#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/SelectionDAG.h"
STATISTIC(StatepointMaxSlotsRequired,
"Maximum number of stack slots required for a singe statepoint");
-void
-StatepointLoweringState::startNewStatepoint(SelectionDAGBuilder &Builder) {
+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();
- RelocLocations.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
AllocatedStackSlots[i] = false;
}
}
+
void StatepointLoweringState::clear() {
Locations.clear();
- RelocLocations.clear();
AllocatedStackSlots.clear();
assert(PendingGCRelocateCalls.empty() &&
"cleared before statepoint sequence completed");
SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
+ auto *MFI = Builder.DAG.getMachineFunction().getFrameInfo();
+ MFI->markAsStatepointSpillSlotObjectIndex(FI);
+
Builder.FuncInfo.StatepointStackSlots.push_back(FI);
AllocatedStackSlots.push_back(true);
return SpillSlot;
return Builder.DAG.getFrameIndex(FI, ValueType);
}
// Note: We deliberately choose to advance this only on the failing path.
- // Doing so on the suceeding path involes a bit of complexity that caused a
- // minor bug previously. Unless performance shows this matters, please
+ // Doing so on the succeeding path involves a bit of complexity that caused
+ // a minor bug previously. Unless performance shows this matters, please
// keep this code as simple as possible.
NextSlotToAllocate++;
}
llvm_unreachable("infinite loop?");
}
+/// 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 Optional<int>();
+
+ // Spill location is known for gc relocates
+ if (isGCRelocate(Val)) {
+ GCRelocateOperands RelocOps(cast<Instruction>(Val));
+
+ FunctionLoweringInfo::StatepointSpilledValueMapTy &SpillMap =
+ Builder.FuncInfo.StatepointRelocatedValues[RelocOps.getStatepoint()];
+
+ auto It = SpillMap.find(RelocOps.getDerivedPtr());
+ if (It == SpillMap.end())
+ return Optional<int>();
+
+ 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 Optional<int>();
+
+ if (MergedResult.hasValue() && *MergedResult != *SpillSlot)
+ return Optional<int>();
+
+ 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 Optional<int>();
+}
+
/// 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 resuffle
+/// This helps to avoid series of loads and stores that only serve to reshuffle
/// values on the stack between calls.
-static void reservePreviousStackSlotForValue(SDValue Incoming,
+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 Loc = Builder.StatepointLowering.getLocation(Incoming);
- if (Loc.getNode()) {
+ SDValue OldLocation = Builder.StatepointLowering.getLocation(Incoming);
+ if (OldLocation.getNode())
// duplicates in input
return;
- }
- // Search back for the load from a stack slot pattern to find the original
- // slot we allocated for this value. We could extend this to deal with
- // simple modification patterns, but simple dealing with trivial load/store
- // sequences helps a lot already.
- if (LoadSDNode *Load = dyn_cast<LoadSDNode>(Incoming)) {
- if (auto *FI = dyn_cast<FrameIndexSDNode>(Load->getBasePtr())) {
- const int Index = FI->getIndex();
- auto Itr = std::find(Builder.FuncInfo.StatepointStackSlots.begin(),
- Builder.FuncInfo.StatepointStackSlots.end(), Index);
- if (Itr == Builder.FuncInfo.StatepointStackSlots.end()) {
- // not one of the lowering stack slots, can't reuse!
- // TODO: Actually, we probably could reuse the stack slot if the value
- // hasn't changed at all, but we'd need to look for intervening writes
- return;
- } else {
- // This is one of our dedicated lowering slots
- const int Offset =
- std::distance(Builder.FuncInfo.StatepointStackSlots.begin(), Itr);
- 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, Incoming.getValueType());
+ const int LookUpDepth = 6;
+ Optional<int> Index =
+ findPreviousSpillSlot(IncomingValue, Builder, LookUpDepth);
+ if (!Index.hasValue())
+ return;
- Builder.StatepointLowering.setLocation(Incoming, Loc);
- }
+ auto Itr = std::find(Builder.FuncInfo.StatepointStackSlots.begin(),
+ Builder.FuncInfo.StatepointStackSlots.end(), *Index);
+ assert(Itr != Builder.FuncInfo.StatepointStackSlots.end() &&
+ "value spilled to the unknown stack slot");
+
+ // This is one of our dedicated lowering slots
+ const int Offset =
+ std::distance(Builder.FuncInfo.StatepointStackSlots.begin(), Itr);
+ 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);
- // TODO: handle case where a reloaded value flows through a phi to
- // another safepoint. e.g.
- // bb1:
- // a' = relocated...
- // bb2: % pred: bb1, bb3, bb4, etc.
- // a_phi = phi(a', ...)
- // statepoint ... a_phi
- // NOTE: This will require reasoning about cross basic block values. This is
- // decidedly non trivial and this might not be the right place to do it. We
- // don't really have the information we need here...
-
- // 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)
+ // Cache this slot so we find it when going through the normal
+ // assignment loop.
+ SDValue Loc = Builder.DAG.getTargetFrameIndex(*Index, Incoming.getValueType());
+ Builder.StatepointLowering.setLocation(Incoming, Loc);
}
/// Remove any duplicate (as SDValues) from the derived pointer pairs. This
SmallVectorImpl<const Value *> &Relocs,
SelectionDAGBuilder &Builder) {
- // This is horribly ineffecient, but I don't care right now
+ // This is horribly inefficient, but I don't care right now
SmallSet<SDValue, 64> Seen;
SmallVector<const Value *, 64> NewBases, NewPtrs, NewRelocs;
/// 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 SDNode *lowerCallFromStatepoint(ImmutableStatepoint StatepointSite,
- MachineBasicBlock *LandingPad,
- SelectionDAGBuilder &Builder) {
-
- ImmutableCallSite CS(StatepointSite.getCallSite());
-
- // Lower the actual call itself - This is a bit of a hack, but we want to
- // avoid modifying the actual lowering code. This is similiar in intent to
- // the LowerCallOperands mechanism used by PATCHPOINT, but is structured
- // differently. Hopefully, this is slightly more robust w.r.t. calling
- // convention, return values, and other function attributes.
- Value *ActualCallee = const_cast<Value *>(StatepointSite.actualCallee());
-
- std::vector<Value *> Args;
- CallInst::const_op_iterator arg_begin = StatepointSite.call_args_begin();
- CallInst::const_op_iterator arg_end = StatepointSite.call_args_end();
- Args.insert(Args.end(), arg_begin, arg_end);
- // TODO: remove the creation of a new instruction! We should not be
- // modifying the IR (even temporarily) at this point.
- CallInst *Tmp = CallInst::Create(ActualCallee, Args);
- Tmp->setTailCall(CS.isTailCall());
- Tmp->setCallingConv(CS.getCallingConv());
- Tmp->setAttributes(CS.getAttributes());
- Builder.LowerCallTo(Tmp, Builder.getValue(ActualCallee), false, LandingPad);
-
- // Handle the return value of the call iff any.
- const bool HasDef = !Tmp->getType()->isVoidTy();
- if (HasDef) {
- if (CS.isInvoke()) {
- // Result value will be used in different basic block for invokes
- // so we need to export it now. But statepoint call has a different type
- // than the actuall call. It means that standart exporting mechanism will
- // create register of the wrong type. So instead we need to create
- // register with correct type and save value into it manually.
- // TODO: To eliminate this problem we can remove gc.result intrinsics
- // completelly and make statepoint call to return a tuple.
- unsigned reg = Builder.FuncInfo.CreateRegs(Tmp->getType());
- Builder.CopyValueToVirtualRegister(Tmp, reg);
- Builder.FuncInfo.ValueMap[CS.getInstruction()] = reg;
- }
- else {
- // The value of the statepoint itself will be the value of call itself.
- // We'll replace the actually call node shortly. gc_result will grab
- // this value.
- Builder.setValue(CS.getInstruction(), Builder.getValue(Tmp));
- }
- } else {
- // The token value is never used from here on, just generate a poison value
- Builder.setValue(CS.getInstruction(), Builder.DAG.getIntPtrConstant(-1));
- }
- // Remove the fake entry we created so we don't have a hanging reference
- // after we delete this node.
- Builder.removeValue(Tmp);
- delete Tmp;
- Tmp = nullptr;
-
- // Search for the call node
- // The following code is essentially reverse engineering X86's
+static SDNode *
+lowerCallFromStatepoint(ImmutableStatepoint ISP, const BasicBlock *EHPadBB,
+ SelectionDAGBuilder &Builder,
+ SmallVectorImpl<SDValue> &PendingExports) {
+
+ ImmutableCallSite CS(ISP.getCallSite());
+
+ 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 = Builder.DAG.getTargetLoweringInfo();
+ const auto &DL = Builder.DAG.getDataLayout();
+
+ unsigned AS = ISP.getCalledValue()->getType()->getPointerAddressSpace();
+ ActualCallee = Builder.DAG.getConstant(0, Builder.getCurSDLoc(),
+ TLI.getPointerTy(DL, AS));
+ } else
+ ActualCallee = Builder.getValue(ISP.getCalledValue());
+
+ assert(CS.getCallingConv() != CallingConv::AnyReg &&
+ "anyregcc is not supported on statepoints!");
+
+ Type *DefTy = ISP.getActualReturnType();
+ bool HasDef = !DefTy->isVoidTy();
+
+ SDValue ReturnValue, CallEndVal;
+ std::tie(ReturnValue, CallEndVal) = Builder.lowerCallOperands(
+ ISP.getCallSite(), ImmutableStatepoint::CallArgsBeginPos,
+ ISP.getNumCallArgs(), ActualCallee, DefTy, EHPadBB,
+ false /* IsPatchPoint */);
+
+ 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
- // ch = eh_label ch (only in case of invoke statepoint)
+ // get_return_value ch, glue
//
- // DAG root will be either last eh_label or callseq_end.
-
- SDNode *CallNode = nullptr;
+ // 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.
- // We just emitted a call, so it should be last thing generated
- SDValue Chain = Builder.DAG.getRoot();
-
- // Find closest CALLSEQ_END walking back through lowered nodes if needed
- SDNode *CallEnd = Chain.getNode();
- int Sanity = 0;
- while (CallEnd->getOpcode() != ISD::CALLSEQ_END) {
- assert(CallEnd->getNumOperands() >= 1 &&
- CallEnd->getOperand(0).getValueType() == MVT::Other);
-
- CallEnd = CallEnd->getOperand(0).getNode();
+ if (HasDef) {
+ if (CallEnd->getOpcode() == ISD::LOAD)
+ CallEnd = CallEnd->getOperand(0).getNode();
+ else
+ while (CallEnd->getOpcode() == ISD::CopyFromReg)
+ CallEnd = CallEnd->getOperand(0).getNode();
+ }
- assert(Sanity < 20 && "should have found call end already");
- Sanity++;
+ assert(CallEnd->getOpcode() == ISD::CALLSEQ_END && "expected!");
+
+ // Export the result value if needed
+ const Instruction *GCResult = ISP.getGCResult();
+ if (HasDef && GCResult) {
+ if (GCResult->getParent() != CS.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 = Builder.FuncInfo.CreateRegs(ISP.getActualReturnType());
+ RegsForValue RFV(
+ *Builder.DAG.getContext(), Builder.DAG.getTargetLoweringInfo(),
+ Builder.DAG.getDataLayout(), Reg, ISP.getActualReturnType());
+ SDValue Chain = Builder.DAG.getEntryNode();
+
+ RFV.getCopyToRegs(ReturnValue, Builder.DAG, Builder.getCurSDLoc(), Chain,
+ nullptr);
+ PendingExports.push_back(Chain);
+ Builder.FuncInfo.ValueMap[CS.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.
+ Builder.setValue(CS.getInstruction(), ReturnValue);
+ }
+ } else {
+ // The token value is never used from here on, just generate a poison value
+ Builder.setValue(CS.getInstruction(),
+ Builder.DAG.getIntPtrConstant(-1, Builder.getCurSDLoc()));
}
- assert(CallEnd->getOpcode() == ISD::CALLSEQ_END &&
- "Expected a callseq node.");
- assert(CallEnd->getGluedNode());
- // Step back inside the CALLSEQ
- CallNode = CallEnd->getGluedNode();
- return CallNode;
+ return CallEnd->getOperand(0).getNode();
}
/// Callect all gc pointers coming into statepoint intrinsic, clean them up,
/// Relocs - the gc_relocate corresponding to each base/ptr pair
/// Elements of this arrays should be in one-to-one correspondence with each
/// other i.e Bases[i], Ptrs[i] are from the same gcrelocate call
-static void
-getIncomingStatepointGCValues(SmallVectorImpl<const Value *> &Bases,
- SmallVectorImpl<const Value *> &Ptrs,
- SmallVectorImpl<const Value *> &Relocs,
- ImmutableStatepoint StatepointSite,
- SelectionDAGBuilder &Builder) {
- for (GCRelocateOperands relocateOpers :
- StatepointSite.getRelocates(StatepointSite)) {
+static void getIncomingStatepointGCValues(
+ SmallVectorImpl<const Value *> &Bases, SmallVectorImpl<const Value *> &Ptrs,
+ SmallVectorImpl<const Value *> &Relocs, ImmutableStatepoint StatepointSite,
+ SelectionDAGBuilder &Builder) {
+ for (GCRelocateOperands relocateOpers : StatepointSite.getRelocates()) {
Relocs.push_back(relocateOpers.getUnderlyingCallSite().getInstruction());
- Bases.push_back(relocateOpers.basePtr());
- Ptrs.push_back(relocateOpers.derivedPtr());
+ Bases.push_back(relocateOpers.getBasePtr());
+ Ptrs.push_back(relocateOpers.getDerivedPtr());
}
// Remove any redundant llvm::Values which map to the same SDValue as another
// chaining stores one after another, this may allow
// a bit more optimal scheduling for them
Chain = Builder.DAG.getStore(Chain, Builder.getCurSDLoc(), Incoming, Loc,
- MachinePointerInfo::getFixedStack(Index),
+ MachinePointerInfo::getFixedStack(
+ Builder.DAG.getMachineFunction(), Index),
false, false, 0);
Builder.StatepointLowering.setLocation(Incoming, Loc);
// 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
- Ops.push_back(
- Builder.DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
- Ops.push_back(Builder.DAG.getTargetConstant(C->getSExtValue(), MVT::i64));
+ 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?)
- Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(),
+ Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(),
Incoming.getValueType()));
} else {
// Otherwise, locate a spill slot and explicitly spill it so it
// be: deopt argument length, deopt arguments.., gc arguments...
SmallVector<const Value *, 64> Bases, Ptrs, Relocations;
- getIncomingStatepointGCValues(Bases, Ptrs, Relocations,
- StatepointSite, Builder);
+ getIncomingStatepointGCValues(Bases, Ptrs, Relocations, StatepointSite,
+ Builder);
#ifndef NDEBUG
// Check that each of the gc pointer and bases we've gotten out of the
// to the GCStrategy from there (yet).
GCStrategy &S = Builder.GFI->getStrategy();
for (const Value *V : Bases) {
- auto Opt = S.isGCManagedPointer(V);
+ auto Opt = S.isGCManagedPointer(V->getType());
if (Opt.hasValue()) {
assert(Opt.getValue() &&
"non gc managed base pointer found in statepoint");
}
}
for (const Value *V : Ptrs) {
- auto Opt = S.isGCManagedPointer(V);
+ auto Opt = S.isGCManagedPointer(V->getType());
if (Opt.hasValue()) {
assert(Opt.getValue() &&
"non gc managed derived pointer found in statepoint");
}
}
for (const Value *V : Relocations) {
- auto Opt = S.isGCManagedPointer(V);
+ auto Opt = S.isGCManagedPointer(V->getType());
if (Opt.hasValue()) {
assert(Opt.getValue() && "non gc managed pointer relocated");
}
}
#endif
-
-
// 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 (auto I = StatepointSite.vm_state_begin() + 1,
- E = StatepointSite.vm_state_end();
- I != E; ++I) {
- Value *V = *I;
- SDValue Incoming = Builder.getValue(V);
- reservePreviousStackSlotForValue(Incoming, Builder);
+ for (const Value *V : StatepointSite.vm_state_args()) {
+ reservePreviousStackSlotForValue(V, Builder);
}
- for (unsigned i = 0; i < Bases.size() * 2; ++i) {
- // Even elements will contain base, odd elements - derived ptr
- const Value *V = i % 2 ? Bases[i / 2] : Ptrs[i / 2];
- SDValue Incoming = Builder.getValue(V);
- reservePreviousStackSlotForValue(Incoming, Builder);
+ for (unsigned i = 0; i < Bases.size(); ++i) {
+ reservePreviousStackSlotForValue(Bases[i], Builder);
+ reservePreviousStackSlotForValue(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 = StatepointSite.numTotalVMSArgs();
- Ops.push_back(
- Builder.DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
- Ops.push_back(Builder.DAG.getTargetConstant(NumVMSArgs, MVT::i64));
+ const int NumVMSArgs = StatepointSite.getNumTotalVMSArgs();
+ pushStackMapConstant(Ops, Builder, NumVMSArgs);
- assert(NumVMSArgs + 1 == std::distance(StatepointSite.vm_state_begin(),
- StatepointSite.vm_state_end()));
+ assert(NumVMSArgs == std::distance(StatepointSite.vm_state_begin(),
+ StatepointSite.vm_state_end()));
// The vm state arguments are lowered in an opaque manner. We do
// not know what type of values are contained within. We skip the
// explicitly just above. We could have left it in the loop and
// not done it explicitly, but it's far easier to understand this
// way.
- for (auto I = StatepointSite.vm_state_begin() + 1,
- E = StatepointSite.vm_state_end();
- I != E; ++I) {
- const Value *V = *I;
+ for (const Value *V : StatepointSite.vm_state_args()) {
SDValue Incoming = Builder.getValue(V);
lowerIncomingStatepointValue(Incoming, Ops, Builder);
}
// 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 < Bases.size() * 2; ++i) {
- // Even elements will contain base, odd elements - derived ptr
- const Value *V = i % 2 ? Bases[i / 2] : Ptrs[i / 2];
- SDValue Incoming = Builder.getValue(V);
- lowerIncomingStatepointValue(Incoming, Ops, Builder);
+ for (unsigned i = 0; i < Bases.size(); ++i) {
+ const Value *Base = Bases[i];
+ lowerIncomingStatepointValue(Builder.getValue(Base), Ops, Builder);
+
+ const Value *Ptr = Ptrs[i];
+ lowerIncomingStatepointValue(Builder.getValue(Ptr), Ops, Builder);
}
- // If there are any explicit spill slots passed to the statepoint, record
+ // 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,
+ // 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 : StatepointSite.gc_args()) {
SDValue Incoming = Builder.getValue(V);
if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Incoming)) {
// This handles allocas as arguments to the statepoint
- Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(),
+ Ops.push_back(Builder.DAG.getTargetFrameIndex(FI->getIndex(),
Incoming.getValueType()));
+ }
+ }
+ // 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 =
+ StatepointSite.getCallSite().getInstruction();
+ FunctionLoweringInfo::StatepointSpilledValueMapTy &SpillMap =
+ Builder.FuncInfo.StatepointRelocatedValues[StatepointInstr];
+
+ for (GCRelocateOperands RelocateOpers : StatepointSite.getRelocates()) {
+ const Value *V = RelocateOpers.getDerivedPtr();
+ SDValue SDV = Builder.getValue(V);
+ SDValue Loc = Builder.StatepointLowering.getLocation(SDV);
+
+ if (Loc.getNode()) {
+ SpillMap[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[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 (RelocateOpers.getUnderlyingCallSite().getParent() !=
+ StatepointInstr->getParent())
+ Builder.ExportFromCurrentBlock(V);
}
}
}
LowerStatepoint(ImmutableStatepoint(&CI));
}
-void
-SelectionDAGBuilder::LowerStatepoint(ImmutableStatepoint ISP,
- MachineBasicBlock *LandingPad/*=nullptr*/) {
+void SelectionDAGBuilder::LowerStatepoint(
+ ImmutableStatepoint ISP, const BasicBlock *EHPadBB /*= nullptr*/) {
// 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.
ImmutableCallSite CS(ISP.getCallSite());
#ifndef NDEBUG
- // Consistency check
+ // Consistency check. Check only relocates in the same basic block as thier
+ // statepoint.
for (const User *U : CS->users()) {
const CallInst *Call = cast<CallInst>(U);
- if (isGCRelocate(Call))
+ if (isGCRelocate(Call) && Call->getParent() == CS.getParent())
StatepointLowering.scheduleRelocCall(*Call);
}
#endif
ISP.verify();
// Check that the associated GCStrategy expects to encounter statepoints.
- // TODO: This if should become an assert. For now, we allow the GCStrategy
- // to be optional for backwards compatibility. This will only last a short
- // period (i.e. a couple of weeks).
assert(GFI->getStrategy().useStatepoints() &&
"GCStrategy does not expect to encounter statepoints");
#endif
// Lower statepoint vmstate and gcstate arguments
- SmallVector<SDValue, 10> LoweredArgs;
- lowerStatepointMetaArgs(LoweredArgs, ISP, *this);
+ SmallVector<SDValue, 10> LoweredMetaArgs;
+ lowerStatepointMetaArgs(LoweredMetaArgs, ISP, *this);
// Get call node, we will replace it later with statepoint
- SDNode *CallNode = lowerCallFromStatepoint(ISP, LandingPad, *this);
+ SDNode *CallNode =
+ lowerCallFromStatepoint(ISP, EHPadBB, *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);
- // Construct the actual STATEPOINT node with all the appropriate arguments
- // and return values.
+ 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 =
+ (ISP.getFlags() & (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 : ISP.gc_transition_args()) {
+ 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(ISP.getID(), getCurSDLoc(), MVT::i64));
+ Ops.push_back(
+ DAG.getTargetConstant(ISP.getNumPatchBytes(), getCurSDLoc(), MVT::i32));
+
// Calculate and push starting position of vmstate arguments
- // Call Node: Chain, Target, {Args}, RegMask, [Glue]
- SDValue Glue;
- if (CallNode->getGluedNode()) {
- // Glue is always last operand
- Glue = CallNode->getOperand(CallNode->getNumOperands() - 1);
- }
// Get number of arguments incoming directly into call node
unsigned NumCallRegArgs =
- CallNode->getNumOperands() - (Glue.getNode() ? 4 : 3);
- Ops.push_back(DAG.getTargetConstant(NumCallRegArgs, MVT::i32));
+ 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);
// Add call arguments
// Get position of register mask in the call
SDNode::op_iterator RegMaskIt;
- if (Glue.getNode())
+ if (CallHasIncomingGlue)
RegMaskIt = CallNode->op_end() - 2;
else
RegMaskIt = CallNode->op_end() - 1;
Ops.insert(Ops.end(), CallNode->op_begin() + 2, RegMaskIt);
- // Add a leading constant argument with the Flags and the calling convention
- // masked together
- CallingConv::ID CallConv = CS.getCallingConv();
- int Flags = cast<ConstantInt>(CS.getArgument(2))->getZExtValue();
- assert(Flags == 0 && "not expected to be used");
- Ops.push_back(DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
- Ops.push_back(
- DAG.getTargetConstant(Flags | ((unsigned)CallConv << 1), MVT::i64));
+ // Add a constant argument for the calling convention
+ pushStackMapConstant(Ops, *this, CS.getCallingConv());
+
+ // Add a constant argument for the flags
+ uint64_t Flags = ISP.getFlags();
+ assert(
+ ((Flags & ~(uint64_t)StatepointFlags::MaskAll) == 0)
+ && "unknown flag used");
+ pushStackMapConstant(Ops, *this, Flags);
// Insert all vmstate and gcstate arguments
- Ops.insert(Ops.end(), LoweredArgs.begin(), LoweredArgs.end());
+ Ops.insert(Ops.end(), LoweredMetaArgs.begin(), LoweredMetaArgs.end());
// Add register mask from call node
Ops.push_back(*RegMaskIt);
// Add chain
- Ops.push_back(CallNode->getOperand(0));
+ Ops.push_back(Chain);
// Same for the glue, but we add it only if original call had it
if (Glue.getNode())
// 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 *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 : ISP.gc_transition_args()) {
+ 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, StatepointMCNode); // This may update Root
- // Remove originall call node
+ 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
// 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.
Instruction *I = cast<Instruction>(CI.getArgOperand(0));
- assert(isStatepoint(I) &&
- "first argument must be a statepoint token");
+ assert(isStatepoint(I) && "first argument must be a statepoint token");
- if (isa<InvokeInst>(I)) {
- // For invokes we should have stored call result in a virtual register.
+ 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 actuall 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).actualCallee()->getType());
- Type *RetTy = cast<FunctionType>(
- CalleeType->getElementType())->getReturnType();
+ ImmutableStatepoint(I).getCalledValue()->getType());
+ Type *RetTy =
+ cast<FunctionType>(CalleeType->getElementType())->getReturnType();
SDValue CopyFromReg = getCopyFromRegs(I, RetTy);
assert(CopyFromReg.getNode());
setValue(&CI, CopyFromReg);
- }
- else {
+ } else {
setValue(&CI, getValue(I));
}
}
void SelectionDAGBuilder::visitGCRelocate(const CallInst &CI) {
+ GCRelocateOperands RelocateOpers(&CI);
+
#ifndef NDEBUG
// Consistency check
- StatepointLowering.relocCallVisited(CI);
+ // We skip this check for relocates not in the same basic block as thier
+ // statepoint. It would be too expensive to preserve validation info through
+ // different basic blocks.
+ if (RelocateOpers.getStatepoint()->getParent() == CI.getParent()) {
+ StatepointLowering.relocCallVisited(CI);
+ }
#endif
- GCRelocateOperands relocateOpers(&CI);
- SDValue SD = getValue(relocateOpers.derivedPtr());
+ const Value *DerivedPtr = RelocateOpers.getDerivedPtr();
+ SDValue SD = getValue(DerivedPtr);
+
+ FunctionLoweringInfo::StatepointSpilledValueMapTy &SpillMap =
+ FuncInfo.StatepointRelocatedValues[RelocateOpers.getStatepoint()];
- if (isa<ConstantSDNode>(SD) || isa<FrameIndexSDNode>(SD)) {
- // We didn't need to spill these special cases (constants and allocas).
- // See the handling in spillIncomingValueForStatepoint for detail.
+ // We should have recorded location for this pointer
+ assert(SpillMap.count(DerivedPtr) && "Relocating not lowered gc value");
+ Optional<int> DerivedPtrLocation = SpillMap[DerivedPtr];
+
+ // We didn't need to spill these special cases (constants and allocas).
+ // See the handling in spillIncomingValueForStatepoint for detail.
+ if (!DerivedPtrLocation) {
setValue(&CI, SD);
return;
}
- SDValue Loc = StatepointLowering.getRelocLocation(SD);
- // Emit new load if we did not emit it before
- if (!Loc.getNode()) {
- SDValue SpillSlot = StatepointLowering.getLocation(SD);
- int FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
+ SDValue SpillSlot = DAG.getTargetFrameIndex(*DerivedPtrLocation,
+ SD.getValueType());
- // Be conservative: flush all pending loads
- // TODO: Probably we can be less restrictive on this,
- // it may allow more scheduling opprtunities
- SDValue Chain = getRoot();
+ // Be conservative: flush all pending loads
+ // TODO: Probably we can be less restrictive on this,
+ // it may allow more scheduling opportunities.
+ SDValue Chain = getRoot();
- Loc = DAG.getLoad(SpillSlot.getValueType(), getCurSDLoc(), Chain,
- SpillSlot, MachinePointerInfo::getFixedStack(FI), false,
- false, false, 0);
+ SDValue SpillLoad =
+ DAG.getLoad(SpillSlot.getValueType(), getCurSDLoc(), Chain, SpillSlot,
+ MachinePointerInfo::getFixedStack(DAG.getMachineFunction(),
+ *DerivedPtrLocation),
+ false, false, false, 0);
- StatepointLowering.setRelocLocation(SD, Loc);
+ // Again, be conservative, don't emit pending loads
+ DAG.setRoot(SpillLoad.getValue(1));
- // Again, be conservative, don't emit pending loads
- DAG.setRoot(Loc.getValue(1));
- }
-
- assert(Loc.getNode());
- setValue(&CI, Loc);
+ assert(SpillLoad.getNode());
+ setValue(&CI, SpillLoad);
}
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