Mercurial > cpython-lru_cache-weakref
diff Python/compile.c @ 38588:5dfb21a37f19 legacy-trunk
Patch #1346214: correctly optimize away "if 0"-style stmts
(thanks to Neal for review)
| author | Georg Brandl <georg@python.org> |
|---|---|
| date | Sun, 04 Jun 2006 21:56:52 +0000 |
| parents | 8f7c7aeac3a5 |
| children | 47d8d19ccadc |
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--- a/Python/compile.c Sun Jun 04 21:46:16 2006 +0000 +++ b/Python/compile.c Sun Jun 04 21:56:52 2006 +0000 @@ -2148,7 +2148,7 @@ compiler_if(struct compiler *c, stmt_ty s) { basicblock *end, *next; - + int constant; assert(s->kind == If_kind); end = compiler_new_block(c); if (end == NULL) @@ -2156,15 +2156,27 @@ next = compiler_new_block(c); if (next == NULL) return 0; - VISIT(c, expr, s->v.If.test); - ADDOP_JREL(c, JUMP_IF_FALSE, next); - ADDOP(c, POP_TOP); - VISIT_SEQ(c, stmt, s->v.If.body); - ADDOP_JREL(c, JUMP_FORWARD, end); - compiler_use_next_block(c, next); - ADDOP(c, POP_TOP); - if (s->v.If.orelse) - VISIT_SEQ(c, stmt, s->v.If.orelse); + + constant = expr_constant(s->v.If.test); + /* constant = 0: "if 0" + * constant = 1: "if 1", "if 2", ... + * constant = -1: rest */ + if (constant == 0) { + if (s->v.If.orelse) + VISIT_SEQ(c, stmt, s->v.If.orelse); + } else if (constant == 1) { + VISIT_SEQ(c, stmt, s->v.If.body); + } else { + VISIT(c, expr, s->v.If.test); + ADDOP_JREL(c, JUMP_IF_FALSE, next); + ADDOP(c, POP_TOP); + VISIT_SEQ(c, stmt, s->v.If.body); + ADDOP_JREL(c, JUMP_FORWARD, end); + compiler_use_next_block(c, next); + ADDOP(c, POP_TOP); + if (s->v.If.orelse) + VISIT_SEQ(c, stmt, s->v.If.orelse); + } compiler_use_next_block(c, end); return 1; } @@ -2639,10 +2651,6 @@ if (c->u->u_ste->ste_type != FunctionBlock) return compiler_error(c, "'return' outside function"); if (s->v.Return.value) { - if (c->u->u_ste->ste_generator) { - return compiler_error(c, - "'return' with argument inside generator"); - } VISIT(c, expr, s->v.Return.value); } else @@ -3356,6 +3364,13 @@ return PyObject_IsTrue(e->v.Num.n); case Str_kind: return PyObject_IsTrue(e->v.Str.s); + case Name_kind: + /* __debug__ is not assignable, so we can optimize + * it away in if and while statements */ + if (strcmp(PyString_AS_STRING(e->v.Name.id), + "__debug__") == 0) + return ! Py_OptimizeFlag; + /* fall through */ default: return -1; }
