1 //===-- NEONPreAllocPass.cpp - Allocate adjacent NEON registers--*- 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 #define DEBUG_TYPE "neon-prealloc"
12 #include "ARMInstrInfo.h"
13 #include "llvm/CodeGen/MachineInstr.h"
14 #include "llvm/CodeGen/MachineInstrBuilder.h"
15 #include "llvm/CodeGen/MachineFunctionPass.h"
19 class VISIBILITY_HIDDEN NEONPreAllocPass : public MachineFunctionPass {
20 const TargetInstrInfo *TII;
24 NEONPreAllocPass() : MachineFunctionPass(&ID) {}
26 virtual bool runOnMachineFunction(MachineFunction &MF);
28 virtual const char *getPassName() const {
29 return "NEON register pre-allocation pass";
33 bool PreAllocNEONRegisters(MachineBasicBlock &MBB);
36 char NEONPreAllocPass::ID = 0;
39 static bool isNEONMultiRegOp(int Opcode, unsigned &FirstOpnd, unsigned &NumRegs,
40 unsigned &Offset, unsigned &Stride) {
41 // Default to unit stride with no offset.
193 bool NEONPreAllocPass::PreAllocNEONRegisters(MachineBasicBlock &MBB) {
194 bool Modified = false;
196 MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
197 for (; MBBI != E; ++MBBI) {
198 MachineInstr *MI = &*MBBI;
199 unsigned FirstOpnd, NumRegs, Offset, Stride;
200 if (!isNEONMultiRegOp(MI->getOpcode(), FirstOpnd, NumRegs, Offset, Stride))
203 MachineBasicBlock::iterator NextI = next(MBBI);
204 for (unsigned R = 0; R < NumRegs; ++R) {
205 MachineOperand &MO = MI->getOperand(FirstOpnd + R);
206 assert(MO.isReg() && MO.getSubReg() == 0 && "unexpected operand");
207 unsigned VirtReg = MO.getReg();
208 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
209 "expected a virtual register");
211 // For now, just assign a fixed set of adjacent registers.
212 // This leaves plenty of room for future improvements.
213 static const unsigned NEONDRegs[] = {
214 ARM::D0, ARM::D1, ARM::D2, ARM::D3,
215 ARM::D4, ARM::D5, ARM::D6, ARM::D7
217 MO.setReg(NEONDRegs[Offset + R * Stride]);
220 // Insert a copy from VirtReg.
221 TII->copyRegToReg(MBB, MBBI, MO.getReg(), VirtReg,
222 ARM::DPRRegisterClass, ARM::DPRRegisterClass);
224 MachineInstr *CopyMI = prior(MBBI);
225 CopyMI->findRegisterUseOperand(VirtReg)->setIsKill();
228 } else if (MO.isDef() && !MO.isDead()) {
229 // Add a copy to VirtReg.
230 TII->copyRegToReg(MBB, NextI, VirtReg, MO.getReg(),
231 ARM::DPRRegisterClass, ARM::DPRRegisterClass);
239 bool NEONPreAllocPass::runOnMachineFunction(MachineFunction &MF) {
240 TII = MF.getTarget().getInstrInfo();
242 bool Modified = false;
243 for (MachineFunction::iterator MFI = MF.begin(), E = MF.end(); MFI != E;
245 MachineBasicBlock &MBB = *MFI;
246 Modified |= PreAllocNEONRegisters(MBB);
252 /// createNEONPreAllocPass - returns an instance of the NEON register
253 /// pre-allocation pass.
254 FunctionPass *llvm::createNEONPreAllocPass() {
255 return new NEONPreAllocPass();