Changeset 236223 in webkit

Timestamp:

Sep 19, 2018, 2:00:08 PM (8 years ago)

Author:

sbarati@apple.com

Message:

AI rule for MultiPutByOffset executes its effects in the wrong order
​https://bugs.webkit.org/show_bug.cgi?id=189757
<rdar://problem/43535257>

Reviewed by Michael Saboff.

JSTests:

• stress/multi-put-by-offset-must-filter-value-before-filtering-base.js: Added.

(foo):
(Foo):
(g):

Source/JavaScriptCore:

The AI rule for MultiPutByOffset was executing effects in the wrong order.
It first executed the transition effects and the effects on the base, and
then executed the filtering effects on the value being stored. However, you
can end up with the wrong type when the base and the value being stored
are the same. E.g, in a program like o.f = o. These effects need to happen
in the opposite order, modeling what happens in the runtime executing of
MultiPutByOffset.

• dfg/DFGAbstractInterpreterInlines.h:

(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/stress/multi-put-by-offset-must-filter-value-before-filtering-base.js (added)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h (modified) (1 diff)

trunk/JSTests/ChangeLog

@@ +1 @@
+2018-09-19  Saam barati  <sbarati@apple.com>
+
+        AI rule for MultiPutByOffset executes its effects in the wrong order
+        https://bugs.webkit.org/show_bug.cgi?id=189757
+        <rdar://problem/43535257>
+
+        Reviewed by Michael Saboff.
+
+        * stress/multi-put-by-offset-must-filter-value-before-filtering-base.js: Added.
+        (foo):
+        (Foo):
+        (g):
+
 2018-09-17  Mark Lam  <mark.lam@apple.com>
 

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2018-09-19  Saam barati  <sbarati@apple.com>
+
+        AI rule for MultiPutByOffset executes its effects in the wrong order
+        https://bugs.webkit.org/show_bug.cgi?id=189757
+        <rdar://problem/43535257>
+
+        Reviewed by Michael Saboff.
+
+        The AI rule for MultiPutByOffset was executing effects in the wrong order.
+        It first executed the transition effects and the effects on the base, and
+        then executed the filtering effects on the value being stored. However, you
+        can end up with the wrong type when the base and the value being stored
+        are the same. E.g, in a program like `o.f = o`. These effects need to happen
+        in the opposite order, modeling what happens in the runtime executing of
+        MultiPutByOffset.
+
+        * dfg/DFGAbstractInterpreterInlines.h:
+        (JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):
+
 2018-09-18  Mark Lam  <mark.lam@apple.com>
 

trunk/Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h

@@ -3300 +3300 @@
         }
         
+        // We need to order AI executing these effects in the same order as they're executed
+        // at runtime. This is critical when you have JS code like `o.f = o;`. We first
+        // filter types on o, then transition o. Not the other way around. If we got
+        // this ordering wrong, we could end up with the wrong type representing o.
+        setForNode(node->child2(), resultingValue);
+        if (!!originalValue && !resultingValue)
+            m_state.setIsValid(false);
+
         observeTransitions(clobberLimit, transitions);
         if (forNode(node->child1()).changeStructure(m_graph, newSet) == Contradiction)
-            m_state.setIsValid(false);
-        setForNode(node->child2(), resultingValue);
-        if (!!originalValue && !resultingValue)
             m_state.setIsValid(false);
         break;