Moved LiveRangeEdit.h so that it can be called from other parts of the backend, not just libCodeGen

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153906 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 202 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/LiveRangeEdit.h b/include/llvm/CodeGen/LiveRangeEdit.h
new file mode 100644
index 0000000..909130f
--- /dev/null
+++ b/include/llvm/CodeGen/LiveRangeEdit.h
@@ -0,0 +1,202 @@
+//===---- LiveRangeEdit.h - Basic tools for split and spill -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The LiveRangeEdit class represents changes done to a virtual register when it
+// is spilled or split.
+//
+// The parent register is never changed. Instead, a number of new virtual
+// registers are created and added to the newRegs vector.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_LIVERANGEEDIT_H
+#define LLVM_CODEGEN_LIVERANGEEDIT_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/Target/TargetMachine.h"
+
+namespace llvm {
+
+class AliasAnalysis;
+class LiveIntervals;
+class MachineLoopInfo;
+class MachineRegisterInfo;
+class VirtRegMap;
+
+class LiveRangeEdit {
+public:
+  /// Callback methods for LiveRangeEdit owners.
+  class Delegate {
+    virtual void anchor();
+  public:
+    /// Called immediately before erasing a dead machine instruction.
+    virtual void LRE_WillEraseInstruction(MachineInstr *MI) {}
+
+    /// Called when a virtual register is no longer used. Return false to defer
+    /// its deletion from LiveIntervals.
+    virtual bool LRE_CanEraseVirtReg(unsigned) { return true; }
+
+    /// Called before shrinking the live range of a virtual register.
+    virtual void LRE_WillShrinkVirtReg(unsigned) {}
+
+    /// Called after cloning a virtual register.
+    /// This is used for new registers representing connected components of Old.
+    virtual void LRE_DidCloneVirtReg(unsigned New, unsigned Old) {}
+
+    virtual ~Delegate() {}
+  };
+
+private:
+  LiveInterval &parent_;
+  SmallVectorImpl<LiveInterval*> &newRegs_;
+  MachineRegisterInfo &MRI;
+  LiveIntervals &LIS;
+  VirtRegMap *VRM;
+  const TargetInstrInfo &TII;
+  Delegate *const delegate_;
+
+  /// firstNew_ - Index of the first register added to newRegs_.
+  const unsigned firstNew_;
+
+  /// scannedRemattable_ - true when remattable values have been identified.
+  bool scannedRemattable_;
+
+  /// remattable_ - Values defined by remattable instructions as identified by
+  /// tii.isTriviallyReMaterializable().
+  SmallPtrSet<const VNInfo*,4> remattable_;
+
+  /// rematted_ - Values that were actually rematted, and so need to have their
+  /// live range trimmed or entirely removed.
+  SmallPtrSet<const VNInfo*,4> rematted_;
+
+  /// scanRemattable - Identify the parent_ values that may rematerialize.
+  void scanRemattable(AliasAnalysis *aa);
+
+  /// allUsesAvailableAt - Return true if all registers used by OrigMI at
+  /// OrigIdx are also available with the same value at UseIdx.
+  bool allUsesAvailableAt(const MachineInstr *OrigMI, SlotIndex OrigIdx,
+                          SlotIndex UseIdx);
+
+  /// foldAsLoad - If LI has a single use and a single def that can be folded as
+  /// a load, eliminate the register by folding the def into the use.
+  bool foldAsLoad(LiveInterval *LI, SmallVectorImpl<MachineInstr*> &Dead);
+
+public:
+  /// Create a LiveRangeEdit for breaking down parent into smaller pieces.
+  /// @param parent The register being spilled or split.
+  /// @param newRegs List to receive any new registers created. This needn't be
+  ///                empty initially, any existing registers are ignored.
+  LiveRangeEdit(LiveInterval &parent,
+                SmallVectorImpl<LiveInterval*> &newRegs,
+                MachineFunction &MF,
+                LiveIntervals &lis,
+                VirtRegMap *vrm,
+                Delegate *delegate = 0)
+    : parent_(parent), newRegs_(newRegs),
+      MRI(MF.getRegInfo()), LIS(lis), VRM(vrm),
+      TII(*MF.getTarget().getInstrInfo()),
+      delegate_(delegate),
+      firstNew_(newRegs.size()),
+      scannedRemattable_(false) {}
+
+  LiveInterval &getParent() const { return parent_; }
+  unsigned getReg() const { return parent_.reg; }
+
+  /// Iterator for accessing the new registers added by this edit.
+  typedef SmallVectorImpl<LiveInterval*>::const_iterator iterator;
+  iterator begin() const { return newRegs_.begin()+firstNew_; }
+  iterator end() const { return newRegs_.end(); }
+  unsigned size() const { return newRegs_.size()-firstNew_; }
+  bool empty() const { return size() == 0; }
+  LiveInterval *get(unsigned idx) const { return newRegs_[idx+firstNew_]; }
+
+  ArrayRef<LiveInterval*> regs() const {
+    return makeArrayRef(newRegs_).slice(firstNew_);
+  }
+
+  /// createFrom - Create a new virtual register based on OldReg.
+  LiveInterval &createFrom(unsigned OldReg);
+
+  /// create - Create a new register with the same class and original slot as
+  /// parent.
+  LiveInterval &create() {
+    return createFrom(getReg());
+  }
+
+  /// anyRematerializable - Return true if any parent values may be
+  /// rematerializable.
+  /// This function must be called before any rematerialization is attempted.
+  bool anyRematerializable(AliasAnalysis*);
+
+  /// checkRematerializable - Manually add VNI to the list of rematerializable
+  /// values if DefMI may be rematerializable.
+  bool checkRematerializable(VNInfo *VNI, const MachineInstr *DefMI,
+                             AliasAnalysis*);
+
+  /// Remat - Information needed to rematerialize at a specific location.
+  struct Remat {
+    VNInfo *ParentVNI;      // parent_'s value at the remat location.
+    MachineInstr *OrigMI;   // Instruction defining ParentVNI.
+    explicit Remat(VNInfo *ParentVNI) : ParentVNI(ParentVNI), OrigMI(0) {}
+  };
+
+  /// canRematerializeAt - Determine if ParentVNI can be rematerialized at
+  /// UseIdx. It is assumed that parent_.getVNINfoAt(UseIdx) == ParentVNI.
+  /// When cheapAsAMove is set, only cheap remats are allowed.
+  bool canRematerializeAt(Remat &RM,
+                          SlotIndex UseIdx,
+                          bool cheapAsAMove);
+
+  /// rematerializeAt - Rematerialize RM.ParentVNI into DestReg by inserting an
+  /// instruction into MBB before MI. The new instruction is mapped, but
+  /// liveness is not updated.
+  /// Return the SlotIndex of the new instruction.
+  SlotIndex rematerializeAt(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MI,
+                            unsigned DestReg,
+                            const Remat &RM,
+                            const TargetRegisterInfo&,
+                            bool Late = false);
+
+  /// markRematerialized - explicitly mark a value as rematerialized after doing
+  /// it manually.
+  void markRematerialized(const VNInfo *ParentVNI) {
+    rematted_.insert(ParentVNI);
+  }
+
+  /// didRematerialize - Return true if ParentVNI was rematerialized anywhere.
+  bool didRematerialize(const VNInfo *ParentVNI) const {
+    return rematted_.count(ParentVNI);
+  }
+
+  /// eraseVirtReg - Notify the delegate that Reg is no longer in use, and try
+  /// to erase it from LIS.
+  void eraseVirtReg(unsigned Reg);
+
+  /// eliminateDeadDefs - Try to delete machine instructions that are now dead
+  /// (allDefsAreDead returns true). This may cause live intervals to be trimmed
+  /// and further dead efs to be eliminated.
+  /// RegsBeingSpilled lists registers currently being spilled by the register
+  /// allocator.  These registers should not be split into new intervals
+  /// as currently those new intervals are not guaranteed to spill.
+  void eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
+                         ArrayRef<unsigned> RegsBeingSpilled 
+                          = ArrayRef<unsigned>());
+
+  /// calculateRegClassAndHint - Recompute register class and hint for each new
+  /// register.
+  void calculateRegClassAndHint(MachineFunction&,
+                                const MachineLoopInfo&);
+};
+
+}
+
+#endif