Don't generate code for empty else blocks.

src/sixtypical/analyzer.py

@@ -178,7 +178,8 @@ def analyze_instr(instr, context, routines):
         context1 = context.clone()
         context2 = context.clone()
         analyze_block(instr.block1, context1, routines)
-        analyze_block(instr.block2, context2, routines)
+        if instr.block2 is not None:
+            analyze_block(instr.block2, context2, routines)
         for ref in context1.each_initialized():
             context2.assert_initialized(ref, exception_class=InconsistentInitializationError)
         for ref in context2.each_initialized():

src/sixtypical/compiler.py

@@ -176,7 +176,7 @@ class Compiler(object):
             else_label = Label('else_label')
             self.emitter.emit(cls(Relative(else_label)))
             self.compile_block(instr.block1)
-            if instr.block2:
+            if instr.block2 is not None:
                 end_label = Label('end_label')
                 self.emitter.emit(JMP(Absolute(end_label)))
                 self.emitter.resolve_label(else_label)

src/sixtypical/parser.py

@@ -172,8 +172,6 @@ class Parser(object):
             block2 = None
             if self.scanner.consume('else'):
                 block2 = self.block()
-            else:
-                block2 = Block(instrs=[])
             return Instr(opcode='if', dest=None, src=src, block1=block1, block2=block2)
         elif self.scanner.token in ("ld", "add", "sub", "cmp", "and", "or", "xor"):
             opcode = self.scanner.token

tests/SixtyPical Compilation.md

@@ -143,4 +143,4 @@ Compiling `if` without `else`.
     |         ld y, 1
     |     }
     | }
-    = 00c0a900d005a0014c0bc0a00260
+    = 00c0a900d002a00160