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add a SETUP_WITH opcode

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It speeds up the with statement and correctly looks up the special
methods involved.
This commit is contained in:
Benjamin Peterson 2009-05-25 13:13:44 +00:00
parent 179bf213ea
commit 1880d8b823
9 changed files with 86 additions and 66 deletions
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65
Python/compile.c
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@ -778,6 +778,8 @@ opcode_stack_effect(int opcode, int oparg)
return -1;
case BREAK_LOOP:
return 0;
case SETUP_WITH:
return 1;
case WITH_CLEANUP:
return -1; /* XXX Sometimes more */
case LOAD_LOCALS:
@ -2821,80 +2823,31 @@ expr_constant(expr_ty e)
static int
compiler_with(struct compiler *c, stmt_ty s)
{
static identifier enter_attr, exit_attr;
basicblock *block, *finally;
identifier tmpvalue = NULL;
assert(s->kind == With_kind);
if (!enter_attr) {
enter_attr = PyString_InternFromString("__enter__");
if (!enter_attr)
return 0;
}
if (!exit_attr) {
exit_attr = PyString_InternFromString("__exit__");
if (!exit_attr)
return 0;
}
block = compiler_new_block(c);
finally = compiler_new_block(c);
if (!block || !finally)
return 0;
if (s->v.With.optional_vars) {
/* Create a temporary variable to hold context.__enter__().
We need to do this rather than preserving it on the stack
because SETUP_FINALLY remembers the stack level.
We need to do the assignment *inside* the try/finally
so that context.__exit__() is called when the assignment
fails. But we need to call context.__enter__() *before*
the try/finally so that if it fails we won't call
context.__exit__().
*/
tmpvalue = compiler_new_tmpname(c);
if (tmpvalue == NULL)
return 0;
PyArena_AddPyObject(c->c_arena, tmpvalue);
}
/* Evaluate EXPR */
VISIT(c, expr, s->v.With.context_expr);
ADDOP_JREL(c, SETUP_WITH, finally);
/* Squirrel away context.__exit__ by stuffing it under context */
ADDOP(c, DUP_TOP);
ADDOP_O(c, LOAD_ATTR, exit_attr, names);
ADDOP(c, ROT_TWO);
/* Call context.__enter__() */
ADDOP_O(c, LOAD_ATTR, enter_attr, names);
ADDOP_I(c, CALL_FUNCTION, 0);
if (s->v.With.optional_vars) {
/* Store it in tmpvalue */
if (!compiler_nameop(c, tmpvalue, Store))
return 0;
}
else {
/* Discard result from context.__enter__() */
ADDOP(c, POP_TOP);
}
/* Start the try block */
ADDOP_JREL(c, SETUP_FINALLY, finally);
/* SETUP_WITH pushes a finally block. */
compiler_use_next_block(c, block);
if (!compiler_push_fblock(c, FINALLY_TRY, block)) {
return 0;
}
if (s->v.With.optional_vars) {
/* Bind saved result of context.__enter__() to VAR */
if (!compiler_nameop(c, tmpvalue, Load) ||
!compiler_nameop(c, tmpvalue, Del))
return 0;
VISIT(c, expr, s->v.With.optional_vars);
VISIT(c, expr, s->v.With.optional_vars);
}
else {
/* Discard result from context.__enter__() */
ADDOP(c, POP_TOP);
}
/* BLOCK code */