Warn on pointless (un)conditional branching

Sometimes performing some 'jmp'/'jsr' can be quite pointless, and the
programmer might not be fully aware of this because of the layout of the
code. Imagine:

      .proc foo
            ;; code
            jmp bar
      .endproc

      ;; Documentation, comments, extra space, etc.

      .proc bar
            ;; whatever
      .endproc

The 'jmp' in the code above tries to perform a call stack optimization,
but it's actually not needed because the next instruction after 'jmp' is
the one inside of 'bar', but that's obfuscated because of the layout.

In these sort of cases (and also for 'jsr' and branches) warn the
programmer about it so it can remove that instruction.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/xixanta/src/object.rs b/lib/xixanta/src/object.rs
index 5904b56..170d872 100644
--- a/lib/xixanta/src/object.rs
+++ b/lib/xixanta/src/object.rs
@@ -98,6 +98,18 @@ impl Bundle {
             ])
         }
     }
+
+    /// Considering that the first element of the 'bytes' property is the
+    /// instruction identifier, returns the two last bytes as if they were a
+    /// 16-bit value.
+    pub fn arg(&self) -> u16 {
+        self.bytes[1] as u16 + ((self.bytes[2] as u16) << 8)
+    }
+
+    /// Returns the address to the next instruction after this bundle.
+    pub fn next_address(&self) -> usize {
+        self.address + self.size as usize
+    }
 }
 
 /// The type of object being referenced, which is either a value as-is, or an