fix: staticcheck and deadcode findings repo-wide, modernize counting loops

cmd/gasm/audit.go

@@ -66,7 +66,7 @@ mnemonic, so the audit tracks whatever toolchain `+"`go env GOROOT`"+` names.
 		return err
 	}
 
-	var superset, backlog, shared, goOnly []string
+	var superset, backlog, shared []string
 	for _, name := range names {
 		switch {
 		case !asm.Encodable(name):
@@ -77,16 +77,8 @@ mnemonic, so the audit tracks whatever toolchain `+"`go env GOROOT`"+` names.
 			shared = append(shared, name)
 		}
 	}
-	for _, name := range names {
-		if goKnown[name] && !seen[name] {
-			goOnly = append(goOnly, name)
-		}
-	}
-	// GO-ONLY is computed from the complement of the gasm table, which this
-	// audit cannot enumerate (Go's table is only visible through probes of
-	// names we already know).  Report it as informational zero instead of a
-	// misleading list.
-	goOnly = nil
+	// GO-ONLY is not enumerable by probing: Go's table is only visible
+	// through names we already know, so nothing can be reported there.
 
 	sort.Strings(superset)
 	sort.Strings(backlog)

cmd/gasm/main.go

@@ -1526,7 +1526,7 @@ func cmdVerifyCall(k *verify.Kernel, path, funcName, bufSpec, scalarSpec string,
 	fmt.Printf("  args before: %s\n", hexDump(args))
 
 	rc := 0
-	for i := 0; i < repeat; i++ {
+	for i := range repeat {
 		out, err := k.CallFunc(funcName, args)
 		if err != nil {
 			fmt.Printf("  call %d: FAIL — %v\n", i+1, err)
@@ -1575,7 +1575,7 @@ func hexDump(buf []byte) string {
 		n = max
 	}
 	var sb strings.Builder
-	for i := 0; i < n; i++ {
+	for i := range n {
 		if i > 0 {
 			sb.WriteByte(' ')
 		}

cmd/gasm/scaffold.go

@@ -60,6 +60,7 @@ bodies, place the file in the kernel's package, and run it in CI.
 	out.WriteString(headerComment)
 	out.WriteString("package " + packageName + "\n\n")
 	out.WriteString("import (\n\t\"bytes\"\n\t\"math/rand\"\n\t\"testing\"\n)\n\n")
+	out.WriteString(generatedHelpers)
 
 	kernels := 0
 	for _, d := range f.Decls {
@@ -305,9 +306,12 @@ func goCast(elem string) string {
 	}
 }
 
-// outputBytes narrows a returned slice to bytes for the comparison; scalar
-// results are compared through the same helper via a reflect-free trick the
-// author may need to adjust for non-slice returns.
+// generatedHelpers is emitted into every generated test file: outputBytes
+// narrows returned slices and scalars to a byte form for the comparison.
+// It lives in the template, not in this binary, because only the generated
+// file ever calls it.
+const generatedHelpers = `// outputBytes narrows a returned slice or scalar to bytes for the
+// comparison; extend the switch when a kernel returns a wider type.
 func outputBytes(v any) []byte {
 	switch t := v.(type) {
 	case []byte:
@@ -324,11 +328,18 @@ func outputBytes(v any) []byte {
 	case []uint16:
 		b := make([]byte, 2*len(t))
 		for i, x := range t {
-			b[i*4/2] = byte(x)
-			b[i*4/2+1] = byte(x >> 8)
+			b[i*2] = byte(x)
+			b[i*2+1] = byte(x >> 8)
+		}
+		return b
+	case int:
+		b := make([]byte, 8)
+		for i := 0; i < 8; i++ {
+			b[i] = byte(uint64(t) >> (8 * i))
 		}
 		return b
 	default:
 		return nil
 	}
 }
+`