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[3.12] gh-109889: fix compiler's redundant NOP detection to look past NOPs with no lineno when looking for the next instruction's lineno (GH-109987) (#110048)

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gh-109889: fix compiler's redundant NOP detection to look past NOPs with no lineno when looking for the next instruction's lineno (GH-109987)
(cherry picked from commit f580edcc6a)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
This commit is contained in:
Miss Islington (bot) 2023-10-02 08:43:16 -07:00 • committed by GitHub
parent c794103417
commit 2b96102f29
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3 changed files with 18 additions and 1 deletions
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5
Lib/test/test_compile.py
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@ -1269,6 +1269,11 @@ class TestSpecifics(unittest.TestCase):
while x: while x:
0 if 1 else 0 0 if 1 else 0
def test_remove_redundant_nop_edge_case(self):
# See gh-109889
def f():
a if (1 if b else c) else d
@requires_debug_ranges() @requires_debug_ranges()
class TestSourcePositions(unittest.TestCase): class TestSourcePositions(unittest.TestCase):
# Ensure that compiled code snippets have correct line and column numbers # Ensure that compiled code snippets have correct line and column numbers

2
Misc/NEWS.d/next/Core and Builtins/2023-09-27-21-35-49.gh-issue-109889.t5hIRT.rst Normal file
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@ -0,0 +1,2 @@
Fix the compiler's redundant NOP detection algorithm to skip over NOPs with
no line number when looking for the next instruction's lineno.

12
Python/flowgraph.c
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@ -981,7 +981,17 @@ remove_redundant_nops(basicblock *bb) {
} }
/* or if last instruction in BB and next BB has same line number */ /* or if last instruction in BB and next BB has same line number */
if (next) { if (next) {
if (lineno == next->b_instr[0].i_loc.lineno) { location next_loc = NO_LOCATION;
for (int next_i=0; next_i < next->b_iused; next_i++) {
cfg_instr *instr = &next->b_instr[next_i];
if (instr->i_opcode == NOP && instr->i_loc.lineno == NO_LOCATION.lineno) {
/* Skip over NOPs without location, they will be removed */
continue;
}
next_loc = instr->i_loc;
break;
}
if (lineno == next_loc.lineno) {
continue; continue;
} }
} }