LLVM  3.7.0
StatepointLowering.h
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1 //===-- StatepointLowering.h - SDAGBuilder's statepoint code -*- C++ -*---===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file includes support code use by SelectionDAGBuilder when lowering a
11 // statepoint sequence in SelectionDAG IR.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
16 #define LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
17 
18 #include "llvm/ADT/DenseMap.h"
21 #include <vector>
22 
23 namespace llvm {
24 class SelectionDAGBuilder;
25 
26 /// This class tracks both per-statepoint and per-selectiondag information.
27 /// For each statepoint it tracks locations of it's gc valuess (incoming and
28 /// relocated) and list of gcreloc calls scheduled for visiting (this is
29 /// used for a debug mode consistency check only). The spill slot tracking
30 /// works in concert with information in FunctionLoweringInfo.
32 public:
33  StatepointLoweringState() : NextSlotToAllocate(0) {}
34 
35  /// Reset all state tracking for a newly encountered safepoint. Also
36  /// performs some consistency checking.
38 
39  /// Clear the memory usage of this object. This is called from
40  /// SelectionDAGBuilder::clear. We require this is never called in the
41  /// midst of processing a statepoint sequence.
42  void clear();
43 
44  /// Returns the spill location of a value incoming to the current
45  /// statepoint. Will return SDValue() if this value hasn't been
46  /// spilled. Otherwise, the value has already been spilled and no
47  /// further action is required by the caller.
49  if (!Locations.count(val))
50  return SDValue();
51  return Locations[val];
52  }
53  void setLocation(SDValue val, SDValue Location) {
54  assert(!Locations.count(val) &&
55  "Trying to allocate already allocated location");
56  Locations[val] = Location;
57  }
58 
59  /// Record the fact that we expect to encounter a given gc_relocate
60  /// before the next statepoint. If we don't see it, we'll report
61  /// an assertion.
62  void scheduleRelocCall(const CallInst &RelocCall) {
63  PendingGCRelocateCalls.push_back(&RelocCall);
64  }
65  /// Remove this gc_relocate from the list we're expecting to see
66  /// before the next statepoint. If we weren't expecting to see
67  /// it, we'll report an assertion.
68  void relocCallVisited(const CallInst &RelocCall) {
70  std::find(PendingGCRelocateCalls.begin(), PendingGCRelocateCalls.end(),
71  &RelocCall);
72  assert(itr != PendingGCRelocateCalls.end() &&
73  "Visited unexpected gcrelocate call");
74  PendingGCRelocateCalls.erase(itr);
75  }
76 
77  // TODO: Should add consistency tracking to ensure we encounter
78  // expected gc_result calls too.
79 
80  /// Get a stack slot we can use to store an value of type ValueType. This
81  /// will hopefully be a recylced slot from another statepoint.
83 
84  void reserveStackSlot(int Offset) {
85  assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
86  "out of bounds");
87  assert(!AllocatedStackSlots[Offset] && "already reserved!");
88  assert(NextSlotToAllocate <= (unsigned)Offset && "consistency!");
89  AllocatedStackSlots[Offset] = true;
90  }
91  bool isStackSlotAllocated(int Offset) {
92  assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
93  "out of bounds");
94  return AllocatedStackSlots[Offset];
95  }
96 
97 private:
98  /// Maps pre-relocation value (gc pointer directly incoming into statepoint)
99  /// into it's location (currently only stack slots)
100  DenseMap<SDValue, SDValue> Locations;
101 
102  /// A boolean indicator for each slot listed in the FunctionInfo as to
103  /// whether it has been used in the current statepoint. Since we try to
104  /// preserve stack slots across safepoints, there can be gaps in which
105  /// slots have been allocated.
106  SmallVector<bool, 50> AllocatedStackSlots;
107 
108  /// Points just beyond the last slot known to have been allocated
109  unsigned NextSlotToAllocate;
110 
111  /// Keep track of pending gcrelocate calls for consistency check
112  SmallVector<const CallInst *, 10> PendingGCRelocateCalls;
113 };
114 } // end namespace llvm
115 
116 #endif // LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
PointerUnion< const Value *, const PseudoSourceValue * > ValueType
SelectionDAGBuilder - This is the common target-independent lowering implementation that is parameter...
CallInst - This class represents a function call, abstracting a target machine's calling convention...
SDValue allocateStackSlot(EVT ValueType, SelectionDAGBuilder &Builder)
Get a stack slot we can use to store an value of type ValueType.
void clear()
Clear the memory usage of this object.
This class tracks both per-statepoint and per-selectiondag information.
EVT - Extended Value Type.
Definition: ValueTypes.h:31
void setLocation(SDValue val, SDValue Location)
void startNewStatepoint(SelectionDAGBuilder &Builder)
Reset all state tracking for a newly encountered safepoint.
SDValue getLocation(SDValue val)
Returns the spill location of a value incoming to the current statepoint.
void scheduleRelocCall(const CallInst &RelocCall)
Record the fact that we expect to encounter a given gc_relocate before the next statepoint.
void relocCallVisited(const CallInst &RelocCall)
Remove this gc_relocate from the list we're expecting to see before the next statepoint.
Unlike LLVM values, Selection DAG nodes may return multiple values as the result of a computation...