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GH-143493: Conform to spec for generator expressions while supporting virtual iterators (GH-143569)

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* Moves the `GET_ITER` instruction into the generator function preamble.
  This means the the iterable is converted into an iterator during generator
  creation, as documented, but keeps it in the same code object allowing
  optimization.
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Mark Shannon 2026-01-16 09:11:58 +00:00 • committed by GitHub
parent c461aa99e2
commit ae53da5758
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14 changed files with 117 additions and 88 deletions
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80
Python/codegen.c
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@ -227,19 +227,25 @@ static int codegen_call_helper(compiler *c, location loc,
static int codegen_try_except(compiler *, stmt_ty);
static int codegen_try_star_except(compiler *, stmt_ty);
typedef enum {
ITERABLE_IN_LOCAL = 0,
ITERABLE_ON_STACK = 1,
ITERATOR_ON_STACK = 2,
} IterStackPosition;
static int codegen_sync_comprehension_generator(
compiler *c, location loc,
asdl_comprehension_seq *generators, int gen_index,
int depth,
expr_ty elt, expr_ty val, int type,
int iter_on_stack);
IterStackPosition iter_pos);
static int codegen_async_comprehension_generator(
compiler *c, location loc,
asdl_comprehension_seq *generators, int gen_index,
int depth,
expr_ty elt, expr_ty val, int type,
int iter_on_stack);
IterStackPosition iter_pos);
static int codegen_pattern(compiler *, pattern_ty, pattern_context *);
static int codegen_match(compiler *, stmt_ty);
@ -665,6 +671,18 @@ codegen_enter_scope(compiler *c, identifier name, int scope_type,
if (scope_type == COMPILE_SCOPE_MODULE) {
loc.lineno = 0;
}
/* Add the generator prefix instructions. */
PySTEntryObject *ste = SYMTABLE_ENTRY(c);
if (ste->ste_coroutine || ste->ste_generator) {
/* Note that RETURN_GENERATOR + POP_TOP have a net stack effect
* of 0. This is because RETURN_GENERATOR pushes the generator
before returning. */
location loc = LOCATION(lineno, lineno, -1, -1);
ADDOP(c, loc, RETURN_GENERATOR);
ADDOP(c, loc, POP_TOP);
}
ADDOP_I(c, loc, RESUME, RESUME_AT_FUNC_START);
if (scope_type == COMPILE_SCOPE_MODULE) {
ADDOP(c, loc, ANNOTATIONS_PLACEHOLDER);
@ -1187,10 +1205,15 @@ codegen_wrap_in_stopiteration_handler(compiler *c)
{
NEW_JUMP_TARGET_LABEL(c, handler);
/* Insert SETUP_CLEANUP at start */
/* Insert SETUP_CLEANUP just before RESUME */
instr_sequence *seq = INSTR_SEQUENCE(c);
int resume = 0;
while (_PyInstructionSequence_GetInstruction(seq, resume).i_opcode != RESUME) {
resume++;
}
RETURN_IF_ERROR(
_PyInstructionSequence_InsertInstruction(
INSTR_SEQUENCE(c), 0,
seq, resume,
SETUP_CLEANUP, handler.id, NO_LOCATION));
ADDOP_LOAD_CONST(c, NO_LOCATION, Py_None);
@ -4401,18 +4424,18 @@ codegen_comprehension_generator(compiler *c, location loc,
asdl_comprehension_seq *generators, int gen_index,
int depth,
expr_ty elt, expr_ty val, int type,
int iter_on_stack)
IterStackPosition iter_pos)
{
comprehension_ty gen;
gen = (comprehension_ty)asdl_seq_GET(generators, gen_index);
if (gen->is_async) {
return codegen_async_comprehension_generator(
c, loc, generators, gen_index, depth, elt, val, type,
iter_on_stack);
iter_pos);
} else {
return codegen_sync_comprehension_generator(
c, loc, generators, gen_index, depth, elt, val, type,
iter_on_stack);
iter_pos);
}
}
@ -4421,7 +4444,7 @@ codegen_sync_comprehension_generator(compiler *c, location loc,
asdl_comprehension_seq *generators,
int gen_index, int depth,
expr_ty elt, expr_ty val, int type,
int iter_on_stack)
IterStackPosition iter_pos)
{
/* generate code for the iterator, then each of the ifs,
and then write to the element */
@ -4433,7 +4456,7 @@ codegen_sync_comprehension_generator(compiler *c, location loc,
comprehension_ty gen = (comprehension_ty)asdl_seq_GET(generators,
gen_index);
if (!iter_on_stack) {
if (iter_pos == ITERABLE_IN_LOCAL) {
if (gen_index == 0) {
assert(METADATA(c)->u_argcount == 1);
ADDOP_I(c, loc, LOAD_FAST, 0);
@ -4468,9 +4491,12 @@ codegen_sync_comprehension_generator(compiler *c, location loc,
}
if (IS_JUMP_TARGET_LABEL(start)) {
depth += 2;
ADDOP(c, LOC(gen->iter), GET_ITER);
if (iter_pos != ITERATOR_ON_STACK) {
ADDOP(c, LOC(gen->iter), GET_ITER);
depth += 1;
}
USE_LABEL(c, start);
depth += 1;
ADDOP_JUMP(c, LOC(gen->iter), FOR_ITER, anchor);
}
VISIT(c, expr, gen->target);
@ -4486,7 +4512,7 @@ codegen_sync_comprehension_generator(compiler *c, location loc,
RETURN_IF_ERROR(
codegen_comprehension_generator(c, loc,
generators, gen_index, depth,
elt, val, type, 0));
elt, val, type, ITERABLE_IN_LOCAL));
}
location elt_loc = LOC(elt);
@ -4545,7 +4571,7 @@ codegen_async_comprehension_generator(compiler *c, location loc,
asdl_comprehension_seq *generators,
int gen_index, int depth,
expr_ty elt, expr_ty val, int type,
int iter_on_stack)
IterStackPosition iter_pos)
{
NEW_JUMP_TARGET_LABEL(c, start);
NEW_JUMP_TARGET_LABEL(c, send);
@ -4555,7 +4581,7 @@ codegen_async_comprehension_generator(compiler *c, location loc,
comprehension_ty gen = (comprehension_ty)asdl_seq_GET(generators,
gen_index);
if (!iter_on_stack) {
if (iter_pos == ITERABLE_IN_LOCAL) {
if (gen_index == 0) {
assert(METADATA(c)->u_argcount == 1);
ADDOP_I(c, loc, LOAD_FAST, 0);
@ -4565,7 +4591,9 @@ codegen_async_comprehension_generator(compiler *c, location loc,
VISIT(c, expr, gen->iter);
}
}
ADDOP(c, LOC(gen->iter), GET_AITER);
if (iter_pos != ITERATOR_ON_STACK) {
ADDOP(c, LOC(gen->iter), GET_AITER);
}
USE_LABEL(c, start);
/* Runtime will push a block here, so we need to account for that */
@ -4795,11 +4823,13 @@ codegen_comprehension(compiler *c, expr_ty e, int type,
location loc = LOC(e);
outermost = (comprehension_ty) asdl_seq_GET(generators, 0);
IterStackPosition iter_state;
if (is_inlined) {
VISIT(c, expr, outermost->iter);
if (push_inlined_comprehension_state(c, loc, entry, &inline_state)) {
goto error;
}
iter_state = ITERABLE_ON_STACK;
}
else {
/* Receive outermost iter as an implicit argument */
@ -4810,6 +4840,23 @@ codegen_comprehension(compiler *c, expr_ty e, int type,
(void *)e, e->lineno, NULL, &umd) < 0) {
goto error;
}
if (type == COMP_GENEXP) {
/* Insert GET_ITER before RETURN_GENERATOR.
https://docs.python.org/3/reference/expressions.html#generator-expressions */
RETURN_IF_ERROR(
_PyInstructionSequence_InsertInstruction(
INSTR_SEQUENCE(c), 0,
LOAD_FAST, 0, LOC(outermost->iter)));
RETURN_IF_ERROR(
_PyInstructionSequence_InsertInstruction(
INSTR_SEQUENCE(c), 1,
outermost->is_async ? GET_AITER : GET_ITER,
0, LOC(outermost->iter)));
iter_state = ITERATOR_ON_STACK;
}
else {
iter_state = ITERABLE_IN_LOCAL;
}
}
Py_CLEAR(entry);
@ -4836,9 +4883,8 @@ codegen_comprehension(compiler *c, expr_ty e, int type,
ADDOP_I(c, loc, SWAP, 2);
}
}
if (codegen_comprehension_generator(c, loc, generators, 0, 0,
elt, val, type, is_inlined) < 0) {
elt, val, type, iter_state) < 0) {
goto error_in_scope;
}