Add icmp for some comparisons.

ll.py

@@ -98,6 +98,10 @@ def insn2s(insn):
         return ('{} {} {}, {}'
                 .format(insn.bop, ty2s(insn.ty),
                         oper2s(insn.left), oper2s(insn.right)))
+    elif isinstance(insn, Icmp):
+        return ('icmp {} {} {}, {}'
+                .format(insn.cnd, ty2s(insn.ty),
+                        oper2s(insn.left), oper2s(insn.right)))
     else:
         # TODO
         print('Unknown insn: {}'

stepper.py

@@ -1,14 +1,17 @@
 import ll
 import parser
 
+
 def TODO(msg):
     print('TODO, not implemented yet at {}'
           .format(msg))
 
+
 def err(msg):
     print('ERROR: {}'
           .format(msg))
 
+
 def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
          tdecs, fdecs, call_res):
     if len(insns) == 0:
@@ -33,6 +36,17 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, memory,
         # TODO
         print('{} {}, {}'
               .format(bop, left_v, right_v))
+    elif isinstance(next_insn, ll.Icmp):
+        cnd = next_insn.cnd
+        left = next_insn.left
+        right = next_insn.right
+        left_v = eval_oper(left, ssa_env, global_env)
+        right_v = eval_oper(right, ssa_env, global_env)
+        res = eval_icmp(cnd, left_v, right_v)
+
+        # TODO
+        print('icmp {} {}, {}'
+              .format(cnd,  left_v, right_v))
     else:
         err('Unknown LLVM instruction: {}'
             .format(next_insn))
@@ -136,6 +150,15 @@ def eval_binop(bop, left, right):
             .format(bop))
 
 
+def eval_icmp(cnd, left, right):
+    if cnd == 'eq':
+        return left == right
+    elif cnd == 'ne':
+        return left != right
+    else:
+        err('eval_icmp: Unknown cnd: {}'
+            .format(cnd))
+        return 0
 
 def gogo():
     p = parser.LLVMParser()
@@ -146,8 +169,8 @@ define i64 @tigermain (i64 %U_mainSL_8, i64 %U_mainDummy_9) {
     br label %L1
 L1:
     %b = add i64 %a, %a
-    %c = add i64 %a, %b
-    ret i64 %c
+    %c = icmp eq i64 %a, %b
+    ret i1 %c
 L2:
     %d = add i64 %a, 1
     %e = add i64 10, %b