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gh-87092: refactor assemble() to a number of separate functions, which do not need the compiler struct #102562

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Merged
iritkatriel merged 10 commits into from
Mar 13, 2023
Merged

gh-87092: refactor assemble() to a number of separate functions, which do not need the compiler struct #102562

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8b71935
remove compiler as arg from some codegen functions
iritkatriel Mar 8, 2023
ed9c7d2
prepare_localsplus doesn't need the whole compiler struct
iritkatriel Mar 8, 2023
1232d41
don't pass compiler around so much in assembler stage
iritkatriel Mar 8, 2023
dbf22d1
extract optimize_code_unit() out of assemble()
iritkatriel Mar 9, 2023
db4b2b8
_PyCompile_CodeGen doesn't need to construct a cfg
iritkatriel Mar 9, 2023
9071570
refactor optimize_code_unit further
iritkatriel Mar 9, 2023
4e7857f
unit tests run all of the optimization stage, not just optimize_cfg
iritkatriel Mar 9, 2023
d0166c4
break up assemble() some more
iritkatriel Mar 10, 2023
c9fc294
remove obsolete comment
iritkatriel Mar 10, 2023
0f198b6
tidy up the no-arg representation in unit test instruction sequences
iritkatriel Mar 10, 2023
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extract optimize_code_unit() out of assemble()
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@iritkatriel
iritkatriel committed Mar 9, 2023
commit dbf22d19693310f74951f388529bd70431aba2f2
125 changes: 58 additions & 67 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -606,6 +606,14 @@ instr_sequence_to_cfg(instr_sequence *seq, cfg_builder *g) {
instruction *instr = &seq->s_instrs[i];
RETURN_IF_ERROR(cfg_builder_addop(g, instr->i_opcode, instr->i_oparg, instr->i_loc));
}
int nblocks = 0;
for (basicblock *b = g->g_block_list; b != NULL; b = b->b_list) {
nblocks++;
}
if ((size_t)nblocks > SIZE_MAX / sizeof(basicblock *)) {
PyErr_NoMemory();
return ERROR;
}
return SUCCESS;
}

Expand Down Expand Up @@ -937,6 +945,7 @@ dictbytype(PyObject *src, int scope_type, int flag, Py_ssize_t offset)
static bool
cfg_builder_check(cfg_builder *g)
{
assert(g->g_entryblock->b_iused > 0);
for (basicblock *block = g->g_block_list; block != NULL; block = block->b_list) {
assert(!_PyMem_IsPtrFreed(block));
if (block->b_instr != NULL) {
Expand Down Expand Up @@ -8636,6 +8645,40 @@ add_return_at_end(struct compiler *c, int addNone)
return SUCCESS;
}

static int
optimize_code_unit(struct compiler_unit *u, cfg_builder *g, PyObject *consts,
PyObject *const_cache, int code_flags)
{
assert(cfg_builder_check(g));
/** Preprocessing **/
/* Set firstlineno if it wasn't explicitly set. */
if (!u->u_firstlineno) {
if (g->g_entryblock->b_instr && g->g_entryblock->b_instr->i_loc.lineno) {
u->u_firstlineno = g->g_entryblock->b_instr->i_loc.lineno;
}
else {
u->u_firstlineno = 1;
}
}
/* Map labels to targets and mark exception handlers */
RETURN_IF_ERROR(translate_jump_labels_to_targets(g->g_entryblock));
RETURN_IF_ERROR(mark_except_handlers(g->g_entryblock));
RETURN_IF_ERROR(label_exception_targets(g->g_entryblock));

/** Optimization **/
RETURN_IF_ERROR(optimize_cfg(g, consts, const_cache));
RETURN_IF_ERROR(remove_unused_consts(g->g_entryblock, consts));
RETURN_IF_ERROR(add_checks_for_loads_of_uninitialized_variables(g->g_entryblock, u));

/** line numbers */
RETURN_IF_ERROR(duplicate_exits_without_lineno(g));
propagate_line_numbers(g->g_entryblock);
guarantee_lineno_for_exits(g->g_entryblock, u->u_firstlineno);

RETURN_IF_ERROR(push_cold_blocks_to_end(g, code_flags));
return SUCCESS;
}

static PyCodeObject *
assemble(struct compiler *c, int addNone)
{
Expand All @@ -8644,9 +8687,6 @@ assemble(struct compiler *c, int addNone)
PyObject *filename = c->c_filename;

PyCodeObject *co = NULL;
PyObject *consts = NULL;
cfg_builder g_;
cfg_builder *g = &g_;
struct assembler a;
memset(&a, 0, sizeof(struct assembler));

Expand All @@ -8659,100 +8699,51 @@ assemble(struct compiler *c, int addNone)
return NULL;
}

/** Preprocessing **/
if (instr_sequence_to_cfg(INSTR_SEQUENCE(c), g) < 0) {
goto error;
}
assert(cfg_builder_check(g));

int nblocks = 0;
for (basicblock *b = g->g_block_list; b != NULL; b = b->b_list) {
nblocks++;
}
if ((size_t)nblocks > SIZE_MAX / sizeof(basicblock *)) {
PyErr_NoMemory();
goto error;
}

/* Set firstlineno if it wasn't explicitly set. */
if (!u->u_firstlineno) {
if (g->g_entryblock->b_instr && g->g_entryblock->b_instr->i_loc.lineno) {
u->u_firstlineno = g->g_entryblock->b_instr->i_loc.lineno;
}
else {
u->u_firstlineno = 1;
}
}

/* Map labels to targets and mark exception handlers */
if (translate_jump_labels_to_targets(g->g_entryblock) < 0) {
goto error;
}
if (mark_except_handlers(g->g_entryblock) < 0) {
goto error;
}
if (label_exception_targets(g->g_entryblock)) {
goto error;
}

/** Optimization **/
consts = consts_dict_keys_inorder(u->u_consts);
PyObject *consts = consts_dict_keys_inorder(u->u_consts);
if (consts == NULL) {
goto error;
}
if (optimize_cfg(g, consts, const_cache)) {
goto error;
}
if (remove_unused_consts(g->g_entryblock, consts) < 0) {
goto error;
}
if (add_checks_for_loads_of_uninitialized_variables(g->g_entryblock, u) < 0) {
goto error;
}

/** line numbers (TODO: move this before optimization stage) */
if (duplicate_exits_without_lineno(g) < 0) {
cfg_builder g;
if (instr_sequence_to_cfg(INSTR_SEQUENCE(c), &g) < 0) {
goto error;
}
propagate_line_numbers(g->g_entryblock);
guarantee_lineno_for_exits(g->g_entryblock, u->u_firstlineno);

if (push_cold_blocks_to_end(g, code_flags) < 0) {
if (optimize_code_unit(u, &g, consts, const_cache, code_flags) < 0) {
goto error;
}

/** Assembly **/

int nlocalsplus = prepare_localsplus(u, g, code_flags);
int nlocalsplus = prepare_localsplus(u, &g, code_flags);
if (nlocalsplus < 0) {
goto error;
}

int maxdepth = stackdepth(g->g_entryblock, code_flags);
int maxdepth = stackdepth(g.g_entryblock, code_flags);
if (maxdepth < 0) {
goto error;
}
/* TO DO -- For 3.12, make sure that `maxdepth <= MAX_ALLOWED_STACK_USE` */

convert_exception_handlers_to_nops(g->g_entryblock);
convert_exception_handlers_to_nops(g.g_entryblock);

/* Order of basic blocks must have been determined by now */
if (normalize_jumps(g) < 0) {
if (normalize_jumps(&g) < 0) {
goto error;
}
assert(no_redundant_jumps(g));
assert(opcode_metadata_is_sane(g));
assert(no_redundant_jumps(&g));
assert(opcode_metadata_is_sane(&g));

/* Can't modify the bytecode after computing jump offsets. */
assemble_jump_offsets(g->g_entryblock);
assemble_jump_offsets(g.g_entryblock);

/* Create assembler */
if (assemble_init(&a, u->u_firstlineno) < 0) {
goto error;
}

/* Emit code. */
for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
for (basicblock *b = g.g_entryblock; b != NULL; b = b->b_next) {
for (int j = 0; j < b->b_iused; j++) {
if (assemble_emit(&a, &b->b_instr[j]) < 0) {
goto error;
Expand All @@ -8764,7 +8755,7 @@ assemble(struct compiler *c, int addNone)
a.a_lineno = u->u_firstlineno;
location loc = NO_LOCATION;
int size = 0;
for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
for (basicblock *b = g.g_entryblock; b != NULL; b = b->b_next) {
for (int j = 0; j < b->b_iused; j++) {
if (!same_location(loc, b->b_instr[j].i_loc)) {
if (assemble_emit_location(&a, loc, size)) {
Expand All @@ -8780,7 +8771,7 @@ assemble(struct compiler *c, int addNone)
goto error;
}

if (assemble_exception_table(&a, g->g_entryblock) < 0) {
if (assemble_exception_table(&a, g.g_entryblock) < 0) {
goto error;
}
if (_PyBytes_Resize(&a.a_except_table, a.a_except_table_off) < 0) {
Expand All @@ -8807,7 +8798,7 @@ assemble(struct compiler *c, int addNone)
co = makecode(u, &a, const_cache, consts, maxdepth, nlocalsplus, code_flags, filename);
error:
Py_XDECREF(consts);
cfg_builder_fini(g);
cfg_builder_fini(&g);
assemble_free(&a);
return co;
}
Expand Down