https://github.com/python/cpython/commit/894cafd9a53f2423adc6b1fb111006883ae... commit: 894cafd9a53f2423adc6b1fb111006883aeac03c branch: main author: Irit Katriel <1055913+iritkatriel@users.noreply.github.com> committer: iritkatriel <1055913+iritkatriel@users.noreply.github.com> date: 2022-09-01T11:03:52+01:00 summary: gh-93678: apply remove_redundant_jumps in optimize_cfg (GH-96274) files: M Lib/test/test_peepholer.py M Python/compile.c diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py index 7ece468363be..7cd9b060f5e9 100644 --- a/Lib/test/test_peepholer.py +++ b/Lib/test/test_peepholer.py @@ -892,7 +892,8 @@ def test_conditional_jump_forward_non_const_condition(self): self.cfg_optimization_test(insts, expected, consts=list(range(5))) def test_conditional_jump_forward_const_condition(self): - # The unreachable branch of the jump is removed + # The unreachable branch of the jump is removed, the jump + # becomes redundant and is replaced by a NOP (for the lineno) insts = [ ('LOAD_CONST', 3, 11), @@ -903,8 +904,7 @@ def test_conditional_jump_forward_const_condition(self): ] expected = [ ('NOP', None, 11), - ('JUMP', lbl := self.Label(), 12), - lbl, + ('NOP', None, 12), ('LOAD_CONST', '3', 14) ] self.cfg_optimization_test(insts, expected, consts=list(range(5))) diff --git a/Python/compile.c b/Python/compile.c index 627f86a8ce91..857fca440ac0 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -7396,6 +7396,9 @@ mark_cold(basicblock *entryblock) { return 0; } +static int +remove_redundant_jumps(cfg_builder *g); + static int push_cold_blocks_to_end(cfg_builder *g, int code_flags) { basicblock *entryblock = g->g_entryblock; @@ -7465,6 +7468,12 @@ push_cold_blocks_to_end(cfg_builder *g, int code_flags) { } assert(b != NULL && b->b_next == NULL); b->b_next = cold_blocks; + + if (cold_blocks != NULL) { + if (remove_redundant_jumps(g) < 0) { + return -1; + } + } return 0; } @@ -8269,9 +8278,6 @@ trim_unused_consts(basicblock *entryblock, PyObject *consts); static int duplicate_exits_without_lineno(cfg_builder *g); -static int -extend_block(basicblock *bb); - static int * build_cellfixedoffsets(struct compiler *c) { @@ -8476,6 +8482,21 @@ propagate_line_numbers(basicblock *entryblock); static void eliminate_empty_basic_blocks(cfg_builder *g); +#ifndef NDEBUG +static bool +no_redundant_jumps(cfg_builder *g) { + for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { + struct instr *last = basicblock_last_instr(b); + if (last != NULL) { + if (last->i_opcode == JUMP || last->i_opcode == JUMP_NO_INTERRUPT) { + assert(last->i_target != b->b_next); + return false; + } + } + } + return true; +} +#endif static int remove_redundant_jumps(cfg_builder *g) { @@ -8592,8 +8613,8 @@ assemble(struct compiler *c, int addNone) if (trim_unused_consts(g->g_entryblock, consts)) { goto error; } - if (duplicate_exits_without_lineno(g)) { - return NULL; + if (duplicate_exits_without_lineno(g) < 0) { + goto error; } propagate_line_numbers(g->g_entryblock); guarantee_lineno_for_exits(g->g_entryblock, c->u->u_firstlineno); @@ -8612,10 +8633,6 @@ assemble(struct compiler *c, int addNone) if (push_cold_blocks_to_end(g, code_flags) < 0) { goto error; } - - if (remove_redundant_jumps(g) < 0) { - goto error; - } for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { clean_basic_block(b); } @@ -8627,6 +8644,8 @@ assemble(struct compiler *c, int addNone) goto error; } + assert(no_redundant_jumps(g)); + /* Can't modify the bytecode after computing jump offsets. */ assemble_jump_offsets(g->g_entryblock); @@ -9488,7 +9507,7 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache) } } for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { - if (extend_block(b)) { + if (extend_block(b) < 0) { return -1; } } @@ -9500,7 +9519,7 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache) assert(b->b_predecessors == 0); } for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { - if (extend_block(b)) { + if (extend_block(b) < 0) { return -1; } } @@ -9517,6 +9536,9 @@ optimize_cfg(cfg_builder *g, PyObject *consts, PyObject *const_cache) for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) { clean_basic_block(b); } + if (remove_redundant_jumps(g) < 0) { + return -1; + } return 0; }