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

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This reverts commit 230b0bad1f.

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>
This commit is contained in:
Heschi Kreinick 2018-02-28 01:41:42 +00:00
parent 21343e07d6
commit f8973fcafb
1 changed files with 0 additions and 71 deletions
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71
src/cmd/link/internal/ld/dwarf.go
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@ -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.
*/