cmd/compile/internal/pkginit: remove dependency on typecheck.Resolve

The use of typecheck.Resolve was previously necessary to interoperate
with the non-unified frontend, because it hooked into iimport. It's no
longer necessary with unified IR, where we can just lookup the
".inittask" symbol and access Def directly.

Updates #57410.

Change-Id: I73bdfd53f65988ececd2b777743cd8b591a6db48
Reviewed-on: https://go-review.googlesource.com/c/go/+/458616
Auto-Submit: Matthew Dempsky <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Run-TryBot: Matthew Dempsky <[email protected]>
Reviewed-by: Keith Randall <[email protected]>

Author: mdempsky

src/cmd/compile/internal/pkginit/init.go

@@ -75,14 +75,14 @@ func Task() *ir.Name {
 
 	// Find imported packages with init tasks.
 	for _, pkg := range typecheck.Target.Imports {
-		n := typecheck.Resolve(ir.NewIdent(base.Pos, pkg.Lookup(".inittask")))
-		if n.Op() == ir.ONONAME {
+		n, ok := pkg.Lookup(".inittask").Def.(*ir.Name)
+		if !ok {
 			continue
 		}
-		if n.Op() != ir.ONAME || n.(*ir.Name).Class != ir.PEXTERN {
+		if n.Op() != ir.ONAME || n.Class != ir.PEXTERN {
 			base.Fatalf("bad inittask: %v", n)
 		}
-		deps = append(deps, n.(*ir.Name).Linksym())
+		deps = append(deps, n.Linksym())
 	}
 	if base.Flag.ASan {
 		// Make an initialization function to call runtime.asanregisterglobals to register an