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[NFC][RA] Refactor RABasic into a Separate Header #149555

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92 changes: 1 addition & 91 deletions llvm/lib/CodeGen/RegAllocBasic.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -11,29 +11,20 @@
//
//===----------------------------------------------------------------------===//

#include "AllocationOrder.h"
#include "RegAllocBase.h"
#include "RegAllocBasic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveDebugVariables.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/LiveRangeEdit.h"
#include "llvm/CodeGen/LiveRegMatrix.h"
#include "llvm/CodeGen/LiveStacks.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/CodeGen/Spiller.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <queue>

using namespace llvm;

Expand All @@ -42,89 +33,8 @@ using namespace llvm;
static RegisterRegAlloc basicRegAlloc("basic", "basic register allocator",
createBasicRegisterAllocator);

namespace {
struct CompSpillWeight {
bool operator()(const LiveInterval *A, const LiveInterval *B) const {
return A->weight() < B->weight();
}
};
}

namespace {
/// RABasic provides a minimal implementation of the basic register allocation
/// algorithm. It prioritizes live virtual registers by spill weight and spills
/// whenever a register is unavailable. This is not practical in production but
/// provides a useful baseline both for measuring other allocators and comparing
/// the speed of the basic algorithm against other styles of allocators.
class RABasic : public MachineFunctionPass,
public RegAllocBase,
private LiveRangeEdit::Delegate {
// context
MachineFunction *MF = nullptr;

// state
std::unique_ptr<Spiller> SpillerInstance;
std::priority_queue<const LiveInterval *, std::vector<const LiveInterval *>,
CompSpillWeight>
Queue;

// Scratch space. Allocated here to avoid repeated malloc calls in
// selectOrSplit().
BitVector UsableRegs;

bool LRE_CanEraseVirtReg(Register) override;
void LRE_WillShrinkVirtReg(Register) override;

public:
RABasic(const RegAllocFilterFunc F = nullptr);

/// Return the pass name.
StringRef getPassName() const override { return "Basic Register Allocator"; }

/// RABasic analysis usage.
void getAnalysisUsage(AnalysisUsage &AU) const override;

void releaseMemory() override;

Spiller &spiller() override { return *SpillerInstance; }

void enqueueImpl(const LiveInterval *LI) override { Queue.push(LI); }

const LiveInterval *dequeue() override {
if (Queue.empty())
return nullptr;
const LiveInterval *LI = Queue.top();
Queue.pop();
return LI;
}

MCRegister selectOrSplit(const LiveInterval &VirtReg,
SmallVectorImpl<Register> &SplitVRegs) override;

/// Perform register allocation.
bool runOnMachineFunction(MachineFunction &mf) override;

MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().setNoPHIs();
}

MachineFunctionProperties getClearedProperties() const override {
return MachineFunctionProperties().setIsSSA();
}

// Helper for spilling all live virtual registers currently unified under preg
// that interfere with the most recently queried lvr. Return true if spilling
// was successful, and append any new spilled/split intervals to splitLVRs.
bool spillInterferences(const LiveInterval &VirtReg, MCRegister PhysReg,
SmallVectorImpl<Register> &SplitVRegs);

static char ID;
};

char RABasic::ID = 0;

} // end anonymous namespace

char &llvm::RABasicID = RABasic::ID;

INITIALIZE_PASS_BEGIN(RABasic, "regallocbasic", "Basic Register Allocator",
Expand Down
107 changes: 107 additions & 0 deletions llvm/lib/CodeGen/RegAllocBasic.h
Original file line number Diff line number Diff line change
@@ -0,0 +1,107 @@
//===-- RegAllocBasic.h - Basic Register Allocator Header -----------------===//
//
// 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 declares the RABasic class, which provides a minimal
// implementation of the basic register allocator.
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use syntax recognized by doxygen (and possibly fix the pre-existing problem in RegAllocBasic.cpp)

Suggested change
// This file declares the RABasic class, which provides a minimal
// implementation of the basic register allocator.
/// \file This file declares the RABasic class, which provides a minimal
/// implementation of the basic register allocator.

//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_REGALLOCBAISC_H_
#define LLVM_CODEGEN_REGALLOCBAISC_H_
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@MatzeB MatzeB Jul 18, 2025

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Suggested change
#ifndef LLVM_CODEGEN_REGALLOCBAISC_H_
#define LLVM_CODEGEN_REGALLOCBAISC_H_
#ifndef LLVM_CODEGEN_REGALLOCBASIC_H
#define LLVM_CODEGEN_REGALLOCBASIC_H

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most files tend to use LLVM_LIB_CODEGEN_XXXX_H it seems...


#include "AllocationOrder.h"
#include "RegAllocBase.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/LiveRangeEdit.h"
#include "llvm/CodeGen/LiveRegMatrix.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/Spiller.h"
#include "llvm/CodeGen/VirtRegMap.h"
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Please check which include files are actually needed, and which ones can be replaced with class xxx; forward declarations. LiveRegMatrix and VirtRegMap seem unused at a first glance...

#include <queue>

namespace llvm {

struct CompSpillWeight {
bool operator()(const LiveInterval *A, const LiveInterval *B) const {
return A->weight() < B->weight();
}
};

/// RABasic provides a minimal implementation of the basic register allocation
/// algorithm. It prioritizes live virtual registers by spill weight and spills
/// whenever a register is unavailable. This is not practical in production but
/// provides a useful baseline both for measuring other allocators and comparing
/// the speed of the basic algorithm against other styles of allocators.
class LLVM_LIBRARY_VISIBILITY RABasic : public MachineFunctionPass,
public RegAllocBase,
private LiveRangeEdit::Delegate {
// context
MachineFunction *MF = nullptr;

// state
std::unique_ptr<Spiller> SpillerInstance;
std::priority_queue<const LiveInterval *, std::vector<const LiveInterval *>,
CompSpillWeight>
Queue;

// Scratch space. Allocated here to avoid repeated malloc calls in
// selectOrSplit().
BitVector UsableRegs;

bool LRE_CanEraseVirtReg(Register) override;
void LRE_WillShrinkVirtReg(Register) override;

public:
RABasic(const RegAllocFilterFunc F = nullptr);

/// Return the pass name.
StringRef getPassName() const override { return "Basic Register Allocator"; }

/// RABasic analysis usage.
void getAnalysisUsage(AnalysisUsage &AU) const override;

void releaseMemory() override;

Spiller &spiller() override { return *SpillerInstance; }

void enqueueImpl(const LiveInterval *LI) override { Queue.push(LI); }

const LiveInterval *dequeue() override {
if (Queue.empty())
return nullptr;
const LiveInterval *LI = Queue.top();
Queue.pop();
return LI;
}

MCRegister selectOrSplit(const LiveInterval &VirtReg,
SmallVectorImpl<Register> &SplitVRegs) override;

/// Perform register allocation.
bool runOnMachineFunction(MachineFunction &mf) override;

MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().set(
MachineFunctionProperties::Property::NoPHIs);
}

MachineFunctionProperties getClearedProperties() const override {
return MachineFunctionProperties().set(
MachineFunctionProperties::Property::IsSSA);
}

// Helper for spilling all live virtual registers currently unified under preg
// that interfere with the most recently queried lvr. Return true if spilling
// was successful, and append any new spilled/split intervals to splitLVRs.
bool spillInterferences(const LiveInterval &VirtReg, MCRegister PhysReg,
SmallVectorImpl<Register> &SplitVRegs);

static char ID;
};
} // namespace llvm
#endif // #ifndef LLVM_CODEGEN_REGALLOCBAISC_H_
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Suggested change
#endif // #ifndef LLVM_CODEGEN_REGALLOCBAISC_H_
#endif

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