Changeset 228411 in webkit for trunk/Source/JavaScriptCore/dfg/DFGDCEPhase.cpp

Timestamp:

Feb 12, 2018, 5:12:28 PM (7 years ago)

Author:

[email protected]

Message:

Add a GetIndexMask node and make it an input to GetByVal for array and typed array accesses in DFG SSA
​https://bugs.webkit.org/show_bug.cgi?id=182633
<rdar://problem/37441037>

Reviewed by Keith Miller.

This patch introduces a GetIndexMask node to DFG SSA. This is an input to
GetByVal for the GetByVal variants that do conservative index masking.
The reason I'm adding this node is I realized there were loads of
the butterfly index mask inside loops that B3 couldn't reason about
because B3 can't arbitrarily hoist loads out of loops if those loops
have side exits (because the side exit might be protecting the safety of the
load). However, for these loops I analyzed, the DFG would be able to hoist
these loads out of loops because it knows about JS semantics to correctly
reason about the safety of hoisting the load.

This is a 1% speedup on JetStream on Mac and iOS in my testing.

This patch also adds some infrastructure for eliminating and doing CSE on
varargs nodes. Because this patch makes GetByVal a varargs node, I ran into
issues we never had before. We never had a varargs node that could be CSEd or be
hoisted out of a loop until I made GetByVal varargs. To make it all work,
I added a CheckVarargs node. This is just like Check, but it's varargs.

• dfg/DFGAbstractInterpreterInlines.h:

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

• dfg/DFGAdjacencyList.h:

(JSC::DFG::AdjacencyList::AdjacencyList):

• dfg/DFGArgumentsEliminationPhase.cpp:
• dfg/DFGBackwardsPropagationPhase.cpp:

(JSC::DFG::BackwardsPropagationPhase::propagate):

• dfg/DFGBasicBlock.cpp:

(JSC::DFG::BasicBlock::replaceTerminal):

• dfg/DFGBasicBlock.h:

(JSC::DFG::BasicBlock::findTerminal const):

• dfg/DFGBasicBlockInlines.h:

(JSC::DFG::BasicBlock::replaceTerminal):

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::parseBlock):

• dfg/DFGCFGSimplificationPhase.cpp:

(JSC::DFG::CFGSimplificationPhase::mergeBlocks):

• dfg/DFGCPSRethreadingPhase.cpp:

(JSC::DFG::CPSRethreadingPhase::canonicalizeGetLocalFor):
(JSC::DFG::CPSRethreadingPhase::canonicalizeFlushOrPhantomLocalFor):

• dfg/DFGCSEPhase.cpp:
• dfg/DFGCleanUpPhase.cpp:

(JSC::DFG::CleanUpPhase::run):

• dfg/DFGClobberize.h:

(JSC::DFG::clobberize):

• dfg/DFGConstantFoldingPhase.cpp:

(JSC::DFG::ConstantFoldingPhase::foldConstants):
(JSC::DFG::ConstantFoldingPhase::fixUpsilons):

• dfg/DFGDCEPhase.cpp:

(JSC::DFG::DCEPhase::run):
(JSC::DFG::DCEPhase::fixupBlock):

• dfg/DFGDoesGC.cpp:

(JSC::DFG::doesGC):

• dfg/DFGFixupPhase.cpp:

(JSC::DFG::FixupPhase::fixupNode):
(JSC::DFG::FixupPhase::fixupChecksInBlock):

• dfg/DFGHeapLocation.cpp:

(WTF::printInternal):

• dfg/DFGHeapLocation.h:
• dfg/DFGIntegerCheckCombiningPhase.cpp:

(JSC::DFG::IntegerCheckCombiningPhase::handleBlock):

• dfg/DFGIntegerRangeOptimizationPhase.cpp:
• dfg/DFGLICMPhase.cpp:

(JSC::DFG::LICMPhase::attemptHoist):

• dfg/DFGMayExit.cpp:
• dfg/DFGNode.cpp:

(JSC::DFG::Node::remove):
(JSC::DFG::Node::convertToIdentityOn):

• dfg/DFGNode.h:

(JSC::DFG::Node::replaceWith):

• dfg/DFGNodeType.h:
• dfg/DFGObjectAllocationSinkingPhase.cpp:
• dfg/DFGPredictionPropagationPhase.cpp:
• dfg/DFGPureValue.cpp:

(JSC::DFG::PureValue::dump const):

• dfg/DFGPureValue.h:

(JSC::DFG::PureValue::PureValue):

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

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

• dfg/DFGSSALoweringPhase.cpp:

(JSC::DFG::SSALoweringPhase::handleNode):

• dfg/DFGSafeToExecute.h:

(JSC::DFG::safeToExecute):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::SpeculativeJIT):
(JSC::DFG::SpeculativeJIT::compileGetByValOnString):
(JSC::DFG::SpeculativeJIT::compileGetByValOnIntTypedArray):
(JSC::DFG::SpeculativeJIT::compileGetByValOnFloatTypedArray):
(JSC::DFG::SpeculativeJIT::compileGetByValForObjectWithString):
(JSC::DFG::SpeculativeJIT::compileGetByValForObjectWithSymbol):
(JSC::DFG::SpeculativeJIT::compileGetByValOnDirectArguments):
(JSC::DFG::SpeculativeJIT::compileGetByValOnScopedArguments):

• dfg/DFGSpeculativeJIT.h:
• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGStoreBarrierClusteringPhase.cpp:
• dfg/DFGValidate.cpp:
• dfg/DFGVarargsForwardingPhase.cpp:
• ftl/FTLCapabilities.cpp:

(JSC::FTL::canCompile):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileGetArrayMask):
(JSC::FTL::DFG::LowerDFGToB3::compileGetByVal):
(JSC::FTL::DFG::LowerDFGToB3::compileStringCharAt):
(JSC::FTL::DFG::LowerDFGToB3::maskedIndex):
(JSC::FTL::DFG::LowerDFGToB3::pointerIntoTypedArray):

File:

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

trunk/Source/JavaScriptCore/dfg/DFGDCEPhase.cpp

@@ -72 +72 @@
                         continue;
                     break;
+                case CheckVarargs: {
+                    bool isEmpty = true;
+                    m_graph.doToChildren(node, [&] (Edge edge) {
+                        isEmpty &= !edge;
+                    });
+                    if (isEmpty)
+                        continue;
+                    break;
+                }
                 default:
                     break;
@@ -127 +136 @@
             }
             
-            node->remove();
+            node->remove(m_graph);
             node->setRefCount(1);
         }