py: Implement break and continue byte codes, and add tests.

Also fixes a bug in the for-in-range optimiser.

I hope to remove break and continue byte codes in the future and just
use jump (if possible).

py/compile.c

@@ -1442,24 +1442,27 @@ void compile_for_stmt_optimised_range(compiler_t *comp, mp_parse_node_t pn_var,
     comp->continue_label = continue_label;
 
     int top_label = comp_next_label(comp);
+    int entry_label = comp_next_label(comp);
 
     // compile: var = start
     compile_node(comp, pn_start);
     c_assign(comp, pn_var, ASSIGN_STORE);
 
-    EMIT(jump, continue_label);
+    EMIT(jump, entry_label);
     EMIT(label_assign, top_label);
 
     // compile body
     compile_node(comp, pn_body);
 
+    EMIT(label_assign, continue_label);
+
     // compile: var += step
     c_assign(comp, pn_var, ASSIGN_AUG_LOAD);
     compile_node(comp, pn_step);
     EMIT(binary_op, RT_BINARY_OP_INPLACE_ADD);
     c_assign(comp, pn_var, ASSIGN_AUG_STORE);
 
-    EMIT(label_assign, continue_label);
+    EMIT(label_assign, entry_label);
 
     // compile: if var <cond> end: goto top
     compile_node(comp, pn_var);

py/vm.c

@@ -326,6 +326,18 @@ bool mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_ob
                         break;
                         */
 
+                    // TODO this might need more sophisticated handling when breaking from within an except
+                    case MP_BC_BREAK_LOOP:
+                        DECODE_ULABEL;
+                        ip += unum;
+                        break;
+
+                    // TODO this might need more sophisticated handling when breaking from within an except
+                    case MP_BC_CONTINUE_LOOP:
+                        DECODE_ULABEL;
+                        ip += unum;
+                        break;
+
                     // matched against: POP_BLOCK or POP_EXCEPT (anything else?)
                     case MP_BC_SETUP_EXCEPT:
                         DECODE_ULABEL; // except labels are always forward
@@ -366,7 +378,7 @@ bool mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_ob
                         exc_sp -= 2; // pop back to previous exception handler
                         break;
 
-                    // matched againts: SETUP_EXCEPT
+                    // matched against: SETUP_EXCEPT
                     case MP_BC_POP_EXCEPT:
                         // TODO need to work out how blocks work etc
                         // pops block, checks it's an exception block, and restores the stack, saving the 3 exception values to local threadstate

tests/basics/break.py

@@ -0,0 +1,13 @@
+while True:
+    break
+
+for i in range(4):
+    print('one', i)
+    if i > 2:
+        break
+    print('two', i)
+
+for i in [1, 2, 3, 4]:
+    if i == 3:
+        break
+    print(i)

tests/basics/continue.py

@@ -0,0 +1,16 @@
+for i in range(4):
+    print('one', i)
+    if i > 2:
+        continue
+    print('two', i)
+
+for i in range(4):
+    print('one', i)
+    if i < 2:
+        continue
+    print('two', i)
+
+for i in [1, 2, 3, 4]:
+    if i == 3:
+        continue
+    print(i)