Line data    Source code

       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"
      19             : #include "llvm/ADT/STLExtras.h"
      20             : #include "llvm/ADT/SmallBitVector.h"
      21             : #include "llvm/ADT/SmallVector.h"
      22             : #include "llvm/CodeGen/SelectionDAGNodes.h"
      23             : #include "llvm/CodeGen/ValueTypes.h"
      24             : #include <cassert>
      25             : 
      26             : namespace llvm {
      27             : 
      28             : class CallInst;
      29             : class SelectionDAGBuilder;
      30             : 
      31             : /// This class tracks both per-statepoint and per-selectiondag information.
      32             : /// For each statepoint it tracks locations of it's gc valuess (incoming and
      33             : /// relocated) and list of gcreloc calls scheduled for visiting (this is
      34             : /// used for a debug mode consistency check only).  The spill slot tracking
      35             : /// works in concert with information in FunctionLoweringInfo.
      36             : class StatepointLoweringState {
      37             : public:
      38       29262 :   StatepointLoweringState() = default;
      39             : 
      40             :   /// Reset all state tracking for a newly encountered safepoint.  Also
      41             :   /// performs some consistency checking.
      42             :   void startNewStatepoint(SelectionDAGBuilder &Builder);
      43             : 
      44             :   /// Clear the memory usage of this object.  This is called from
      45             :   /// SelectionDAGBuilder::clear.  We require this is never called in the
      46             :   /// midst of processing a statepoint sequence.
      47             :   void clear();
      48             : 
      49             :   /// Returns the spill location of a value incoming to the current
      50             :   /// statepoint.  Will return SDValue() if this value hasn't been
      51             :   /// spilled.  Otherwise, the value has already been spilled and no
      52             :   /// further action is required by the caller.
      53         314 :   SDValue getLocation(SDValue Val) {
      54         314 :     auto I = Locations.find(Val);
      55         314 :     if (I == Locations.end())
      56         184 :       return SDValue();
      57         130 :     return I->second;
      58             :   }
      59             : 
      60             :   void setLocation(SDValue Val, SDValue Location) {
      61             :     assert(!Locations.count(Val) &&
      62             :            "Trying to allocate already allocated location");
      63          69 :     Locations[Val] = Location;
      64             :   }
      65             : 
      66             :   /// Record the fact that we expect to encounter a given gc_relocate
      67             :   /// before the next statepoint.  If we don't see it, we'll report
      68             :   /// an assertion.
      69             :   void scheduleRelocCall(const CallInst &RelocCall) {
      70             :     PendingGCRelocateCalls.push_back(&RelocCall);
      71             :   }
      72             : 
      73             :   /// Remove this gc_relocate from the list we're expecting to see
      74             :   /// before the next statepoint.  If we weren't expecting to see
      75             :   /// it, we'll report an assertion.
      76             :   void relocCallVisited(const CallInst &RelocCall) {
      77             :     auto I = llvm::find(PendingGCRelocateCalls, &RelocCall);
      78             :     assert(I != PendingGCRelocateCalls.end() &&
      79             :            "Visited unexpected gcrelocate call");
      80             :     PendingGCRelocateCalls.erase(I);
      81             :   }
      82             : 
      83             :   // TODO: Should add consistency tracking to ensure we encounter
      84             :   // expected gc_result calls too.
      85             : 
      86             :   /// Get a stack slot we can use to store an value of type ValueType.  This
      87             :   /// will hopefully be a recylced slot from another statepoint.
      88             :   SDValue allocateStackSlot(EVT ValueType, SelectionDAGBuilder &Builder);
      89             : 
      90             :   void reserveStackSlot(int Offset) {
      91             :     assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
      92             :            "out of bounds");
      93             :     assert(!AllocatedStackSlots.test(Offset) && "already reserved!");
      94             :     assert(NextSlotToAllocate <= (unsigned)Offset && "consistency!");
      95           9 :     AllocatedStackSlots.set(Offset);
      96             :   }
      97             : 
      98             :   bool isStackSlotAllocated(int Offset) {
      99             :     assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
     100             :            "out of bounds");
     101           9 :     return AllocatedStackSlots.test(Offset);
     102             :   }
     103             : 
     104             : private:
     105             :   /// Maps pre-relocation value (gc pointer directly incoming into statepoint)
     106             :   /// into it's location (currently only stack slots)
     107             :   DenseMap<SDValue, SDValue> Locations;
     108             : 
     109             :   /// A boolean indicator for each slot listed in the FunctionInfo as to
     110             :   /// whether it has been used in the current statepoint.  Since we try to
     111             :   /// preserve stack slots across safepoints, there can be gaps in which
     112             :   /// slots have been allocated.
     113             :   SmallBitVector AllocatedStackSlots;
     114             : 
     115             :   /// Points just beyond the last slot known to have been allocated
     116             :   unsigned NextSlotToAllocate = 0;
     117             : 
     118             :   /// Keep track of pending gcrelocate calls for consistency check
     119             :   SmallVector<const CallInst *, 10> PendingGCRelocateCalls;
     120             : };
     121             : 
     122             : } // end namespace llvm
     123             : 
     124             : #endif // LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H