fix: resolve audit findings — stale text, dead code, build tags, docs

Assisted-by: MiMo V2.5 Pro

cmd/gasm/debug_linux.go

@@ -17,7 +17,7 @@ import (
 
 func cmdDebug(args []string) int {
 	fs := newCommand("debug", "gasm debug <file.s> --func <name>", `
-Interactive debugger for JIT-assembled amd64 functions.  Launches the
+Interactive debugger for JIT-assembled functions.  Launches the
 function in a traced subprocess (ptrace), then provides a REPL for
 single-stepping, breakpoints, register and memory inspection.
 

cmd/gasm/main.go

@@ -117,9 +117,9 @@ func usage(w io.Writer) {
 		{"parse", "parse and report syntax errors"},
 		{"fmt", "canonicalise formatting (gofmt for assembly)"},
 		{"lint", "run static checks"},
-		{"asm", "assemble .s files to machine code (amd64, riscv64)"},
-		{"verify", "JIT-assemble and run dynamic checks (amd64, riscv64)"},
-		{"debug", "interactive source-level debugger (amd64)"},
+		{"asm", "assemble .s files to machine code (amd64, arm64, riscv64, loong64)"},
+		{"verify", "JIT-assemble and run dynamic checks (amd64, arm64, riscv64, loong64)"},
+		{"debug", "interactive source-level debugger (amd64, arm64, riscv64, loong64)"},
 		{"diff", "compare machine code of two .s files"},
 		{"profile", "show basic-block structure of functions"},
 		{"lsp", "run the language server over stdio"},
@@ -1073,7 +1073,7 @@ decoders) that crash on random input but should succeed on valid data.
 		// AArch64: ground-truth only (no JIT on non-ARM64 hosts).
 		return cmdVerifyARM64(path, *groundTruth, *profile)
 	default:
-		fmt.Fprintln(os.Stderr, "gasm verify: only amd64, riscv64 and loong64 are supported")
+		fmt.Fprintln(os.Stderr, "gasm verify: unsupported architecture")
 		return 1
 	}