Update aosp/master LLVM for rebase to r230699.
Change-Id: I2b5be30509658cb8266be782de0ab24f9099f9b9
diff --git a/lib/CodeGen/SelectionDAG/StatepointLowering.cpp b/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
new file mode 100644
index 0000000..1271f6b
--- /dev/null
+++ b/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -0,0 +1,679 @@
+//===-- 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/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/FunctionLoweringInfo.h"
+#include "llvm/CodeGen/GCMetadata.h"
+#include "llvm/CodeGen/GCStrategy.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/CodeGen/StackMaps.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Statepoint.h"
+#include "llvm/Target/TargetLowering.h"
+#include <algorithm>
+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");
+
+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
+ // to FunctionLoweringInfo.
+ AllocatedStackSlots.resize(Builder.FuncInfo.StatepointStackSlots.size());
+ for (size_t i = 0; i < AllocatedStackSlots.size(); i++) {
+ AllocatedStackSlots[i] = false;
+ }
+}
+void StatepointLoweringState::clear() {
+ Locations.clear();
+ RelocLocations.clear();
+ AllocatedStackSlots.clear();
+ assert(PendingGCRelocateCalls.empty() &&
+ "cleared before statepoint sequence completed");
+}
+
+SDValue
+StatepointLoweringState::allocateStackSlot(EVT ValueType,
+ SelectionDAGBuilder &Builder) {
+
+ NumSlotsAllocatedForStatepoints++;
+
+ // The basic scheme here is to 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.
+
+ // If this doesn't succeed in 40000 iterations, something is seriously wrong
+ for (int i = 0; i < 40000; i++) {
+ assert(Builder.FuncInfo.StatepointStackSlots.size() ==
+ AllocatedStackSlots.size() &&
+ "broken invariant");
+ const size_t NumSlots = AllocatedStackSlots.size();
+ assert(NextSlotToAllocate <= NumSlots && "broken invariant");
+
+ if (NextSlotToAllocate >= NumSlots) {
+ assert(NextSlotToAllocate == NumSlots);
+ // record stats
+ if (NumSlots + 1 > StatepointMaxSlotsRequired) {
+ StatepointMaxSlotsRequired = NumSlots + 1;
+ }
+
+ SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
+ const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
+ Builder.FuncInfo.StatepointStackSlots.push_back(FI);
+ AllocatedStackSlots.push_back(true);
+ return SpillSlot;
+ }
+ if (!AllocatedStackSlots[NextSlotToAllocate]) {
+ const int FI = Builder.FuncInfo.StatepointStackSlots[NextSlotToAllocate];
+ AllocatedStackSlots[NextSlotToAllocate] = true;
+ 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
+ // keep this code as simple as possible.
+ NextSlotToAllocate++;
+ }
+ llvm_unreachable("infinite loop?");
+}
+
+/// 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
+/// values on the stack between calls.
+static void reservePreviousStackSlotForValue(SDValue Incoming,
+ SelectionDAGBuilder &Builder) {
+
+ 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()) {
+ // 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());
+
+ Builder.StatepointLowering.setLocation(Incoming, Loc);
+ }
+ }
+
+ // 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)
+}
+
+/// 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 removeDuplicatesGCPtrs(SmallVectorImpl<const Value *> &Bases,
+ SmallVectorImpl<const Value *> &Ptrs,
+ SmallVectorImpl<const Value *> &Relocs,
+ SelectionDAGBuilder &Builder) {
+
+ // This is horribly ineffecient, but I don't care right now
+ SmallSet<SDValue, 64> Seen;
+
+ SmallVector<const Value *, 64> NewBases, NewPtrs, NewRelocs;
+ for (size_t i = 0; i < Ptrs.size(); i++) {
+ SDValue SD = Builder.getValue(Ptrs[i]);
+ // Only add non-duplicates
+ if (Seen.count(SD) == 0) {
+ NewBases.push_back(Bases[i]);
+ NewPtrs.push_back(Ptrs[i]);
+ NewRelocs.push_back(Relocs[i]);
+ }
+ Seen.insert(SD);
+ }
+ 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 SDNode *lowerCallFromStatepoint(ImmutableStatepoint StatepointSite,
+ 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);
+
+ // Handle the return value of the call iff any.
+ const bool HasDef = !Tmp->getType()->isVoidTy();
+ if (HasDef) {
+ // 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
+ // LowerCallTo.
+ SDNode *CallNode = nullptr;
+
+ // 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) {
+ CallEnd = CallEnd->getGluedNode();
+ assert(CallEnd && "Can not find call node");
+ assert(Sanity < 20 && "should have found call end already");
+ Sanity++;
+ }
+ assert(CallEnd->getOpcode() == ISD::CALLSEQ_END &&
+ "Expected a callseq node.");
+ assert(CallEnd->getGluedNode());
+
+ // Step back inside the CALLSEQ
+ CallNode = CallEnd->getGluedNode();
+ return CallNode;
+}
+
+/// Callect all gc pointers coming into statepoint intrinsic, clean them up,
+/// and return two arrays:
+/// Bases - base pointers incoming to this statepoint
+/// Ptrs - derived pointers incoming to this statepoint
+/// 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)) {
+ Relocs.push_back(relocateOpers.getUnderlyingCallSite().getInstruction());
+ Bases.push_back(relocateOpers.basePtr());
+ Ptrs.push_back(relocateOpers.derivedPtr());
+ }
+
+ // 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.
+ removeDuplicatesGCPtrs(Bases, Ptrs, Relocs, Builder);
+
+ assert(Bases.size() == Ptrs.size() && Ptrs.size() == Relocs.size());
+}
+
+/// 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);
+ assert(isa<FrameIndexSDNode>(Loc));
+ int Index = cast<FrameIndexSDNode>(Loc)->getIndex();
+ // We use TargetFrameIndex so that isel will not select it into LEA
+ Loc = Builder.DAG.getTargetFrameIndex(Index, Incoming.getValueType());
+
+ // TODO: We can create TokenFactor node instead of
+ // 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),
+ false, false, 0);
+
+ 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,
+ 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
+ Ops.push_back(
+ Builder.DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
+ Ops.push_back(Builder.DAG.getTargetConstant(C->getSExtValue(), MVT::i64));
+ } else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Incoming)) {
+ // This handles allocas as arguments to the statepoint
+ const TargetLowering &TLI = Builder.DAG.getTargetLoweringInfo();
+ Ops.push_back(
+ Builder.DAG.getTargetFrameIndex(FI->getIndex(), TLI.getPointerTy()));
+ } 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.
+ std::pair<SDValue, SDValue> 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,
+ ImmutableStatepoint StatepointSite,
+ SelectionDAGBuilder &Builder) {
+
+ // Lower the deopt and gc arguments for this statepoint. Layout will
+ // be: deopt argument length, deopt arguments.., gc arguments...
+
+ SmallVector<const Value *, 64> Bases, Ptrs, Relocations;
+ getIncomingStatepointGCValues(Bases, Ptrs, Relocations,
+ StatepointSite, Builder);
+
+#ifndef NDEBUG
+ // 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 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).
+ if (Builder.GFI) {
+ GCStrategy &S = Builder.GFI->getStrategy();
+ for (const Value *V : Bases) {
+ auto Opt = S.isGCManagedPointer(V);
+ if (Opt.hasValue()) {
+ assert(Opt.getValue() &&
+ "non gc managed base pointer found in statepoint");
+ }
+ }
+ for (const Value *V : Ptrs) {
+ auto Opt = S.isGCManagedPointer(V);
+ if (Opt.hasValue()) {
+ assert(Opt.getValue() &&
+ "non gc managed derived pointer found in statepoint");
+ }
+ }
+ for (const Value *V : Relocations) {
+ auto Opt = S.isGCManagedPointer(V);
+ 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 (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);
+ }
+
+ // 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));
+
+ assert(NumVMSArgs + 1 == 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
+ // first one since that happens to be the total number we lowered
+ // 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;
+ SDValue Incoming = Builder.getValue(V);
+ lowerIncomingStatepointValue(Incoming, 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 < 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);
+ }
+}
+
+void SelectionDAGBuilder::visitStatepoint(const CallInst &CI) {
+ // Check some preconditions for sanity
+ assert(isStatepoint(&CI) &&
+ "function called must be the statepoint function");
+
+ LowerStatepoint(ImmutableStatepoint(&CI));
+}
+
+void SelectionDAGBuilder::LowerStatepoint(ImmutableStatepoint ISP) {
+ // 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);
+
+ ImmutableCallSite CS(ISP.getCallSite());
+
+#ifndef NDEBUG
+ // Consistency check
+ for (const User *U : CS->users()) {
+ const CallInst *Call = cast<CallInst>(U);
+ if (isGCRelocate(Call))
+ StatepointLowering.scheduleRelocCall(*Call);
+ }
+#endif
+
+#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.
+ // 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).
+ if (GFI) {
+ 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);
+
+ // Get call node, we will replace it later with statepoint
+ SDNode *CallNode = lowerCallFromStatepoint(ISP, *this);
+
+ // Construct the actual STATEPOINT node with all the appropriate arguments
+ // and return values.
+
+ // 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;
+
+ // 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));
+
+ // 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 (Glue.getNode())
+ 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 = dyn_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));
+
+ // Insert all vmstate and gcstate arguments
+ Ops.insert(Ops.end(), LoweredArgs.begin(), LoweredArgs.end());
+
+ // Add register mask from call node
+ Ops.push_back(*RegMaskIt);
+
+ // Add chain
+ Ops.push_back(CallNode->getOperand(0));
+
+ // 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);
+
+ // Replace original call
+ DAG.ReplaceAllUsesWith(CallNode, StatepointMCNode); // This may update Root
+ // Remove originall 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.
+}
+
+void SelectionDAGBuilder::visitGCResult(const CallInst &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.
+ Instruction *I = cast<Instruction>(CI.getArgOperand(0));
+ assert(isStatepoint(I) &&
+ "first argument must be a statepoint token");
+
+ setValue(&CI, getValue(I));
+}
+
+void SelectionDAGBuilder::visitGCRelocate(const CallInst &CI) {
+#ifndef NDEBUG
+ // Consistency check
+ StatepointLowering.relocCallVisited(CI);
+#endif
+
+ GCRelocateOperands relocateOpers(&CI);
+ SDValue SD = getValue(relocateOpers.derivedPtr());
+
+ 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.
+ 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();
+
+ // Be conservative: flush all pending loads
+ // TODO: Probably we can be less restrictive on this,
+ // it may allow more scheduling opprtunities
+ SDValue Chain = getRoot();
+
+ Loc = DAG.getLoad(SpillSlot.getValueType(), getCurSDLoc(), Chain,
+ SpillSlot, MachinePointerInfo::getFixedStack(FI), false,
+ false, false, 0);
+
+ StatepointLowering.setRelocLocation(SD, Loc);
+
+ // Again, be conservative, don't emit pending loads
+ DAG.setRoot(Loc.getValue(1));
+ }
+
+ assert(Loc.getNode());
+ setValue(&CI, Loc);
+}