LLVM  13.0.0git
Macros | Typedefs | Functions | Variables
StatepointLowering.cpp File Reference
#include "StatepointLowering.h"
#include "SelectionDAGBuilder.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/RuntimeLibcalls.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/GCStrategy.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Statepoint.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MachineValueType.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <tuple>
#include <utility>
Include dependency graph for StatepointLowering.cpp:

Go to the source code of this file.

Macros

#define DEBUG_TYPE   "statepoint-lowering"
 

Typedefs

typedef FunctionLoweringInfo::StatepointRelocationRecord RecordType
 

Functions

 STATISTIC (NumSlotsAllocatedForStatepoints, "Number of stack slots allocated for statepoints")
 
 STATISTIC (NumOfStatepoints, "Number of statepoint nodes encountered")
 
 STATISTIC (StatepointMaxSlotsRequired, "Maximum number of stack slots required for a singe statepoint")
 
static void pushStackMapConstant (SmallVectorImpl< SDValue > &Ops, SelectionDAGBuilder &Builder, uint64_t Value)
 
static Optional< intfindPreviousSpillSlot (const Value *Val, SelectionDAGBuilder &Builder, int LookUpDepth)
 Utility function for reservePreviousStackSlotForValue. More...
 
static bool willLowerDirectly (SDValue Incoming)
 Return true if-and-only-if the given SDValue can be lowered as either a constant argument or a stack reference. More...
 
static void reservePreviousStackSlotForValue (const Value *IncomingValue, SelectionDAGBuilder &Builder)
 Try to find existing copies of the incoming values in stack slots used for statepoint spilling. More...
 
static std::pair< SDValue, SDNode * > lowerCallFromStatepointLoweringInfo (SelectionDAGBuilder::StatepointLoweringInfo &SI, SelectionDAGBuilder &Builder, SmallVectorImpl< SDValue > &PendingExports)
 Extract call from statepoint, lower it and return pointer to the call node. More...
 
static MachineMemOperandgetMachineMemOperand (MachineFunction &MF, FrameIndexSDNode &FI)
 
static std::tuple< SDValue, SDValue, MachineMemOperand * > spillIncomingStatepointValue (SDValue Incoming, SDValue Chain, SelectionDAGBuilder &Builder)
 Spill a value incoming to the statepoint. More...
 
static void lowerIncomingStatepointValue (SDValue Incoming, bool RequireSpillSlot, SmallVectorImpl< SDValue > &Ops, SmallVectorImpl< MachineMemOperand * > &MemRefs, SelectionDAGBuilder &Builder)
 Lower a single value incoming to a statepoint node. More...
 
static bool isGCValue (const Value *V, SelectionDAGBuilder &Builder)
 Return true if value V represents the GC value. More...
 
static void lowerStatepointMetaArgs (SmallVectorImpl< SDValue > &Ops, SmallVectorImpl< MachineMemOperand * > &MemRefs, SmallVectorImpl< SDValue > &GCPtrs, DenseMap< SDValue, int > &LowerAsVReg, SelectionDAGBuilder::StatepointLoweringInfo &SI, SelectionDAGBuilder &Builder)
 Lower deopt state and gc pointer arguments of the statepoint. More...
 

Variables

cl::opt< bool > UseRegistersForDeoptValues ("use-registers-for-deopt-values", cl::Hidden, cl::init(false), cl::desc("Allow using registers for non pointer deopt args"))
 
cl::opt< bool > UseRegistersForGCPointersInLandingPad ("use-registers-for-gc-values-in-landing-pad", cl::Hidden, cl::init(false), cl::desc("Allow using registers for gc pointer in landing pad"))
 
cl::opt< unsigned > MaxRegistersForGCPointers ("max-registers-for-gc-values", cl::Hidden, cl::init(0), cl::desc("Max number of VRegs allowed to pass GC pointer meta args in"))
 

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE   "statepoint-lowering"

Definition at line 55 of file StatepointLowering.cpp.

Typedef Documentation

◆ RecordType

Definition at line 75 of file StatepointLowering.cpp.

Function Documentation

◆ findPreviousSpillSlot()

static Optional<int> findPreviousSpillSlot ( const Value Val,
SelectionDAGBuilder Builder,
int  LookUpDepth 
)
static

Utility function for reservePreviousStackSlotForValue.

Tries to find stack slot index to which we have spilled value for previous statepoints. LookUpDepth specifies maximum DFS depth this function is allowed to look.

Definition at line 159 of file StatepointLowering.cpp.

References Builder, llvm::Optional< T >::hasValue(), llvm::None, and llvm::FunctionLoweringInfo::StatepointRelocationRecord::Spill.

Referenced by reservePreviousStackSlotForValue().

◆ getMachineMemOperand()

static MachineMemOperand* getMachineMemOperand ( MachineFunction MF,
FrameIndexSDNode FI 
)
static

◆ isGCValue()

static bool isGCValue ( const Value V,
SelectionDAGBuilder Builder 
)
static

Return true if value V represents the GC value.

The behavior is conservative in case it is not sure that value is not GC the function returns true.

Definition at line 493 of file StatepointLowering.cpp.

References Builder, and llvm::Value::getType().

Referenced by llvm::SelectionDAGBuilder::LowerStatepoint(), and lowerStatepointMetaArgs().

◆ lowerCallFromStatepointLoweringInfo()

static std::pair<SDValue, SDNode *> lowerCallFromStatepointLoweringInfo ( SelectionDAGBuilder::StatepointLoweringInfo SI,
SelectionDAGBuilder Builder,
SmallVectorImpl< SDValue > &  PendingExports 
)
static

Extract call from statepoint, lower it and return pointer to the call node.

Also update NodeMap so that getValue(statepoint) will reference lowered call result

Definition at line 312 of file StatepointLowering.cpp.

References assert(), Builder, llvm::ISD::CALLSEQ_END, llvm::ISD::CopyFromReg, llvm::SDValue::getNode(), llvm::SDNode::getOpcode(), llvm::SDNode::getOperand(), llvm::ISD::LOAD, and SI.

Referenced by llvm::SelectionDAGBuilder::LowerAsSTATEPOINT().

◆ lowerIncomingStatepointValue()

static void lowerIncomingStatepointValue ( SDValue  Incoming,
bool  RequireSpillSlot,
SmallVectorImpl< SDValue > &  Ops,
SmallVectorImpl< MachineMemOperand * > &  MemRefs,
SelectionDAGBuilder Builder 
)
static

Lower a single value incoming to a statepoint node.

This value can be either a deopt value or a gc value, the handling is the same. We special case constants and allocas, then fall back to spilling if required.

Definition at line 415 of file StatepointLowering.cpp.

References assert(), Builder, getMachineMemOperand(), llvm::EVT::getSizeInBits(), llvm::SDValue::getValueType(), llvm::SDValue::isUndef(), llvm_unreachable, pushStackMapConstant(), spillIncomingStatepointValue(), and willLowerDirectly().

Referenced by lowerStatepointMetaArgs().

◆ lowerStatepointMetaArgs()

static void lowerStatepointMetaArgs ( SmallVectorImpl< SDValue > &  Ops,
SmallVectorImpl< MachineMemOperand * > &  MemRefs,
SmallVectorImpl< SDValue > &  GCPtrs,
DenseMap< SDValue, int > &  LowerAsVReg,
SelectionDAGBuilder::StatepointLoweringInfo SI,
SelectionDAGBuilder Builder 
)
static

Lower deopt state and gc pointer arguments of the statepoint.

The actual lowering is described in lowerIncomingStatepointValue. This function is responsible for lowering everything in the right position and playing some tricks to avoid redundant stack manipulation where possible. On completion, 'Ops' will contain ready to use operands for machine code statepoint. The chain nodes will have already been created and the DAG root will be set to the last value spilled (if any were).

Definition at line 511 of file StatepointLowering.cpp.

References llvm::SmallVectorImpl< T >::append(), Arg, assert(), llvm::sampleprof::Base, Builder, llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::count(), llvm::SmallSet< T, N, C >::count(), llvm::dbgs(), llvm::DeoptLiveIn, llvm::SDValue::dump(), getMachineMemOperand(), llvm::SDValue::getNode(), llvm::Type::getScalarType(), llvm::Value::getType(), llvm::SDValue::getValueType(), i, llvm::MVT::i64, llvm::SetVector< T, SmallVector< T, N >, SmallDenseSet< T, N > >::insert(), llvm::SmallSet< T, N, C >::insert(), isGCValue(), llvm::EVT::isVector(), LLVM_DEBUG, lowerIncomingStatepointValue(), MaxRegistersForGCPointers, pushStackMapConstant(), reservePreviousStackSlotForValue(), S, SI, llvm::SetVector< T, SmallVector< T, N >, SmallDenseSet< T, N > >::size(), llvm::DenseMapBase< DenseMap< KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::size(), UseRegistersForDeoptValues, UseRegistersForGCPointersInLandingPad, and willLowerDirectly().

Referenced by llvm::SelectionDAGBuilder::LowerAsSTATEPOINT().

◆ pushStackMapConstant()

static void pushStackMapConstant ( SmallVectorImpl< SDValue > &  Ops,
SelectionDAGBuilder Builder,
uint64_t  Value 
)
static

◆ reservePreviousStackSlotForValue()

static void reservePreviousStackSlotForValue ( const Value IncomingValue,
SelectionDAGBuilder Builder 
)
static

Try to find existing copies of the incoming values in stack slots used for statepoint spilling.

If we can find a spill slot for the incoming value, mark that slot as allocated, and reuse the same slot for this safepoint. This helps to avoid series of loads and stores that only serve to reshuffle values on the stack between calls.

Definition at line 262 of file StatepointLowering.cpp.

References assert(), Builder, llvm::find(), findPreviousSpillSlot(), llvm::SDValue::getNode(), Index, Offset, and willLowerDirectly().

Referenced by lowerStatepointMetaArgs().

◆ spillIncomingStatepointValue()

static std::tuple<SDValue, SDValue, MachineMemOperand*> spillIncomingStatepointValue ( SDValue  Incoming,
SDValue  Chain,
SelectionDAGBuilder Builder 
)
static

Spill a value incoming to the statepoint.

It might be either part of vmstate or gcstate. In both cases unconditionally spill it on the stack unless it is a null constant. Return pair with first element being frame index containing saved value and second element with outgoing chain from the emitted store

Definition at line 367 of file StatepointLowering.cpp.

References assert(), Builder, llvm::MachinePointerInfo::getFixedStack(), getMachineMemOperand(), llvm::SDValue::getNode(), llvm::MachineFrameInfo::getObjectAlign(), llvm::MachineFrameInfo::getObjectSize(), llvm::SDValue::getValueSizeInBits(), llvm::SDValue::getValueType(), Index, and llvm::MachineMemOperand::MOStore.

Referenced by lowerIncomingStatepointValue().

◆ STATISTIC() [1/3]

STATISTIC ( NumOfStatepoints  ,
"Number of statepoint nodes encountered"   
)

◆ STATISTIC() [2/3]

STATISTIC ( NumSlotsAllocatedForStatepoints  ,
"Number of stack slots allocated for statepoints  
)

◆ STATISTIC() [3/3]

STATISTIC ( StatepointMaxSlotsRequired  ,
"Maximum number of stack slots required for a singe statepoint"   
)

◆ willLowerDirectly()

static bool willLowerDirectly ( SDValue  Incoming)
static

Return true if-and-only-if the given SDValue can be lowered as either a constant argument or a stack reference.

The key point is that the value doesn't need to be spilled or tracked as a vreg use.

Definition at line 240 of file StatepointLowering.cpp.

References llvm::EVT::getSizeInBits(), llvm::SDValue::getValueType(), and llvm::SDValue::isUndef().

Referenced by lowerIncomingStatepointValue(), lowerStatepointMetaArgs(), and reservePreviousStackSlotForValue().

Variable Documentation

◆ MaxRegistersForGCPointers

cl::opt<unsigned> MaxRegistersForGCPointers("max-registers-for-gc-values", cl::Hidden, cl::init(0), cl::desc("Max number of VRegs allowed to pass GC pointer meta args in"))

Referenced by lowerStatepointMetaArgs().

◆ UseRegistersForDeoptValues

cl::opt<bool> UseRegistersForDeoptValues("use-registers-for-deopt-values", cl::Hidden, cl::init(false), cl::desc("Allow using registers for non pointer deopt args"))

Referenced by lowerStatepointMetaArgs().

◆ UseRegistersForGCPointersInLandingPad

cl::opt<bool> UseRegistersForGCPointersInLandingPad("use-registers-for-gc-values-in-landing-pad", cl::Hidden, cl::init(false), cl::desc("Allow using registers for gc pointer in landing pad"))

Referenced by lowerStatepointMetaArgs().