120 lines
4.5 KiB
C++
120 lines
4.5 KiB
C++
//===-- StatepointLowering.h - SDAGBuilder's statepoint code -*- C++ -*---===//
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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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#ifndef LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
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#define LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallBitVector.h"
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#include "llvm/CodeGen/SelectionDAG.h"
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#include "llvm/CodeGen/SelectionDAGNodes.h"
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#include <vector>
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namespace llvm {
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class SelectionDAGBuilder;
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/// This class tracks both per-statepoint and per-selectiondag information.
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/// For each statepoint it tracks locations of it's gc valuess (incoming and
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/// relocated) and list of gcreloc calls scheduled for visiting (this is
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/// used for a debug mode consistency check only). The spill slot tracking
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/// works in concert with information in FunctionLoweringInfo.
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class StatepointLoweringState {
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public:
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StatepointLoweringState() : NextSlotToAllocate(0) {}
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/// Reset all state tracking for a newly encountered safepoint. Also
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/// performs some consistency checking.
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void startNewStatepoint(SelectionDAGBuilder &Builder);
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/// Clear the memory usage of this object. This is called from
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/// SelectionDAGBuilder::clear. We require this is never called in the
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/// midst of processing a statepoint sequence.
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void clear();
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/// Returns the spill location of a value incoming to the current
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/// statepoint. Will return SDValue() if this value hasn't been
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/// spilled. Otherwise, the value has already been spilled and no
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/// further action is required by the caller.
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SDValue getLocation(SDValue Val) {
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auto I = Locations.find(Val);
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if (I == Locations.end())
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return SDValue();
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return I->second;
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}
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void setLocation(SDValue Val, SDValue Location) {
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assert(!Locations.count(Val) &&
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"Trying to allocate already allocated location");
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Locations[Val] = Location;
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}
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/// Record the fact that we expect to encounter a given gc_relocate
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/// before the next statepoint. If we don't see it, we'll report
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/// an assertion.
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void scheduleRelocCall(const CallInst &RelocCall) {
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PendingGCRelocateCalls.push_back(&RelocCall);
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}
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/// Remove this gc_relocate from the list we're expecting to see
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/// before the next statepoint. If we weren't expecting to see
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/// it, we'll report an assertion.
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void relocCallVisited(const CallInst &RelocCall) {
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auto I = find(PendingGCRelocateCalls, &RelocCall);
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assert(I != PendingGCRelocateCalls.end() &&
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"Visited unexpected gcrelocate call");
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PendingGCRelocateCalls.erase(I);
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}
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// TODO: Should add consistency tracking to ensure we encounter
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// expected gc_result calls too.
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/// Get a stack slot we can use to store an value of type ValueType. This
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/// will hopefully be a recylced slot from another statepoint.
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SDValue allocateStackSlot(EVT ValueType, SelectionDAGBuilder &Builder);
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void reserveStackSlot(int Offset) {
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assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
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"out of bounds");
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assert(!AllocatedStackSlots.test(Offset) && "already reserved!");
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assert(NextSlotToAllocate <= (unsigned)Offset && "consistency!");
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AllocatedStackSlots.set(Offset);
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}
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bool isStackSlotAllocated(int Offset) {
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assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
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"out of bounds");
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return AllocatedStackSlots.test(Offset);
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}
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private:
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/// Maps pre-relocation value (gc pointer directly incoming into statepoint)
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/// into it's location (currently only stack slots)
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DenseMap<SDValue, SDValue> Locations;
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/// A boolean indicator for each slot listed in the FunctionInfo as to
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/// whether it has been used in the current statepoint. Since we try to
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/// preserve stack slots across safepoints, there can be gaps in which
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/// slots have been allocated.
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SmallBitVector AllocatedStackSlots;
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/// Points just beyond the last slot known to have been allocated
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unsigned NextSlotToAllocate;
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/// Keep track of pending gcrelocate calls for consistency check
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SmallVector<const CallInst *, 10> PendingGCRelocateCalls;
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};
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} // end namespace llvm
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#endif // LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
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