cmd/link: revert CL 89535: "fix up location lists for dsymutil"

This reverts commit 230b0bad1f9685e824c9096deb4badbe93377733.

Reason for revert: breaking the build.

Fixes #24165

Change-Id: I9d8dda59f97a47e5c436f1c061b34ced82bde8ec
Reviewed-on: https://go-review.googlesource.com/97575
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index 116a8493ff2530555afcb14c34c9634cc1db3347..ae0d3c07a3a03a197bce46733221ad5c04e18da6 100644 (file)
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1759,10 +1759,6 @@ func collectlocs(ctxt *Link, syms []*sym.Symbol, units []*compilationUnit) []*sy
                                        reloc.Sym.Attr |= sym.AttrReachable | sym.AttrNotInSymbolTable
                                        syms = append(syms, reloc.Sym)
                                        empty = false
-                                       // LLVM doesn't support base address entries. Strip them out so LLDB and dsymutil don't get confused.
-                                       if ctxt.HeadType == objabi.Hdarwin {
-                                               removeLocationListBaseAddress(ctxt, fn, reloc.Sym)
-                                       }
                                        // One location list entry per function, but many relocations to it. Don't duplicate.
                                        break
                                }
@@ -1779,73 +1775,6 @@ func collectlocs(ctxt *Link, syms []*sym.Symbol, units []*compilationUnit) []*sy
        return syms
 }
 
-func removeLocationListBaseAddress(ctxt *Link, info, list *sym.Symbol) {
-       // The list symbol contains multiple lists, but they're all for the
-       // same function, and it's not empty.
-       fn := list.R[0].Sym
-
-       // Discard the relocations for the base address entries.
-       list.R = list.R[:0]
-
-       // Add relocations for each location entry's start and end addresses,
-       // so that the base address entries aren't necessary.
-       // We could remove them entirely, but that's more work for a relatively
-       // small size win. If dsymutil runs it'll throw them away anyway.
-
-       // relocate adds a CU-relative relocation to fn+addr at offset.
-       relocate := func(addr uint64, offset int) {
-               list.R = append(list.R, sym.Reloc{
-                       Off:  int32(offset),
-                       Siz:  uint8(ctxt.Arch.PtrSize),
-                       Type: objabi.R_ADDRCUOFF,
-                       Add:  int64(addr),
-                       Sym:  fn,
-               })
-       }
-
-       for i := 0; i < len(list.P); {
-               first := readPtr(ctxt, list.P[i:])
-               second := readPtr(ctxt, list.P[i+ctxt.Arch.PtrSize:])
-
-               if first == 0 ||
-                       first == ^uint64(0) ||
-                       (ctxt.Arch.PtrSize == 4 && first == uint64(^uint32(0))) {
-                       // Base address selection entry or end of list. Ignore.
-                       i += ctxt.Arch.PtrSize * 2
-                       continue
-               }
-
-               relocate(first, i)
-               relocate(second, i+ctxt.Arch.PtrSize)
-
-               // Skip past the actual location.
-               i += ctxt.Arch.PtrSize * 2
-               i += 2 + int(ctxt.Arch.ByteOrder.Uint16(list.P[i:]))
-       }
-
-       // Rewrite the DIE's relocations to point to the first location entry,
-       // not the now-useless base address selection entry.
-       for i := range info.R {
-               r := &info.R[i]
-               if r.Sym != list {
-                       continue
-               }
-               r.Add += int64(2 * ctxt.Arch.PtrSize)
-       }
-}
-
-// Read a pointer-sized uint from the beginning of buf.
-func readPtr(ctxt *Link, buf []byte) uint64 {
-       switch ctxt.Arch.PtrSize {
-       case 4:
-               return uint64(ctxt.Arch.ByteOrder.Uint32(buf))
-       case 8:
-               return ctxt.Arch.ByteOrder.Uint64(buf)
-       default:
-               panic("unexpected pointer size")
-       }
-}
-
 /*
  *  Elf.
  */