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Diffstat (limited to 'gnu/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp')
| -rw-r--r-- | gnu/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp | 1030 |
1 files changed, 0 insertions, 1030 deletions
diff --git a/gnu/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp b/gnu/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp deleted file mode 100644 index 90a1b350fc9..00000000000 --- a/gnu/llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp +++ /dev/null @@ -1,1030 +0,0 @@ -//===- StatepointLowering.cpp - SDAGBuilder's statepoint code -------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This file includes support code use by SelectionDAGBuilder when lowering a -// statepoint sequence in SelectionDAG IR. -// -//===----------------------------------------------------------------------===// - -#include "StatepointLowering.h" -#include "SelectionDAGBuilder.h" -#include "llvm/ADT/ArrayRef.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/None.h" -#include "llvm/ADT/Optional.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/CodeGen/FunctionLoweringInfo.h" -#include "llvm/CodeGen/GCMetadata.h" -#include "llvm/CodeGen/GCStrategy.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/SelectionDAGNodes.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/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/MachineValueType.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetOptions.h" -#include <cassert> -#include <cstddef> -#include <cstdint> -#include <iterator> -#include <tuple> -#include <utility> - -using namespace llvm; - -#define DEBUG_TYPE "statepoint-lowering" - -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) { - SDLoc L = Builder.getCurSDLoc(); - Ops.push_back(Builder.DAG.getTargetConstant(StackMaps::ConstantOp, L, - MVT::i64)); - Ops.push_back(Builder.DAG.getTargetConstant(Value, L, MVT::i64)); -} - -void StatepointLoweringState::startNewStatepoint(SelectionDAGBuilder &Builder) { - // Consistency check - assert(PendingGCRelocateCalls.empty() && - "Trying to visit statepoint before finished processing previous one"); - Locations.clear(); - NextSlotToAllocate = 0; - // Need to resize this on each safepoint - we need the two to stay in sync and - // the clear patterns of a SelectionDAGBuilder have no relation to - // FunctionLoweringInfo. Also need to ensure used bits get cleared. - AllocatedStackSlots.clear(); - AllocatedStackSlots.resize(Builder.FuncInfo.StatepointStackSlots.size()); -} - -void StatepointLoweringState::clear() { - Locations.clear(); - AllocatedStackSlots.clear(); - assert(PendingGCRelocateCalls.empty() && - "cleared before statepoint sequence completed"); -} - -SDValue -StatepointLoweringState::allocateStackSlot(EVT ValueType, - SelectionDAGBuilder &Builder) { - NumSlotsAllocatedForStatepoints++; - MachineFrameInfo &MFI = Builder.DAG.getMachineFunction().getFrameInfo(); - - unsigned SpillSize = ValueType.getStoreSize(); - assert((SpillSize * 8) == ValueType.getSizeInBits() && "Size not in bytes?"); - - // First look for a previously created stack slot which is not in - // use (accounting for the fact arbitrary slots may already be - // reserved), or to create a new stack slot and use it. - - const size_t NumSlots = AllocatedStackSlots.size(); - assert(NextSlotToAllocate <= NumSlots && "Broken invariant"); - - assert(AllocatedStackSlots.size() == - Builder.FuncInfo.StatepointStackSlots.size() && - "Broken invariant"); - - for (; NextSlotToAllocate < NumSlots; NextSlotToAllocate++) { - if (!AllocatedStackSlots.test(NextSlotToAllocate)) { - const int FI = Builder.FuncInfo.StatepointStackSlots[NextSlotToAllocate]; - if (MFI.getObjectSize(FI) == SpillSize) { - AllocatedStackSlots.set(NextSlotToAllocate); - // TODO: Is ValueType the right thing to use here? - return Builder.DAG.getFrameIndex(FI, ValueType); - } - } - } - - // Couldn't find a free slot, so create a new one: - - SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType); - const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex(); - MFI.markAsStatepointSpillSlotObjectIndex(FI); - - Builder.FuncInfo.StatepointStackSlots.push_back(FI); - AllocatedStackSlots.resize(AllocatedStackSlots.size()+1, true); - assert(AllocatedStackSlots.size() == - Builder.FuncInfo.StatepointStackSlots.size() && - "Broken invariant"); - - StatepointMaxSlotsRequired.updateMax( - Builder.FuncInfo.StatepointStackSlots.size()); - - return SpillSlot; -} - -/// 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. -static Optional<int> findPreviousSpillSlot(const Value *Val, - SelectionDAGBuilder &Builder, - int LookUpDepth) { - // Can not look any further - give up now - if (LookUpDepth <= 0) - return None; - - // Spill location is known for gc relocates - if (const auto *Relocate = dyn_cast<GCRelocateInst>(Val)) { - const auto &SpillMap = - Builder.FuncInfo.StatepointSpillMaps[Relocate->getStatepoint()]; - - auto It = SpillMap.find(Relocate->getDerivedPtr()); - if (It == SpillMap.end()) - return None; - - return It->second; - } - - // Look through bitcast instructions. - if (const BitCastInst *Cast = dyn_cast<BitCastInst>(Val)) - return findPreviousSpillSlot(Cast->getOperand(0), Builder, LookUpDepth - 1); - - // Look through phi nodes - // All incoming values should have same known stack slot, otherwise result - // is unknown. - if (const PHINode *Phi = dyn_cast<PHINode>(Val)) { - Optional<int> MergedResult = None; - - for (auto &IncomingValue : Phi->incoming_values()) { - Optional<int> SpillSlot = - findPreviousSpillSlot(IncomingValue, Builder, LookUpDepth - 1); - if (!SpillSlot.hasValue()) - return None; - - if (MergedResult.hasValue() && *MergedResult != *SpillSlot) - return None; - - MergedResult = SpillSlot; - } - return MergedResult; - } - - // TODO: We can do better for PHI nodes. In cases like this: - // ptr = phi(relocated_pointer, not_relocated_pointer) - // statepoint(ptr) - // We will return that stack slot for ptr is unknown. And later we might - // assign different stack slots for ptr and relocated_pointer. This limits - // llvm's ability to remove redundant stores. - // Unfortunately it's hard to accomplish in current infrastructure. - // We use this function to eliminate spill store completely, while - // in example we still need to emit store, but instead of any location - // we need to use special "preferred" location. - - // TODO: handle simple updates. If a value is modified and the original - // value is no longer live, it would be nice to put the modified value in the - // same slot. This allows folding of the memory accesses for some - // instructions types (like an increment). - // statepoint (i) - // i1 = i+1 - // statepoint (i1) - // However we need to be careful for cases like this: - // statepoint(i) - // i1 = i+1 - // statepoint(i, i1) - // Here we want to reserve spill slot for 'i', but not for 'i+1'. If we just - // put handling of simple modifications in this function like it's done - // for bitcasts we might end up reserving i's slot for 'i+1' because order in - // which we visit values is unspecified. - - // Don't know any information about this instruction - return None; -} - -/// 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. -static void reservePreviousStackSlotForValue(const Value *IncomingValue, - SelectionDAGBuilder &Builder) { - SDValue Incoming = Builder.getValue(IncomingValue); - - if (isa<ConstantSDNode>(Incoming) || isa<FrameIndexSDNode>(Incoming)) { - // We won't need to spill this, so no need to check for previously - // allocated stack slots - return; - } - - SDValue OldLocation = Builder.StatepointLowering.getLocation(Incoming); - if (OldLocation.getNode()) - // Duplicates in input - return; - - const int LookUpDepth = 6; - Optional<int> Index = - findPreviousSpillSlot(IncomingValue, Builder, LookUpDepth); - if (!Index.hasValue()) - return; - - const auto &StatepointSlots = Builder.FuncInfo.StatepointStackSlots; - - auto SlotIt = find(StatepointSlots, *Index); - assert(SlotIt != StatepointSlots.end() && - "Value spilled to the unknown stack slot"); - - // This is one of our dedicated lowering slots - const int Offset = std::distance(StatepointSlots.begin(), SlotIt); - if (Builder.StatepointLowering.isStackSlotAllocated(Offset)) { - // stack slot already assigned to someone else, can't use it! - // TODO: currently we reserve space for gc arguments after doing - // normal allocation for deopt arguments. We should reserve for - // _all_ deopt and gc arguments, then start allocating. This - // will prevent some moves being inserted when vm state changes, - // but gc state doesn't between two calls. - return; - } - // Reserve this stack slot - Builder.StatepointLowering.reserveStackSlot(Offset); - - // Cache this slot so we find it when going through the normal - // assignment loop. - SDValue Loc = - Builder.DAG.getTargetFrameIndex(*Index, Builder.getFrameIndexTy()); - Builder.StatepointLowering.setLocation(Incoming, Loc); -} - -/// Remove any duplicate (as SDValues) from the derived pointer pairs. This -/// is not required for correctness. It's purpose is to reduce the size of -/// StackMap section. It has no effect on the number of spill slots required -/// or the actual lowering. -static void -removeDuplicateGCPtrs(SmallVectorImpl<const Value *> &Bases, - SmallVectorImpl<const Value *> &Ptrs, - SmallVectorImpl<const GCRelocateInst *> &Relocs, - SelectionDAGBuilder &Builder, - FunctionLoweringInfo::StatepointSpillMap &SSM) { - DenseMap<SDValue, const Value *> Seen; - - SmallVector<const Value *, 64> NewBases, NewPtrs; - SmallVector<const GCRelocateInst *, 64> NewRelocs; - for (size_t i = 0, e = Ptrs.size(); i < e; i++) { - SDValue SD = Builder.getValue(Ptrs[i]); - auto SeenIt = Seen.find(SD); - - if (SeenIt == Seen.end()) { - // Only add non-duplicates - NewBases.push_back(Bases[i]); - NewPtrs.push_back(Ptrs[i]); - NewRelocs.push_back(Relocs[i]); - Seen[SD] = Ptrs[i]; - } else { - // Duplicate pointer found, note in SSM and move on: - SSM.DuplicateMap[Ptrs[i]] = SeenIt->second; - } - } - assert(Bases.size() >= NewBases.size()); - assert(Ptrs.size() >= NewPtrs.size()); - assert(Relocs.size() >= NewRelocs.size()); - Bases = NewBases; - Ptrs = NewPtrs; - Relocs = NewRelocs; - assert(Ptrs.size() == Bases.size()); - assert(Ptrs.size() == Relocs.size()); -} - -/// 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 -static std::pair<SDValue, SDNode *> lowerCallFromStatepointLoweringInfo( - SelectionDAGBuilder::StatepointLoweringInfo &SI, - SelectionDAGBuilder &Builder, SmallVectorImpl<SDValue> &PendingExports) { - SDValue ReturnValue, CallEndVal; - std::tie(ReturnValue, CallEndVal) = - Builder.lowerInvokable(SI.CLI, SI.EHPadBB); - SDNode *CallEnd = CallEndVal.getNode(); - - // Get a call instruction from the call sequence chain. Tail calls are not - // allowed. The following code is essentially reverse engineering X86's - // LowerCallTo. - // - // We are expecting DAG to have the following form: - // - // ch = eh_label (only in case of invoke statepoint) - // ch, glue = callseq_start ch - // ch, glue = X86::Call ch, glue - // ch, glue = callseq_end ch, glue - // get_return_value ch, glue - // - // get_return_value can either be a sequence of CopyFromReg instructions - // to grab the return value from the return register(s), or it can be a LOAD - // to load a value returned by reference via a stack slot. - - bool HasDef = !SI.CLI.RetTy->isVoidTy(); - if (HasDef) { - if (CallEnd->getOpcode() == ISD::LOAD) - CallEnd = CallEnd->getOperand(0).getNode(); - else - while (CallEnd->getOpcode() == ISD::CopyFromReg) - CallEnd = CallEnd->getOperand(0).getNode(); - } - - assert(CallEnd->getOpcode() == ISD::CALLSEQ_END && "expected!"); - return std::make_pair(ReturnValue, CallEnd->getOperand(0).getNode()); -} - -/// 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 -static std::pair<SDValue, SDValue> -spillIncomingStatepointValue(SDValue Incoming, SDValue Chain, - SelectionDAGBuilder &Builder) { - SDValue Loc = Builder.StatepointLowering.getLocation(Incoming); - - // Emit new store if we didn't do it for this ptr before - if (!Loc.getNode()) { - Loc = Builder.StatepointLowering.allocateStackSlot(Incoming.getValueType(), - Builder); - int Index = cast<FrameIndexSDNode>(Loc)->getIndex(); - // We use TargetFrameIndex so that isel will not select it into LEA - Loc = Builder.DAG.getTargetFrameIndex(Index, Builder.getFrameIndexTy()); - - // TODO: We can create TokenFactor node instead of - // chaining stores one after another, this may allow - // a bit more optimal scheduling for them - -#ifndef NDEBUG - // Right now we always allocate spill slots that are of the same - // size as the value we're about to spill (the size of spillee can - // vary since we spill vectors of pointers too). At some point we - // can consider allowing spills of smaller values to larger slots - // (i.e. change the '==' in the assert below to a '>='). - MachineFrameInfo &MFI = Builder.DAG.getMachineFunction().getFrameInfo(); - assert((MFI.getObjectSize(Index) * 8) == Incoming.getValueSizeInBits() && - "Bad spill: stack slot does not match!"); -#endif - - Chain = Builder.DAG.getStore(Chain, Builder.getCurSDLoc(), Incoming, Loc, - MachinePointerInfo::getFixedStack( - Builder.DAG.getMachineFunction(), Index)); - - Builder.StatepointLowering.setLocation(Incoming, Loc); - } - - assert(Loc.getNode()); - return std::make_pair(Loc, Chain); -} - -/// 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. -static void lowerIncomingStatepointValue(SDValue Incoming, bool LiveInOnly, - SmallVectorImpl<SDValue> &Ops, - SelectionDAGBuilder &Builder) { - SDValue Chain = Builder.getRoot(); - - if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Incoming)) { - // If the original value was a constant, make sure it gets recorded as - // such in the stackmap. This is required so that the consumer can - // parse any internal format to the deopt state. It also handles null - // pointers and other constant pointers in GC states. Note the constant - // vectors do not appear to actually hit this path and that anything larger - // than an i64 value (not type!) will fail asserts here. - pushStackMapConstant(Ops, Builder, C->getSExtValue()); - } else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Incoming)) { - // This handles allocas as arguments to the statepoint (this is only - // really meaningful for a deopt value. For GC, we'd be trying to - // relocate the address of the alloca itself?) - assert(Incoming.getValueType() == Builder.getFrameIndexTy() && - "Incoming value is a frame index!"); - Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(), - Builder.getFrameIndexTy())); - } else if (LiveInOnly) { - // If this value is live in (not live-on-return, or live-through), we can - // treat it the same way patchpoint treats it's "live in" values. We'll - // end up folding some of these into stack references, but they'll be - // handled by the register allocator. Note that we do not have the notion - // of a late use so these values might be placed in registers which are - // clobbered by the call. This is fine for live-in. - Ops.push_back(Incoming); - } else { - // Otherwise, locate a spill slot and explicitly spill it so it - // can be found by the runtime later. We currently do not support - // tracking values through callee saved registers to their eventual - // spill location. This would be a useful optimization, but would - // need to be optional since it requires a lot of complexity on the - // runtime side which not all would support. - auto Res = spillIncomingStatepointValue(Incoming, Chain, Builder); - Ops.push_back(Res.first); - Chain = Res.second; - } - - Builder.DAG.setRoot(Chain); -} - -/// 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). -static void -lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops, - SelectionDAGBuilder::StatepointLoweringInfo &SI, - SelectionDAGBuilder &Builder) { - // Lower the deopt and gc arguments for this statepoint. Layout will be: - // deopt argument length, deopt arguments.., gc arguments... -#ifndef NDEBUG - if (auto *GFI = Builder.GFI) { - // Check that each of the gc pointer and bases we've gotten out of the - // safepoint is something the strategy thinks might be a pointer (or vector - // of pointers) into the GC heap. This is basically just here to help catch - // errors during statepoint insertion. TODO: This should actually be in the - // Verifier, but we can't get to the GCStrategy from there (yet). - GCStrategy &S = GFI->getStrategy(); - for (const Value *V : SI.Bases) { - auto Opt = S.isGCManagedPointer(V->getType()->getScalarType()); - if (Opt.hasValue()) { - assert(Opt.getValue() && - "non gc managed base pointer found in statepoint"); - } - } - for (const Value *V : SI.Ptrs) { - auto Opt = S.isGCManagedPointer(V->getType()->getScalarType()); - if (Opt.hasValue()) { - assert(Opt.getValue() && - "non gc managed derived pointer found in statepoint"); - } - } - assert(SI.Bases.size() == SI.Ptrs.size() && "Pointer without base!"); - } else { - assert(SI.Bases.empty() && "No gc specified, so cannot relocate pointers!"); - assert(SI.Ptrs.empty() && "No gc specified, so cannot relocate pointers!"); - } -#endif - - // Figure out what lowering strategy we're going to use for each part - // Note: Is is conservatively correct to lower both "live-in" and "live-out" - // as "live-through". A "live-through" variable is one which is "live-in", - // "live-out", and live throughout the lifetime of the call (i.e. we can find - // it from any PC within the transitive callee of the statepoint). In - // particular, if the callee spills callee preserved registers we may not - // be able to find a value placed in that register during the call. This is - // fine for live-out, but not for live-through. If we were willing to make - // assumptions about the code generator producing the callee, we could - // potentially allow live-through values in callee saved registers. - const bool LiveInDeopt = - SI.StatepointFlags & (uint64_t)StatepointFlags::DeoptLiveIn; - - auto isGCValue =[&](const Value *V) { - return is_contained(SI.Ptrs, V) || is_contained(SI.Bases, V); - }; - - // Before we actually start lowering (and allocating spill slots for values), - // reserve any stack slots which we judge to be profitable to reuse for a - // particular value. This is purely an optimization over the code below and - // doesn't change semantics at all. It is important for performance that we - // reserve slots for both deopt and gc values before lowering either. - for (const Value *V : SI.DeoptState) { - if (!LiveInDeopt || isGCValue(V)) - reservePreviousStackSlotForValue(V, Builder); - } - for (unsigned i = 0; i < SI.Bases.size(); ++i) { - reservePreviousStackSlotForValue(SI.Bases[i], Builder); - reservePreviousStackSlotForValue(SI.Ptrs[i], Builder); - } - - // First, prefix the list with the number of unique values to be - // lowered. Note that this is the number of *Values* not the - // number of SDValues required to lower them. - const int NumVMSArgs = SI.DeoptState.size(); - pushStackMapConstant(Ops, Builder, NumVMSArgs); - - // The vm state arguments are lowered in an opaque manner. We do not know - // what type of values are contained within. - for (const Value *V : SI.DeoptState) { - SDValue Incoming; - // If this is a function argument at a static frame index, generate it as - // the frame index. - if (const Argument *Arg = dyn_cast<Argument>(V)) { - int FI = Builder.FuncInfo.getArgumentFrameIndex(Arg); - if (FI != INT_MAX) - Incoming = Builder.DAG.getFrameIndex(FI, Builder.getFrameIndexTy()); - } - if (!Incoming.getNode()) - Incoming = Builder.getValue(V); - const bool LiveInValue = LiveInDeopt && !isGCValue(V); - lowerIncomingStatepointValue(Incoming, LiveInValue, Ops, Builder); - } - - // Finally, go ahead and lower all the gc arguments. There's no prefixed - // length for this one. After lowering, we'll have the base and pointer - // arrays interwoven with each (lowered) base pointer immediately followed by - // it's (lowered) derived pointer. i.e - // (base[0], ptr[0], base[1], ptr[1], ...) - for (unsigned i = 0; i < SI.Bases.size(); ++i) { - const Value *Base = SI.Bases[i]; - lowerIncomingStatepointValue(Builder.getValue(Base), /*LiveInOnly*/ false, - Ops, Builder); - - const Value *Ptr = SI.Ptrs[i]; - lowerIncomingStatepointValue(Builder.getValue(Ptr), /*LiveInOnly*/ false, - Ops, Builder); - } - - // If there are any explicit spill slots passed to the statepoint, record - // them, but otherwise do not do anything special. These are user provided - // allocas and give control over placement to the consumer. In this case, - // it is the contents of the slot which may get updated, not the pointer to - // the alloca - for (Value *V : SI.GCArgs) { - SDValue Incoming = Builder.getValue(V); - if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Incoming)) { - // This handles allocas as arguments to the statepoint - assert(Incoming.getValueType() == Builder.getFrameIndexTy() && - "Incoming value is a frame index!"); - Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(), - Builder.getFrameIndexTy())); - } - } - - // Record computed locations for all lowered values. - // This can not be embedded in lowering loops as we need to record *all* - // values, while previous loops account only values with unique SDValues. - const Instruction *StatepointInstr = SI.StatepointInstr; - auto &SpillMap = Builder.FuncInfo.StatepointSpillMaps[StatepointInstr]; - - for (const GCRelocateInst *Relocate : SI.GCRelocates) { - const Value *V = Relocate->getDerivedPtr(); - SDValue SDV = Builder.getValue(V); - SDValue Loc = Builder.StatepointLowering.getLocation(SDV); - - if (Loc.getNode()) { - SpillMap.SlotMap[V] = cast<FrameIndexSDNode>(Loc)->getIndex(); - } else { - // Record value as visited, but not spilled. This is case for allocas - // and constants. For this values we can avoid emitting spill load while - // visiting corresponding gc_relocate. - // Actually we do not need to record them in this map at all. - // We do this only to check that we are not relocating any unvisited - // value. - SpillMap.SlotMap[V] = None; - - // Default llvm mechanisms for exporting values which are used in - // different basic blocks does not work for gc relocates. - // Note that it would be incorrect to teach llvm that all relocates are - // uses of the corresponding values so that it would automatically - // export them. Relocates of the spilled values does not use original - // value. - if (Relocate->getParent() != StatepointInstr->getParent()) - Builder.ExportFromCurrentBlock(V); - } - } -} - -SDValue SelectionDAGBuilder::LowerAsSTATEPOINT( - SelectionDAGBuilder::StatepointLoweringInfo &SI) { - // The basic scheme here is that information about both the original call and - // the safepoint is encoded in the CallInst. We create a temporary call and - // lower it, then reverse engineer the calling sequence. - - NumOfStatepoints++; - // Clear state - StatepointLowering.startNewStatepoint(*this); - -#ifndef NDEBUG - // We schedule gc relocates before removeDuplicateGCPtrs since we _will_ - // encounter the duplicate gc relocates we elide in removeDuplicateGCPtrs. - for (auto *Reloc : SI.GCRelocates) - if (Reloc->getParent() == SI.StatepointInstr->getParent()) - StatepointLowering.scheduleRelocCall(*Reloc); -#endif - - // Remove any redundant llvm::Values which map to the same SDValue as another - // input. Also has the effect of removing duplicates in the original - // llvm::Value input list as well. This is a useful optimization for - // reducing the size of the StackMap section. It has no other impact. - removeDuplicateGCPtrs(SI.Bases, SI.Ptrs, SI.GCRelocates, *this, - FuncInfo.StatepointSpillMaps[SI.StatepointInstr]); - assert(SI.Bases.size() == SI.Ptrs.size() && - SI.Ptrs.size() == SI.GCRelocates.size()); - - // Lower statepoint vmstate and gcstate arguments - SmallVector<SDValue, 10> LoweredMetaArgs; - lowerStatepointMetaArgs(LoweredMetaArgs, SI, *this); - - // Now that we've emitted the spills, we need to update the root so that the - // call sequence is ordered correctly. - SI.CLI.setChain(getRoot()); - - // Get call node, we will replace it later with statepoint - SDValue ReturnVal; - SDNode *CallNode; - std::tie(ReturnVal, CallNode) = - lowerCallFromStatepointLoweringInfo(SI, *this, PendingExports); - - // Construct the actual GC_TRANSITION_START, STATEPOINT, and GC_TRANSITION_END - // nodes with all the appropriate arguments and return values. - - // Call Node: Chain, Target, {Args}, RegMask, [Glue] - SDValue Chain = CallNode->getOperand(0); - - SDValue Glue; - bool CallHasIncomingGlue = CallNode->getGluedNode(); - if (CallHasIncomingGlue) { - // Glue is always last operand - Glue = CallNode->getOperand(CallNode->getNumOperands() - 1); - } - - // Build the GC_TRANSITION_START node if necessary. - // - // The operands to the GC_TRANSITION_{START,END} nodes are laid out in the - // order in which they appear in the call to the statepoint intrinsic. If - // any of the operands is a pointer-typed, that operand is immediately - // followed by a SRCVALUE for the pointer that may be used during lowering - // (e.g. to form MachinePointerInfo values for loads/stores). - const bool IsGCTransition = - (SI.StatepointFlags & (uint64_t)StatepointFlags::GCTransition) == - (uint64_t)StatepointFlags::GCTransition; - if (IsGCTransition) { - SmallVector<SDValue, 8> TSOps; - - // Add chain - TSOps.push_back(Chain); - - // Add GC transition arguments - for (const Value *V : SI.GCTransitionArgs) { - TSOps.push_back(getValue(V)); - if (V->getType()->isPointerTy()) - TSOps.push_back(DAG.getSrcValue(V)); - } - - // Add glue if necessary - if (CallHasIncomingGlue) - TSOps.push_back(Glue); - - SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue); - - SDValue GCTransitionStart = - DAG.getNode(ISD::GC_TRANSITION_START, getCurSDLoc(), NodeTys, TSOps); - - Chain = GCTransitionStart.getValue(0); - Glue = GCTransitionStart.getValue(1); - } - - // TODO: Currently, all of these operands are being marked as read/write in - // PrologEpilougeInserter.cpp, we should special case the VMState arguments - // and flags to be read-only. - SmallVector<SDValue, 40> Ops; - - // Add the <id> and <numBytes> constants. - Ops.push_back(DAG.getTargetConstant(SI.ID, getCurSDLoc(), MVT::i64)); - Ops.push_back( - DAG.getTargetConstant(SI.NumPatchBytes, getCurSDLoc(), MVT::i32)); - - // Calculate and push starting position of vmstate arguments - // Get number of arguments incoming directly into call node - unsigned NumCallRegArgs = - CallNode->getNumOperands() - (CallHasIncomingGlue ? 4 : 3); - Ops.push_back(DAG.getTargetConstant(NumCallRegArgs, getCurSDLoc(), MVT::i32)); - - // Add call target - SDValue CallTarget = SDValue(CallNode->getOperand(1).getNode(), 0); - Ops.push_back(CallTarget); - - // Add call arguments - // Get position of register mask in the call - SDNode::op_iterator RegMaskIt; - if (CallHasIncomingGlue) - RegMaskIt = CallNode->op_end() - 2; - else - RegMaskIt = CallNode->op_end() - 1; - Ops.insert(Ops.end(), CallNode->op_begin() + 2, RegMaskIt); - - // Add a constant argument for the calling convention - pushStackMapConstant(Ops, *this, SI.CLI.CallConv); - - // Add a constant argument for the flags - uint64_t Flags = SI.StatepointFlags; - assert(((Flags & ~(uint64_t)StatepointFlags::MaskAll) == 0) && - "Unknown flag used"); - pushStackMapConstant(Ops, *this, Flags); - - // Insert all vmstate and gcstate arguments - Ops.insert(Ops.end(), LoweredMetaArgs.begin(), LoweredMetaArgs.end()); - - // Add register mask from call node - Ops.push_back(*RegMaskIt); - - // Add chain - Ops.push_back(Chain); - - // Same for the glue, but we add it only if original call had it - if (Glue.getNode()) - Ops.push_back(Glue); - - // Compute return values. Provide a glue output since we consume one as - // input. This allows someone else to chain off us as needed. - SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue); - - SDNode *StatepointMCNode = - DAG.getMachineNode(TargetOpcode::STATEPOINT, getCurSDLoc(), NodeTys, Ops); - - SDNode *SinkNode = StatepointMCNode; - - // Build the GC_TRANSITION_END node if necessary. - // - // See the comment above regarding GC_TRANSITION_START for the layout of - // the operands to the GC_TRANSITION_END node. - if (IsGCTransition) { - SmallVector<SDValue, 8> TEOps; - - // Add chain - TEOps.push_back(SDValue(StatepointMCNode, 0)); - - // Add GC transition arguments - for (const Value *V : SI.GCTransitionArgs) { - TEOps.push_back(getValue(V)); - if (V->getType()->isPointerTy()) - TEOps.push_back(DAG.getSrcValue(V)); - } - - // Add glue - TEOps.push_back(SDValue(StatepointMCNode, 1)); - - SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue); - - SDValue GCTransitionStart = - DAG.getNode(ISD::GC_TRANSITION_END, getCurSDLoc(), NodeTys, TEOps); - - SinkNode = GCTransitionStart.getNode(); - } - - // Replace original call - DAG.ReplaceAllUsesWith(CallNode, SinkNode); // This may update Root - // Remove original call node - DAG.DeleteNode(CallNode); - - // DON'T set the root - under the assumption that it's already set past the - // inserted node we created. - - // TODO: A better future implementation would be to emit a single variable - // argument, variable return value STATEPOINT node here and then hookup the - // return value of each gc.relocate to the respective output of the - // previously emitted STATEPOINT value. Unfortunately, this doesn't appear - // to actually be possible today. - - return ReturnVal; -} - -void -SelectionDAGBuilder::LowerStatepoint(ImmutableStatepoint ISP, - const BasicBlock *EHPadBB /*= nullptr*/) { - assert(ISP.getCallSite().getCallingConv() != CallingConv::AnyReg && - "anyregcc is not supported on statepoints!"); - -#ifndef NDEBUG - // If this is a malformed statepoint, report it early to simplify debugging. - // This should catch any IR level mistake that's made when constructing or - // transforming statepoints. - ISP.verify(); - - // Check that the associated GCStrategy expects to encounter statepoints. - assert(GFI->getStrategy().useStatepoints() && - "GCStrategy does not expect to encounter statepoints"); -#endif - - SDValue ActualCallee; - - if (ISP.getNumPatchBytes() > 0) { - // If we've been asked to emit a nop sequence instead of a call instruction - // for this statepoint then don't lower the call target, but use a constant - // `null` instead. Not lowering the call target lets statepoint clients get - // away without providing a physical address for the symbolic call target at - // link time. - - const auto &TLI = DAG.getTargetLoweringInfo(); - const auto &DL = DAG.getDataLayout(); - - unsigned AS = ISP.getCalledValue()->getType()->getPointerAddressSpace(); - ActualCallee = DAG.getConstant(0, getCurSDLoc(), TLI.getPointerTy(DL, AS)); - } else { - ActualCallee = getValue(ISP.getCalledValue()); - } - - StatepointLoweringInfo SI(DAG); - populateCallLoweringInfo(SI.CLI, ISP.getCallSite(), - ImmutableStatepoint::CallArgsBeginPos, - ISP.getNumCallArgs(), ActualCallee, - ISP.getActualReturnType(), false /* IsPatchPoint */); - - for (const GCRelocateInst *Relocate : ISP.getRelocates()) { - SI.GCRelocates.push_back(Relocate); - SI.Bases.push_back(Relocate->getBasePtr()); - SI.Ptrs.push_back(Relocate->getDerivedPtr()); - } - - SI.GCArgs = ArrayRef<const Use>(ISP.gc_args_begin(), ISP.gc_args_end()); - SI.StatepointInstr = ISP.getInstruction(); - SI.GCTransitionArgs = - ArrayRef<const Use>(ISP.gc_args_begin(), ISP.gc_args_end()); - SI.ID = ISP.getID(); - SI.DeoptState = ArrayRef<const Use>(ISP.deopt_begin(), ISP.deopt_end()); - SI.StatepointFlags = ISP.getFlags(); - SI.NumPatchBytes = ISP.getNumPatchBytes(); - SI.EHPadBB = EHPadBB; - - SDValue ReturnValue = LowerAsSTATEPOINT(SI); - - // Export the result value if needed - const GCResultInst *GCResult = ISP.getGCResult(); - Type *RetTy = ISP.getActualReturnType(); - if (!RetTy->isVoidTy() && GCResult) { - if (GCResult->getParent() != ISP.getCallSite().getParent()) { - // Result value will be used in a different basic block so we need to - // export it now. Default exporting mechanism will not work here because - // statepoint call has a different type than the actual call. It means - // that by default llvm will create export register of the wrong type - // (always i32 in our case). So instead we need to create export register - // with correct type manually. - // TODO: To eliminate this problem we can remove gc.result intrinsics - // completely and make statepoint call to return a tuple. - unsigned Reg = FuncInfo.CreateRegs(RetTy); - RegsForValue RFV(*DAG.getContext(), DAG.getTargetLoweringInfo(), - DAG.getDataLayout(), Reg, RetTy, - ISP.getCallSite().getCallingConv()); - SDValue Chain = DAG.getEntryNode(); - - RFV.getCopyToRegs(ReturnValue, DAG, getCurSDLoc(), Chain, nullptr); - PendingExports.push_back(Chain); - FuncInfo.ValueMap[ISP.getInstruction()] = Reg; - } else { - // Result value will be used in a same basic block. Don't export it or - // perform any explicit register copies. - // We'll replace the actuall call node shortly. gc_result will grab - // this value. - setValue(ISP.getInstruction(), ReturnValue); - } - } else { - // The token value is never used from here on, just generate a poison value - setValue(ISP.getInstruction(), DAG.getIntPtrConstant(-1, getCurSDLoc())); - } -} - -void SelectionDAGBuilder::LowerCallSiteWithDeoptBundleImpl( - ImmutableCallSite CS, SDValue Callee, const BasicBlock *EHPadBB, - bool VarArgDisallowed, bool ForceVoidReturnTy) { - StatepointLoweringInfo SI(DAG); - unsigned ArgBeginIndex = CS.arg_begin() - CS.getInstruction()->op_begin(); - populateCallLoweringInfo( - SI.CLI, CS, ArgBeginIndex, CS.getNumArgOperands(), Callee, - ForceVoidReturnTy ? Type::getVoidTy(*DAG.getContext()) : CS.getType(), - false); - if (!VarArgDisallowed) - SI.CLI.IsVarArg = CS.getFunctionType()->isVarArg(); - - auto DeoptBundle = *CS.getOperandBundle(LLVMContext::OB_deopt); - - unsigned DefaultID = StatepointDirectives::DeoptBundleStatepointID; - - auto SD = parseStatepointDirectivesFromAttrs(CS.getAttributes()); - SI.ID = SD.StatepointID.getValueOr(DefaultID); - SI.NumPatchBytes = SD.NumPatchBytes.getValueOr(0); - - SI.DeoptState = - ArrayRef<const Use>(DeoptBundle.Inputs.begin(), DeoptBundle.Inputs.end()); - SI.StatepointFlags = static_cast<uint64_t>(StatepointFlags::None); - SI.EHPadBB = EHPadBB; - - // NB! The GC arguments are deliberately left empty. - - if (SDValue ReturnVal = LowerAsSTATEPOINT(SI)) { - const Instruction *Inst = CS.getInstruction(); - ReturnVal = lowerRangeToAssertZExt(DAG, *Inst, ReturnVal); - setValue(Inst, ReturnVal); - } -} - -void SelectionDAGBuilder::LowerCallSiteWithDeoptBundle( - ImmutableCallSite CS, SDValue Callee, const BasicBlock *EHPadBB) { - LowerCallSiteWithDeoptBundleImpl(CS, Callee, EHPadBB, - /* VarArgDisallowed = */ false, - /* ForceVoidReturnTy = */ false); -} - -void SelectionDAGBuilder::visitGCResult(const GCResultInst &CI) { - // The result value of the gc_result is simply the result of the actual - // call. We've already emitted this, so just grab the value. - const Instruction *I = CI.getStatepoint(); - - if (I->getParent() != CI.getParent()) { - // Statepoint is in different basic block so we should have stored call - // result in a virtual register. - // We can not use default getValue() functionality to copy value from this - // register because statepoint and actual call return types can be - // different, and getValue() will use CopyFromReg of the wrong type, - // which is always i32 in our case. - PointerType *CalleeType = cast<PointerType>( - ImmutableStatepoint(I).getCalledValue()->getType()); - Type *RetTy = - cast<FunctionType>(CalleeType->getElementType())->getReturnType(); - SDValue CopyFromReg = getCopyFromRegs(I, RetTy); - - assert(CopyFromReg.getNode()); - setValue(&CI, CopyFromReg); - } else { - setValue(&CI, getValue(I)); - } -} - -void SelectionDAGBuilder::visitGCRelocate(const GCRelocateInst &Relocate) { -#ifndef NDEBUG - // Consistency check - // We skip this check for relocates not in the same basic block as their - // statepoint. It would be too expensive to preserve validation info through - // different basic blocks. - if (Relocate.getStatepoint()->getParent() == Relocate.getParent()) - StatepointLowering.relocCallVisited(Relocate); - - auto *Ty = Relocate.getType()->getScalarType(); - if (auto IsManaged = GFI->getStrategy().isGCManagedPointer(Ty)) - assert(*IsManaged && "Non gc managed pointer relocated!"); -#endif - - const Value *DerivedPtr = Relocate.getDerivedPtr(); - SDValue SD = getValue(DerivedPtr); - - auto &SpillMap = FuncInfo.StatepointSpillMaps[Relocate.getStatepoint()]; - auto SlotIt = SpillMap.find(DerivedPtr); - assert(SlotIt != SpillMap.end() && "Relocating not lowered gc value"); - Optional<int> DerivedPtrLocation = SlotIt->second; - - // We didn't need to spill these special cases (constants and allocas). - // See the handling in spillIncomingValueForStatepoint for detail. - if (!DerivedPtrLocation) { - setValue(&Relocate, SD); - return; - } - - SDValue SpillSlot = - DAG.getTargetFrameIndex(*DerivedPtrLocation, getFrameIndexTy()); - - // Be conservative: flush all pending loads - // TODO: Probably we can be less restrictive on this, - // it may allow more scheduling opportunities. - SDValue Chain = getRoot(); - - SDValue SpillLoad = - DAG.getLoad(DAG.getTargetLoweringInfo().getValueType(DAG.getDataLayout(), - Relocate.getType()), - getCurSDLoc(), Chain, SpillSlot, - MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), - *DerivedPtrLocation)); - - // Again, be conservative, don't emit pending loads - DAG.setRoot(SpillLoad.getValue(1)); - - assert(SpillLoad.getNode()); - setValue(&Relocate, SpillLoad); -} - -void SelectionDAGBuilder::LowerDeoptimizeCall(const CallInst *CI) { - const auto &TLI = DAG.getTargetLoweringInfo(); - SDValue Callee = DAG.getExternalSymbol(TLI.getLibcallName(RTLIB::DEOPTIMIZE), - TLI.getPointerTy(DAG.getDataLayout())); - - // We don't lower calls to __llvm_deoptimize as varargs, but as a regular - // call. We also do not lower the return value to any virtual register, and - // change the immediately following return to a trap instruction. - LowerCallSiteWithDeoptBundleImpl(CI, Callee, /* EHPadBB = */ nullptr, - /* VarArgDisallowed = */ true, - /* ForceVoidReturnTy = */ true); -} - -void SelectionDAGBuilder::LowerDeoptimizingReturn() { - // We do not lower the return value from llvm.deoptimize to any virtual - // register, and change the immediately following return to a trap - // instruction. - if (DAG.getTarget().Options.TrapUnreachable) - DAG.setRoot( - DAG.getNode(ISD::TRAP, getCurSDLoc(), MVT::Other, DAG.getRoot())); -} |