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cmd/link: add variable_parameter attr to functype outparams

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When generating DW_TAG_subroutine_type DIEs during linker DWARF type
synthesis, ensure that in the list of children of the subroutine type
DIE (correspondings to input/output params) the output params are
marked with the DW_AT_variable_parameter attribute. In addition, fix
up the generated types of the output params: prior to this patch for a
given output parameter of type T, we would emit the DIE type as *T
(presumably due to how parameter passing/returning worked prior to the
register ABI); with this patch the emitted type will just be T, not *T.

Fixes #59977.

Change-Id: I5b5600be86473695663c75b85baeecad667b9245
Reviewed-on: https://go-review.googlesource.com/c/go/+/595715
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Than McIntosh 2024-06-27 14:54:06 +00:00
parent 13b3af0391
commit ae33b66c19
2 changed files with 30 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

24
src/cmd/internal/dwarf/dwarf.go
View file

@ -338,6 +338,7 @@ const (
DW_ABRV_LEXICAL_BLOCK_SIMPLE
DW_ABRV_STRUCTFIELD
DW_ABRV_FUNCTYPEPARAM
DW_ABRV_FUNCTYPEOUTPARAM
DW_ABRV_DOTDOTDOT
DW_ABRV_ARRAYRANGE
DW_ABRV_NULLTYPE
@ -572,6 +573,8 @@ var abbrevs = []dwAbbrev{
{
DW_TAG_member,
DW_CHILDREN_no,
// This abbrev is special-cased by the linker (unlike other DIEs
// we don't want a loader.Sym created for this DIE).
[]dwAttrForm{
{DW_AT_name, DW_FORM_string},
{DW_AT_data_member_location, DW_FORM_udata},
@ -586,15 +589,34 @@ var abbrevs = []dwAbbrev{
DW_CHILDREN_no,
// No name!
// This abbrev is special-cased by the linker (unlike other DIEs
// we don't want a loader.Sym created for this DIE).
[]dwAttrForm{
{DW_AT_type, DW_FORM_ref_addr},
},
},
/* FUNCTYPEOUTPARAM */
{
DW_TAG_formal_parameter,
DW_CHILDREN_no,
// No name!
// This abbrev is special-cased by the linker (unlike other DIEs
// we don't want a loader.Sym created for this DIE).
[]dwAttrForm{
{DW_AT_variable_parameter, DW_FORM_flag},
{DW_AT_type, DW_FORM_ref_addr},
},
},
/* DOTDOTDOT */
{
DW_TAG_unspecified_parameters,
DW_CHILDREN_no,
// No name.
// This abbrev is special-cased by the linker (unlike other DIEs
// we don't want a loader.Sym created for this DIE).
[]dwAttrForm{},
},
@ -604,6 +626,8 @@ var abbrevs = []dwAbbrev{
DW_CHILDREN_no,
// No name!
// This abbrev is special-cased by the linker (unlike other DIEs
// we don't want a loader.Sym created for this DIE).
[]dwAttrForm{
{DW_AT_type, DW_FORM_ref_addr},
{DW_AT_count, DW_FORM_udata},

10
src/cmd/link/internal/ld/dwarf.go
View file

@ -286,7 +286,7 @@ func (d *dwctxt) newdie(parent *dwarf.DWDie, abbrev int, name string) *dwarf.DWD
var st sym.SymKind
switch abbrev {
case dwarf.DW_ABRV_FUNCTYPEPARAM, dwarf.DW_ABRV_DOTDOTDOT, dwarf.DW_ABRV_STRUCTFIELD, dwarf.DW_ABRV_ARRAYRANGE:
case dwarf.DW_ABRV_FUNCTYPEPARAM, dwarf.DW_ABRV_FUNCTYPEOUTPARAM, 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
@ -622,8 +622,9 @@ func (d *dwctxt) newtype(gotype loader.Sym) *dwarf.DWDie {
for i := 0; i < nfields; i++ {
s := decodetypeFuncOutType(d.ldr, d.arch, gotype, &relocs, i)
sn := d.ldr.SymName(s)
fld := d.newdie(die, dwarf.DW_ABRV_FUNCTYPEPARAM, sn[5:])
d.newrefattr(fld, dwarf.DW_AT_type, d.defptrto(d.defgotype(s)))
fld := d.newdie(die, dwarf.DW_ABRV_FUNCTYPEOUTPARAM, sn[5:])
newattr(fld, dwarf.DW_AT_variable_parameter, dwarf.DW_CLS_FLAG, 1, 0)
d.newrefattr(fld, dwarf.DW_AT_type, d.defgotype(s))
}
case abi.Interface:
@ -2096,7 +2097,8 @@ func (d *dwctxt) dwarfGenerateDebugSyms() {
seen := loader.MakeBitmap(d.ldr.NSym())
for _, s := range infoSec.syms {
if seen.Has(s) {
log.Fatalf("symbol %s listed multiple times", d.ldr.SymName(s))
log.Fatalf("dwarf symbol %s listed multiple times",
d.ldr.SymName(s))
}
seen.Set(s)
}