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Issue #9011: Remove buggy and unnecessary ST->AST compilation code

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dealing with unary minus applied to a constant.  The removed code was
mutating the ST, causing a second compilation to fail.  (The peephole
optimizer already takes care of optimizing this case, so there's no
lost optimization opportunity here.)
This commit is contained in:
Mark Dickinson 2010-06-17 12:33:22 +00:00
parent a1b3740d04
commit d35a32e12e
3 changed files with 16 additions and 27 deletions
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26
Python/ast.c
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@ -1678,34 +1678,8 @@ ast_for_trailer(struct compiling *c, const node *n, expr_ty left_expr)
static expr_ty
ast_for_factor(struct compiling *c, const node *n)
{
node *pfactor, *ppower, *patom, *pnum;
expr_ty expression;
/* If the unary - operator is applied to a constant, don't generate
a UNARY_NEGATIVE opcode. Just store the approriate value as a
constant. The peephole optimizer already does something like
this but it doesn't handle the case where the constant is
(sys.maxint - 1). In that case, we want a PyIntObject, not a
PyLongObject.
*/
if (TYPE(CHILD(n, 0)) == MINUS
&& NCH(n) == 2
&& TYPE((pfactor = CHILD(n, 1))) == factor
&& NCH(pfactor) == 1
&& TYPE((ppower = CHILD(pfactor, 0))) == power
&& NCH(ppower) == 1
&& TYPE((patom = CHILD(ppower, 0))) == atom
&& TYPE((pnum = CHILD(patom, 0))) == NUMBER) {
char *s = PyObject_MALLOC(strlen(STR(pnum)) + 2);
if (s == NULL)
return NULL;
s[0] = '-';
strcpy(s + 1, STR(pnum));
PyObject_FREE(STR(pnum));
STR(pnum) = s;
return ast_for_atom(c, patom);
}
expression = ast_for_expr(c, CHILD(n, 1));
if (!expression)
return NULL;