another fuzz victory!

4 files changed, 17 insertions, 3 deletions

diff --git a/fuzz/fuzz_targets/fresh-decode.rs b/fuzz/fuzz_targets/fresh-decode.rs
index 76a402e..a3da0ed 100644
--- a/fuzz/fuzz_targets/fresh-decode.rs
+++ b/fuzz/fuzz_targets/fresh-decode.rs
@@ -17,5 +17,9 @@ fuzz_target!(|data: &[u8]| {
         let mut words = yaxpeax_arch::U8Reader::new(data);
         let fresh_inst = decoder.decode(&mut words).expect("decoded before, can decode again");
         assert_eq!(reused_inst, fresh_inst);
+
+        let s = reused_inst.to_string();
+        assert!(!s.contains("BUG"));
+        assert!(!s.contains("<invalid decode>"));
     }
 });
diff --git a/src/display.rs b/src/display.rs
index 90dfca4..810d07f 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -294,7 +294,7 @@ impl fmt::Display for Instruction {
                 Some(AssignMode::SetBit) => ("= setbit", true),
             };
             write!(f, "{}({}){} {}{}{}{}",
-                self.opcode, self.dest.expect("unreachable; store has a destination"),
+                self.opcode, display_or_partial(self.dest.as_ref()),
                 match self.flags.threads {
                     Some(DomainHint::Same) => { ":st" },
                     Some(DomainHint::All) => { ":at" },
@@ -314,8 +314,8 @@ impl fmt::Display for Instruction {
         if SC_STORES.contains(&self.opcode) {
             write!(f, "{}({}, {}) = {}",
                 self.opcode,
-                self.dest.expect("unreachable; store has a destination"),
-                self.alt_dest.expect("unreachable; store-conditional has a predicate reg"),
+                display_or_partial(self.dest.as_ref()),
+                display_or_partial(self.alt_dest.as_ref()),
                 self.sources[0]
             )?;
             return Ok(());
diff --git a/src/lib.rs b/src/lib.rs
index 6c89dec..3b816f9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2115,6 +2115,8 @@ fn decode_packet<
         current_word += 1;
     }
 
+    opcode_check!(extender.is_none());
+
     handler.on_decode_end();
 
     Ok(())
diff --git a/tests/from_brain.rs b/tests/from_brain.rs
index 9c33dbf..0c9be88 100644
--- a/tests/from_brain.rs
+++ b/tests/from_brain.rs
@@ -2468,3 +2468,11 @@ fn no_panic() {
         DecodeError::InvalidOpcode
     );
 }
+#[test]
+fn display() {
+    // if there is only an extender and no instruction, return an error.
+    test_invalid(
+        &[252, 205, 99, 0],
+        DecodeError::InvalidOpcode
+    );
+}