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cmd/link: eliminate a couple of unused DWARF attrs

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The linker's DWARF generation occasionally computes and attaches an
attribute X to a type even though the type's abbrev doesn't have the
specified attr. For example, the DW_TAG_subroutine_type abbrev entry
has no type attribute, but a type attr is given to it (wasting
memory). Similarly there are some places where a byte size attr is
added to a DIE whose abbrev lacks that attr. This patch trims away a
few of these not-needed attrs, saving some very tiny amount of memory.

Updates #26186

Change-Id: I69e853df468ac54b07772a614b4106d7c4dae01d
Reviewed-on: https://go-review.googlesource.com/123296
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Than McIntosh 2018-07-11 12:30:05 -04:00
parent ebdba42d9e
commit 204c618f0a
1 changed files with 0 additions and 3 deletions
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3
src/cmd/link/internal/ld/dwarf.go
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@ -451,7 +451,6 @@ func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
case objabi.KindChan:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_CHANTYPE, name, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
s := decodetypeChanElem(ctxt.Arch, gotype)
newrefattr(die, dwarf.DW_AT_go_elem, defgotype(ctxt, s))
// Save elem type for synthesizechantypes. We could synthesize here
@ -462,7 +461,6 @@ func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_FUNCTYPE, name, 0)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
dotypedef(ctxt, &dwtypes, name, die)
newrefattr(die, dwarf.DW_AT_type, mustFind(ctxt, "void"))
nfields := decodetypeFuncInCount(ctxt.Arch, gotype)
for i := 0; i < nfields; i++ {
s := decodetypeFuncInType(ctxt.Arch, gotype, i)
@ -483,7 +481,6 @@ func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
case objabi.KindInterface:
die = newdie(ctxt, &dwtypes, dwarf.DW_ABRV_IFACETYPE, name, 0)
dotypedef(ctxt, &dwtypes, name, die)
newattr(die, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, bytesize, 0)
nfields := int(decodetypeIfaceMethodCount(ctxt.Arch, gotype))
var s *sym.Symbol
if nfields == 0 {