Added support for ``if __debug__:'' -- if -O is given, this form is
recognized by the code generator and code generation for the test and
the subsequent suite is suppressed.
One must write *exactly* ``if __debug__:'' or ``elif __debug__:'' --
no parentheses or operators must be present, or the optimization is
not carried through. Whitespace doesn't matter. Other uses of
__debug__ will find __debug__ defined as 0 or 1 in the __builtin__
module.
diff --git a/Python/compile.c b/Python/compile.c
index b4377ec..36c78aa 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -1891,6 +1891,7 @@
}
}
}
+
/* Forward */ static node *get_rawdocstring PROTO((node *));
static void
@@ -2170,6 +2171,90 @@
com_pop(c, 3);
}
+static int
+is_constant_false(c, n)
+ struct compiling *c;
+ node *n;
+{
+ object *v;
+ int i;
+
+ /* Label to avoid tail recursion */
+ next:
+ switch (TYPE(n)) {
+
+ case suite:
+ if (NCH(n) == 1) {
+ n = CHILD(n, 0);
+ goto next;
+ }
+ /* Fall through */
+ case file_input:
+ for (i = 0; i < NCH(n); i++) {
+ node *ch = CHILD(n, i);
+ if (TYPE(ch) == stmt) {
+ n = ch;
+ goto next;
+ }
+ }
+ break;
+
+ case stmt:
+ case simple_stmt:
+ case small_stmt:
+ n = CHILD(n, 0);
+ goto next;
+
+ case expr_stmt:
+ case testlist:
+ case test:
+ case and_test:
+ case not_test:
+ case comparison:
+ case expr:
+ case xor_expr:
+ case and_expr:
+ case shift_expr:
+ case arith_expr:
+ case term:
+ case factor:
+ case power:
+ case atom:
+ if (NCH(n) == 1) {
+ n = CHILD(n, 0);
+ goto next;
+ }
+ break;
+
+ case NAME:
+ if (Py_OptimizeFlag && strcmp(STR(n), "__debug__") == 0)
+ return 1;
+ break;
+
+ case NUMBER:
+ v = parsenumber(c, STR(n));
+ if (v == NULL) {
+ err_clear();
+ break;
+ }
+ i = testbool(v);
+ DECREF(v);
+ return i == 0;
+
+ case STRING:
+ v = parsestrplus(n);
+ if (v == NULL) {
+ err_clear();
+ break;
+ }
+ i = testbool(v);
+ DECREF(v);
+ return i == 0;
+
+ }
+ return 0;
+}
+
static void
com_if_stmt(c, n)
struct compiling *c;
@@ -2182,9 +2267,11 @@
for (i = 0; i+3 < NCH(n); i+=4) {
int a = 0;
node *ch = CHILD(n, i+1);
+ if (is_constant_false(c, ch))
+ continue;
if (i > 0)
com_addoparg(c, SET_LINENO, ch->n_lineno);
- com_node(c, CHILD(n, i+1));
+ com_node(c, ch);
com_addfwref(c, JUMP_IF_FALSE, &a);
com_addbyte(c, POP_TOP);
com_pop(c, 1);
@@ -2196,7 +2283,8 @@
}
if (i+2 < NCH(n))
com_node(c, CHILD(n, i+2));
- com_backpatch(c, anchor);
+ if (anchor)
+ com_backpatch(c, anchor);
}
static void