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):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@179477 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp b/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp
index 17564e1..0650b8f 100644
--- a/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp
+++ b/Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp
@@ -1,5 +1,5 @@
/*
- * 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
* modification, are permitted provided that the following conditions
@@ -280,10 +280,10 @@
if (!setLocal)
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;
break;
