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[dev.link] cmd/{compile,link}: split SDWARFINFO symtype into sub-types

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This change splits the SDWARFINFO symbol type (a generic container of
DWARF content) into separate sub-classes. The new symbol types are

 SDWARFCUINFO    comp unit DIE, also CU info and CU packagename syms
 SDWARFCONST     constant DIE
 SDWARFFCN       subprogram DIE (default and concrete)
 SDWARFABSFCN    abstract function DIE
 SDWARFTYPE      type DIE
 SDWARFVAR       global variable DIE

Advantage of doing this: in the linker there are several places where
we have to iterate over a symbol's relocations to pick out references
to specific classes of DWARF sub-symbols (for example, looking for all
abstract function DIEs referenced by a subprogram DIE, or looking at
all the type DIEs used in a subprogram DIE). By splitting SDWARFINFO
into parts clients can now look only at the relocation target's sym
type as opposed to having to materialize the target sym name, or do a
lookup.

Change-Id: I4e0ee3216d3c8f1a78bec3d296c01e95b3d025b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/234684
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This commit is contained in:
Than McIntosh 2020-05-20 13:51:59 -04:00
parent de1f07d56d
commit 96ec09da48
9 changed files with 95 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/cmd/compile/internal/gc/main.go
View File

@ -1488,7 +1488,7 @@ func recordFlags(flags ...string) {
return
}
s := Ctxt.Lookup(dwarf.CUInfoPrefix + "producer." + myimportpath)
s.Type = objabi.SDWARFINFO
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)
@ -1500,7 +1500,7 @@ func recordFlags(flags ...string) {
// compiled, so that the linker can save it in the compile unit's DIE.
func recordPackageName() {
s := Ctxt.Lookup(dwarf.CUInfoPrefix + "packagename." + myimportpath)
s.Type = objabi.SDWARFINFO
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)

6
src/cmd/internal/obj/objfile.go
View File

@ -205,7 +205,7 @@ func (ctxt *Link) dwarfSym(s *LSym) (dwarfInfoSym, dwarfLocSym, dwarfRangesSym,
}
if s.Func.dwarfInfoSym == nil {
s.Func.dwarfInfoSym = &LSym{
Type: objabi.SDWARFINFO,
Type: objabi.SDWARFFCN,
}
if ctxt.Flag_locationlists {
s.Func.dwarfLocSym = &LSym{
@ -296,7 +296,7 @@ func (ctxt *Link) DwarfIntConst(myimportpath, name, typename string, val int64)
return
}
s := ctxt.LookupInit(dwarf.ConstInfoPrefix+myimportpath, func(s *LSym) {
s.Type = objabi.SDWARFINFO
s.Type = objabi.SDWARFCONST
ctxt.Data = append(ctxt.Data, s)
})
dwarf.PutIntConst(dwCtxt{ctxt}, s, ctxt.Lookup(dwarf.InfoPrefix+typename), myimportpath+"."+name, val)
@ -422,7 +422,7 @@ func (ft *DwarfFixupTable) SetPrecursorFunc(s *LSym, fn interface{}) {
// the back end.
absfn := ft.ctxt.LookupDerived(s, dwarf.InfoPrefix+s.Name+dwarf.AbstractFuncSuffix)
absfn.Set(AttrDuplicateOK, true)
absfn.Type = objabi.SDWARFINFO
absfn.Type = objabi.SDWARFABSFCN
ft.ctxt.Data = append(ft.ctxt.Data, absfn)
// In the case of "late" inlining (inlines that happen during

3
src/cmd/internal/obj/objfile2.go
View File

@ -428,7 +428,8 @@ func writeAuxSymDebug(ctxt *Link, par *LSym, aux *LSym) {
// Most aux symbols (ex: funcdata) are not interesting--
// pick out just the DWARF ones for now.
if aux.Type != objabi.SDWARFLOC &&
aux.Type != objabi.SDWARFINFO &&
aux.Type != objabi.SDWARFFCN &&
aux.Type != objabi.SDWARFABSFCN &&
aux.Type != objabi.SDWARFLINES &&
aux.Type != objabi.SDWARFRANGE {
return

7
src/cmd/internal/objabi/symkind.go
View File

@ -56,7 +56,12 @@ const (
// Thread-local data that is initially all 0s
STLSBSS
// Debugging data
SDWARFINFO
SDWARFCUINFO
SDWARFCONST
SDWARFFCN
SDWARFABSFCN
SDWARFTYPE
SDWARFVAR
SDWARFRANGE
SDWARFLOC
SDWARFLINES

21
src/cmd/internal/objabi/symkind_string.go
View File

@ -16,17 +16,22 @@ func _() {
_ = x[SBSS-5]
_ = x[SNOPTRBSS-6]
_ = x[STLSBSS-7]
_ = x[SDWARFINFO-8]
_ = x[SDWARFRANGE-9]
_ = x[SDWARFLOC-10]
_ = x[SDWARFLINES-11]
_ = x[SABIALIAS-12]
_ = x[SLIBFUZZER_EXTRA_COUNTER-13]
_ = x[SDWARFCUINFO-8]
_ = x[SDWARFCONST-9]
_ = x[SDWARFFCN-10]
_ = x[SDWARFABSFCN-11]
_ = x[SDWARFTYPE-12]
_ = x[SDWARFVAR-13]
_ = x[SDWARFRANGE-14]
_ = x[SDWARFLOC-15]
_ = x[SDWARFLINES-16]
_ = x[SABIALIAS-17]
_ = x[SLIBFUZZER_EXTRA_COUNTER-18]
}
const _SymKind_name = "SxxxSTEXTSRODATASNOPTRDATASDATASBSSSNOPTRBSSSTLSBSSSDWARFINFOSDWARFRANGESDWARFLOCSDWARFLINESSABIALIASSLIBFUZZER_EXTRA_COUNTER"
const _SymKind_name = "SxxxSTEXTSRODATASNOPTRDATASDATASBSSSNOPTRBSSSTLSBSSSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSABIALIASSLIBFUZZER_EXTRA_COUNTER"
var _SymKind_index = [...]uint8{0, 4, 9, 16, 26, 31, 35, 44, 51, 61, 72, 81, 92, 101, 125}
var _SymKind_index = [...]uint8{0, 4, 9, 16, 26, 31, 35, 44, 51, 63, 74, 83, 95, 105, 114, 125, 134, 145, 154, 178}
func (i SymKind) String() string {
if i >= SymKind(len(_SymKind_index)-1) {

68
src/cmd/link/internal/ld/dwarf.go
View File

@ -277,24 +277,37 @@ func (d *dwctxt) newdie(parent *dwarf.DWDie, abbrev int, name string, version in
newattr(die, dwarf.DW_AT_name, dwarf.DW_CLS_STRING, int64(len(name)), name)
if name != "" && (abbrev <= dwarf.DW_ABRV_VARIABLE || abbrev >= dwarf.DW_ABRV_NULLTYPE) {
// Q: do we need version here? My understanding is that all these
// symbols should be version 0.
if abbrev != dwarf.DW_ABRV_VARIABLE || version == 0 {
if abbrev == dwarf.DW_ABRV_COMPUNIT {
// Avoid collisions with "real" symbol names.
name = fmt.Sprintf(".pkg.%s.%d", name, len(d.linkctxt.compUnits))
}
ds := d.ldr.LookupOrCreateSym(dwarf.InfoPrefix+name, version)
dsu := d.ldr.MakeSymbolUpdater(ds)
dsu.SetType(sym.SDWARFINFO)
d.ldr.SetAttrNotInSymbolTable(ds, true)
d.ldr.SetAttrReachable(ds, true)
die.Sym = dwSym(ds)
if abbrev >= dwarf.DW_ABRV_NULLTYPE && abbrev <= dwarf.DW_ABRV_TYPEDECL {
d.tmap[name] = ds
}
}
// Sanity check: all DIEs created in the linker should have a non-empty
// name and be version zero.
if name == "" || version != 0 {
panic("nameless or version non-zero DWARF DIE")
}
var st sym.SymKind
switch abbrev {
case dwarf.DW_ABRV_FUNCTYPEPARAM, dwarf.DW_ABRV_DOTDOTDOT, dwarf.DW_ABRV_STRUCTFIELD, dwarf.DW_ABRV_ARRAYRANGE:
// There are no relocations against these dies, and their names
// are not unique, so don't create a symbol.
return die
case dwarf.DW_ABRV_COMPUNIT, dwarf.DW_ABRV_COMPUNIT_TEXTLESS:
// Avoid collisions with "real" symbol names.
name = fmt.Sprintf(".pkg.%s.%d", name, len(d.linkctxt.compUnits))
st = sym.SDWARFCUINFO
case dwarf.DW_ABRV_VARIABLE:
st = sym.SDWARFVAR
default:
// Everything else is assigned a type of SDWARFTYPE. that
// this also includes loose ends such as STRUCT_FIELD.
st = sym.SDWARFTYPE
}
ds := d.ldr.LookupOrCreateSym(dwarf.InfoPrefix+name, version)
dsu := d.ldr.MakeSymbolUpdater(ds)
dsu.SetType(st)
d.ldr.SetAttrNotInSymbolTable(ds, true)
d.ldr.SetAttrReachable(ds, true)
die.Sym = dwSym(ds)
if abbrev >= dwarf.DW_ABRV_NULLTYPE && abbrev <= dwarf.DW_ABRV_TYPEDECL {
d.tmap[name] = ds
}
return die
@ -480,7 +493,7 @@ func (d *dwctxt) dotypedef(parent *dwarf.DWDie, gotype loader.Sym, name string,
// to be an anonymous symbol (we want this for perf reasons).
tds := d.ldr.CreateExtSym("", 0)
tdsu := d.ldr.MakeSymbolUpdater(tds)
tdsu.SetType(sym.SDWARFINFO)
tdsu.SetType(sym.SDWARFTYPE)
def.Sym = dwSym(tds)
d.ldr.SetAttrNotInSymbolTable(tds, true)
d.ldr.SetAttrReachable(tds, true)
@ -850,7 +863,7 @@ func (d *dwctxt) mkinternaltype(ctxt *Link, abbrev int, typename, keyname, valna
name := mkinternaltypename(typename, keyname, valname)
symname := dwarf.InfoPrefix + name
s := d.ldr.Lookup(symname, 0)
if s != 0 && d.ldr.SymType(s) == sym.SDWARFINFO {
if s != 0 && d.ldr.SymType(s) == sym.SDWARFTYPE {
return s
}
die := d.newdie(&dwtypes, abbrev, name, 0)
@ -1122,7 +1135,8 @@ func getCompilationDir() string {
func (d *dwctxt) importInfoSymbol(ctxt *Link, dsym loader.Sym) {
d.ldr.SetAttrReachable(dsym, true)
d.ldr.SetAttrNotInSymbolTable(dsym, true)
if d.ldr.SymType(dsym) != sym.SDWARFINFO {
dst := d.ldr.SymType(dsym)
if dst != sym.SDWARFCONST && dst != sym.SDWARFABSFCN {
log.Fatalf("error: DWARF info sym %d/%s with incorrect type %s", dsym, d.ldr.SymName(dsym), d.ldr.SymType(dsym).String())
}
relocs := d.ldr.Relocs(dsym)
@ -1492,7 +1506,7 @@ func (d *dwctxt) writeinfo(units []*sym.CompilationUnit, abbrevsym loader.Sym, p
infosec := d.ldr.LookupOrCreateSym(".debug_info", 0)
disu := d.ldr.MakeSymbolUpdater(infosec)
disu.SetType(sym.SDWARFINFO)
disu.SetType(sym.SDWARFCUINFO)
d.ldr.SetAttrReachable(infosec, true)
syms := []loader.Sym{infosec}
@ -1814,7 +1828,11 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
ctxt.runtimeCU = unit
}
unit.DWInfo = d.newdie(&dwroot, dwarf.DW_ABRV_COMPUNIT, unit.Lib.Pkg, 0)
cuabrv := dwarf.DW_ABRV_COMPUNIT
if len(unit.Textp) == 0 {
cuabrv = dwarf.DW_ABRV_COMPUNIT_TEXTLESS
}
unit.DWInfo = d.newdie(&dwroot, cuabrv, unit.Lib.Pkg, 0)
newattr(unit.DWInfo, dwarf.DW_AT_language, dwarf.DW_CLS_CONSTANT, int64(dwarf.DW_LANG_Go), 0)
// OS X linker requires compilation dir or absolute path in comp unit name to output debug info.
compDir := getCompilationDir()
@ -1850,10 +1868,6 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
}
newattr(unit.DWInfo, dwarf.DW_AT_go_package_name, dwarf.DW_CLS_STRING, int64(len(pkgname)), pkgname)
if len(unit.Textp) == 0 {
unit.DWInfo.Abbrev = dwarf.DW_ABRV_COMPUNIT_TEXTLESS
}
// Scan all functions in this compilation unit, create DIEs for all
// referenced types, create the file table for debug_line, find all
// referenced abstract functions.

4
src/cmd/link/internal/loader/loader.go
View File

@ -1539,7 +1539,7 @@ func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, a
switch a.Type() {
case goobj2.AuxDwarfInfo:
auxDwarfInfo = l.resolve(r, a.Sym())
if l.SymType(auxDwarfInfo) != sym.SDWARFINFO {
if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
panic("aux dwarf info sym with wrong type")
}
case goobj2.AuxDwarfLoc:
@ -2105,7 +2105,7 @@ func topLevelSym(sname string, skind sym.SymKind) bool {
return true
}
switch skind {
case sym.SDWARFINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
return true
default:
return false

15
src/cmd/link/internal/sym/symkind.go
View File

@ -108,7 +108,13 @@ const (
// Sections for debugging information
SDWARFSECT
SDWARFINFO
// DWARF symbol types
SDWARFCUINFO
SDWARFCONST
SDWARFFCN
SDWARFABSFCN
SDWARFTYPE
SDWARFVAR
SDWARFRANGE
SDWARFLOC
SDWARFLINES
@ -128,7 +134,12 @@ var AbiSymKindToSymKind = [...]SymKind{
SBSS,
SNOPTRBSS,
STLSBSS,
SDWARFINFO,
SDWARFCUINFO,
SDWARFCONST,
SDWARFFCN,
SDWARFABSFCN,
SDWARFTYPE,
SDWARFVAR,
SDWARFRANGE,
SDWARFLOC,
SDWARFLINES,

21
src/cmd/link/internal/sym/symkind_string.go
View File

@ -1,4 +1,4 @@
// Code generated by "stringer -type=SymKind"; DO NOT EDIT.
// Code generated by "stringer -type=SymKindstringer -type=SymKind"; DO NOT EDIT.
package sym
@ -56,16 +56,21 @@ func _() {
_ = x[SHOSTOBJ-45]
_ = x[SUNDEFEXT-46]
_ = x[SDWARFSECT-47]
_ = x[SDWARFINFO-48]
_ = x[SDWARFRANGE-49]
_ = x[SDWARFLOC-50]
_ = x[SDWARFLINES-51]
_ = x[SABIALIAS-52]
_ = x[SDWARFCUINFO-48]
_ = x[SDWARFCONST-49]
_ = x[SDWARFFCN-50]
_ = x[SDWARFABSFCN-51]
_ = x[SDWARFTYPE-52]
_ = x[SDWARFVAR-53]
_ = x[SDWARFRANGE-54]
_ = x[SDWARFLOC-55]
_ = x[SDWARFLINES-56]
_ = x[SABIALIAS-57]
}
const _SymKind_name = "SxxxSTEXTSELFRXSECTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSMACHOPLTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSTYPELINKSITABLINKSSYMTABSPCLNTABSFirstWritableSBUILDINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_EXTRA_COUNTERSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILEPATHSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFINFOSDWARFRANGESDWARFLOCSDWARFLINESSABIALIAS"
const _SymKind_name = "SxxxSTEXTSELFRXSECTSTYPESSTRINGSGOSTRINGSGOFUNCSGCBITSSRODATASFUNCTABSELFROSECTSMACHOPLTSTYPERELROSSTRINGRELROSGOSTRINGRELROSGOFUNCRELROSGCBITSRELROSRODATARELROSFUNCTABRELROSTYPELINKSITABLINKSSYMTABSPCLNTABSFirstWritableSBUILDINFOSELFSECTSMACHOSMACHOGOTSWINDOWSSELFGOTSNOPTRDATASINITARRSDATASXCOFFTOCSBSSSNOPTRBSSSLIBFUZZER_EXTRA_COUNTERSTLSBSSSXREFSMACHOSYMSTRSMACHOSYMTABSMACHOINDIRECTPLTSMACHOINDIRECTGOTSFILEPATHSDYNIMPORTSHOSTOBJSUNDEFEXTSDWARFSECTSDWARFCUINFOSDWARFCONSTSDWARFFCNSDWARFABSFCNSDWARFTYPESDWARFVARSDWARFRANGESDWARFLOCSDWARFLINESSABIALIAS"
var _SymKind_index = [...]uint16{0, 4, 9, 19, 24, 31, 40, 47, 54, 61, 69, 79, 88, 98, 110, 124, 136, 148, 160, 173, 182, 191, 198, 206, 220, 230, 238, 244, 253, 261, 268, 278, 286, 291, 300, 304, 313, 337, 344, 349, 361, 373, 390, 407, 416, 426, 434, 443, 453, 463, 474, 483, 494, 503}
var _SymKind_index = [...]uint16{0, 4, 9, 19, 24, 31, 40, 47, 54, 61, 69, 79, 88, 98, 110, 124, 136, 148, 160, 173, 182, 191, 198, 206, 220, 230, 238, 244, 253, 261, 268, 278, 286, 291, 300, 304, 313, 337, 344, 349, 361, 373, 390, 407, 416, 426, 434, 443, 453, 465, 476, 485, 497, 507, 516, 527, 536, 547, 556}
func (i SymKind) String() string {
if i >= SymKind(len(_SymKind_index)-1) {