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gh-138714: Don't assume next block has instructions when propagating line numbers (#138770)

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Co-authored-by: Irit Katriel <iritkatriel@yahoo.com>
This commit is contained in:
Dino Viehland
2025-09-17 17:52:56 +01:00
committed by GitHub
parent 4b78fe9665
commit e92599e677
2 changed files with 30 additions and 13 deletions
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11
Lib/test/test_compile.py
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@@ -1615,6 +1615,17 @@ class TestSpecifics(unittest.TestCase):
def f(): def f():
a if (1 if b else c) else d a if (1 if b else c) else d
def test_lineno_propagation_empty_blocks(self):
# Smoke test. See gh-138714.
def f():
while name:
try:
break
except:
pass
else:
1 if 1 else 1
def test_global_declaration_in_except_used_in_else(self): def test_global_declaration_in_except_used_in_else(self):
# See gh-111123 # See gh-111123
code = textwrap.dedent("""\ code = textwrap.dedent("""\

32
Python/flowgraph.c
View File

@@ -3591,8 +3591,19 @@ duplicate_exits_without_lineno(cfg_builder *g)
* Also reduces the size of the line number table, * Also reduces the size of the line number table,
* but has no impact on the generated line number events. * but has no impact on the generated line number events.
*/ */
static inline void
maybe_propagate_location(basicblock *b, int i, location loc)
{
assert(b->b_iused > i);
if (b->b_instr[i].i_loc.lineno == NO_LOCATION.lineno) {
b->b_instr[i].i_loc = loc;
}
}
static void static void
propagate_line_numbers(basicblock *entryblock) { propagate_line_numbers(basicblock *entryblock)
{
for (basicblock *b = entryblock; b != NULL; b = b->b_next) { for (basicblock *b = entryblock; b != NULL; b = b->b_next) {
cfg_instr *last = basicblock_last_instr(b); cfg_instr *last = basicblock_last_instr(b);
if (last == NULL) { if (last == NULL) {
@@ -3601,26 +3612,21 @@ propagate_line_numbers(basicblock *entryblock) {
location prev_location = NO_LOCATION; location prev_location = NO_LOCATION;
for (int i = 0; i < b->b_iused; i++) { for (int i = 0; i < b->b_iused; i++) {
if (b->b_instr[i].i_loc.lineno == NO_LOCATION.lineno) { maybe_propagate_location(b, i, prev_location);
b->b_instr[i].i_loc = prev_location; prev_location = b->b_instr[i].i_loc;
}
else {
prev_location = b->b_instr[i].i_loc;
}
} }
if (BB_HAS_FALLTHROUGH(b) && b->b_next->b_predecessors == 1) { if (BB_HAS_FALLTHROUGH(b) && b->b_next->b_predecessors == 1) {
if (b->b_next->b_iused > 0) { if (b->b_next->b_iused > 0) {
if (b->b_next->b_instr[0].i_loc.lineno == NO_LOCATION.lineno) { maybe_propagate_location(b->b_next, 0, prev_location);
b->b_next->b_instr[0].i_loc = prev_location;
}
} }
} }
if (is_jump(last)) { if (is_jump(last)) {
basicblock *target = last->i_target; basicblock *target = last->i_target;
while (target->b_iused == 0 && target->b_predecessors == 1) {
target = target->b_next;
}
if (target->b_predecessors == 1) { if (target->b_predecessors == 1) {
if (target->b_instr[0].i_loc.lineno == NO_LOCATION.lineno) { maybe_propagate_location(target, 0, prev_location);
target->b_instr[0].i_loc = prev_location;
}
} }
} }
} }