cmd/compile: move Linksym, linksymname, and isblanksym to types package

Response to code review feedback on CL 40693.

This CL was prepared by:

(1) manually adding new implementations and the Ctxt var to package types

(2) running eg with template:

func before(s *types.Sym) *obj.LSym { return gc.Linksym(s) }
func after(s *types.Sym) *obj.LSym  { return s.Linksym() }

(3) running gofmt -r:

gofmt -r 'isblanksym(a) -> a.IsBlank()'

(4) manually removing old implementations from package gc

Passes toolstash-check.

Change-Id: I39c35def7cae5bcbcc7c77253e5d2b066b981dea
Reviewed-on: https://go-review.googlesource.com/41302
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/types/sym.go b/src/cmd/compile/internal/types/sym.go
index af6eccc485..92be6ca1a6 100644
--- a/src/cmd/compile/internal/types/sym.go
+++ b/src/cmd/compile/internal/types/sym.go
@@ -59,3 +59,27 @@ func (sym *Sym) SetUniq(b bool)     { sym.flags.set(symUniq, b) }
 func (sym *Sym) SetSiggen(b bool)   { sym.flags.set(symSiggen, b) }
 func (sym *Sym) SetAsm(b bool)      { sym.flags.set(symAsm, b) }
 func (sym *Sym) SetAlgGen(b bool)   { sym.flags.set(symAlgGen, b) }
+
+func (sym *Sym) IsBlank() bool {
+	return sym != nil && sym.Name == "_"
+}
+
+func (sym *Sym) LinksymName() string {
+	if sym.IsBlank() {
+		return "_"
+	}
+	if sym.Linkname != "" {
+		return sym.Linkname
+	}
+	return sym.Pkg.Prefix + "." + sym.Name
+}
+
+func (sym *Sym) Linksym() *obj.LSym {
+	if sym == nil {
+		return nil
+	}
+	if sym.Lsym == nil {
+		sym.Lsym = Ctxt.Lookup(sym.LinksymName())
+	}
+	return sym.Lsym
+}