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gh-107901: make compiler inline basic blocks with no line number and no fallthrough (#114750)

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Irit Katriel 2024-02-02 11:26:31 +00:00 • committed by GitHub
parent 41fde89e47
commit 2091fb2a85
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3 changed files with 108 additions and 39 deletions
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75
Python/flowgraph.c
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@ -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;