From ec4ae29f52cee3f6e448d8279708ea47d553f35f Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Mon, 22 Oct 2018 16:36:24 -0400 Subject: [PATCH] cmd/link: abstract DWARF metadata symbol lookup The compiler passes a lot of DWARF metadata about functions to the linker via symbols whose names are derived from the function's own symbol name. We look up these symbols in several places. This is about to get slightly more complex as we introduce ABIs as symbol versions, so abstract this lookup pattern into a helper function. For #27539. Change-Id: Ic71f6b5dc6608a5a5f5f515808981e6d6f5d728e Reviewed-on: https://go-review.googlesource.com/c/146858 Run-TryBot: Austin Clements TryBot-Result: Gobot Gobot Reviewed-by: David Chase Reviewed-by: Heschi Kreinick --- src/cmd/link/internal/ld/dwarf.go | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go index 7a20650d9c..b733bc690e 100644 --- a/src/cmd/link/internal/ld/dwarf.go +++ b/src/cmd/link/internal/ld/dwarf.go @@ -342,6 +342,16 @@ func lookupOrDiag(ctxt *Link, n string) *sym.Symbol { return s } +// dwarfFuncSym looks up a DWARF metadata symbol for function symbol s. +// If the symbol does not exist, it creates it if create is true, +// or returns nil otherwise. +func dwarfFuncSym(ctxt *Link, s *sym.Symbol, meta string, create bool) *sym.Symbol { + if create { + return ctxt.Syms.Lookup(meta+s.Name, int(s.Version)) + } + return ctxt.Syms.ROLookup(meta+s.Name, int(s.Version)) +} + func dotypedef(ctxt *Link, parent *dwarf.DWDie, name string, def *dwarf.DWDie) *dwarf.DWDie { // Only emit typedefs for real names. if strings.HasPrefix(name, "map[") { @@ -1146,7 +1156,7 @@ func writelines(ctxt *Link, unit *compilationUnit, ls *sym.Symbol) { // indexes (created by numberfile) to CU-local indexes. fileNums := make(map[int]int) for _, s := range unit.lib.Textp { // textp has been dead-code-eliminated already. - dsym := ctxt.Syms.Lookup(dwarf.InfoPrefix+s.Name, int(s.Version)) + dsym := dwarfFuncSym(ctxt, s, dwarf.InfoPrefix, true) for _, f := range s.FuncInfo.File { if _, ok := fileNums[int(f.Value)]; ok { continue @@ -1756,12 +1766,12 @@ func dwarfGenerateDebugInfo(ctxt *Link) { // referenced abstract functions. // Collect all debug_range symbols in unit.rangeSyms for _, s := range lib.Textp { // textp has been dead-code-eliminated already. - dsym := ctxt.Syms.ROLookup(dwarf.InfoPrefix+s.Name, int(s.Version)) + dsym := dwarfFuncSym(ctxt, s, dwarf.InfoPrefix, false) dsym.Attr |= sym.AttrNotInSymbolTable | sym.AttrReachable dsym.Type = sym.SDWARFINFO unit.funcDIEs = append(unit.funcDIEs, dsym) - rangeSym := ctxt.Syms.ROLookup(dwarf.RangePrefix+s.Name, int(s.Version)) + rangeSym := dwarfFuncSym(ctxt, s, dwarf.RangePrefix, false) if rangeSym != nil && rangeSym.Size > 0 { rangeSym.Attr |= sym.AttrReachable | sym.AttrNotInSymbolTable rangeSym.Type = sym.SDWARFRANGE -- 2.50.0