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Merged
merged 4 commits into from
Feb 25, 2022
Merged

bpo-46808: remove NEXT_BLOCK() from compile.c #31448

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7c10c86
generate end of block for jumps etc, NEXT_BLOCK is a NOP.
iritkatriel Feb 19, 2022
86e80b4
remove NEXT_BLOCK
iritkatriel Feb 20, 2022
0f276dc
avoid creating empty implicit blocks
iritkatriel Feb 20, 2022
2173c07
📜🤖 Added by blurb_it.
blurb-it[bot] Feb 20, 2022
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-02-20-23-10-14.bpo-46808.vouNSF.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Remove the ``NEXT_BLOCK`` macro from compile.c, and make the compiler automatically generate implicit blocks when they are needed.
135 changes: 72 additions & 63 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,9 @@ struct compiler_unit {
int u_col_offset; /* the offset of the current stmt */
int u_end_lineno; /* the end line of the current stmt */
int u_end_col_offset; /* the end offset of the current stmt */

/* true if we need to create an implicit basicblock before the next instr */
int u_need_new_implicit_block;
};

/* This struct captures the global state of a compilation.
Expand Down Expand Up @@ -721,23 +724,13 @@ compiler_new_block(struct compiler *c)
return b;
}

static basicblock *
compiler_next_block(struct compiler *c)
{
basicblock *block = compiler_new_block(c);
if (block == NULL)
return NULL;
c->u->u_curblock->b_next = block;
c->u->u_curblock = block;
return block;
}

static basicblock *
compiler_use_next_block(struct compiler *c, basicblock *block)
{
assert(block != NULL);
c->u->u_curblock->b_next = block;
c->u->u_curblock = block;
c->u->u_need_new_implicit_block = 0;
return block;
}

Expand Down Expand Up @@ -1105,6 +1098,37 @@ PyCompile_OpcodeStackEffect(int opcode, int oparg)
return stack_effect(opcode, oparg, -1);
}

static int is_end_of_basic_block(struct instr *instr)
{
int opcode = instr->i_opcode;

return is_jump(instr) ||
opcode == RETURN_VALUE ||
opcode == RAISE_VARARGS ||
opcode == RERAISE;
}

static int
compiler_use_new_implicit_block_if_needed(struct compiler *c)
{
if (c->u->u_need_new_implicit_block) {
basicblock *b = compiler_new_block(c);
if (b == NULL) {
return -1;
}
compiler_use_next_block(c, b);
}
return 0;
}

static void
compiler_check_if_end_of_block(struct compiler *c, struct instr *instr)
{
if (is_end_of_basic_block(instr)) {
c->u->u_need_new_implicit_block = 1;
}
}

/* Add an opcode with no argument.
Returns 0 on failure, 1 on success.
*/
Expand All @@ -1113,23 +1137,29 @@ static int
compiler_addop_line(struct compiler *c, int opcode, int line,
int end_line, int col_offset, int end_col_offset)
{
basicblock *b;
struct instr *i;
int off;
assert(!HAS_ARG(opcode) || IS_ARTIFICIAL(opcode));
off = compiler_next_instr(c->u->u_curblock);
if (off < 0)

if (compiler_use_new_implicit_block_if_needed(c) < 0) {
return -1;
}

basicblock *b = c->u->u_curblock;
int off = compiler_next_instr(b);
if (off < 0) {
return 0;
b = c->u->u_curblock;
i = &b->b_instr[off];
}
struct instr *i = &b->b_instr[off];
i->i_opcode = opcode;
i->i_oparg = 0;
if (opcode == RETURN_VALUE)
if (opcode == RETURN_VALUE) {
b->b_return = 1;
}
i->i_lineno = line;
i->i_end_lineno = end_line;
i->i_col_offset = col_offset;
i->i_end_col_offset = end_col_offset;

compiler_check_if_end_of_block(c, i);
return 1;
}

Expand Down Expand Up @@ -1341,29 +1371,35 @@ compiler_addop_i_line(struct compiler *c, int opcode, Py_ssize_t oparg,
int lineno, int end_lineno,
int col_offset, int end_col_offset)
{
struct instr *i;
int off;

/* oparg value is unsigned, but a signed C int is usually used to store
it in the C code (like Python/ceval.c).

Limit to 32-bit signed C int (rather than INT_MAX) for portability.

The argument of a concrete bytecode instruction is limited to 8-bit.
EXTENDED_ARG is used for 16, 24, and 32-bit arguments. */

assert(HAS_ARG(opcode));
assert(0 <= oparg && oparg <= 2147483647);

off = compiler_next_instr(c->u->u_curblock);
if (off < 0)
if (compiler_use_new_implicit_block_if_needed(c) < 0) {
return -1;
}

basicblock *b = c->u->u_curblock;
int off = compiler_next_instr(b);
if (off < 0) {
return 0;
i = &c->u->u_curblock->b_instr[off];
}
struct instr *i = &b->b_instr[off];
i->i_opcode = opcode;
i->i_oparg = Py_SAFE_DOWNCAST(oparg, Py_ssize_t, int);
i->i_lineno = lineno;
i->i_end_lineno = end_lineno;
i->i_col_offset = col_offset;
i->i_end_col_offset = end_col_offset;

compiler_check_if_end_of_block(c, i);
return 1;
}

Expand All @@ -1381,15 +1417,19 @@ compiler_addop_i_noline(struct compiler *c, int opcode, Py_ssize_t oparg)
return compiler_addop_i_line(c, opcode, oparg, -1, 0, 0, 0);
}

static int add_jump_to_block(basicblock *b, int opcode,
static int add_jump_to_block(struct compiler *c, int opcode,
int lineno, int end_lineno,
int col_offset, int end_col_offset,
basicblock *target)
{
assert(HAS_ARG(opcode));
assert(b != NULL);
assert(target != NULL);

if (compiler_use_new_implicit_block_if_needed(c) < 0) {
return -1;
}

basicblock *b = c->u->u_curblock;
int off = compiler_next_instr(b);
struct instr *i = &b->b_instr[off];
if (off < 0) {
Expand All @@ -1401,32 +1441,23 @@ static int add_jump_to_block(basicblock *b, int opcode,
i->i_end_lineno = end_lineno;
i->i_col_offset = col_offset;
i->i_end_col_offset = end_col_offset;

compiler_check_if_end_of_block(c, i);
return 1;
}

static int
compiler_addop_j(struct compiler *c, int opcode, basicblock *b)
{
return add_jump_to_block(c->u->u_curblock, opcode, c->u->u_lineno,
return add_jump_to_block(c, opcode, c->u->u_lineno,
c->u->u_end_lineno, c->u->u_col_offset,
c->u->u_end_col_offset, b);
}

static int
compiler_addop_j_noline(struct compiler *c, int opcode, basicblock *b)
{
return add_jump_to_block(c->u->u_curblock, opcode, -1, 0, 0, 0, b);
}

/* NEXT_BLOCK() creates an implicit jump from the current block
to the new block.

The returns inside this macro make it impossible to decref objects
created in the local function. Local objects should use the arena.
*/
#define NEXT_BLOCK(C) { \
if (compiler_next_block((C)) == NULL) \
return 0; \
return add_jump_to_block(c, opcode, -1, 0, 0, 0, b);
}

#define ADDOP(C, OP) { \
Expand Down Expand Up @@ -2806,12 +2837,10 @@ compiler_jump_if(struct compiler *c, expr_ty e, basicblock *next, int cond)
ADDOP_I(c, COPY, 2);
ADDOP_COMPARE(c, asdl_seq_GET(e->v.Compare.ops, i));
ADDOP_JUMP(c, POP_JUMP_IF_FALSE, cleanup);
NEXT_BLOCK(c);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(e->v.Compare.comparators, n));
ADDOP_COMPARE(c, asdl_seq_GET(e->v.Compare.ops, n));
ADDOP_JUMP(c, cond ? POP_JUMP_IF_TRUE : POP_JUMP_IF_FALSE, next);
NEXT_BLOCK(c);
basicblock *end = compiler_new_block(c);
if (end == NULL)
return 0;
Expand All @@ -2835,7 +2864,6 @@ compiler_jump_if(struct compiler *c, expr_ty e, basicblock *next, int cond)
/* general implementation */
VISIT(c, expr, e);
ADDOP_JUMP(c, cond ? POP_JUMP_IF_TRUE : POP_JUMP_IF_FALSE, next);
NEXT_BLOCK(c);
return 1;
}

Expand Down Expand Up @@ -3111,7 +3139,6 @@ compiler_return(struct compiler *c, stmt_ty s)
ADDOP_LOAD_CONST(c, s->v.Return.value->v.Constant.value);
}
ADDOP(c, RETURN_VALUE);
NEXT_BLOCK(c);

return 1;
}
Expand All @@ -3132,7 +3159,6 @@ compiler_break(struct compiler *c)
return 0;
}
ADDOP_JUMP(c, JUMP_ABSOLUTE, loop->fb_exit);
NEXT_BLOCK(c);
return 1;
}

Expand All @@ -3149,7 +3175,6 @@ compiler_continue(struct compiler *c)
return compiler_error(c, "'continue' not properly in loop");
}
ADDOP_JUMP(c, JUMP_ABSOLUTE, loop->fb_block);
NEXT_BLOCK(c)
return 1;
}

Expand Down Expand Up @@ -3331,7 +3356,6 @@ compiler_try_except(struct compiler *c, stmt_ty s)
compiler_pop_fblock(c, TRY_EXCEPT, body);
ADDOP_NOLINE(c, POP_BLOCK);
if (s->v.Try.orelse && asdl_seq_LEN(s->v.Try.orelse)) {
NEXT_BLOCK(c);
VISIT_SEQ(c, stmt, s->v.Try.orelse);
}
ADDOP_JUMP_NOLINE(c, JUMP_FORWARD, end);
Expand All @@ -3357,7 +3381,6 @@ compiler_try_except(struct compiler *c, stmt_ty s)
if (handler->v.ExceptHandler.type) {
VISIT(c, expr, handler->v.ExceptHandler.type);
ADDOP_JUMP(c, JUMP_IF_NOT_EXC_MATCH, except);
NEXT_BLOCK(c);
}
if (handler->v.ExceptHandler.name) {
basicblock *cleanup_end, *cleanup_body;
Expand Down Expand Up @@ -3563,7 +3586,6 @@ compiler_try_star_except(struct compiler *c, stmt_ty s)
if (handler->v.ExceptHandler.type) {
VISIT(c, expr, handler->v.ExceptHandler.type);
ADDOP_JUMP(c, JUMP_IF_NOT_EG_MATCH, except);
NEXT_BLOCK(c);
}

basicblock *cleanup_end = compiler_new_block(c);
Expand Down Expand Up @@ -3648,7 +3670,6 @@ compiler_try_star_except(struct compiler *c, stmt_ty s)
ADDOP(c, PREP_RERAISE_STAR);
ADDOP_I(c, COPY, 1);
ADDOP_JUMP(c, POP_JUMP_IF_NOT_NONE, reraise);
NEXT_BLOCK(c);

/* Nothing to reraise */
ADDOP(c, POP_TOP);
Expand Down Expand Up @@ -3940,7 +3961,6 @@ compiler_visit_stmt(struct compiler *c, stmt_ty s)
}
}
ADDOP_I(c, RAISE_VARARGS, (int)n);
NEXT_BLOCK(c);
break;
case Try_kind:
return compiler_try(c, s);
Expand Down Expand Up @@ -4486,7 +4506,6 @@ compiler_compare(struct compiler *c, expr_ty e)
ADDOP_I(c, COPY, 2);
ADDOP_COMPARE(c, asdl_seq_GET(e->v.Compare.ops, i));
ADDOP_JUMP(c, JUMP_IF_FALSE_OR_POP, cleanup);
NEXT_BLOCK(c);
}
VISIT(c, expr, (expr_ty)asdl_seq_GET(e->v.Compare.comparators, n));
ADDOP_COMPARE(c, asdl_seq_GET(e->v.Compare.ops, n));
Expand Down Expand Up @@ -5087,7 +5106,6 @@ compiler_sync_comprehension_generator(struct compiler *c,
depth++;
compiler_use_next_block(c, start);
ADDOP_JUMP(c, FOR_ITER, anchor);
NEXT_BLOCK(c);
}
VISIT(c, expr, gen->target);

Expand All @@ -5097,7 +5115,6 @@ compiler_sync_comprehension_generator(struct compiler *c,
expr_ty e = (expr_ty)asdl_seq_GET(gen->ifs, i);
if (!compiler_jump_if(c, e, if_cleanup, 0))
return 0;
NEXT_BLOCK(c);
}

if (++gen_index < asdl_seq_LEN(generators))
Expand Down Expand Up @@ -5192,7 +5209,6 @@ compiler_async_comprehension_generator(struct compiler *c,
expr_ty e = (expr_ty)asdl_seq_GET(gen->ifs, i);
if (!compiler_jump_if(c, e, if_cleanup, 0))
return 0;
NEXT_BLOCK(c);
}

depth++;
Expand Down Expand Up @@ -5404,7 +5420,6 @@ compiler_with_except_finish(struct compiler *c, basicblock * cleanup) {
if (exit == NULL)
return 0;
ADDOP_JUMP(c, POP_JUMP_IF_TRUE, exit);
NEXT_BLOCK(c);
ADDOP_I(c, RERAISE, 2);
compiler_use_next_block(c, cleanup);
POP_EXCEPT_AND_RERAISE(c);
Expand Down Expand Up @@ -6143,7 +6158,6 @@ jump_to_fail_pop(struct compiler *c, pattern_context *pc, int op)
Py_ssize_t pops = pc->on_top + PyList_GET_SIZE(pc->stores);
RETURN_IF_FALSE(ensure_fail_pop(c, pc, pops));
ADDOP_JUMP(c, op, pc->fail_pop[pops]);
NEXT_BLOCK(c);
return 1;
}

Expand All @@ -6153,7 +6167,6 @@ emit_and_reset_fail_pop(struct compiler *c, pattern_context *pc)
{
if (!pc->fail_pop_size) {
assert(pc->fail_pop == NULL);
NEXT_BLOCK(c);
return 1;
}
while (--pc->fail_pop_size) {
Expand Down Expand Up @@ -6656,7 +6669,6 @@ compiler_pattern_or(struct compiler *c, pattern_ty p, pattern_context *pc)
}
assert(control);
if (!compiler_addop_j(c, JUMP_FORWARD, end) ||
!compiler_next_block(c) ||
!emit_and_reset_fail_pop(c, pc))
{
goto error;
Expand Down Expand Up @@ -8131,10 +8143,7 @@ assemble(struct compiler *c, int addNone)
PyCodeObject *co = NULL;
PyObject *consts = NULL;

/* Make sure every block that falls off the end returns None.
XXX NEXT_BLOCK() isn't quite right, because if the last
block ends with a jump or return b_next shouldn't set.
*/
/* Make sure every block that falls off the end returns None. */
if (!c->u->u_curblock->b_return) {
UNSET_LOC(c);
if (addNone)
Expand Down