Issue #2183: Simplify and optimize bytecode for list comprehensions.
diff --git a/Python/compile.c b/Python/compile.c
index 88d54ab..756a903 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -693,7 +693,7 @@
return 0;
case LIST_APPEND:
- return -2;
+ return -1;
case BINARY_POWER:
case BINARY_MULTIPLY:
@@ -2599,9 +2599,8 @@
}
static int
-compiler_listcomp_generator(struct compiler *c, PyObject *tmpname,
- asdl_seq *generators, int gen_index,
- expr_ty elt)
+compiler_listcomp_generator(struct compiler *c, asdl_seq *generators,
+ int gen_index, expr_ty elt)
{
/* generate code for the iterator, then each of the ifs,
and then write to the element */
@@ -2638,16 +2637,13 @@
}
if (++gen_index < asdl_seq_LEN(generators))
- if (!compiler_listcomp_generator(c, tmpname,
- generators, gen_index, elt))
+ if (!compiler_listcomp_generator(c, generators, gen_index, elt))
return 0;
/* only append after the last for generator */
if (gen_index >= asdl_seq_LEN(generators)) {
- if (!compiler_nameop(c, tmpname, Load))
- return 0;
VISIT(c, expr, elt);
- ADDOP(c, LIST_APPEND);
+ ADDOP_I(c, LIST_APPEND, gen_index+1);
compiler_use_next_block(c, skip);
}
@@ -2659,10 +2655,6 @@
}
ADDOP_JABS(c, JUMP_ABSOLUTE, start);
compiler_use_next_block(c, anchor);
- /* delete the temporary list name added to locals */
- if (gen_index == 1)
- if (!compiler_nameop(c, tmpname, Del))
- return 0;
return 1;
}
@@ -2670,21 +2662,10 @@
static int
compiler_listcomp(struct compiler *c, expr_ty e)
{
- identifier tmp;
- int rc = 0;
- asdl_seq *generators = e->v.ListComp.generators;
-
assert(e->kind == ListComp_kind);
- tmp = compiler_new_tmpname(c);
- if (!tmp)
- return 0;
ADDOP_I(c, BUILD_LIST, 0);
- ADDOP(c, DUP_TOP);
- if (compiler_nameop(c, tmp, Store))
- rc = compiler_listcomp_generator(c, tmp, generators, 0,
- e->v.ListComp.elt);
- Py_DECREF(tmp);
- return rc;
+ return compiler_listcomp_generator(c, e->v.ListComp.generators, 0,
+ e->v.ListComp.elt);
}
static int