From 1b563edc58b664a1be201ffdd387e958e42a79ef Mon Sep 17 00:00:00 2001 From: Irit Katriel <1055913+iritkatriel@users.noreply.github.com> Date: Fri, 2 Feb 2024 11:26:31 +0000 Subject: [PATCH] gh-107901: make compiler inline basic blocks with no line number and no fallthrough (#114750) --- Lib/test/test_compile.py | 62 ++++++++++++++++++++++++------ Lib/test/test_monitoring.py | 10 ++--- Python/flowgraph.c | 75 ++++++++++++++++++++++++++----------- 3 files changed, 108 insertions(+), 39 deletions(-) diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py index 3b1ceceaa6305f7..ebb479f2de7c633 100644 --- a/Lib/test/test_compile.py +++ b/Lib/test/test_compile.py @@ -1104,6 +1104,17 @@ async def test(aseq): code_lines = self.get_code_lines(test.__code__) self.assertEqual(expected_lines, code_lines) + def check_line_numbers(self, code, opnames=None): + # Check that all instructions whose op matches opnames + # have a line number. opnames can be a single name, or + # a sequence of names. If it is None, match all ops. + + if isinstance(opnames, str): + opnames = (opnames, ) + for inst in dis.Bytecode(code): + if opnames and inst.opname in opnames: + self.assertIsNotNone(inst.positions.lineno) + def test_line_number_synthetic_jump_multiple_predecessors(self): def f(): for x in it: @@ -1113,25 +1124,52 @@ def f(): except OSError: pass - # Ensure that all JUMP_BACKWARDs have line number - code = f.__code__ - for inst in dis.Bytecode(code): - if inst.opname == 'JUMP_BACKWARD': - self.assertIsNotNone(inst.positions.lineno) + self.check_line_numbers(f.__code__, 'JUMP_BACKWARD') - def test_lineno_of_backward_jump(self): + def test_line_number_synthetic_jump_multiple_predecessors_nested(self): + def f(): + for x in it: + try: + X = 3 + except OSError: + try: + if C3: + X = 4 + except OSError: + pass + return 42 + + self.check_line_numbers(f.__code__, 'JUMP_BACKWARD') + + def test_line_number_synthetic_jump_multiple_predecessors_more_nested(self): + def f(): + for x in it: + try: + X = 3 + except OSError: + try: + if C3: + if C4: + X = 4 + except OSError: + try: + if C3: + if C4: + X = 5 + except OSError: + pass + return 42 + + self.check_line_numbers(f.__code__, 'JUMP_BACKWARD') + + def test_lineno_of_backward_jump_conditional_in_loop(self): # Issue gh-107901 def f(): for i in x: if y: pass - linenos = list(inst.positions.lineno - for inst in dis.get_instructions(f.__code__) - if inst.opname == 'JUMP_BACKWARD') - - self.assertTrue(len(linenos) > 0) - self.assertTrue(all(l is not None for l in linenos)) + self.check_line_numbers(f.__code__, 'JUMP_BACKWARD') def test_big_dict_literal(self): # The compiler has a flushing point in "compiler_dict" that calls compiles diff --git a/Lib/test/test_monitoring.py b/Lib/test/test_monitoring.py index a64d1ed79decd83..60b6326bfbad5e9 100644 --- a/Lib/test/test_monitoring.py +++ b/Lib/test/test_monitoring.py @@ -1466,9 +1466,8 @@ def func(): ('branch', 'func', 4, 4), ('line', 'func', 5), ('line', 'meth', 1), - ('jump', 'func', 5, 5), - ('jump', 'func', 5, '[offset=114]'), - ('branch', 'func', '[offset=120]', '[offset=124]'), + ('jump', 'func', 5, '[offset=118]'), + ('branch', 'func', '[offset=122]', '[offset=126]'), ('line', 'get_events', 11)]) self.check_events(func, recorders = FLOW_AND_LINE_RECORDERS, expected = [ @@ -1482,9 +1481,8 @@ def func(): ('line', 'func', 5), ('line', 'meth', 1), ('return', 'meth', None), - ('jump', 'func', 5, 5), - ('jump', 'func', 5, '[offset=114]'), - ('branch', 'func', '[offset=120]', '[offset=124]'), + ('jump', 'func', 5, '[offset=118]'), + ('branch', 'func', '[offset=122]', '[offset=126]'), ('return', 'func', None), ('line', 'get_events', 11)]) diff --git a/Python/flowgraph.c b/Python/flowgraph.c index bfc23a298ff492d..1a648edf0880c02 100644 --- a/Python/flowgraph.c +++ b/Python/flowgraph.c @@ -212,14 +212,14 @@ basicblock_add_jump(basicblock *b, int opcode, basicblock *target, location loc) } static inline int -basicblock_append_instructions(basicblock *target, basicblock *source) +basicblock_append_instructions(basicblock *to, basicblock *from) { - for (int i = 0; i < source->b_iused; i++) { - int n = basicblock_next_instr(target); + for (int i = 0; i < from->b_iused; i++) { + int n = basicblock_next_instr(to); if (n < 0) { return ERROR; } - target->b_instr[n] = source->b_instr[i]; + to->b_instr[n] = from->b_instr[i]; } return SUCCESS; } @@ -292,9 +292,9 @@ static void dump_basicblock(const basicblock *b) { const char *b_return = basicblock_returns(b) ? "return " : ""; - fprintf(stderr, "%d: [EH=%d CLD=%d WRM=%d NO_FT=%d %p] used: %d, depth: %d, %s\n", + fprintf(stderr, "%d: [EH=%d CLD=%d WRM=%d NO_FT=%d %p] used: %d, depth: %d, preds: %d %s\n", b->b_label.id, b->b_except_handler, b->b_cold, b->b_warm, BB_NO_FALLTHROUGH(b), b, b->b_iused, - b->b_startdepth, b_return); + b->b_startdepth, b->b_predecessors, b_return); if (b->b_instr) { int i; for (i = 0; i < b->b_iused; i++) { @@ -1165,15 +1165,26 @@ remove_redundant_jumps(cfg_builder *g) { return changes; } +static inline bool +basicblock_has_no_lineno(basicblock *b) { + for (int i = 0; i < b->b_iused; i++) { + if (b->b_instr[i].i_loc.lineno >= 0) { + return false; + } + } + return true; +} + /* Maximum size of basic block that should be copied in optimizer */ #define MAX_COPY_SIZE 4 -/* If this block ends with an unconditional jump to a small exit block, then +/* If this block ends with an unconditional jump to a small exit block or + * a block that has no line numbers (and no fallthrough), then * remove the jump and extend this block with the target. * Returns 1 if extended, 0 if no change, and -1 on error. */ static int -inline_small_exit_blocks(basicblock *bb) { +basicblock_inline_small_or_no_lineno_blocks(basicblock *bb) { cfg_instr *last = basicblock_last_instr(bb); if (last == NULL) { return 0; @@ -1182,14 +1193,46 @@ inline_small_exit_blocks(basicblock *bb) { return 0; } basicblock *target = last->i_target; - if (basicblock_exits_scope(target) && target->b_iused <= MAX_COPY_SIZE) { + bool small_exit_block = (basicblock_exits_scope(target) && + target->b_iused <= MAX_COPY_SIZE); + bool no_lineno_no_fallthrough = (basicblock_has_no_lineno(target) && + !BB_HAS_FALLTHROUGH(target)); + if (small_exit_block || no_lineno_no_fallthrough) { + assert(is_jump(last)); + int removed_jump_opcode = last->i_opcode; INSTR_SET_OP0(last, NOP); RETURN_IF_ERROR(basicblock_append_instructions(bb, target)); + if (no_lineno_no_fallthrough) { + last = basicblock_last_instr(bb); + if (IS_UNCONDITIONAL_JUMP_OPCODE(last->i_opcode) && + removed_jump_opcode == JUMP) + { + /* Make sure we don't lose eval breaker checks */ + last->i_opcode = JUMP; + } + } + target->b_predecessors--; return 1; } return 0; } +static int +inline_small_or_no_lineno_blocks(basicblock *entryblock) { + bool changes; + do { + changes = false; + for (basicblock *b = entryblock; b != NULL; b = b->b_next) { + int res = basicblock_inline_small_or_no_lineno_blocks(b); + RETURN_IF_ERROR(res); + if (res) { + changes = true; + } + } + } while(changes); /* every change removes a jump, ensuring convergence */ + return changes; +} + // Attempt to eliminate jumps to jumps by updating inst to jump to // target->i_target using the provided opcode. Return whether or not the // optimization was successful. @@ -1804,9 +1847,7 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache, int firstl { assert(PyDict_CheckExact(const_cache)); RETURN_IF_ERROR(check_cfg(g)); - for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { - RETURN_IF_ERROR(inline_small_exit_blocks(b)); - } + RETURN_IF_ERROR(inline_small_or_no_lineno_blocks(g->g_entryblock)); RETURN_IF_ERROR(remove_unreachable(g->g_entryblock)); RETURN_IF_ERROR(resolve_line_numbers(g, firstlineno)); RETURN_IF_ERROR(optimize_load_const(const_cache, g, consts)); @@ -1814,9 +1855,6 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache, int firstl RETURN_IF_ERROR(optimize_basic_block(const_cache, b, consts)); } RETURN_IF_ERROR(remove_redundant_nops_and_pairs(g->g_entryblock)); - for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { - RETURN_IF_ERROR(inline_small_exit_blocks(b)); - } RETURN_IF_ERROR(remove_unreachable(g->g_entryblock)); int removed_nops, removed_jumps; @@ -2333,12 +2371,7 @@ convert_pseudo_ops(cfg_builder *g) static inline bool is_exit_or_eval_check_without_lineno(basicblock *b) { if (basicblock_exits_scope(b) || basicblock_has_eval_break(b)) { - for (int i = 0; i < b->b_iused; i++) { - if (b->b_instr[i].i_loc.lineno >= 0) { - return false; - } - } - return true; + return basicblock_has_no_lineno(b); } else { return false;