Break anti-dependence breaking out into its own class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85127 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 95 insertions, 0 deletions

diff --git a/lib/CodeGen/CriticalAntiDepBreaker.h b/lib/CodeGen/CriticalAntiDepBreaker.h
new file mode 100644
index 0000000..830b29a
--- /dev/null
+++ b/lib/CodeGen/CriticalAntiDepBreaker.h
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+//=- llvm/CodeGen/CriticalAntiDepBreaker.h - Anti-Dep Support -*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the CriticalAntiDepBreaker class, which
+// implements register anti-dependence breaking along a blocks
+// critical path during post-RA scheduler.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H
+#define LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H
+
+#include "llvm/CodeGen/AntiDepBreaker.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/SmallSet.h"
+
+namespace llvm {
+  class CriticalAntiDepBreaker : public AntiDepBreaker {
+    MachineFunction& MF;
+    MachineRegisterInfo &MRI;
+    const TargetRegisterInfo *TRI;
+
+    /// AllocatableSet - The set of allocatable registers.
+    /// We'll be ignoring anti-dependencies on non-allocatable registers,
+    /// because they may not be safe to break.
+    const BitVector AllocatableSet;
+
+    /// Classes - For live regs that are only used in one register class in a
+    /// live range, the register class. If the register is not live, the
+    /// corresponding value is null. If the register is live but used in
+    /// multiple register classes, the corresponding value is -1 casted to a
+    /// pointer.
+    const TargetRegisterClass *
+      Classes[TargetRegisterInfo::FirstVirtualRegister];
+
+    /// RegRegs - Map registers to all their references within a live range.
+    std::multimap<unsigned, MachineOperand *> RegRefs;
+
+    /// KillIndices - The index of the most recent kill (proceding bottom-up),
+    /// or ~0u if the register is not live.
+    unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister];
+
+    /// DefIndices - The index of the most recent complete def (proceding bottom
+    /// up), or ~0u if the register is live.
+    unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister];
+
+    /// KeepRegs - A set of registers which are live and cannot be changed to
+    /// break anti-dependencies.
+    SmallSet<unsigned, 4> KeepRegs;
+
+  public:
+    CriticalAntiDepBreaker(MachineFunction& MFi);
+    ~CriticalAntiDepBreaker();
+    
+    /// Start - Initialize anti-dep breaking for a new basic block.
+    void StartBlock(MachineBasicBlock *BB);
+
+    /// BreakAntiDependencies - Identifiy anti-dependencies along the critical path
+    /// of the ScheduleDAG and break them by renaming registers.
+    ///
+    unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
+                                   MachineBasicBlock::iterator& Begin,
+                                   MachineBasicBlock::iterator& End,
+                                   unsigned InsertPosIndex);
+
+    /// Observe - Update liveness information to account for the current
+    /// instruction, which will not be scheduled.
+    ///
+    void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex);
+
+    /// Finish - Finish anti-dep breaking for a basic block.
+    void FinishBlock();
+
+  private:
+    void PrescanInstruction(MachineInstr *MI);
+    void ScanInstruction(MachineInstr *MI, unsigned Count);
+    unsigned findSuitableFreeRegister(unsigned AntiDepReg,
+                                      unsigned LastNewReg,
+                                      const TargetRegisterClass *);
+  };
+}
+
+#endif