Add unconditional branching.

stepper.py

@@ -51,6 +51,11 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
 
 
 def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory):
+    def clear_block_from_ssa_env(insns, ssa_env):
+        for (id, insn) in insns:
+            if id is not None and id in ssa_env:
+                del ssa_env[id]
+
     if isinstance(terminator, ll.Ret):
         oper = terminator.oper
         if oper is None:
@@ -64,6 +69,22 @@ def terminate(terminator, blocks, stack_frames, ssa_env, global_env, memory):
             new_stack_frames = stack_frames[1:]
             return (new_insns, new_terminator, new_blocks, new_stack_frames,
                     new_ssa_env, memory, oper_v)
+    elif isinstance(terminator, ll.Br):
+        label = terminator.label
+        next_block = blocks[label]
+        new_insns = next_block.insns
+        new_terminator = next_block.terminator
+
+        # TODO: Might need to find a better solution as we will ignore
+        # multiple assignments, if they are spread over multiple
+        # blocks.
+        clear_block_from_ssa_env(new_insns, ssa_env)
+
+        print('Jumping unconditionally to {}'
+              .format(label))
+
+        return (new_insns, new_terminator, blocks, stack_frames,
+                ssa_env, memory, None)
     else:
         err('Unknown LLVM terminator: {}'
             .format(terminator))
@@ -118,18 +139,19 @@ def gogo():
     data = r'''
 define i64 @tigermain (i64 %U_mainSL_8, i64 %U_mainDummy_9) {
     %a = add i64 3, 5 ; please be 8
+    br label %L1
+L1:
     %b = add i64 %a, %a
     %c = add i64 %a, %b
-    %d = add i64 100, %c
-    %e = mul i64 7, %b
-    %f = sdiv i64 %e, 2
-    %g = sub i64 %d, %f
-    %h = or i64 1, %g
-    %i = shl i64 %h, 2
-    ret i64 %g
+    ret i64 %c
+L2:
+    %d = add i64 %a, 1
+    %e = add i64 10, %b
+    ret i64 %e
 }
-    '''
+'''
 
+    print(data)
     ast = p.parse(data)
 
     tdecs = ast.tdecls