From 5b5562c1d13fa0b78fd13731cebdaa911eb47726 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Sat, 31 May 2014 17:59:11 +0100
Subject: [PATCH] py: Fix stack underflow with optimised for loop.
---
py/compile.c | 2 +-
py/vm.c | 6 +++---
tests/basics/for_return.py | 7 +++++++
3 files changed, 11 insertions(+), 4 deletions(-)
create mode 100644 tests/basics/for_return.py
diff --git a/py/compile.c b/py/compile.c
index c90772a7e..1f0d90570 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -1745,7 +1745,7 @@ void compile_while_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
// And, if the loop never runs, the loop variable should never be assigned
void compile_for_stmt_optimised_range(compiler_t *comp, mp_parse_node_t pn_var, mp_parse_node_t pn_start, mp_parse_node_t pn_end, mp_parse_node_t pn_step, mp_parse_node_t pn_body, mp_parse_node_t pn_else) {
START_BREAK_CONTINUE_BLOCK
- comp->break_label |= MP_EMIT_BREAK_FROM_FOR;
+ // note that we don't need to pop anything when breaking from an optimise for loop
uint top_label = comp_next_label(comp);
uint entry_label = comp_next_label(comp);
diff --git a/py/vm.c b/py/vm.c
index aa7e0e2cf..75093d240 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -159,8 +159,8 @@ mp_vm_return_kind_t mp_execute_bytecode(const byte *code, const mp_obj_t *args,
#if DETECT_VM_STACK_OVERFLOW
if (vm_return_kind == MP_VM_RETURN_NORMAL) {
- if (sp != state) {
- printf("Stack misalign: %d\n", sp - state);
+ if (sp < state) {
+ printf("VM stack underflow: " INT_FMT "\n", sp - state);
assert(0);
}
}
@@ -178,7 +178,7 @@ mp_vm_return_kind_t mp_execute_bytecode(const byte *code, const mp_obj_t *args,
}
}
if (overflow) {
- printf("VM stack overflow state=%p n_state+1=%u\n", state, n_state);
+ printf("VM stack overflow state=%p n_state+1=" UINT_FMT "\n", state, n_state);
assert(0);
}
}
diff --git a/tests/basics/for_return.py b/tests/basics/for_return.py
new file mode 100644
index 000000000..0441352ad
--- /dev/null
+++ b/tests/basics/for_return.py
@@ -0,0 +1,7 @@
+# test returning from within a for loop
+
+def f():
+ for i in [1, 2, 3]:
+ return i
+
+print(f())
--
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