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/MachineRegisterInfo.h"
16 #include "llvm/CodeGen/MachineFunctionPass.h"
20 class NEONPreAllocPass : public MachineFunctionPass {
21 const TargetInstrInfo *TII;
22 MachineRegisterInfo *MRI;
26 NEONPreAllocPass() : MachineFunctionPass(ID) {}
28 virtual bool runOnMachineFunction(MachineFunction &MF);
30 virtual const char *getPassName() const {
31 return "NEON register pre-allocation pass";
35 bool FormsRegSequence(MachineInstr *MI,
36 unsigned FirstOpnd, unsigned NumRegs,
37 unsigned Offset, unsigned Stride) const;
38 bool PreAllocNEONRegisters(MachineBasicBlock &MBB);
41 char NEONPreAllocPass::ID = 0;
44 static bool isNEONMultiRegOp(int Opcode, unsigned &FirstOpnd, unsigned &NumRegs,
45 unsigned &Offset, unsigned &Stride) {
46 // Default to unit stride with no offset.
69 case ARM::VLD2LNq16odd:
70 case ARM::VLD2LNq32odd:
89 case ARM::VLD3q16_UPD:
90 case ARM::VLD3q32_UPD:
97 case ARM::VLD3q8odd_UPD:
98 case ARM::VLD3q16odd_UPD:
99 case ARM::VLD3q32odd_UPD:
114 case ARM::VLD3LNq16odd:
115 case ARM::VLD3LNq32odd:
133 case ARM::VLD4q8_UPD:
134 case ARM::VLD4q16_UPD:
135 case ARM::VLD4q32_UPD:
142 case ARM::VLD4q8odd_UPD:
143 case ARM::VLD4q16odd_UPD:
144 case ARM::VLD4q32odd_UPD:
159 case ARM::VLD4LNq16odd:
160 case ARM::VLD4LNq32odd:
182 case ARM::VST2LNq16odd:
183 case ARM::VST2LNq32odd:
205 case ARM::VST3LNq16odd:
206 case ARM::VST3LNq32odd:
228 case ARM::VST4LNq16odd:
229 case ARM::VST4LNq32odd:
271 NEONPreAllocPass::FormsRegSequence(MachineInstr *MI,
272 unsigned FirstOpnd, unsigned NumRegs,
273 unsigned Offset, unsigned Stride) const {
274 MachineOperand &FMO = MI->getOperand(FirstOpnd);
275 assert(FMO.isReg() && FMO.getSubReg() == 0 && "unexpected operand");
276 unsigned VirtReg = FMO.getReg();
278 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
279 "expected a virtual register");
281 unsigned LastSubIdx = 0;
283 MachineInstr *RegSeq = 0;
284 for (unsigned R = 0; R < NumRegs; ++R) {
285 const MachineOperand &MO = MI->getOperand(FirstOpnd + R);
286 assert(MO.isReg() && MO.getSubReg() == 0 && "unexpected operand");
287 unsigned VirtReg = MO.getReg();
288 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
289 "expected a virtual register");
290 // Feeding into a REG_SEQUENCE.
291 if (!MRI->hasOneNonDBGUse(VirtReg))
293 MachineInstr *UseMI = &*MRI->use_nodbg_begin(VirtReg);
294 if (!UseMI->isRegSequence())
296 if (RegSeq && RegSeq != UseMI)
298 unsigned OpIdx = 1 + (Offset + R * Stride) * 2;
299 if (UseMI->getOperand(OpIdx).getReg() != VirtReg)
300 llvm_unreachable("Malformed REG_SEQUENCE instruction!");
301 unsigned SubIdx = UseMI->getOperand(OpIdx + 1).getImm();
303 if (LastSubIdx != SubIdx-Stride)
306 // Must start from dsub_0 or qsub_0.
307 if (SubIdx != (ARM::dsub_0+Offset) &&
308 SubIdx != (ARM::qsub_0+Offset))
315 // In the case of vld3, etc., make sure the trailing operand of
316 // REG_SEQUENCE is an undef.
318 unsigned OpIdx = 1 + (Offset + 3 * Stride) * 2;
319 const MachineOperand &MO = RegSeq->getOperand(OpIdx);
320 unsigned VirtReg = MO.getReg();
321 MachineInstr *DefMI = MRI->getVRegDef(VirtReg);
322 if (!DefMI || !DefMI->isImplicitDef())
328 unsigned LastSrcReg = 0;
329 SmallVector<unsigned, 4> SubIds;
330 for (unsigned R = 0; R < NumRegs; ++R) {
331 const MachineOperand &MO = MI->getOperand(FirstOpnd + R);
332 assert(MO.isReg() && MO.getSubReg() == 0 && "unexpected operand");
333 unsigned VirtReg = MO.getReg();
334 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
335 "expected a virtual register");
336 // Extracting from a Q or QQ register.
337 MachineInstr *DefMI = MRI->getVRegDef(VirtReg);
338 if (!DefMI || !DefMI->isCopy() || !DefMI->getOperand(1).getSubReg())
340 VirtReg = DefMI->getOperand(1).getReg();
341 if (LastSrcReg && LastSrcReg != VirtReg)
343 LastSrcReg = VirtReg;
344 const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
345 if (RC != ARM::QPRRegisterClass &&
346 RC != ARM::QQPRRegisterClass &&
347 RC != ARM::QQQQPRRegisterClass)
349 unsigned SubIdx = DefMI->getOperand(1).getSubReg();
351 if (LastSubIdx != SubIdx-Stride)
354 // Must start from dsub_0 or qsub_0.
355 if (SubIdx != (ARM::dsub_0+Offset) &&
356 SubIdx != (ARM::qsub_0+Offset))
359 SubIds.push_back(SubIdx);
363 // FIXME: Update the uses of EXTRACT_SUBREG from REG_SEQUENCE is
364 // currently required for correctness. e.g.
365 // %reg1041<def> = REG_SEQUENCE %reg1040<kill>, 5, %reg1035<kill>, 6
366 // %reg1042<def> = EXTRACT_SUBREG %reg1041, 6
367 // %reg1043<def> = EXTRACT_SUBREG %reg1041, 5
368 // VST1q16 %reg1025<kill>, 0, %reg1043<kill>, %reg1042<kill>,
369 // reg1042 and reg1043 should be replaced with reg1041:6 and reg1041:5
371 // We need to change how we model uses of REG_SEQUENCE.
372 for (unsigned R = 0; R < NumRegs; ++R) {
373 MachineOperand &MO = MI->getOperand(FirstOpnd + R);
374 unsigned OldReg = MO.getReg();
375 MachineInstr *DefMI = MRI->getVRegDef(OldReg);
376 assert(DefMI->isCopy());
377 MO.setReg(LastSrcReg);
378 MO.setSubReg(SubIds[R]);
380 // Delete the EXTRACT_SUBREG if its result is now dead.
381 if (MRI->use_empty(OldReg))
382 DefMI->eraseFromParent();
388 bool NEONPreAllocPass::PreAllocNEONRegisters(MachineBasicBlock &MBB) {
389 bool Modified = false;
391 MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
392 for (; MBBI != E; ++MBBI) {
393 MachineInstr *MI = &*MBBI;
394 unsigned FirstOpnd, NumRegs, Offset, Stride;
395 if (!isNEONMultiRegOp(MI->getOpcode(), FirstOpnd, NumRegs, Offset, Stride))
397 if (FormsRegSequence(MI, FirstOpnd, NumRegs, Offset, Stride))
400 MachineBasicBlock::iterator NextI = llvm::next(MBBI);
401 for (unsigned R = 0; R < NumRegs; ++R) {
402 MachineOperand &MO = MI->getOperand(FirstOpnd + R);
403 assert(MO.isReg() && MO.getSubReg() == 0 && "unexpected operand");
404 unsigned VirtReg = MO.getReg();
405 assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
406 "expected a virtual register");
408 // For now, just assign a fixed set of adjacent registers.
409 // This leaves plenty of room for future improvements.
410 static const unsigned NEONDRegs[] = {
411 ARM::D0, ARM::D1, ARM::D2, ARM::D3,
412 ARM::D4, ARM::D5, ARM::D6, ARM::D7
414 MO.setReg(NEONDRegs[Offset + R * Stride]);
417 // Insert a copy from VirtReg.
418 BuildMI(MBB, MBBI, DebugLoc(), TII->get(TargetOpcode::COPY),MO.getReg())
419 .addReg(VirtReg, getKillRegState(MO.isKill()));
421 } else if (MO.isDef() && !MO.isDead()) {
422 // Add a copy to VirtReg.
423 BuildMI(MBB, NextI, DebugLoc(), TII->get(TargetOpcode::COPY), VirtReg)
424 .addReg(MO.getReg());
432 bool NEONPreAllocPass::runOnMachineFunction(MachineFunction &MF) {
433 TII = MF.getTarget().getInstrInfo();
434 MRI = &MF.getRegInfo();
436 bool Modified = false;
437 for (MachineFunction::iterator MFI = MF.begin(), E = MF.end(); MFI != E;
439 MachineBasicBlock &MBB = *MFI;
440 Modified |= PreAllocNEONRegisters(MBB);
446 /// createNEONPreAllocPass - returns an instance of the NEON register
447 /// pre-allocation pass.
448 FunctionPass *llvm::createNEONPreAllocPass() {
449 return new NEONPreAllocPass();