FTL should be able to convey branch weights to LLVM
https://bugs.webkit.org/show_bug.cgi?id=129054
Reviewed by Michael Saboff.
This introduces a really nice way to convey branch weights to LLVM. The basic class
is Weight, which just wraps a float; NaN is used when you are not sure. You can
pass this alongside a LBasicBlock to branching instructions like condbr and switch.
But for simplicity, you can just pass a WeightedTarget, which is a tuple of the
two. And for even greater simplicity, you can create WeightedTargets from
LBasicBlocks by doing:
usually(b) => WeightedTarget(b, Weight(1))
rarely(b) => WeightedTarget(b, Weight(0))
unsure(b) => WeightedTarget(b, Weight()) or WeightedTarget(b, Weight(NaN))
This allows for constructs like:
m_out.branch(isCell(value), usually(isCellCase), rarely(slowCase));
This was intended to be perf-neutral for now, but it did end up creating a ~1%
speed-up on V8v7 and Octane2.
* JavaScriptCore.xcodeproj/project.pbxproj:
* ftl/FTLAbbreviations.h:
(JSC::FTL::mdNode):
* ftl/FTLCommonValues.cpp:
(JSC::FTL::CommonValues::CommonValues):
* ftl/FTLCommonValues.h:
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::LowerDFGToLLVM::lower):
(JSC::FTL::LowerDFGToLLVM::compileValueToInt32):
(JSC::FTL::LowerDFGToLLVM::compileStoreBarrierWithNullCheck):
(JSC::FTL::LowerDFGToLLVM::compileToThis):
(JSC::FTL::LowerDFGToLLVM::compileArithMul):
(JSC::FTL::LowerDFGToLLVM::compileArithDiv):
(JSC::FTL::LowerDFGToLLVM::compileArithMod):
(JSC::FTL::LowerDFGToLLVM::compileArithMinOrMax):
(JSC::FTL::LowerDFGToLLVM::compileCheckStructure):
(JSC::FTL::LowerDFGToLLVM::compileArrayifyToStructure):
(JSC::FTL::LowerDFGToLLVM::compileGetById):
(JSC::FTL::LowerDFGToLLVM::compileGetIndexedPropertyStorage):
(JSC::FTL::LowerDFGToLLVM::compileGetTypedArrayByteOffset):
(JSC::FTL::LowerDFGToLLVM::compileGetByVal):
(JSC::FTL::LowerDFGToLLVM::compilePutByVal):
(JSC::FTL::LowerDFGToLLVM::compileArrayPush):
(JSC::FTL::LowerDFGToLLVM::compileArrayPop):
(JSC::FTL::LowerDFGToLLVM::compileNewArrayWithSize):
(JSC::FTL::LowerDFGToLLVM::compileToString):
(JSC::FTL::LowerDFGToLLVM::compileToPrimitive):
(JSC::FTL::LowerDFGToLLVM::compileStringCharAt):
(JSC::FTL::LowerDFGToLLVM::compileStringCharCodeAt):
(JSC::FTL::LowerDFGToLLVM::compileMultiGetByOffset):
(JSC::FTL::LowerDFGToLLVM::compileNotifyWrite):
(JSC::FTL::LowerDFGToLLVM::compileBranch):
(JSC::FTL::LowerDFGToLLVM::compileSwitch):
(JSC::FTL::LowerDFGToLLVM::compareEqObjectOrOtherToObject):
(JSC::FTL::LowerDFGToLLVM::nonSpeculativeCompare):
(JSC::FTL::LowerDFGToLLVM::allocateCell):
(JSC::FTL::LowerDFGToLLVM::allocateBasicStorageAndGetEnd):
(JSC::FTL::LowerDFGToLLVM::boolify):
(JSC::FTL::LowerDFGToLLVM::equalNullOrUndefined):
(JSC::FTL::LowerDFGToLLVM::contiguousPutByValOutOfBounds):
(JSC::FTL::LowerDFGToLLVM::buildSwitch):
(JSC::FTL::LowerDFGToLLVM::doubleToInt32):
(JSC::FTL::LowerDFGToLLVM::sensibleDoubleToInt32):
(JSC::FTL::LowerDFGToLLVM::lowDouble):
(JSC::FTL::LowerDFGToLLVM::strictInt52ToJSValue):
(JSC::FTL::LowerDFGToLLVM::speculateObjectOrOther):
(JSC::FTL::LowerDFGToLLVM::speculateStringOrStringObject):
(JSC::FTL::LowerDFGToLLVM::emitStoreBarrier):
(JSC::FTL::LowerDFGToLLVM::callCheck):
(JSC::FTL::LowerDFGToLLVM::appendOSRExit):
* ftl/FTLOutput.cpp:
(JSC::FTL::Output::initialize):
(JSC::FTL::Output::appendTo):
(JSC::FTL::Output::newBlock):
(JSC::FTL::Output::sensibleDoubleToInt):
(JSC::FTL::Output::load):
(JSC::FTL::Output::store):
(JSC::FTL::Output::baseIndex):
(JSC::FTL::Output::branch):
(JSC::FTL::Output::crashNonTerminal):
* ftl/FTLOutput.h:
(JSC::FTL::Output::branch):
(JSC::FTL::Output::switchInstruction):
* ftl/FTLSwitchCase.h:
(JSC::FTL::SwitchCase::SwitchCase):
(JSC::FTL::SwitchCase::weight):
* ftl/FTLWeight.h: Added.
(JSC::FTL::Weight::Weight):
(JSC::FTL::Weight::isSet):
(JSC::FTL::Weight::operator!):
(JSC::FTL::Weight::value):
(JSC::FTL::Weight::scaleToTotal):
* ftl/FTLWeightedTarget.h: Added.
(JSC::FTL::WeightedTarget::WeightedTarget):
(JSC::FTL::WeightedTarget::target):
(JSC::FTL::WeightedTarget::weight):
(JSC::FTL::usually):
(JSC::FTL::rarely):
(JSC::FTL::unsure):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@164389 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/ftl/FTLOutput.cpp b/Source/JavaScriptCore/ftl/FTLOutput.cpp
index fb2fc93..986d374 100644
--- a/Source/JavaScriptCore/ftl/FTLOutput.cpp
+++ b/Source/JavaScriptCore/ftl/FTLOutput.cpp
@@ -45,6 +45,104 @@
llvm->DisposeBuilder(m_builder);
}
+void Output::initialize(LModule module, LValue function, AbstractHeapRepository& heaps)
+{
+ IntrinsicRepository::initialize(module);
+ m_function = function;
+ m_heaps = &heaps;
+}
+
+LBasicBlock Output::appendTo(LBasicBlock block, LBasicBlock nextBlock)
+{
+ appendTo(block);
+ return insertNewBlocksBefore(nextBlock);
+}
+
+void Output::appendTo(LBasicBlock block)
+{
+ m_block = block;
+
+ llvm->PositionBuilderAtEnd(m_builder, block);
+}
+
+LBasicBlock Output::newBlock(const char* name)
+{
+ if (!m_nextBlock)
+ return appendBasicBlock(m_context, m_function, name);
+ return insertBasicBlock(m_context, m_nextBlock, name);
+}
+
+LValue Output::sensibleDoubleToInt(LValue value)
+{
+ RELEASE_ASSERT(isX86());
+ return call(
+ x86SSE2CvtTSD2SIIntrinsic(),
+ insertElement(
+ insertElement(getUndef(vectorType(doubleType, 2)), value, int32Zero),
+ doubleZero, int32One));
+}
+
+LValue Output::load(TypedPointer pointer, LType refType)
+{
+ LValue result = get(intToPtr(pointer.value(), refType));
+ pointer.heap().decorateInstruction(result, *m_heaps);
+ return result;
+}
+
+void Output::store(LValue value, TypedPointer pointer, LType refType)
+{
+ LValue result = set(value, intToPtr(pointer.value(), refType));
+ pointer.heap().decorateInstruction(result, *m_heaps);
+}
+
+LValue Output::baseIndex(LValue base, LValue index, Scale scale, ptrdiff_t offset)
+{
+ LValue accumulatedOffset;
+
+ switch (scale) {
+ case ScaleOne:
+ accumulatedOffset = index;
+ break;
+ case ScaleTwo:
+ accumulatedOffset = shl(index, intPtrOne);
+ break;
+ case ScaleFour:
+ accumulatedOffset = shl(index, intPtrTwo);
+ break;
+ case ScaleEight:
+ case ScalePtr:
+ accumulatedOffset = shl(index, intPtrThree);
+ break;
+ }
+
+ if (offset)
+ accumulatedOffset = add(accumulatedOffset, constIntPtr(offset));
+
+ return add(base, accumulatedOffset);
+}
+
+void Output::branch(LValue condition, LBasicBlock taken, Weight takenWeight, LBasicBlock notTaken, Weight notTakenWeight)
+{
+ LValue branch = buildCondBr(m_builder, condition, taken, notTaken);
+
+ if (!takenWeight || !notTakenWeight)
+ return;
+
+ double total = takenWeight.value() + notTakenWeight.value();
+
+ setMetadata(
+ branch, profKind,
+ mdNode(
+ m_context, branchWeights,
+ constInt32(takenWeight.scaleToTotal(total)),
+ constInt32(notTakenWeight.scaleToTotal(total))));
+}
+
+void Output::crashNonTerminal()
+{
+ call(intToPtr(constIntPtr(abort), pointerType(functionType(voidType))));
+}
+
} } // namespace JSC::FTL
#endif // ENABLE(FTL_JIT)
