[pypy-commit] pypy default: Only strengthen guard_*_class to guard_value when the classes matches (might fix issue1207)

[hakanardo]

Author: Hakan Ardo <hakan at debian.org>
Branch: 
Changeset: r56199:5fcf9d1c9713
Date: 2012-07-18 22:37 +0200
http://bitbucket.org/pypy/pypy/changeset/5fcf9d1c9713/

Log:	Only strengthen guard_*_class to guard_value when the classes
	matches (might fix issue1207)

diff --git a/pypy/jit/metainterp/optimizeopt/rewrite.py b/pypy/jit/metainterp/optimizeopt/rewrite.py
--- a/pypy/jit/metainterp/optimizeopt/rewrite.py
+++ b/pypy/jit/metainterp/optimizeopt/rewrite.py
@@ -241,6 +241,16 @@
             # guard_nonnull_class on this value, which is rather silly.
             # replace the original guard with a guard_value
             old_guard_op = value.last_guard
+            if old_guard_op.getopnum() != rop.GUARD_NONNULL:
+                # This is only safe if the class of the guard_value matches the
+                # class of the guard_*_class, otherwise the intermediate ops might
+                # be executed with wrong classes.
+                previous_classbox = value.get_constant_class(self.optimizer.cpu)            
+                expected_classbox = self.optimizer.cpu.ts.cls_of_box(op.getarg(1))
+                assert previous_classbox is not None
+                assert expected_classbox is not None
+                if not previous_classbox.same_constant(expected_classbox):
+                    raise InvalidLoop('A GUARD_VALUE was proven to always fail')
             op = old_guard_op.copy_and_change(rop.GUARD_VALUE,
                                       args = [old_guard_op.getarg(0), op.getarg(1)])
             self.optimizer.replaces_guard[op] = old_guard_op
@@ -251,6 +261,8 @@
             assert isinstance(descr, compile.ResumeGuardDescr)
             descr.guard_opnum = rop.GUARD_VALUE
             descr.make_a_counter_per_value(op)
+            # to be safe
+            value.last_guard = None
         constbox = op.getarg(1)
         assert isinstance(constbox, Const)
         self.optimize_guard(op, constbox)
diff --git a/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py b/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
--- a/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
+++ b/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
@@ -7862,6 +7862,17 @@
         """
         self.optimize_loop(ops, expected)
 
+    def test_only_strengthen_guard_if_class_matches(self):
+        ops = """
+        [p1]
+        guard_class(p1, ConstClass(node_vtable2)) []
+        guard_value(p1, ConstPtr(myptr)) []
+        jump(p1)
+        """
+        self.raises(InvalidLoop, self.optimize_loop,
+                       ops, ops)
+
+
 class TestLLtype(OptimizeOptTest, LLtypeMixin):
     pass