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[3.8] bpo-37830: Fix compilation of break and continue in finally. (GH-15320) (GH-15456)

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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 ef61c524dd)
This commit is contained in:
Serhiy Storchaka 2019-08-24 13:41:53 +03:00 • committed by GitHub
parent 920ec4b776
commit ed146b52a3
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 305 additions and 194 deletions
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66
Python/compile.c
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@ -81,7 +81,7 @@ It's called a frame block to distinguish it from a basic block in the
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 @@ compiler_unwind_fblock(struct compiler *c, struct fblockinfo *info,
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 @@ compiler_unwind_fblock(struct compiler *c, struct fblockinfo *info,
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 @@ compiler_continue(struct compiler *c)
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 @@ compiler_try_finally(struct compiler *c, stmt_ty s)
}
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);
c->u->u_curblock->b_next = end;
c->u->u_curblock = newcurblock;
/* `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);
return 1;
}