -682,6 +697,9 @@ func createComplexVar(debugInfo *ssa.FuncDebug, n *Node, parts []varPart) *dwarf
if genDwarfInline > 1 {
if n.InlFormal() || n.InlLocal() {
inlIndex = posInlIndex(n.Pos) + 1
if n.InlFormal() {
abbrev = dwarf.DW_ABRV_PARAM_LOCLIST
}
}
}
declpos := Ctxt.InnermostPos(n.Pos)