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cmd/internal/obj: tweak implicit {ArgsPointerMaps,ArgInfo} behavior

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This CL changes cmd/internal/obj to also implicitly set
ArgsPointerMaps and ArgInfo for assembly functions that are explicitly
package qualified (e.g., "pkg·name", not just "·name"). This is a
prerequisite for changing cmd/asm to stop emitting `"".`-prefixed
symbol names.

Change-Id: I4e14bc24c87cf4d7114a7aed9beaf0c8d1f9c07f
Reviewed-on: https://go-review.googlesource.com/c/go/+/523335
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2023-08-27 15:31:33 -07:00 committed by Gopher Robot
parent 2e644cce9d
commit 208f361800
3 changed files with 26 additions and 4 deletions
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13
src/cmd/internal/obj/plist.go
View File

@ -96,8 +96,9 @@ func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc) {
// Add reference to Go arguments for assembly functions without them.
if ctxt.IsAsm {
pkgPrefix := objabi.PathToPrefix(ctxt.Pkgpath) + "."
for _, s := range text {
if !strings.HasPrefix(s.Name, "\"\".") {
if !strings.HasPrefix(s.Name, `"".`) && !strings.HasPrefix(s.Name, pkgPrefix) {
continue
}
// The current args_stackmap generation in the compiler assumes
@ -107,6 +108,16 @@ func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc) {
if s.ABI() != ABI0 {
continue
}
// runtime.addmoduledata is a host ABI function, so it doesn't
// need FUNCDATA anyway. Moreover, cmd/link has special logic
// for linking it in eccentric build modes, which breaks if it
// has FUNCDATA references (e.g., cmd/cgo/internal/testplugin).
//
// TODO(cherryyz): Fix cmd/link's handling of plugins (see
// discussion on CL 523355).
if s.Name == "runtime.addmoduledata" {
continue
}
foundArgMap, foundArgInfo := false, false
for p := s.Func().Text; p != nil; p = p.Link {
if p.As == AFUNCDATA && p.From.Type == TYPE_CONST {

11
src/cmd/link/internal/ld/pcln.go
View File

@ -727,6 +727,17 @@ func writeFuncs(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, inlSym
for j := range funcdata {
dataoff := off + int64(4*j)
fdsym := funcdata[j]
// cmd/internal/obj optimistically populates ArgsPointerMaps and
// ArgInfo for assembly functions, hoping that the compiler will
// emit appropriate symbols from their Go stub declarations. If
// it didn't though, just ignore it.
//
// TODO(cherryyz): Fix arg map generation (see discussion on CL 523335).
if fdsym != 0 && (j == abi.FUNCDATA_ArgsPointerMaps || j == abi.FUNCDATA_ArgInfo) && ldr.IsFromAssembly(s) && ldr.Data(fdsym) == nil {
fdsym = 0
}
if fdsym == 0 {
sb.SetUint32(ctxt.Arch, dataoff, ^uint32(0)) // ^0 is a sentinel for "no value"
continue

6
src/runtime/funcdata.h
View File

@ -35,9 +35,9 @@
// defines the pointer map for the function's arguments.
// GO_ARGS should be the first instruction in a function that uses it.
// It can be omitted if there are no arguments at all.
// GO_ARGS is inserted implicitly by the linker for any function whose
// name starts with a middle-dot and that also has a Go prototype; it
// is therefore usually not necessary to write explicitly.
// GO_ARGS is inserted implicitly by the assembler for any function
// whose package-qualified symbol name belongs to the current package;
// it is therefore usually not necessary to write explicitly.
#define GO_ARGS FUNCDATA $FUNCDATA_ArgsPointerMaps, go_args_stackmap(SB)
// GO_RESULTS_INITIALIZED indicates that the assembly function