Changeset 179477 in webkit for trunk/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp

Timestamp:

Feb 2, 2015, 10:15:44 AM (10 years ago)

Author:

[email protected]

Message:

Converting Flushes and PhantomLocals to Phantoms requires an OSR availability analysis rather than just using the SetLocal's child
​https://bugs.webkit.org/show_bug.cgi?id=141107

Reviewed by Michael Saboff.

See the bugzilla for a discussion of the problem. This addresses the problem by ensuring
that Flushes are always strength-reduced to PhantomLocals, and CPS rethreading does a mini
OSR availability analysis to determine the right MovHint value to use for the Phantom.

• dfg/DFGCPSRethreadingPhase.cpp:

(JSC::DFG::CPSRethreadingPhase::CPSRethreadingPhase):
(JSC::DFG::CPSRethreadingPhase::freeUnnecessaryNodes):
(JSC::DFG::CPSRethreadingPhase::clearVariables):
(JSC::DFG::CPSRethreadingPhase::canonicalizeFlushOrPhantomLocalFor):
(JSC::DFG::CPSRethreadingPhase::canonicalizeLocalsInBlock):
(JSC::DFG::CPSRethreadingPhase::clearVariablesAtHeadAndTail): Deleted.

• dfg/DFGNode.h:

(JSC::DFG::Node::convertPhantomToPhantomLocal):
(JSC::DFG::Node::convertFlushToPhantomLocal):
(JSC::DFG::Node::convertToPhantomLocal): Deleted.

• dfg/DFGStrengthReductionPhase.cpp:

(JSC::DFG::StrengthReductionPhase::handleNode):

• tests/stress/inline-call-that-doesnt-use-all-args.js: Added.

(foo):
(bar):
(baz):

File:

• trunk/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2013, 2014 Apple Inc. All rights reserved.
+ * Copyright (C) 2013-2015 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -281 +281 @@
                 break;
             
-            m_node->convertToPhantom();
-            Node* dataNode = setLocal->child1().node();
-            DFG_ASSERT(m_graph, m_node, dataNode->hasResult());
-            m_node->child1() = dataNode->defaultEdge();
+            // The Flush should become a PhantomLocal at this point. This means that we want the
+            // local's value during OSR, but we don't care if the value is stored to the stack. CPS
+            // rethreading can canonicalize PhantomLocals for us.
+            m_node->convertFlushToPhantomLocal();
             m_graph.dethread();
             m_changed = true;