Changeset 189013 in webkit for trunk/Source/JavaScriptCore/dfg/DFGLoopPreHeaderCreationPhase.cpp

Timestamp:

Aug 27, 2015, 12:16:07 AM (10 years ago)

Author:

[email protected]

Message:

Node::origin should always be set, and the dead zone due to SSA Phis can just use exitOK=false
​https://bugs.webkit.org/show_bug.cgi?id=148462

Reviewed by Saam Barati.

The need to label nodes that absolutely cannot exit was first observed when we introduced SSA form.
We indicated this by not setting the CodeOrigin.

But just recently (​http://trac.webkit.org/changeset/188979), we added a more comprehensive "exitOK"
bit in NodeOrigin. After that change, there were two ways of indicating that you cannot exit:
!exitOK and an unset NodeOrigin. An unset NodeOrigin implied !exitOK.

Now, this change is about removing the old way so that we only use !exitOK. From now on, all nodes
must have their NodeOrigin set, and the IR validation will check this. This means that I could
remove various pieces of cruft for dealing with unset NodeOrigins, but I did have to add some new
cruft to ensure that all nodes we create have a NodeOrigin.

This change simplifies our IR by having a simpler rule about when NodeOrigin is set: it's always
set.

• dfg/DFGBasicBlock.cpp:

(JSC::DFG::BasicBlock::isInBlock):
(JSC::DFG::BasicBlock::removePredecessor):
(JSC::DFG::BasicBlock::firstOriginNode): Deleted.
(JSC::DFG::BasicBlock::firstOrigin): Deleted.

• dfg/DFGBasicBlock.h:

(JSC::DFG::BasicBlock::begin):
(JSC::DFG::BasicBlock::end):
(JSC::DFG::BasicBlock::numSuccessors):
(JSC::DFG::BasicBlock::successor):

• dfg/DFGCombinedLiveness.cpp:

(JSC::DFG::liveNodesAtHead):

• dfg/DFGConstantHoistingPhase.cpp:
• dfg/DFGCriticalEdgeBreakingPhase.cpp:

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

• dfg/DFGForAllKills.h:

(JSC::DFG::forAllKilledOperands):

• dfg/DFGIntegerRangeOptimizationPhase.cpp:
• dfg/DFGLoopPreHeaderCreationPhase.cpp:

(JSC::DFG::createPreHeader):
(JSC::DFG::LoopPreHeaderCreationPhase::run):

• dfg/DFGOSRAvailabilityAnalysisPhase.cpp:

(JSC::DFG::OSRAvailabilityAnalysisPhase::run):

• dfg/DFGObjectAllocationSinkingPhase.cpp:
• dfg/DFGPutStackSinkingPhase.cpp:
• dfg/DFGSSAConversionPhase.cpp:

(JSC::DFG::SSAConversionPhase::run):

• dfg/DFGValidate.cpp:

(JSC::DFG::Validate::validate):
(JSC::DFG::Validate::validateSSA):

File:

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

trunk/Source/JavaScriptCore/dfg/DFGLoopPreHeaderCreationPhase.cpp

@@ -43 +43 @@
     BasicBlock* preHeader = insertionSet.insertBefore(block, PNaN);
     preHeader->appendNode(
-        graph, SpecNone, Jump, block->firstOrigin(), OpInfo(block));
+        graph, SpecNone, Jump, block->at(0)->origin, OpInfo(block));
     
     for (unsigned predecessorIndex = 0; predecessorIndex < block->predecessors.size(); predecessorIndex++) {
@@ -109 +109 @@
             // if the terminal of the existing pre-header doesn't allow for exit, but the first
             // origin of the loop header does, then we should create a new pre-header.
-            if (!needsNewPreHeader && loop.header()->firstOrigin().exitOK
+            if (!needsNewPreHeader && loop.header()->at(0)->origin.exitOK
                 && !existingPreHeader->terminal()->origin.exitOK)
                 needsNewPreHeader = true;