Changeset 153279 in webkit for trunk/Source/JavaScriptCore/dfg/DFGCriticalEdgeBreakingPhase.cpp

Timestamp:

Jul 24, 2013, 9:04:55 PM (12 years ago)

Author:

[email protected]

Message:

fourthTier: Add a phase to create loop pre-headers
​https://bugs.webkit.org/show_bug.cgi?id=118778

Reviewed by Oliver Hunt.

Add a loop pre-header creation phase. Any loop that doesn't already have
just one predecessor that isn't part of the loop has a pre-header
prepended. All non-loop predecessors then jump to that pre-header.

Also fix a handful of bugs:

• DFG::Analysis should set m_valid before running the analysis, since that makes it easier to use ASSERT(m_valid) in the analysis' methods, which may be called by the analysis before the analysis completes. NaturalLoops does this with loopsOf().

• NaturalLoops::headerOf() was missing a check for innerMostLoopOf() returning 0, since that'll happen if the block isn't in any loop.

• Change BlockInsertionSet to dethread the graph, since anyone using it will want to do so.

• Change dethreading to ignore SSA form graphs.

This also adds NaturalLoops::belongsTo(), which I always used in the
pre-header creation phase. I didn't end up using it but I'll probably use
it in the near future.

• JavaScriptCore.xcodeproj/project.pbxproj:
• dfg/DFGAnalysis.h:

(JSC::DFG::Analysis::computeIfNecessary):

• dfg/DFGBlockInsertionSet.cpp:

(JSC::DFG::BlockInsertionSet::execute):

• dfg/DFGCriticalEdgeBreakingPhase.cpp:

(JSC::DFG::CriticalEdgeBreakingPhase::breakCriticalEdge):

• dfg/DFGGraph.cpp:

(JSC::DFG::Graph::dethread):

• dfg/DFGLoopPreHeaderCreationPhase.cpp: Added.

(DFG):
(LoopPreHeaderCreationPhase):
(JSC::DFG::LoopPreHeaderCreationPhase::LoopPreHeaderCreationPhase):
(JSC::DFG::LoopPreHeaderCreationPhase::run):
(JSC::DFG::performLoopPreHeaderCreation):

• dfg/DFGLoopPreHeaderCreationPhase.h: Added.

(DFG):

• dfg/DFGNaturalLoops.h:

(NaturalLoop):
(JSC::DFG::NaturalLoops::headerOf):
(JSC::DFG::NaturalLoops::innerMostLoopOf):
(JSC::DFG::NaturalLoops::innerMostOuterLoop):
(JSC::DFG::NaturalLoops::belongsTo):
(NaturalLoops):

• dfg/DFGPlan.cpp:

(JSC::DFG::Plan::compileInThreadImpl):

Conflicts:

Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj

File:

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

trunk/Source/JavaScriptCore/dfg/DFGCriticalEdgeBreakingPhase.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2012, 2013 Apple Inc. All rights reserved.
+ * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -74 +74 @@
     void breakCriticalEdge(BasicBlock* predecessor, BasicBlock** successor)
     {
-        m_graph.dethread();
-        
         BasicBlock* pad = m_insertionSet.insertBefore(*successor);
         pad->appendNode(