llvm/llvm/lib/Target/AMDGPU/GCNPreRAOptimizations.cpp

//===-- GCNPreRAOptimizations.cpp -----------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This pass combines split register tuple initialization into a single pseudo:
///
///   undef %0.sub1:sreg_64 = S_MOV_B32 1
///   %0.sub0:sreg_64 = S_MOV_B32 2
/// =>
///   %0:sreg_64 = S_MOV_B64_IMM_PSEUDO 0x200000001
///
/// This is to allow rematerialization of a value instead of spilling. It is
/// supposed to be done after register coalescer to allow it to do its job and
/// before actual register allocation to allow rematerialization.
///
/// Right now the pass only handles 64 bit SGPRs with immediate initializers,
/// although the same shall be possible with other register classes and
/// instructions if necessary.
///
//===----------------------------------------------------------------------===//

#include "AMDGPU.h"
#include "GCNSubtarget.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/InitializePasses.h"

usingnamespacellvm;

#define DEBUG_TYPE …

namespace {

class GCNPreRAOptimizations : public MachineFunctionPass { … };

} // End anonymous namespace.

INITIALIZE_PASS_BEGIN(GCNPreRAOptimizations, DEBUG_TYPE,
                      "AMDGPU Pre-RA optimizations", false, false)
INITIALIZE_PASS_DEPENDENCY(LiveIntervalsWrapperPass)
INITIALIZE_PASS_END(GCNPreRAOptimizations, DEBUG_TYPE, "Pre-RA optimizations",
                    false, false)

char GCNPreRAOptimizations::ID = …;

char &llvm::GCNPreRAOptimizationsID = …;

FunctionPass *llvm::createGCNPreRAOptimizationsPass() { … }

bool GCNPreRAOptimizations::processReg(Register Reg) { … }

bool GCNPreRAOptimizations::runOnMachineFunction(MachineFunction &MF) { … }