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llvm-mirror/lib/CodeGen/CMakeLists.txt
Hongtao Yu 4cefe8e200 [CSSPGO] Pseudo probes for function calls.
An indirect call site needs to be probed for its potential call targets. With CSSPGO a direct call also needs a probe so that a calling context can be represented by a stack of callsite probes. Unlike pseudo probes for basic blocks that are in form of standalone intrinsic call instructions, pseudo probes for callsites have to be attached to the call instruction, thus a separate instruction would not work.

One possible way of attaching a probe to a call instruction is to use a special metadata that carries information about the probe. The special metadata will have to make its way through the optimization pipeline down to object emission. This requires additional efforts to maintain the metadata in various places. Given that the `!dbg` metadata is a first-class metadata and has all essential support in place , leveraging the `!dbg` metadata as a channel to encode pseudo probe information is probably the easiest solution.

With the requirement of not inflating `!dbg` metadata that is allocated for almost every instruction, we found that the 32-bit DWARF discriminator field which mainly serves AutoFDO can be reused for pseudo probes. DWARF discriminators distinguish identical source locations between instructions and with pseudo probes such support is not required. In this change we are using the discriminator field to encode the ID and type of a callsite probe and the encoded value will be unpacked and consumed right before object emission. When a callsite is inlined, the callsite discriminator field will go with the inlined instructions. The `!dbg` metadata of an inlined instruction is in form of a scope stack. The top of the stack is the instruction's original `!dbg` metadata and the bottom of the stack is for the original callsite of the top-level inliner. Except for the top of the stack, all other elements of the stack actually refer to the nested inlined callsites whose discriminator field (which actually represents a calliste probe) can be used together to represent the inline context of an inlined PseudoProbeInst or CallInst.

To avoid collision with the baseline AutoFDO in various places that handles dwarf discriminators where a check against  the `-pseudo-probe-for-profiling` switch is not available, a special encoding scheme is used to tell apart a pseudo probe discriminator from a regular discriminator. For the regular discriminator, if all lowest 3 bits are non-zero, it means the discriminator is basically empty and all higher 29 bits can be reversed for pseudo probe use.

Callsite pseudo probes are inserted in `SampleProfileProbePass` and a target-independent MIR pass `PseudoProbeInserter` is added to unpack the probe ID/type from `!dbg`.

Note that with this work the switch -debug-info-for-profiling will not work with -pseudo-probe-for-profiling anymore. They cannot be used at the same time.

Reviewed By: wmi

Differential Revision: https://reviews.llvm.org/D91756
2020-12-02 13:45:20 -08:00

219 lines
4.8 KiB
CMake

add_llvm_component_library(LLVMCodeGen
AggressiveAntiDepBreaker.cpp
AllocationOrder.cpp
Analysis.cpp
AtomicExpandPass.cpp
BasicTargetTransformInfo.cpp
BranchFolding.cpp
BranchRelaxation.cpp
BreakFalseDeps.cpp
BuiltinGCs.cpp
BasicBlockSections.cpp
CalcSpillWeights.cpp
CallingConvLower.cpp
CFGuardLongjmp.cpp
CFIInstrInserter.cpp
CodeGen.cpp
CodeGenPrepare.cpp
CommandFlags.cpp
CriticalAntiDepBreaker.cpp
DeadMachineInstructionElim.cpp
DetectDeadLanes.cpp
DFAPacketizer.cpp
DwarfEHPrepare.cpp
EarlyIfConversion.cpp
EdgeBundles.cpp
ExecutionDomainFix.cpp
ExpandMemCmp.cpp
ExpandPostRAPseudos.cpp
ExpandReductions.cpp
FaultMaps.cpp
FEntryInserter.cpp
FinalizeISel.cpp
FixupStatepointCallerSaved.cpp
FuncletLayout.cpp
GCMetadata.cpp
GCMetadataPrinter.cpp
GCRootLowering.cpp
GCStrategy.cpp
GlobalMerge.cpp
HardwareLoops.cpp
IfConversion.cpp
ImplicitNullChecks.cpp
IndirectBrExpandPass.cpp
InlineSpiller.cpp
InterferenceCache.cpp
InterleavedAccessPass.cpp
InterleavedLoadCombinePass.cpp
IntrinsicLowering.cpp
LatencyPriorityQueue.cpp
LazyMachineBlockFrequencyInfo.cpp
LexicalScopes.cpp
LiveDebugVariables.cpp
LiveIntervals.cpp
LiveInterval.cpp
LiveIntervalUnion.cpp
LivePhysRegs.cpp
LiveRangeCalc.cpp
LiveIntervalCalc.cpp
LiveRangeEdit.cpp
LiveRangeShrink.cpp
LiveRegMatrix.cpp
LiveRegUnits.cpp
LiveStacks.cpp
LiveVariables.cpp
LLVMTargetMachine.cpp
LocalStackSlotAllocation.cpp
LoopTraversal.cpp
LowLevelType.cpp
LowerEmuTLS.cpp
MachineBasicBlock.cpp
MachineBlockFrequencyInfo.cpp
MachineBlockPlacement.cpp
MachineBranchProbabilityInfo.cpp
MachineCombiner.cpp
MachineCopyPropagation.cpp
MachineCSE.cpp
MachineDebugify.cpp
MachineDominanceFrontier.cpp
MachineDominators.cpp
MachineFrameInfo.cpp
MachineFunction.cpp
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp
MachineFunctionSplitter.cpp
MachineInstrBundle.cpp
MachineInstr.cpp
MachineLICM.cpp
MachineLoopInfo.cpp
MachineLoopUtils.cpp
MachineModuleInfo.cpp
MachineModuleInfoImpls.cpp
MachineOperand.cpp
MachineOptimizationRemarkEmitter.cpp
MachineOutliner.cpp
MachinePassManager.cpp
MachinePipeliner.cpp
MachinePostDominators.cpp
MachineRegionInfo.cpp
MachineRegisterInfo.cpp
MachineScheduler.cpp
MachineSink.cpp
MachineSizeOpts.cpp
MachineSSAUpdater.cpp
MachineStripDebug.cpp
MachineTraceMetrics.cpp
MachineVerifier.cpp
ModuloSchedule.cpp
MultiHazardRecognizer.cpp
PatchableFunction.cpp
MBFIWrapper.cpp
MIRPrinter.cpp
MIRPrintingPass.cpp
MacroFusion.cpp
NonRelocatableStringpool.cpp
OptimizePHIs.cpp
ParallelCG.cpp
PeepholeOptimizer.cpp
PHIElimination.cpp
PHIEliminationUtils.cpp
PostRAHazardRecognizer.cpp
PostRASchedulerList.cpp
PreISelIntrinsicLowering.cpp
ProcessImplicitDefs.cpp
PrologEpilogInserter.cpp
PseudoProbeInserter.cpp
PseudoSourceValue.cpp
RDFGraph.cpp
RDFLiveness.cpp
RDFRegisters.cpp
ReachingDefAnalysis.cpp
RegAllocBase.cpp
RegAllocBasic.cpp
RegAllocFast.cpp
RegAllocGreedy.cpp
RegAllocPBQP.cpp
RegisterClassInfo.cpp
RegisterCoalescer.cpp
RegisterPressure.cpp
RegisterScavenging.cpp
RenameIndependentSubregs.cpp
MachineStableHash.cpp
MIRVRegNamerUtils.cpp
MIRNamerPass.cpp
MIRCanonicalizerPass.cpp
RegisterUsageInfo.cpp
RegUsageInfoCollector.cpp
RegUsageInfoPropagate.cpp
ResetMachineFunctionPass.cpp
SafeStack.cpp
SafeStackLayout.cpp
ScalarizeMaskedMemIntrin.cpp
ScheduleDAG.cpp
ScheduleDAGInstrs.cpp
ScheduleDAGPrinter.cpp
ScoreboardHazardRecognizer.cpp
ShadowStackGCLowering.cpp
ShrinkWrap.cpp
SjLjEHPrepare.cpp
SlotIndexes.cpp
SpillPlacement.cpp
SplitKit.cpp
StackColoring.cpp
StackMapLivenessAnalysis.cpp
StackMaps.cpp
StackProtector.cpp
StackSlotColoring.cpp
SwiftErrorValueTracking.cpp
SwitchLoweringUtils.cpp
TailDuplication.cpp
TailDuplicator.cpp
TargetFrameLoweringImpl.cpp
TargetInstrInfo.cpp
TargetLoweringBase.cpp
TargetLoweringObjectFileImpl.cpp
TargetOptionsImpl.cpp
TargetPassConfig.cpp
TargetRegisterInfo.cpp
TargetSchedule.cpp
TargetSubtargetInfo.cpp
TypePromotion.cpp
TwoAddressInstructionPass.cpp
UnreachableBlockElim.cpp
ValueTypes.cpp
VirtRegMap.cpp
WasmEHPrepare.cpp
WinEHPrepare.cpp
XRayInstrumentation.cpp
LiveDebugValues/LiveDebugValues.cpp
LiveDebugValues/VarLocBasedImpl.cpp
LiveDebugValues/InstrRefBasedImpl.cpp
ADDITIONAL_HEADER_DIRS
${LLVM_MAIN_INCLUDE_DIR}/llvm/CodeGen
${LLVM_MAIN_INCLUDE_DIR}/llvm/CodeGen/PBQP
LINK_LIBS ${LLVM_PTHREAD_LIB}
DEPENDS
intrinsics_gen
LINK_COMPONENTS
Analysis
BitReader
BitWriter
Core
MC
ProfileData
Scalar
Support
Target
TransformUtils
)
add_subdirectory(SelectionDAG)
add_subdirectory(AsmPrinter)
add_subdirectory(MIRParser)
add_subdirectory(GlobalISel)