feat(verify): combine ABI checks with fuzzing for deep-path testing

cmd/gasm/main.go

@@ -633,6 +633,7 @@ With -profile, the static basic-block structure is listed for each function.
 `)
 	smoke := fs.Bool("smoke", false, "call each NOSPLIT function with zeroed args")
 	abi := fs.Bool("abi", false, "run ABI-checking calls (sentinel registers + red zone)")
+	abiN := fs.Int("abi-n", 100, "number of ABI check iterations with varied inputs")
 	profile := fs.Bool("profile", false, "list basic-block structure per function")
 	groundTruth := fs.Bool("ground-truth", false, "compare machine code byte-for-byte against go tool asm")
 	fuzz := fs.Bool("fuzz", false, "differential fuzz: JIT both gasm and go-tool-asm versions, compare outputs")
@@ -823,16 +824,28 @@ With -profile, the static basic-block structure is listed for each function.
 		}
 
 		if *abi && fl.NoSplit {
-			args := make([]byte, fl.Args)
-			_, report, err := k.CallFuncChecked(name, args)
-			if err != nil {
-				fmt.Printf("    abi: FAIL — %v\n", err)
-				rc = 1
-			} else if !report.OK() {
-				fmt.Printf("    abi: %s\n", report)
-				rc = 1
+			// Try varied-input ABI fuzzing first.
+			if src, err := readSource(path); err == nil {
+				result := k.FuzzFuncCheckedByName(name, src, *abiN, int64(*abiN))
+				if result.Mismatches > 0 {
+					fmt.Printf("    abi: %s\n", result)
+					rc = 1
+				} else {
+					fmt.Printf("    abi: clean (%d varied inputs)\n", result.Matches)
+				}
 			} else {
-				fmt.Printf("    abi: clean\n")
+				// Fallback: single zeroed-arg call.
+				args := make([]byte, fl.Args)
+				_, report, err := k.CallFuncChecked(name, args)
+				if err != nil {
+					fmt.Printf("    abi: FAIL — %v\n", err)
+					rc = 1
+				} else if !report.OK() {
+					fmt.Printf("    abi: %s\n", report)
+					rc = 1
+				} else {
+					fmt.Printf("    abi: clean\n")
+				}
 			}
 		}
 	}