Implement load.

ll.py

@@ -110,6 +110,10 @@ def insn2s(insn):
     if isinstance(insn, Alloca):
         return ('alloca {}'
                 .format(ty2s(insn.ty)))
+    if isinstance(insn, Load):
+        return ('load {}, {}* {}'
+                .format(ty2s(insn.ty), ty2s(insn.ty),
+                        oper2s(insn.location)))
     if isinstance(insn, Store):
         return ('store {} {}, {}* {}'
                 .format(ty2s(insn.ty),

stepper.py

@@ -62,7 +62,22 @@ def step(insns, terminator, blocks, stack_frames, ssa_env, global_env, heap,
 
         res = ptr
     elif isinstance(next_insn, ll.Load):
-        TODO('Load')
+        ty = next_insn.ty
+        base_ty = ty2base_ty(ty, tdecs)
+        size = base_ty2size(base_ty)
+        location = next_insn.location
+        location_v = eval_oper(location, ssa_env, global_env)
+
+        # TODO
+        print('load heap[{}]'
+              .format(location_v))
+
+        if size != 1:
+            err(('This emulator cannot load objects larger than 1 cell.'
+                 ' Current size is {}')
+                .format(size))
+
+        res = heap[location_v]
     elif isinstance(next_insn, ll.Store):
         ty = next_insn.ty
         base_ty = ty2base_ty(ty, tdecs)
@@ -351,8 +366,11 @@ def gogo():
     data = r'''
 define i64 @tigermain (i64 %U_mainSL_8, i64 %U_mainDummy_9) {
     %a = alloca i64
+    %a_alt = alloca i64
     store i64 9, i64* %a
-    ret i64 77
+    %b = load i64, i64* %a
+    %b_alt = load i64, i64* %a_alt
+    ret i64 %b
 }
 '''