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https://github.com/c64scene-ar/llvm-6502.git
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301256d436
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223150 91177308-0d34-0410-b5e6-96231b3b80d8
642 lines
26 KiB
C++
642 lines
26 KiB
C++
//===-- StatepointLowering.cpp - SDAGBuilder's statepoint code -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file includes support code use by SelectionDAGBuilder when lowering a
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// statepoint sequence in SelectionDAG IR.
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//
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//===----------------------------------------------------------------------===//
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#include "StatepointLowering.h"
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#include "SelectionDAGBuilder.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/FunctionLoweringInfo.h"
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#include "llvm/CodeGen/SelectionDAG.h"
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#include "llvm/CodeGen/StackMaps.h"
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#include "llvm/IR/CallingConv.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/Statepoint.h"
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#include "llvm/Target/TargetLowering.h"
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#include <algorithm>
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using namespace llvm;
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#define DEBUG_TYPE "statepoint-lowering"
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STATISTIC(NumSlotsAllocatedForStatepoints,
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"Number of stack slots allocated for statepoints");
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STATISTIC(NumOfStatepoints, "Number of statepoint nodes encountered");
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STATISTIC(StatepointMaxSlotsRequired,
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"Maximum number of stack slots required for a singe statepoint");
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void
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StatepointLoweringState::startNewStatepoint(SelectionDAGBuilder &Builder) {
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// Consistency check
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assert(PendingGCRelocateCalls.empty() &&
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"Trying to visit statepoint before finished processing previous one");
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Locations.clear();
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RelocLocations.clear();
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NextSlotToAllocate = 0;
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// Need to resize this on each safepoint - we need the two to stay in
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// sync and the clear patterns of a SelectionDAGBuilder have no relation
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// to FunctionLoweringInfo.
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AllocatedStackSlots.resize(Builder.FuncInfo.StatepointStackSlots.size());
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for (size_t i = 0; i < AllocatedStackSlots.size(); i++) {
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AllocatedStackSlots[i] = false;
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}
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}
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void StatepointLoweringState::clear() {
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Locations.clear();
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RelocLocations.clear();
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AllocatedStackSlots.clear();
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assert(PendingGCRelocateCalls.empty() &&
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"cleared before statepoint sequence completed");
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}
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SDValue
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StatepointLoweringState::allocateStackSlot(EVT ValueType,
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SelectionDAGBuilder &Builder) {
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NumSlotsAllocatedForStatepoints++;
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// The basic scheme here is to first look for a previously created stack slot
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// which is not in use (accounting for the fact arbitrary slots may already
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// be reserved), or to create a new stack slot and use it.
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// If this doesn't succeed in 40000 iterations, something is seriously wrong
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for (int i = 0; i < 40000; i++) {
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assert(Builder.FuncInfo.StatepointStackSlots.size() ==
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AllocatedStackSlots.size() &&
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"broken invariant");
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const size_t NumSlots = AllocatedStackSlots.size();
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assert(NextSlotToAllocate <= NumSlots && "broken invariant");
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if (NextSlotToAllocate >= NumSlots) {
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assert(NextSlotToAllocate == NumSlots);
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// record stats
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if (NumSlots + 1 > StatepointMaxSlotsRequired) {
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StatepointMaxSlotsRequired = NumSlots + 1;
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}
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SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
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const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
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Builder.FuncInfo.StatepointStackSlots.push_back(FI);
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AllocatedStackSlots.push_back(true);
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return SpillSlot;
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}
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if (!AllocatedStackSlots[NextSlotToAllocate]) {
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const int FI = Builder.FuncInfo.StatepointStackSlots[NextSlotToAllocate];
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AllocatedStackSlots[NextSlotToAllocate] = true;
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return Builder.DAG.getFrameIndex(FI, ValueType);
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}
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// Note: We deliberately choose to advance this only on the failing path.
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// Doing so on the suceeding path involes a bit of complexity that caused a
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// minor bug previously. Unless performance shows this matters, please
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// keep this code as simple as possible.
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NextSlotToAllocate++;
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}
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llvm_unreachable("infinite loop?");
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}
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/// Try to find existing copies of the incoming values in stack slots used for
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/// statepoint spilling. If we can find a spill slot for the incoming value,
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/// mark that slot as allocated, and reuse the same slot for this safepoint.
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/// This helps to avoid series of loads and stores that only serve to resuffle
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/// values on the stack between calls.
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static void reservePreviousStackSlotForValue(SDValue Incoming,
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SelectionDAGBuilder &Builder) {
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if (isa<ConstantSDNode>(Incoming) || isa<FrameIndexSDNode>(Incoming)) {
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// We won't need to spill this, so no need to check for previously
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// allocated stack slots
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return;
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}
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SDValue Loc = Builder.StatepointLowering.getLocation(Incoming);
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if (Loc.getNode()) {
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// duplicates in input
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return;
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}
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// Search back for the load from a stack slot pattern to find the original
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// slot we allocated for this value. We could extend this to deal with
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// simple modification patterns, but simple dealing with trivial load/store
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// sequences helps a lot already.
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if (LoadSDNode *Load = dyn_cast<LoadSDNode>(Incoming)) {
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if (auto *FI = dyn_cast<FrameIndexSDNode>(Load->getBasePtr())) {
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const int Index = FI->getIndex();
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auto Itr = std::find(Builder.FuncInfo.StatepointStackSlots.begin(),
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Builder.FuncInfo.StatepointStackSlots.end(), Index);
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if (Itr == Builder.FuncInfo.StatepointStackSlots.end()) {
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// not one of the lowering stack slots, can't reuse!
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// TODO: Actually, we probably could reuse the stack slot if the value
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// hasn't changed at all, but we'd need to look for intervening writes
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return;
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} else {
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// This is one of our dedicated lowering slots
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const int Offset =
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std::distance(Builder.FuncInfo.StatepointStackSlots.begin(), Itr);
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if (Builder.StatepointLowering.isStackSlotAllocated(Offset)) {
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// stack slot already assigned to someone else, can't use it!
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// TODO: currently we reserve space for gc arguments after doing
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// normal allocation for deopt arguments. We should reserve for
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// _all_ deopt and gc arguments, then start allocating. This
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// will prevent some moves being inserted when vm state changes,
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// but gc state doesn't between two calls.
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return;
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}
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// Reserve this stack slot
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Builder.StatepointLowering.reserveStackSlot(Offset);
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}
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// Cache this slot so we find it when going through the normal
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// assignment loop.
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SDValue Loc =
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Builder.DAG.getTargetFrameIndex(Index, Incoming.getValueType());
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Builder.StatepointLowering.setLocation(Incoming, Loc);
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}
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}
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// TODO: handle case where a reloaded value flows through a phi to
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// another safepoint. e.g.
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// bb1:
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// a' = relocated...
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// bb2: % pred: bb1, bb3, bb4, etc.
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// a_phi = phi(a', ...)
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// statepoint ... a_phi
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// NOTE: This will require reasoning about cross basic block values. This is
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// decidedly non trivial and this might not be the right place to do it. We
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// don't really have the information we need here...
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// TODO: handle simple updates. If a value is modified and the original
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// value is no longer live, it would be nice to put the modified value in the
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// same slot. This allows folding of the memory accesses for some
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// instructions types (like an increment).
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// statepoint (i)
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// i1 = i+1
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// statepoint (i1)
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}
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/// Remove any duplicate (as SDValues) from the derived pointer pairs. This
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/// is not required for correctness. It's purpose is to reduce the size of
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/// StackMap section. It has no effect on the number of spill slots required
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/// or the actual lowering.
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static void removeDuplicatesGCPtrs(SmallVectorImpl<const Value *> &Bases,
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SmallVectorImpl<const Value *> &Ptrs,
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SmallVectorImpl<const Value *> &Relocs,
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SelectionDAGBuilder &Builder) {
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// This is horribly ineffecient, but I don't care right now
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SmallSet<SDValue, 64> Seen;
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SmallVector<const Value *, 64> NewBases, NewPtrs, NewRelocs;
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for (size_t i = 0; i < Ptrs.size(); i++) {
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SDValue SD = Builder.getValue(Ptrs[i]);
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// Only add non-duplicates
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if (Seen.count(SD) == 0) {
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NewBases.push_back(Bases[i]);
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NewPtrs.push_back(Ptrs[i]);
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NewRelocs.push_back(Relocs[i]);
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}
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Seen.insert(SD);
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}
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assert(Bases.size() >= NewBases.size());
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assert(Ptrs.size() >= NewPtrs.size());
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assert(Relocs.size() >= NewRelocs.size());
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Bases = NewBases;
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Ptrs = NewPtrs;
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Relocs = NewRelocs;
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assert(Ptrs.size() == Bases.size());
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assert(Ptrs.size() == Relocs.size());
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}
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/// Extract call from statepoint, lower it and return pointer to the
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/// call node. Also update NodeMap so that getValue(statepoint) will
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/// reference lowered call result
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static SDNode *lowerCallFromStatepoint(const CallInst &CI,
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SelectionDAGBuilder &Builder) {
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assert(Intrinsic::experimental_gc_statepoint ==
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dyn_cast<IntrinsicInst>(&CI)->getIntrinsicID() &&
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"function called must be the statepoint function");
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ImmutableStatepoint StatepointOperands(&CI);
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// Lower the actual call itself - This is a bit of a hack, but we want to
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// avoid modifying the actual lowering code. This is similiar in intent to
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// the LowerCallOperands mechanism used by PATCHPOINT, but is structured
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// differently. Hopefully, this is slightly more robust w.r.t. calling
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// convention, return values, and other function attributes.
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Value *ActualCallee = const_cast<Value *>(StatepointOperands.actualCallee());
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std::vector<Value *> Args;
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CallInst::const_op_iterator arg_begin = StatepointOperands.call_args_begin();
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CallInst::const_op_iterator arg_end = StatepointOperands.call_args_end();
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Args.insert(Args.end(), arg_begin, arg_end);
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// TODO: remove the creation of a new instruction! We should not be
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// modifying the IR (even temporarily) at this point.
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CallInst *Tmp = CallInst::Create(ActualCallee, Args);
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Tmp->setTailCall(CI.isTailCall());
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Tmp->setCallingConv(CI.getCallingConv());
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Tmp->setAttributes(CI.getAttributes());
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Builder.LowerCallTo(Tmp, Builder.getValue(ActualCallee), false);
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// Handle the return value of the call iff any.
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const bool HasDef = !Tmp->getType()->isVoidTy();
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if (HasDef) {
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// The value of the statepoint itself will be the value of call itself.
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// We'll replace the actually call node shortly. gc_result will grab
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// this value.
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Builder.setValue(&CI, Builder.getValue(Tmp));
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} else {
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// The token value is never used from here on, just generate a poison value
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Builder.setValue(&CI, Builder.DAG.getIntPtrConstant(-1));
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}
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// Remove the fake entry we created so we don't have a hanging reference
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// after we delete this node.
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Builder.removeValue(Tmp);
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delete Tmp;
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Tmp = nullptr;
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// Search for the call node
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// The following code is essentially reverse engineering X86's
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// LowerCallTo.
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SDNode *CallNode = nullptr;
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// We just emitted a call, so it should be last thing generated
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SDValue Chain = Builder.DAG.getRoot();
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// Find closest CALLSEQ_END walking back through lowered nodes if needed
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SDNode *CallEnd = Chain.getNode();
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int Sanity = 0;
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while (CallEnd->getOpcode() != ISD::CALLSEQ_END) {
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CallEnd = CallEnd->getGluedNode();
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assert(CallEnd && "Can not find call node");
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assert(Sanity < 20 && "should have found call end already");
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Sanity++;
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}
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assert(CallEnd->getOpcode() == ISD::CALLSEQ_END &&
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"Expected a callseq node.");
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assert(CallEnd->getGluedNode());
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// Step back inside the CALLSEQ
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CallNode = CallEnd->getGluedNode();
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return CallNode;
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}
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/// Callect all gc pointers coming into statepoint intrinsic, clean them up,
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/// and return two arrays:
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/// Bases - base pointers incoming to this statepoint
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/// Ptrs - derived pointers incoming to this statepoint
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/// Relocs - the gc_relocate corresponding to each base/ptr pair
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/// Elements of this arrays should be in one-to-one correspondence with each
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/// other i.e Bases[i], Ptrs[i] are from the same gcrelocate call
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static void
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getIncomingStatepointGCValues(SmallVectorImpl<const Value *> &Bases,
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SmallVectorImpl<const Value *> &Ptrs,
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SmallVectorImpl<const Value *> &Relocs,
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ImmutableCallSite Statepoint,
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SelectionDAGBuilder &Builder) {
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// Search for relocated pointers. Note that working backwards from the
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// gc_relocates ensures that we only get pairs which are actually relocated
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// and used after the statepoint.
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// TODO: This logic should probably become a utility function in Statepoint.h
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for (const User *U : cast<CallInst>(Statepoint.getInstruction())->users()) {
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if (!isGCRelocate(U)) {
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continue;
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}
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GCRelocateOperands relocateOpers(U);
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Relocs.push_back(cast<Value>(U));
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Bases.push_back(relocateOpers.basePtr());
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Ptrs.push_back(relocateOpers.derivedPtr());
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}
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// Remove any redundant llvm::Values which map to the same SDValue as another
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// input. Also has the effect of removing duplicates in the original
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// llvm::Value input list as well. This is a useful optimization for
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// reducing the size of the StackMap section. It has no other impact.
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removeDuplicatesGCPtrs(Bases, Ptrs, Relocs, Builder);
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assert(Bases.size() == Ptrs.size() && Ptrs.size() == Relocs.size());
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}
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/// Spill a value incoming to the statepoint. It might be either part of
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/// vmstate
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/// or gcstate. In both cases unconditionally spill it on the stack unless it
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/// is a null constant. Return pair with first element being frame index
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/// containing saved value and second element with outgoing chain from the
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/// emitted store
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static std::pair<SDValue, SDValue>
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spillIncomingStatepointValue(SDValue Incoming, SDValue Chain,
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SelectionDAGBuilder &Builder) {
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SDValue Loc = Builder.StatepointLowering.getLocation(Incoming);
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// Emit new store if we didn't do it for this ptr before
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if (!Loc.getNode()) {
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Loc = Builder.StatepointLowering.allocateStackSlot(Incoming.getValueType(),
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Builder);
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assert(isa<FrameIndexSDNode>(Loc));
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int Index = cast<FrameIndexSDNode>(Loc)->getIndex();
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// We use TargetFrameIndex so that isel will not select it into LEA
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Loc = Builder.DAG.getTargetFrameIndex(Index, Incoming.getValueType());
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// TODO: We can create TokenFactor node instead of
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// chaining stores one after another, this may allow
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// a bit more optimal scheduling for them
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Chain = Builder.DAG.getStore(Chain, Builder.getCurSDLoc(), Incoming, Loc,
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MachinePointerInfo::getFixedStack(Index),
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false, false, 0);
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Builder.StatepointLowering.setLocation(Incoming, Loc);
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}
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assert(Loc.getNode());
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return std::make_pair(Loc, Chain);
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}
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/// Lower a single value incoming to a statepoint node. This value can be
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/// either a deopt value or a gc value, the handling is the same. We special
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/// case constants and allocas, then fall back to spilling if required.
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static void lowerIncomingStatepointValue(SDValue Incoming,
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SmallVectorImpl<SDValue> &Ops,
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SelectionDAGBuilder &Builder) {
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SDValue Chain = Builder.getRoot();
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if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Incoming)) {
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// If the original value was a constant, make sure it gets recorded as
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// such in the stackmap. This is required so that the consumer can
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// parse any internal format to the deopt state. It also handles null
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// pointers and other constant pointers in GC states
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Ops.push_back(
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Builder.DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
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Ops.push_back(Builder.DAG.getTargetConstant(C->getSExtValue(), MVT::i64));
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} else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Incoming)) {
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// This handles allocas as arguments to the statepoint
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const TargetLowering &TLI = Builder.DAG.getTargetLoweringInfo();
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Ops.push_back(
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Builder.DAG.getTargetFrameIndex(FI->getIndex(), TLI.getPointerTy()));
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} else {
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// Otherwise, locate a spill slot and explicitly spill it so it
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// can be found by the runtime later. We currently do not support
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// tracking values through callee saved registers to their eventual
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// spill location. This would be a useful optimization, but would
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// need to be optional since it requires a lot of complexity on the
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// runtime side which not all would support.
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std::pair<SDValue, SDValue> Res =
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spillIncomingStatepointValue(Incoming, Chain, Builder);
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Ops.push_back(Res.first);
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Chain = Res.second;
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}
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Builder.DAG.setRoot(Chain);
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}
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/// Lower deopt state and gc pointer arguments of the statepoint. The actual
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/// lowering is described in lowerIncomingStatepointValue. This function is
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/// responsible for lowering everything in the right position and playing some
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/// tricks to avoid redundant stack manipulation where possible. On
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/// completion, 'Ops' will contain ready to use operands for machine code
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/// statepoint. The chain nodes will have already been created and the DAG root
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/// will be set to the last value spilled (if any were).
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static void lowerStatepointMetaArgs(SmallVectorImpl<SDValue> &Ops,
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ImmutableStatepoint Statepoint,
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SelectionDAGBuilder &Builder) {
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// Lower the deopt and gc arguments for this statepoint. Layout will
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// be: deopt argument length, deopt arguments.., gc arguments...
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SmallVector<const Value *, 64> Bases, Ptrs, Relocations;
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getIncomingStatepointGCValues(Bases, Ptrs, Relocations,
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Statepoint.getCallSite(), Builder);
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// Before we actually start lowering (and allocating spill slots for values),
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// reserve any stack slots which we judge to be profitable to reuse for a
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// particular value. This is purely an optimization over the code below and
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// doesn't change semantics at all. It is important for performance that we
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// reserve slots for both deopt and gc values before lowering either.
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for (auto I = Statepoint.vm_state_begin() + 1, E = Statepoint.vm_state_end();
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I != E; ++I) {
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Value *V = *I;
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SDValue Incoming = Builder.getValue(V);
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reservePreviousStackSlotForValue(Incoming, Builder);
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}
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for (unsigned i = 0; i < Bases.size() * 2; ++i) {
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// Even elements will contain base, odd elements - derived ptr
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const Value *V = i % 2 ? Bases[i / 2] : Ptrs[i / 2];
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SDValue Incoming = Builder.getValue(V);
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reservePreviousStackSlotForValue(Incoming, Builder);
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}
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// First, prefix the list with the number of unique values to be
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// lowered. Note that this is the number of *Values* not the
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// number of SDValues required to lower them.
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const int NumVMSArgs = Statepoint.numTotalVMSArgs();
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Ops.push_back(
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Builder.DAG.getTargetConstant(StackMaps::ConstantOp, MVT::i64));
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Ops.push_back(Builder.DAG.getTargetConstant(NumVMSArgs, MVT::i64));
|
|
|
|
assert(NumVMSArgs + 1 == std::distance(Statepoint.vm_state_begin(),
|
|
Statepoint.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 = Statepoint.vm_state_begin() + 1, E = Statepoint.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) {
|
|
// 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.
|
|
|
|
// Check some preconditions for sanity
|
|
assert(isStatepoint(&CI) &&
|
|
"function called must be the statepoint function");
|
|
NumOfStatepoints++;
|
|
// Clear state
|
|
StatepointLowering.startNewStatepoint(*this);
|
|
|
|
#ifndef NDEBUG
|
|
// Consistency check
|
|
for (const User *U : CI.users()) {
|
|
const CallInst *Call = cast<CallInst>(U);
|
|
if (isGCRelocate(Call))
|
|
StatepointLowering.scheduleRelocCall(*Call);
|
|
}
|
|
#endif
|
|
|
|
ImmutableStatepoint ISP(&CI);
|
|
#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();
|
|
#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(CI, *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 = CI.getCallingConv();
|
|
int Flags = dyn_cast<ConstantInt>(CI.getArgOperand(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
|
|
SmallVector<EVT, 21> ValueVTs;
|
|
ValueVTs.push_back(MVT::Other);
|
|
ValueVTs.push_back(MVT::Glue); // provide a glue output since we consume one
|
|
// as input. This allows someone else to chain
|
|
// off us as needed.
|
|
SDVTList NodeTys = DAG.getVTList(ValueVTs);
|
|
|
|
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);
|
|
}
|