cmd/compile: skip generating args_stackmap for "pulled" funcs

In golang.org/cl/171464, we cleaned up generation of .stkobj linker
symbols, but we couldn't figure out why a similar cleanup to
.args_stackmap linker symbols caused problems.

The issue is that we only need/want to generate .args_stackmap for
functions that are implemented in assembly in the same package. When
"pulling" a function from another package via //go:linkname, we can
safely skip emitting .args_stackmap, because compiling that package
will have generated it, if necessary.

Fixes #31615.

Change-Id: If8680aa7dd5b4e8f268b6b032d746f1b8536c867
Reviewed-on: https://go-review.googlesource.com/c/go/+/223238
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index e8141b52376c9c9b8dd174083133fc1f0587ab3c..6ccd0b8d943a70a060da296b47703e1050d42ad9 100644 (file)
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -12,7 +12,6 @@ import (
        "cmd/internal/objabi"
        "cmd/internal/src"
        "cmd/internal/sys"
-       "fmt"
        "internal/race"
        "math/rand"
        "sort"
@@ -28,11 +27,10 @@ var (
 )
 
 func emitptrargsmap(fn *Node) {
-       if fn.funcname() == "_" {
+       if fn.funcname() == "_" || fn.Func.Nname.Sym.Linkname != "" {
                return
        }
-       sym := lookup(fmt.Sprintf("%s.args_stackmap", fn.funcname()))
-       lsym := sym.Linksym()
+       lsym := Ctxt.Lookup(fn.Func.lsym.Name + ".args_stackmap")
 
        nptr := int(fn.Type.ArgWidth() / int64(Widthptr))
        bv := bvalloc(int32(nptr) * 2)