Run branch folding if if-converter make some transformations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80994 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/BranchFolding.h b/lib/CodeGen/BranchFolding.h
new file mode 100644
index 0000000..9763e33
--- /dev/null
+++ b/lib/CodeGen/BranchFolding.h
@@ -0,0 +1,84 @@
+//===-- BranchFolding.h - Fold machine code branch instructions --*- C++ -*===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_BRANCHFOLDING_HPP
+#define LLVM_CODEGEN_BRANCHFOLDING_HPP
+
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include <vector>
+
+namespace llvm {
+ class MachineFunction;
+ class MachineModuleInfo;
+ class RegScavenger;
+ class TargetInstrInfo;
+ class TargetRegisterInfo;
+
+ class BranchFolder {
+ public:
+ explicit BranchFolder(bool defaultEnableTailMerge);
+
+ bool OptimizeFunction(MachineFunction &MF,
+ const TargetInstrInfo *tii,
+ const TargetRegisterInfo *tri,
+ MachineModuleInfo *mmi);
+ private:
+ typedef std::pair<unsigned,MachineBasicBlock*> MergePotentialsElt;
+ typedef std::vector<MergePotentialsElt>::iterator MPIterator;
+ std::vector<MergePotentialsElt> MergePotentials;
+
+ typedef std::pair<MPIterator, MachineBasicBlock::iterator> SameTailElt;
+ std::vector<SameTailElt> SameTails;
+
+ bool EnableTailMerge;
+ const TargetInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
+ MachineModuleInfo *MMI;
+ RegScavenger *RS;
+
+ bool TailMergeBlocks(MachineFunction &MF);
+ bool TryMergeBlocks(MachineBasicBlock* SuccBB,
+ MachineBasicBlock* PredBB);
+ void ReplaceTailWithBranchTo(MachineBasicBlock::iterator OldInst,
+ MachineBasicBlock *NewDest);
+ MachineBasicBlock *SplitMBBAt(MachineBasicBlock &CurMBB,
+ MachineBasicBlock::iterator BBI1);
+ unsigned ComputeSameTails(unsigned CurHash, unsigned minCommonTailLength);
+ void RemoveBlocksWithHash(unsigned CurHash, MachineBasicBlock* SuccBB,
+ MachineBasicBlock* PredBB);
+ unsigned CreateCommonTailOnlyBlock(MachineBasicBlock *&PredBB,
+ unsigned maxCommonTailLength);
+
+ bool OptimizeBranches(MachineFunction &MF);
+ bool OptimizeBlock(MachineBasicBlock *MBB);
+ void RemoveDeadBlock(MachineBasicBlock *MBB);
+ bool OptimizeImpDefsBlock(MachineBasicBlock *MBB);
+
+ bool CanFallThrough(MachineBasicBlock *CurBB);
+ bool CanFallThrough(MachineBasicBlock *CurBB, bool BranchUnAnalyzable,
+ MachineBasicBlock *TBB, MachineBasicBlock *FBB,
+ const SmallVectorImpl<MachineOperand> &Cond);
+ };
+
+
+ /// BranchFolderPass - Wrap branch folder in a machine function pass.
+ class BranchFolderPass : public MachineFunctionPass,
+ public BranchFolder {
+ public:
+ static char ID;
+ explicit BranchFolderPass(bool defaultEnableTailMerge)
+ : MachineFunctionPass(&ID), BranchFolder(defaultEnableTailMerge) {}
+
+ virtual bool runOnMachineFunction(MachineFunction &MF);
+ virtual const char *getPassName() const { return "Control Flow Optimizer"; }
+ };
+}
+
+#endif /* LLVM_CODEGEN_BRANCHFOLDING_HPP */