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//===-- StatepointLowering.h - SDAGBuilder's statepoint code -*- C++ -*---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file includes support code use by SelectionDAGBuilder when lowering a
// statepoint sequence in SelectionDAG IR.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
#define LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include <vector>
namespace llvm {
class SelectionDAGBuilder;
/// This class tracks both per-statepoint and per-selectiondag information.
/// For each statepoint it tracks locations of it's gc valuess (incoming and
/// relocated) and list of gcreloc calls scheduled for visiting (this is
/// used for a debug mode consistency check only). The spill slot tracking
/// works in concert with information in FunctionLoweringInfo.
class StatepointLoweringState {
public:
StatepointLoweringState() : NextSlotToAllocate(0) {
}
/// Reset all state tracking for a newly encountered safepoint. Also
/// performs some consistency checking.
void startNewStatepoint(SelectionDAGBuilder &Builder);
/// Clear the memory usage of this object. This is called from
/// SelectionDAGBuilder::clear. We require this is never called in the
/// midst of processing a statepoint sequence.
void clear();
/// Returns the spill location of a value incoming to the current
/// statepoint. Will return SDValue() if this value hasn't been
/// spilled. Otherwise, the value has already been spilled and no
/// further action is required by the caller.
SDValue getLocation(SDValue val) {
if (!Locations.count(val))
return SDValue();
return Locations[val];
}
void setLocation(SDValue val, SDValue Location) {
assert(!Locations.count(val) &&
"Trying to allocate already allocated location");
Locations[val] = Location;
}
/// Returns the relocated value for a given input pointer. Will
/// return SDValue() if this value hasn't yet been reloaded from
/// it's stack slot after the statepoint. Otherwise, the value
/// has already been reloaded and the SDValue of that reload will
/// be returned. Note that VMState values are spilled but not
/// reloaded (since they don't change at the safepoint unless
/// also listed in the GC pointer section) and will thus never
/// be in this map
SDValue getRelocLocation(SDValue val) {
if (!RelocLocations.count(val))
return SDValue();
return RelocLocations[val];
}
void setRelocLocation(SDValue val, SDValue Location) {
assert(!RelocLocations.count(val) &&
"Trying to allocate already allocated location");
RelocLocations[val] = Location;
}
/// Record the fact that we expect to encounter a given gc_relocate
/// before the next statepoint. If we don't see it, we'll report
/// an assertion.
void scheduleRelocCall(const CallInst &RelocCall) {
PendingGCRelocateCalls.push_back(&RelocCall);
}
/// Remove this gc_relocate from the list we're expecting to see
/// before the next statepoint. If we weren't expecting to see
/// it, we'll report an assertion.
void relocCallVisited(const CallInst &RelocCall) {
SmallVectorImpl<const CallInst *>::iterator itr =
std::find(PendingGCRelocateCalls.begin(), PendingGCRelocateCalls.end(),
&RelocCall);
assert(itr != PendingGCRelocateCalls.end() &&
"Visited unexpected gcrelocate call");
PendingGCRelocateCalls.erase(itr);
}
// TODO: Should add consistency tracking to ensure we encounter
// expected gc_result calls too.
/// Get a stack slot we can use to store an value of type ValueType. This
/// will hopefully be a recylced slot from another statepoint.
SDValue allocateStackSlot(EVT ValueType, SelectionDAGBuilder &Builder);
void reserveStackSlot(int Offset) {
assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
"out of bounds");
assert(!AllocatedStackSlots[Offset] && "already reserved!");
assert(NextSlotToAllocate <= (unsigned)Offset && "consistency!");
AllocatedStackSlots[Offset] = true;
}
bool isStackSlotAllocated(int Offset) {
assert(Offset >= 0 && Offset < (int)AllocatedStackSlots.size() &&
"out of bounds");
return AllocatedStackSlots[Offset];
}
private:
/// Maps pre-relocation value (gc pointer directly incoming into statepoint)
/// into it's location (currently only stack slots)
DenseMap<SDValue, SDValue> Locations;
/// Map pre-relocated value into it's new relocated location
DenseMap<SDValue, SDValue> RelocLocations;
/// A boolean indicator for each slot listed in the FunctionInfo as to
/// whether it has been used in the current statepoint. Since we try to
/// preserve stack slots across safepoints, there can be gaps in which
/// slots have been allocated.
SmallVector<bool, 50> AllocatedStackSlots;
/// Points just beyond the last slot known to have been allocated
unsigned NextSlotToAllocate;
/// Keep track of pending gcrelocate calls for consistency check
SmallVector<const CallInst *, 10> PendingGCRelocateCalls;
};
} // end namespace llvm
#endif // LLVM_LIB_CODEGEN_SELECTIONDAG_STATEPOINTLOWERING_H
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