1 //===-- StatepointLowering.h - SDAGBuilder's statepoint code -*- C++ -*---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file includes support code use by SelectionDAGBuilder when lowering a
11 // statepoint sequence in SelectionDAG IR.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
16 #define LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/SmallBitVector.h"
20 #include "llvm/CodeGen/SelectionDAG.h"
21 #include "llvm/CodeGen/SelectionDAGNodes.h"
24 class SelectionDAGBuilder;
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.
31 class StatepointLoweringState {
33 StatepointLoweringState() : NextSlotToAllocate(0) {}
35 /// Reset all state tracking for a newly encountered safepoint. Also
36 /// performs some consistency checking.
37 void startNewStatepoint(SelectionDAGBuilder &Builder);
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.
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.
48 SDValue getLocation(SDValue Val) {
49 auto I = Locations.find(Val);
50 if (I == Locations.end())
55 void setLocation(SDValue Val, SDValue Location) {
56 assert(!Locations.count(Val) &&
57 "Trying to allocate already allocated location");
58 Locations[Val] = Location;
61 /// Record the fact that we expect to encounter a given gc_relocate
62 /// before the next statepoint. If we don't see it, we'll report
64 void scheduleRelocCall(const CallInst &RelocCall) {
65 PendingGCRelocateCalls.push_back(&RelocCall);
68 /// Remove this gc_relocate from the list we're expecting to see
69 /// before the next statepoint. If we weren't expecting to see
70 /// it, we'll report an assertion.
71 void relocCallVisited(const CallInst &RelocCall) {
72 auto I = find(PendingGCRelocateCalls, &RelocCall);
73 assert(I != PendingGCRelocateCalls.end() &&
74 "Visited unexpected gcrelocate call");
75 PendingGCRelocateCalls.erase(I);
78 // TODO: Should add consistency tracking to ensure we encounter
79 // expected gc_result calls too.
81 /// Get a stack slot we can use to store an value of type ValueType. This
82 /// will hopefully be a recylced slot from another statepoint.
83 SDValue allocateStackSlot(EVT ValueType, SelectionDAGBuilder &Builder);
85 void reserveStackSlot(int Offset) {
86 assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
88 assert(!AllocatedStackSlots.test(Offset) && "already reserved!");
89 assert(NextSlotToAllocate <= (unsigned)Offset && "consistency!");
90 AllocatedStackSlots.set(Offset);
93 bool isStackSlotAllocated(int Offset) {
94 assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
96 return AllocatedStackSlots.test(Offset);
100 /// Maps pre-relocation value (gc pointer directly incoming into statepoint)
101 /// into it's location (currently only stack slots)
102 DenseMap<SDValue, SDValue> Locations;
104 /// A boolean indicator for each slot listed in the FunctionInfo as to
105 /// whether it has been used in the current statepoint. Since we try to
106 /// preserve stack slots across safepoints, there can be gaps in which
107 /// slots have been allocated.
108 SmallBitVector AllocatedStackSlots;
110 /// Points just beyond the last slot known to have been allocated
111 unsigned NextSlotToAllocate;
113 /// Keep track of pending gcrelocate calls for consistency check
114 SmallVector<const CallInst *, 10> PendingGCRelocateCalls;
116 } // end namespace llvm
118 #endif // LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H