1 //=- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the AntiDepBreaker class, which implements
11 // anti-dependence breaking heuristics for post-register-allocation scheduling.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H
16 #define LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H
18 #include "llvm/CodeGen/MachineBasicBlock.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/CodeGen/ScheduleDAG.h"
23 #include "llvm/Target/TargetRegisterInfo.h"
28 /// This class works in conjunction with the post-RA scheduler to rename
29 /// registers to break register anti-dependencies (WAR hazards).
30 class AntiDepBreaker {
32 typedef std::vector<std::pair<MachineInstr *, MachineInstr *> >
35 virtual ~AntiDepBreaker();
37 /// Initialize anti-dep breaking for a new basic block.
38 virtual void StartBlock(MachineBasicBlock *BB) =0;
40 /// Identifiy anti-dependencies within a basic-block region and break them by
41 /// renaming registers. Return the number of anti-dependencies broken.
42 virtual unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits,
43 MachineBasicBlock::iterator Begin,
44 MachineBasicBlock::iterator End,
45 unsigned InsertPosIndex,
46 DbgValueVector &DbgValues) = 0;
48 /// Update liveness information to account for the current
49 /// instruction, which will not be scheduled.
50 virtual void Observe(MachineInstr *MI, unsigned Count,
51 unsigned InsertPosIndex) =0;
53 /// Finish anti-dep breaking for a basic block.
54 virtual void FinishBlock() =0;
56 /// Update DBG_VALUE if dependency breaker is updating
57 /// other machine instruction to use NewReg.
58 void UpdateDbgValue(MachineInstr *MI, unsigned OldReg, unsigned NewReg) {
59 assert (MI->isDebugValue() && "MI is not DBG_VALUE!");
60 if (MI && MI->getOperand(0).isReg() && MI->getOperand(0).getReg() == OldReg)
61 MI->getOperand(0).setReg(NewReg);