// register allocation algorithm and interface for extending it. It provides the
// building blocks on which to construct other experimental allocators and test
// the validity of two principles:
-//
+//
// - If virtual and physical register liveness is modeled using intervals, then
// on-the-fly interference checking is cheap. Furthermore, interferences can be
// lazily cached and reused.
-//
+//
// - Register allocation complexity, and generated code performance is
// determined by the effectiveness of live range splitting rather than optimal
// coloring.
// of registers, if a more sophisticated allocator chooses to do that.
//
// This framework provides a way to engineer the compile time vs. code
-// quality trade-off without relying a particular theoretical solver.
+// quality trade-off without relying on a particular theoretical solver.
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_CODEGEN_REGALLOCBASE
-#define LLVM_CODEGEN_REGALLOCBASE
+#ifndef LLVM_LIB_CODEGEN_REGALLOCBASE_H
+#define LLVM_LIB_CODEGEN_REGALLOCBASE_H
-#include "llvm/ADT/OwningPtr.h"
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/CodeGen/RegisterClassInfo.h"
namespace llvm {
class TargetRegisterInfo;
class VirtRegMap;
class LiveIntervals;
-
-// Heuristic that determines the priority of assigning virtual to physical
-// registers. The main impact of the heuristic is expected to be compile time.
-// The default is to simply compare spill weights.
-struct LessSpillWeightPriority
- : public std::binary_function<LiveInterval,LiveInterval, bool> {
- bool operator()(const LiveInterval *left, const LiveInterval *right) const {
- return left->weight < right->weight;
- }
-};
-
-// Forward declare a priority queue of live virtual registers. If an
-// implementation needs to prioritize by anything other than spill weight, then
-// this will become an abstract base class with virtual calls to push/get.
-class LiveVirtRegQueue;
+class LiveRegMatrix;
+class Spiller;
/// RegAllocBase provides the register allocation driver and interface that can
/// be extended to add interesting heuristics.
///
-/// More sophisticated allocators must override the selectOrSplit() method to
-/// implement live range splitting and must specify a comparator to determine
-/// register assignment priority. LessSpillWeightPriority is provided as a
-/// standard comparator.
+/// Register allocators must override the selectOrSplit() method to implement
+/// live range splitting. They must also override enqueue/dequeue to provide an
+/// assignment order.
class RegAllocBase {
+ virtual void anchor();
protected:
- // Array of LiveIntervalUnions indexed by physical register.
- class LIUArray {
- unsigned nRegs_;
- OwningArrayPtr<LiveIntervalUnion> array_;
- public:
- LIUArray(): nRegs_(0) {}
-
- unsigned numRegs() const { return nRegs_; }
-
- void init(unsigned nRegs);
-
- void clear();
-
- LiveIntervalUnion& operator[](unsigned physReg) {
- assert(physReg < nRegs_ && "physReg out of bounds");
- return array_[physReg];
- }
- };
-
- const TargetRegisterInfo *tri_;
- VirtRegMap *vrm_;
- LiveIntervals *lis_;
- LIUArray physReg2liu_;
-
- // Current queries, one per physreg. They must be reinitialized each time we
- // query on a new live virtual register.
- OwningArrayPtr<LiveIntervalUnion::Query> queries_;
-
- RegAllocBase(): tri_(0), vrm_(0), lis_(0) {}
+ const TargetRegisterInfo *TRI;
+ MachineRegisterInfo *MRI;
+ VirtRegMap *VRM;
+ LiveIntervals *LIS;
+ LiveRegMatrix *Matrix;
+ RegisterClassInfo RegClassInfo;
+
+ RegAllocBase()
+ : TRI(nullptr), MRI(nullptr), VRM(nullptr), LIS(nullptr), Matrix(nullptr) {}
virtual ~RegAllocBase() {}
// A RegAlloc pass should call this before allocatePhysRegs.
- void init(const TargetRegisterInfo &tri, VirtRegMap &vrm, LiveIntervals &lis);
+ void init(VirtRegMap &vrm, LiveIntervals &lis, LiveRegMatrix &mat);
// The top-level driver. The output is a VirtRegMap that us updated with
// physical register assignments.
- //
- // If an implementation wants to override the LiveInterval comparator, we
- // should modify this interface to allow passing in an instance derived from
- // LiveVirtRegQueue.
void allocatePhysRegs();
+ // Get a temporary reference to a Spiller instance.
+ virtual Spiller &spiller() = 0;
+
+ /// enqueue - Add VirtReg to the priority queue of unassigned registers.
+ virtual void enqueue(LiveInterval *LI) = 0;
+
+ /// dequeue - Return the next unassigned register, or NULL.
+ virtual LiveInterval *dequeue() = 0;
+
// A RegAlloc pass should override this to provide the allocation heuristics.
// Each call must guarantee forward progess by returning an available PhysReg
// or new set of split live virtual registers. It is up to the splitter to
// converge quickly toward fully spilled live ranges.
- virtual unsigned selectOrSplit(LiveInterval &lvr,
- SmallVectorImpl<LiveInterval*> &splitLVRs) = 0;
+ virtual unsigned selectOrSplit(LiveInterval &VirtReg,
+ SmallVectorImpl<unsigned> &splitLVRs) = 0;
- // A RegAlloc pass should call this when PassManager releases its memory.
- virtual void releaseMemory();
+ // Use this group name for NamedRegionTimer.
+ static const char TimerGroupName[];
- // Helper for checking interference between a live virtual register and a
- // physical register, including all its register aliases. If an interference
- // exists, return the interfering register, which may be preg or an alias.
- unsigned checkPhysRegInterference(LiveInterval& lvr, unsigned preg);
+ /// Method called when the allocator is about to remove a LiveInterval.
+ virtual void aboutToRemoveInterval(LiveInterval &LI) {}
- // Helper that spills all live virtual registers currently unified under preg
- // that interfere with the most recently queried lvr.
- void spillInterferences(unsigned preg,
- SmallVectorImpl<LiveInterval*> &splitLVRs);
+public:
+ /// VerifyEnabled - True when -verify-regalloc is given.
+ static bool VerifyEnabled;
private:
- void seedLiveVirtRegs(LiveVirtRegQueue &lvrQ);
+ void seedLiveRegs();
};
} // end namespace llvm
-#endif // !defined(LLVM_CODEGEN_REGALLOCBASE)
+#endif
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