feat(asm): the operand forms and defines GOROOT writes

Assisted-by: GLM 5.3 Flash

cmd/gasm/audit.go

@@ -664,6 +664,7 @@ func runCorpusAudit(root string, dirs includeDirs) (*corpusStats, error) {
 				f, errs := parser.ParseWithOptions(path, src, parser.Options{
 					Expand:      true,
 					IncludeDirs: append(slices.Clone(dirs), hdrDir),
+					Predefines:  platformPredefinesFor(goarchName(tg.a), goos),
 				})
 				if len(errs) > 0 {
 					ok = false
@@ -683,12 +684,19 @@ func runCorpusAudit(root string, dirs includeDirs) (*corpusStats, error) {
 			continue
 		}
 
-		f, errs := parser.ParseWithOptions(path, src, parser.Options{Expand: true, IncludeDirs: dirs})
-
 		ok := true
 		for _, i := range wanted {
 			tg, t := targets[i], tallies[i]
 			t.attempted++
+			// The parse carries the target's platform predefines, so it
+			// cannot be shared across targets the way a header-free file's
+			// could: a #ifdef GOARCH_arm block must be live on arm64 and
+			// dead everywhere else.
+			f, errs := parser.ParseWithOptions(path, src, parser.Options{
+				Expand:      true,
+				IncludeDirs: dirs,
+				Predefines:  platformPredefinesFor(goarchName(tg.a), goos),
+			})
 			var err error
 			if len(errs) > 0 {
 				err = errs[0] // a parse failure is a failure for every target