[dev.regabi] cmd/compile: fix GOEXPERIMENT=regabi builder

I misread the FIXME comment in InitLSym the first time. It's referring
to how InitLSym is supposed to be called exactly once per
function (see function documentation), but this is evidently not
actually the case currently in GOEXPERIMENT=regabi mode.

So just move the NeedFuncSym call below the GOEXPERIMENT=regabi
workaround.

Also, to fix the linux-arm64-{aws,packet} builders, move the call to
reflectdata.WriteFuncSyms() to after the second batch of functions are
compiled. This is necessary to make sure we catch all the funcsyms
that can be added by late function compilation.

Change-Id: I6d6396d48e2ee29c1fb007fa2b99e065b36375db
Reviewed-on: https://go-review.googlesource.com/c/go/+/283552
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Trust: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/compile/internal/gc/obj.go

@@ -111,7 +111,6 @@ func dumpdata() {
 	numDecls := len(typecheck.Target.Decls)
 
 	dumpglobls(typecheck.Target.Externs)
-	staticdata.WriteFuncSyms()
 	reflectdata.CollectPTabs()
 	numExports := len(typecheck.Target.Exports)
 	addsignats(typecheck.Target.Externs)
@@ -151,6 +150,7 @@ func dumpdata() {
 		objw.Global(zero, int32(reflectdata.ZeroSize), obj.DUPOK|obj.RODATA)
 	}
 
+	staticdata.WriteFuncSyms()
 	addGCLocals()
 
 	if numExports != len(typecheck.Target.Exports) {

src/cmd/compile/internal/ssagen/abi.go

@@ -138,13 +138,12 @@ func ReadSymABIs(file, myimportpath string) {
 // For body-less functions, we only create the LSym; for functions
 // with bodies call a helper to setup up / populate the LSym.
 func InitLSym(f *ir.Func, hasBody bool) {
-	staticdata.NeedFuncSym(f.Sym())
-
 	// FIXME: for new-style ABI wrappers, we set up the lsym at the
 	// point the wrapper is created.
 	if f.LSym != nil && base.Flag.ABIWrap {
 		return
 	}
+	staticdata.NeedFuncSym(f.Sym())
 	selectLSym(f, hasBody)
 	if hasBody {
 		setupTextLSym(f, 0)