[3.8] bpo-37830: Fix compilation of break and continue in finally. (GH-15320) (GH-15456)
Fix compilation of "break" and "continue" in the
"finally" block when the corresponding "try" block
contains "return" with a non-constant value.
(cherry picked from commit ef61c524ddeeb56da3858b86e349e7288d68178e)
diff --git a/Python/compile.c b/Python/compile.c
index 0336959..a6c5ab6 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -81,7 +81,7 @@
compiler IR.
*/
-enum fblocktype { WHILE_LOOP, FOR_LOOP, EXCEPT, FINALLY_TRY, FINALLY_END,
+enum fblocktype { WHILE_LOOP, FOR_LOOP, EXCEPT, FINALLY_TRY, FINALLY_TRY2, FINALLY_END,
WITH, ASYNC_WITH, HANDLER_CLEANUP };
struct fblockinfo {
@@ -1664,7 +1664,12 @@
return 1;
case FINALLY_END:
+ info->fb_exit = NULL;
ADDOP_I(c, POP_FINALLY, preserve_tos);
+ if (preserve_tos) {
+ ADDOP(c, ROT_TWO);
+ }
+ ADDOP(c, POP_TOP);
return 1;
case FOR_LOOP:
@@ -1684,6 +1689,19 @@
ADDOP_JREL(c, CALL_FINALLY, info->fb_exit);
return 1;
+ case FINALLY_TRY2:
+ ADDOP(c, POP_BLOCK);
+ if (preserve_tos) {
+ ADDOP(c, ROT_TWO);
+ ADDOP(c, POP_TOP);
+ ADDOP_JREL(c, CALL_FINALLY, info->fb_exit);
+ }
+ else {
+ ADDOP_JREL(c, CALL_FINALLY, info->fb_exit);
+ ADDOP(c, POP_TOP);
+ }
+ return 1;
+
case WITH:
case ASYNC_WITH:
ADDOP(c, POP_BLOCK);
@@ -2869,17 +2887,47 @@
static int
compiler_try_finally(struct compiler *c, stmt_ty s)
{
- basicblock *body, *end;
+ basicblock *start, *newcurblock, *body, *end;
+ int break_finally = 1;
body = compiler_new_block(c);
end = compiler_new_block(c);
if (body == NULL || end == NULL)
return 0;
+ start = c->u->u_curblock;
+
+ /* `finally` block. Compile it first to determine if any of "break",
+ "continue" or "return" are used in it. */
+ compiler_use_next_block(c, end);
+ if (!compiler_push_fblock(c, FINALLY_END, end, end))
+ return 0;
+ VISIT_SEQ(c, stmt, s->v.Try.finalbody);
+ ADDOP(c, END_FINALLY);
+ break_finally = (c->u->u_fblock[c->u->u_nfblocks - 1].fb_exit == NULL);
+ if (break_finally) {
+ /* Pops a placeholder. See below */
+ ADDOP(c, POP_TOP);
+ }
+ compiler_pop_fblock(c, FINALLY_END, end);
+
+ newcurblock = c->u->u_curblock;
+ c->u->u_curblock = start;
+ start->b_next = NULL;
+
/* `try` block */
+ c->u->u_lineno_set = 0;
+ c->u->u_lineno = s->lineno;
+ c->u->u_col_offset = s->col_offset;
+ if (break_finally) {
+ /* Pushes a placeholder for the value of "return" in the "try" block
+ to balance the stack for "break", "continue" and "return" in
+ the "finally" block. */
+ ADDOP_LOAD_CONST(c, Py_None);
+ }
ADDOP_JREL(c, SETUP_FINALLY, end);
compiler_use_next_block(c, body);
- if (!compiler_push_fblock(c, FINALLY_TRY, body, end))
+ if (!compiler_push_fblock(c, break_finally ? FINALLY_TRY2 : FINALLY_TRY, body, end))
return 0;
if (s->v.Try.handlers && asdl_seq_LEN(s->v.Try.handlers)) {
if (!compiler_try_except(c, s))
@@ -2890,15 +2938,11 @@
}
ADDOP(c, POP_BLOCK);
ADDOP(c, BEGIN_FINALLY);
- compiler_pop_fblock(c, FINALLY_TRY, body);
+ compiler_pop_fblock(c, break_finally ? FINALLY_TRY2 : FINALLY_TRY, body);
- /* `finally` block */
- compiler_use_next_block(c, end);
- if (!compiler_push_fblock(c, FINALLY_END, end, NULL))
- return 0;
- VISIT_SEQ(c, stmt, s->v.Try.finalbody);
- ADDOP(c, END_FINALLY);
- compiler_pop_fblock(c, FINALLY_END, end);
+ c->u->u_curblock->b_next = end;
+ c->u->u_curblock = newcurblock;
+
return 1;
}