feat(cli): add gasm profile command for basic-block structure

Assisted-by: DeepSeek V4 Pro

cmd/gasm/main.go

@@ -16,6 +16,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 	"syscall"
@@ -57,6 +58,8 @@ func main() {
 		os.Exit(cmdDebug(os.Args[2:]))
 	case "diff":
 		os.Exit(cmdDiff(os.Args[2:]))
+	case "profile":
+		os.Exit(cmdProfile(os.Args[2:]))
 	case "lsp":
 		os.Exit(cmdLSP(os.Args[2:]))
 	case "version", "--version", "-V":
@@ -118,6 +121,7 @@ func usage(w io.Writer) {
 		{"verify", "JIT-assemble and run dynamic checks (amd64, riscv64)"},
 		{"debug", "interactive source-level debugger (amd64)"},
 		{"diff", "compare machine code of two .s files"},
+		{"profile", "show basic-block structure of functions"},
 		{"lsp", "run the language server over stdio"},
 		{"version", "print the version (same as --version)"},
 	}
@@ -637,6 +641,67 @@ func printByteDiff(a, b []byte) {
 	}
 }
 
+// cmdProfile shows the basic-block structure of functions in an assembly file.
+func cmdProfile(args []string) int {
+	fs := newCommand("profile", "gasm profile <file.s>", `
+Show the basic-block structure of functions in an assembly file.
+Lists each function's labels, their offsets, and the block boundaries.
+This is the static structure; for runtime execution counts, use
+gasm verify --fuzz which exercises the code paths.
+`)
+	fs.Parse(args)
+	if fs.NArg() != 1 {
+		fmt.Fprintln(os.Stderr, "usage: gasm profile <file.s>")
+		return 2
+	}
+	path := fs.Arg(0)
+
+	// Load the file to get function metadata.
+	k, err := verify.Load(path)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "gasm profile: %v\n", err)
+		return 1
+	}
+	defer k.Close()
+
+	for _, name := range k.FuncNames() {
+		fl, err := k.Func(name)
+		if err != nil {
+			continue
+		}
+		fmt.Printf("%s: %d bytes, args=%d, frame=%d", name, fl.Size, fl.Args, fl.Frame)
+		if fl.NoSplit {
+			fmt.Printf(" NOSPLIT")
+		}
+		fmt.Println()
+
+		// Show labels and their offsets.
+		if len(fl.Labels) > 0 {
+			fmt.Println("  labels:")
+			// Sort labels by offset.
+			type labelOff struct {
+				name string
+				off  int
+			}
+			var labels []labelOff
+			for name, off := range fl.Labels {
+				labels = append(labels, labelOff{name, off})
+			}
+			sort.Slice(labels, func(i, j int) bool { return labels[i].off < labels[j].off })
+			for _, l := range labels {
+				fmt.Printf("    %-20s +%#04x\n", l.name, l.off)
+			}
+		}
+
+		// Show basic blocks.
+		blocks, err := k.Blocks(name)
+		if err == nil && len(blocks) > 0 {
+			fmt.Printf("  basic blocks: %d\n", len(blocks))
+		}
+	}
+	return 0
+}
+
 // cmdVerifyRISCV handles the verify subcommand for RISC-V files.
 // JIT requires RISC-V hardware; only ground-truth and profile are available.
 func cmdVerifyRISCV(path string, groundTruth, profile bool) int {