88 lines
3.4 KiB
C++
88 lines
3.4 KiB
C++
//===- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- C++ -*-===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements the AntiDepBreaker class, which implements
|
|
// anti-dependence breaking heuristics for post-register-allocation scheduling.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H
|
|
#define LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H
|
|
|
|
#include "llvm/ADT/iterator_range.h"
|
|
#include "llvm/CodeGen/MachineBasicBlock.h"
|
|
#include "llvm/CodeGen/MachineInstr.h"
|
|
#include "llvm/CodeGen/MachineOperand.h"
|
|
#include "llvm/CodeGen/ScheduleDAG.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include <cassert>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
namespace llvm {
|
|
|
|
/// This class works in conjunction with the post-RA scheduler to rename
|
|
/// registers to break register anti-dependencies (WAR hazards).
|
|
class LLVM_LIBRARY_VISIBILITY AntiDepBreaker {
|
|
public:
|
|
using DbgValueVector =
|
|
std::vector<std::pair<MachineInstr *, MachineInstr *>>;
|
|
|
|
virtual ~AntiDepBreaker();
|
|
|
|
/// Initialize anti-dep breaking for a new basic block.
|
|
virtual void StartBlock(MachineBasicBlock *BB) = 0;
|
|
|
|
/// Identifiy anti-dependencies within a basic-block region and break them by
|
|
/// renaming registers. Return the number of anti-dependencies broken.
|
|
virtual unsigned BreakAntiDependencies(const std::vector<SUnit> &SUnits,
|
|
MachineBasicBlock::iterator Begin,
|
|
MachineBasicBlock::iterator End,
|
|
unsigned InsertPosIndex,
|
|
DbgValueVector &DbgValues) = 0;
|
|
|
|
/// Update liveness information to account for the current
|
|
/// instruction, which will not be scheduled.
|
|
virtual void Observe(MachineInstr &MI, unsigned Count,
|
|
unsigned InsertPosIndex) = 0;
|
|
|
|
/// Finish anti-dep breaking for a basic block.
|
|
virtual void FinishBlock() = 0;
|
|
|
|
/// Update DBG_VALUE if dependency breaker is updating
|
|
/// other machine instruction to use NewReg.
|
|
void UpdateDbgValue(MachineInstr &MI, unsigned OldReg, unsigned NewReg) {
|
|
assert(MI.isDebugValue() && "MI is not DBG_VALUE!");
|
|
if (MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == OldReg)
|
|
MI.getOperand(0).setReg(NewReg);
|
|
}
|
|
|
|
/// Update all DBG_VALUE instructions that may be affected by the dependency
|
|
/// breaker's update of ParentMI to use NewReg.
|
|
void UpdateDbgValues(const DbgValueVector &DbgValues, MachineInstr *ParentMI,
|
|
unsigned OldReg, unsigned NewReg) {
|
|
// The following code is dependent on the order in which the DbgValues are
|
|
// constructed in ScheduleDAGInstrs::buildSchedGraph.
|
|
MachineInstr *PrevDbgMI = nullptr;
|
|
for (const auto &DV : make_range(DbgValues.crbegin(), DbgValues.crend())) {
|
|
MachineInstr *PrevMI = DV.second;
|
|
if ((PrevMI == ParentMI) || (PrevMI == PrevDbgMI)) {
|
|
MachineInstr *DbgMI = DV.first;
|
|
UpdateDbgValue(*DbgMI, OldReg, NewReg);
|
|
PrevDbgMI = DbgMI;
|
|
} else if (PrevDbgMI) {
|
|
break; // If no match and already found a DBG_VALUE, we're done.
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
} // end namespace llvm
|
|
|
|
#endif // LLVM_LIB_CODEGEN_ANTIDEPBREAKER_H
|