bpo-37830: Fix compilation of break and continue in finally. (GH-15320)

Fix compilation of "break" and "continue" in the
"finally" block when the corresponding "try" block
contains "return" with a non-constant value.

1 files changed, 16 insertions, 7 deletions

diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 5deb985..a796a59 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -233,6 +233,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
      * the 'finally' blocks. */
     memset(blockstack, '\0', sizeof(blockstack));
     blockstack_top = 0;
+    unsigned char prevop = NOP;
     for (addr = 0; addr < code_len; addr += sizeof(_Py_CODEUNIT)) {
         unsigned char op = code[addr];
         switch (op) {
@@ -259,17 +260,24 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
                                 "can't jump into the middle of a block");
                 return -1;
             }
+            int in_for_loop = op == FOR_ITER || code[target_addr] == END_ASYNC_FOR;
             if (first_in && !second_in) {
-                if (op != FOR_ITER && code[target_addr] != END_ASYNC_FOR) {
-                    delta_iblock++;
+                if (!delta_iblock) {
+                    if (in_for_loop) {
+                        /* Pop the iterators of any 'for' and 'async for' loop
+                         * we're jumping out of. */
+                        delta++;
+                    }
+                    else if (prevop == LOAD_CONST) {
+                        /* Pops None pushed before SETUP_FINALLY. */
+                        delta++;
+                    }
                 }
-                else if (!delta_iblock) {
-                    /* Pop the iterators of any 'for' and 'async for' loop
-                     * we're jumping out of. */
-                    delta++;
+                if (!in_for_loop) {
+                    delta_iblock++;
                 }
             }
-            if (op != FOR_ITER && code[target_addr] != END_ASYNC_FOR) {
+            if (!in_for_loop) {
                 blockstack[blockstack_top++] = target_addr;
             }
             break;
@@ -293,6 +301,7 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno, void *Py_UNUSED(ignore
             break;
         }
         }
+        prevop = op;
     }
 
     /* Verify that the blockstack tracking code didn't get lost. */