716 lines
		
	
	
		
			23 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			716 lines
		
	
	
		
			23 KiB
		
	
	
	
		
			C++
		
	
	
	
| //===- SIFixSGPRCopies.cpp - Remove potential VGPR => SGPR copies ---------===//
 | |
| //
 | |
| //                     The LLVM Compiler Infrastructure
 | |
| //
 | |
| // This file is distributed under the University of Illinois Open Source
 | |
| // License. See LICENSE.TXT for details.
 | |
| //
 | |
| //===----------------------------------------------------------------------===//
 | |
| //
 | |
| /// \file
 | |
| /// Copies from VGPR to SGPR registers are illegal and the register coalescer
 | |
| /// will sometimes generate these illegal copies in situations like this:
 | |
| ///
 | |
| ///  Register Class <vsrc> is the union of <vgpr> and <sgpr>
 | |
| ///
 | |
| /// BB0:
 | |
| ///   %0 <sgpr> = SCALAR_INST
 | |
| ///   %1 <vsrc> = COPY %0 <sgpr>
 | |
| ///    ...
 | |
| ///    BRANCH %cond BB1, BB2
 | |
| ///  BB1:
 | |
| ///    %2 <vgpr> = VECTOR_INST
 | |
| ///    %3 <vsrc> = COPY %2 <vgpr>
 | |
| ///  BB2:
 | |
| ///    %4 <vsrc> = PHI %1 <vsrc>, <%bb.0>, %3 <vrsc>, <%bb.1>
 | |
| ///    %5 <vgpr> = VECTOR_INST %4 <vsrc>
 | |
| ///
 | |
| ///
 | |
| /// The coalescer will begin at BB0 and eliminate its copy, then the resulting
 | |
| /// code will look like this:
 | |
| ///
 | |
| /// BB0:
 | |
| ///   %0 <sgpr> = SCALAR_INST
 | |
| ///    ...
 | |
| ///    BRANCH %cond BB1, BB2
 | |
| /// BB1:
 | |
| ///   %2 <vgpr> = VECTOR_INST
 | |
| ///   %3 <vsrc> = COPY %2 <vgpr>
 | |
| /// BB2:
 | |
| ///   %4 <sgpr> = PHI %0 <sgpr>, <%bb.0>, %3 <vsrc>, <%bb.1>
 | |
| ///   %5 <vgpr> = VECTOR_INST %4 <sgpr>
 | |
| ///
 | |
| /// Now that the result of the PHI instruction is an SGPR, the register
 | |
| /// allocator is now forced to constrain the register class of %3 to
 | |
| /// <sgpr> so we end up with final code like this:
 | |
| ///
 | |
| /// BB0:
 | |
| ///   %0 <sgpr> = SCALAR_INST
 | |
| ///    ...
 | |
| ///    BRANCH %cond BB1, BB2
 | |
| /// BB1:
 | |
| ///   %2 <vgpr> = VECTOR_INST
 | |
| ///   %3 <sgpr> = COPY %2 <vgpr>
 | |
| /// BB2:
 | |
| ///   %4 <sgpr> = PHI %0 <sgpr>, <%bb.0>, %3 <sgpr>, <%bb.1>
 | |
| ///   %5 <vgpr> = VECTOR_INST %4 <sgpr>
 | |
| ///
 | |
| /// Now this code contains an illegal copy from a VGPR to an SGPR.
 | |
| ///
 | |
| /// In order to avoid this problem, this pass searches for PHI instructions
 | |
| /// which define a <vsrc> register and constrains its definition class to
 | |
| /// <vgpr> if the user of the PHI's definition register is a vector instruction.
 | |
| /// If the PHI's definition class is constrained to <vgpr> then the coalescer
 | |
| /// will be unable to perform the COPY removal from the above example  which
 | |
| /// ultimately led to the creation of an illegal COPY.
 | |
| //===----------------------------------------------------------------------===//
 | |
| 
 | |
| #include "AMDGPU.h"
 | |
| #include "AMDGPUSubtarget.h"
 | |
| #include "SIInstrInfo.h"
 | |
| #include "SIRegisterInfo.h"
 | |
| #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
 | |
| #include "llvm/ADT/DenseSet.h"
 | |
| #include "llvm/ADT/STLExtras.h"
 | |
| #include "llvm/ADT/SmallSet.h"
 | |
| #include "llvm/ADT/SmallVector.h"
 | |
| #include "llvm/CodeGen/MachineBasicBlock.h"
 | |
| #include "llvm/CodeGen/MachineDominators.h"
 | |
| #include "llvm/CodeGen/MachineFunction.h"
 | |
| #include "llvm/CodeGen/MachineFunctionPass.h"
 | |
| #include "llvm/CodeGen/MachineInstr.h"
 | |
| #include "llvm/CodeGen/MachineInstrBuilder.h"
 | |
| #include "llvm/CodeGen/MachineOperand.h"
 | |
| #include "llvm/CodeGen/MachineRegisterInfo.h"
 | |
| #include "llvm/CodeGen/TargetRegisterInfo.h"
 | |
| #include "llvm/Pass.h"
 | |
| #include "llvm/Support/CodeGen.h"
 | |
| #include "llvm/Support/CommandLine.h"
 | |
| #include "llvm/Support/Debug.h"
 | |
| #include "llvm/Support/raw_ostream.h"
 | |
| #include "llvm/Target/TargetMachine.h"
 | |
| #include <cassert>
 | |
| #include <cstdint>
 | |
| #include <iterator>
 | |
| #include <list>
 | |
| #include <map>
 | |
| #include <tuple>
 | |
| #include <utility>
 | |
| 
 | |
| using namespace llvm;
 | |
| 
 | |
| #define DEBUG_TYPE "si-fix-sgpr-copies"
 | |
| 
 | |
| static cl::opt<bool> EnableM0Merge(
 | |
|   "amdgpu-enable-merge-m0",
 | |
|   cl::desc("Merge and hoist M0 initializations"),
 | |
|   cl::init(false));
 | |
| 
 | |
| namespace {
 | |
| 
 | |
| class SIFixSGPRCopies : public MachineFunctionPass {
 | |
|   MachineDominatorTree *MDT;
 | |
| 
 | |
| public:
 | |
|   static char ID;
 | |
| 
 | |
|   SIFixSGPRCopies() : MachineFunctionPass(ID) {}
 | |
| 
 | |
|   bool runOnMachineFunction(MachineFunction &MF) override;
 | |
| 
 | |
|   StringRef getPassName() const override { return "SI Fix SGPR copies"; }
 | |
| 
 | |
|   void getAnalysisUsage(AnalysisUsage &AU) const override {
 | |
|     AU.addRequired<MachineDominatorTree>();
 | |
|     AU.addPreserved<MachineDominatorTree>();
 | |
|     AU.setPreservesCFG();
 | |
|     MachineFunctionPass::getAnalysisUsage(AU);
 | |
|   }
 | |
| };
 | |
| 
 | |
| } // end anonymous namespace
 | |
| 
 | |
| INITIALIZE_PASS_BEGIN(SIFixSGPRCopies, DEBUG_TYPE,
 | |
|                      "SI Fix SGPR copies", false, false)
 | |
| INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
 | |
| INITIALIZE_PASS_END(SIFixSGPRCopies, DEBUG_TYPE,
 | |
|                      "SI Fix SGPR copies", false, false)
 | |
| 
 | |
| char SIFixSGPRCopies::ID = 0;
 | |
| 
 | |
| char &llvm::SIFixSGPRCopiesID = SIFixSGPRCopies::ID;
 | |
| 
 | |
| FunctionPass *llvm::createSIFixSGPRCopiesPass() {
 | |
|   return new SIFixSGPRCopies();
 | |
| }
 | |
| 
 | |
| static bool hasVGPROperands(const MachineInstr &MI, const SIRegisterInfo *TRI) {
 | |
|   const MachineRegisterInfo &MRI = MI.getParent()->getParent()->getRegInfo();
 | |
|   for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
 | |
|     if (!MI.getOperand(i).isReg() ||
 | |
|         !TargetRegisterInfo::isVirtualRegister(MI.getOperand(i).getReg()))
 | |
|       continue;
 | |
| 
 | |
|     if (TRI->hasVGPRs(MRI.getRegClass(MI.getOperand(i).getReg())))
 | |
|       return true;
 | |
|   }
 | |
|   return false;
 | |
| }
 | |
| 
 | |
| static std::pair<const TargetRegisterClass *, const TargetRegisterClass *>
 | |
| getCopyRegClasses(const MachineInstr &Copy,
 | |
|                   const SIRegisterInfo &TRI,
 | |
|                   const MachineRegisterInfo &MRI) {
 | |
|   unsigned DstReg = Copy.getOperand(0).getReg();
 | |
|   unsigned SrcReg = Copy.getOperand(1).getReg();
 | |
| 
 | |
|   const TargetRegisterClass *SrcRC =
 | |
|     TargetRegisterInfo::isVirtualRegister(SrcReg) ?
 | |
|     MRI.getRegClass(SrcReg) :
 | |
|     TRI.getPhysRegClass(SrcReg);
 | |
| 
 | |
|   // We don't really care about the subregister here.
 | |
|   // SrcRC = TRI.getSubRegClass(SrcRC, Copy.getOperand(1).getSubReg());
 | |
| 
 | |
|   const TargetRegisterClass *DstRC =
 | |
|     TargetRegisterInfo::isVirtualRegister(DstReg) ?
 | |
|     MRI.getRegClass(DstReg) :
 | |
|     TRI.getPhysRegClass(DstReg);
 | |
| 
 | |
|   return std::make_pair(SrcRC, DstRC);
 | |
| }
 | |
| 
 | |
| static bool isVGPRToSGPRCopy(const TargetRegisterClass *SrcRC,
 | |
|                              const TargetRegisterClass *DstRC,
 | |
|                              const SIRegisterInfo &TRI) {
 | |
|   return TRI.isSGPRClass(DstRC) && TRI.hasVGPRs(SrcRC);
 | |
| }
 | |
| 
 | |
| static bool isSGPRToVGPRCopy(const TargetRegisterClass *SrcRC,
 | |
|                              const TargetRegisterClass *DstRC,
 | |
|                              const SIRegisterInfo &TRI) {
 | |
|   return TRI.isSGPRClass(SrcRC) && TRI.hasVGPRs(DstRC);
 | |
| }
 | |
| 
 | |
| static bool tryChangeVGPRtoSGPRinCopy(MachineInstr &MI,
 | |
|                                       const SIRegisterInfo *TRI,
 | |
|                                       const SIInstrInfo *TII) {
 | |
|   MachineRegisterInfo &MRI = MI.getParent()->getParent()->getRegInfo();
 | |
|   auto &Src = MI.getOperand(1);
 | |
|   unsigned DstReg = MI.getOperand(0).getReg();
 | |
|   unsigned SrcReg = Src.getReg();
 | |
|   if (!TargetRegisterInfo::isVirtualRegister(SrcReg) ||
 | |
|       !TargetRegisterInfo::isVirtualRegister(DstReg))
 | |
|     return false;
 | |
| 
 | |
|   for (const auto &MO : MRI.reg_nodbg_operands(DstReg)) {
 | |
|     const auto *UseMI = MO.getParent();
 | |
|     if (UseMI == &MI)
 | |
|       continue;
 | |
|     if (MO.isDef() || UseMI->getParent() != MI.getParent() ||
 | |
|         UseMI->getOpcode() <= TargetOpcode::GENERIC_OP_END ||
 | |
|         !TII->isOperandLegal(*UseMI, UseMI->getOperandNo(&MO), &Src))
 | |
|       return false;
 | |
|   }
 | |
|   // Change VGPR to SGPR destination.
 | |
|   MRI.setRegClass(DstReg, TRI->getEquivalentSGPRClass(MRI.getRegClass(DstReg)));
 | |
|   return true;
 | |
| }
 | |
| 
 | |
| // Distribute an SGPR->VGPR copy of a REG_SEQUENCE into a VGPR REG_SEQUENCE.
 | |
| //
 | |
| // SGPRx = ...
 | |
| // SGPRy = REG_SEQUENCE SGPRx, sub0 ...
 | |
| // VGPRz = COPY SGPRy
 | |
| //
 | |
| // ==>
 | |
| //
 | |
| // VGPRx = COPY SGPRx
 | |
| // VGPRz = REG_SEQUENCE VGPRx, sub0
 | |
| //
 | |
| // This exposes immediate folding opportunities when materializing 64-bit
 | |
| // immediates.
 | |
| static bool foldVGPRCopyIntoRegSequence(MachineInstr &MI,
 | |
|                                         const SIRegisterInfo *TRI,
 | |
|                                         const SIInstrInfo *TII,
 | |
|                                         MachineRegisterInfo &MRI) {
 | |
|   assert(MI.isRegSequence());
 | |
| 
 | |
|   unsigned DstReg = MI.getOperand(0).getReg();
 | |
|   if (!TRI->isSGPRClass(MRI.getRegClass(DstReg)))
 | |
|     return false;
 | |
| 
 | |
|   if (!MRI.hasOneUse(DstReg))
 | |
|     return false;
 | |
| 
 | |
|   MachineInstr &CopyUse = *MRI.use_instr_begin(DstReg);
 | |
|   if (!CopyUse.isCopy())
 | |
|     return false;
 | |
| 
 | |
|   // It is illegal to have vreg inputs to a physreg defining reg_sequence.
 | |
|   if (TargetRegisterInfo::isPhysicalRegister(CopyUse.getOperand(0).getReg()))
 | |
|     return false;
 | |
| 
 | |
|   const TargetRegisterClass *SrcRC, *DstRC;
 | |
|   std::tie(SrcRC, DstRC) = getCopyRegClasses(CopyUse, *TRI, MRI);
 | |
| 
 | |
|   if (!isSGPRToVGPRCopy(SrcRC, DstRC, *TRI))
 | |
|     return false;
 | |
| 
 | |
|   if (tryChangeVGPRtoSGPRinCopy(CopyUse, TRI, TII))
 | |
|     return true;
 | |
| 
 | |
|   // TODO: Could have multiple extracts?
 | |
|   unsigned SubReg = CopyUse.getOperand(1).getSubReg();
 | |
|   if (SubReg != AMDGPU::NoSubRegister)
 | |
|     return false;
 | |
| 
 | |
|   MRI.setRegClass(DstReg, DstRC);
 | |
| 
 | |
|   // SGPRx = ...
 | |
|   // SGPRy = REG_SEQUENCE SGPRx, sub0 ...
 | |
|   // VGPRz = COPY SGPRy
 | |
| 
 | |
|   // =>
 | |
|   // VGPRx = COPY SGPRx
 | |
|   // VGPRz = REG_SEQUENCE VGPRx, sub0
 | |
| 
 | |
|   MI.getOperand(0).setReg(CopyUse.getOperand(0).getReg());
 | |
| 
 | |
|   for (unsigned I = 1, N = MI.getNumOperands(); I != N; I += 2) {
 | |
|     unsigned SrcReg = MI.getOperand(I).getReg();
 | |
|     unsigned SrcSubReg = MI.getOperand(I).getSubReg();
 | |
| 
 | |
|     const TargetRegisterClass *SrcRC = MRI.getRegClass(SrcReg);
 | |
|     assert(TRI->isSGPRClass(SrcRC) &&
 | |
|            "Expected SGPR REG_SEQUENCE to only have SGPR inputs");
 | |
| 
 | |
|     SrcRC = TRI->getSubRegClass(SrcRC, SrcSubReg);
 | |
|     const TargetRegisterClass *NewSrcRC = TRI->getEquivalentVGPRClass(SrcRC);
 | |
| 
 | |
|     unsigned TmpReg = MRI.createVirtualRegister(NewSrcRC);
 | |
| 
 | |
|     BuildMI(*MI.getParent(), &MI, MI.getDebugLoc(), TII->get(AMDGPU::COPY),
 | |
|             TmpReg)
 | |
|         .add(MI.getOperand(I));
 | |
| 
 | |
|     MI.getOperand(I).setReg(TmpReg);
 | |
|   }
 | |
| 
 | |
|   CopyUse.eraseFromParent();
 | |
|   return true;
 | |
| }
 | |
| 
 | |
| static bool phiHasVGPROperands(const MachineInstr &PHI,
 | |
|                                const MachineRegisterInfo &MRI,
 | |
|                                const SIRegisterInfo *TRI,
 | |
|                                const SIInstrInfo *TII) {
 | |
|   for (unsigned i = 1; i < PHI.getNumOperands(); i += 2) {
 | |
|     unsigned Reg = PHI.getOperand(i).getReg();
 | |
|     if (TRI->hasVGPRs(MRI.getRegClass(Reg)))
 | |
|       return true;
 | |
|   }
 | |
|   return false;
 | |
| }
 | |
| 
 | |
| static bool phiHasBreakDef(const MachineInstr &PHI,
 | |
|                            const MachineRegisterInfo &MRI,
 | |
|                            SmallSet<unsigned, 8> &Visited) {
 | |
|   for (unsigned i = 1; i < PHI.getNumOperands(); i += 2) {
 | |
|     unsigned Reg = PHI.getOperand(i).getReg();
 | |
|     if (Visited.count(Reg))
 | |
|       continue;
 | |
| 
 | |
|     Visited.insert(Reg);
 | |
| 
 | |
|     MachineInstr *DefInstr = MRI.getVRegDef(Reg);
 | |
|     switch (DefInstr->getOpcode()) {
 | |
|     default:
 | |
|       break;
 | |
|     case AMDGPU::SI_BREAK:
 | |
|     case AMDGPU::SI_IF_BREAK:
 | |
|     case AMDGPU::SI_ELSE_BREAK:
 | |
|       return true;
 | |
|     case AMDGPU::PHI:
 | |
|       if (phiHasBreakDef(*DefInstr, MRI, Visited))
 | |
|         return true;
 | |
|     }
 | |
|   }
 | |
|   return false;
 | |
| }
 | |
| 
 | |
| static bool hasTerminatorThatModifiesExec(const MachineBasicBlock &MBB,
 | |
|                                           const TargetRegisterInfo &TRI) {
 | |
|   for (MachineBasicBlock::const_iterator I = MBB.getFirstTerminator(),
 | |
|        E = MBB.end(); I != E; ++I) {
 | |
|     if (I->modifiesRegister(AMDGPU::EXEC, &TRI))
 | |
|       return true;
 | |
|   }
 | |
|   return false;
 | |
| }
 | |
| 
 | |
| static bool isSafeToFoldImmIntoCopy(const MachineInstr *Copy,
 | |
|                                     const MachineInstr *MoveImm,
 | |
|                                     const SIInstrInfo *TII,
 | |
|                                     unsigned &SMovOp,
 | |
|                                     int64_t &Imm) {
 | |
|   if (Copy->getOpcode() != AMDGPU::COPY)
 | |
|     return false;
 | |
| 
 | |
|   if (!MoveImm->isMoveImmediate())
 | |
|     return false;
 | |
| 
 | |
|   const MachineOperand *ImmOp =
 | |
|       TII->getNamedOperand(*MoveImm, AMDGPU::OpName::src0);
 | |
|   if (!ImmOp->isImm())
 | |
|     return false;
 | |
| 
 | |
|   // FIXME: Handle copies with sub-regs.
 | |
|   if (Copy->getOperand(0).getSubReg())
 | |
|     return false;
 | |
| 
 | |
|   switch (MoveImm->getOpcode()) {
 | |
|   default:
 | |
|     return false;
 | |
|   case AMDGPU::V_MOV_B32_e32:
 | |
|     SMovOp = AMDGPU::S_MOV_B32;
 | |
|     break;
 | |
|   case AMDGPU::V_MOV_B64_PSEUDO:
 | |
|     SMovOp = AMDGPU::S_MOV_B64;
 | |
|     break;
 | |
|   }
 | |
|   Imm = ImmOp->getImm();
 | |
|   return true;
 | |
| }
 | |
| 
 | |
| template <class UnaryPredicate>
 | |
| bool searchPredecessors(const MachineBasicBlock *MBB,
 | |
|                         const MachineBasicBlock *CutOff,
 | |
|                         UnaryPredicate Predicate) {
 | |
|   if (MBB == CutOff)
 | |
|     return false;
 | |
| 
 | |
|   DenseSet<const MachineBasicBlock *> Visited;
 | |
|   SmallVector<MachineBasicBlock *, 4> Worklist(MBB->pred_begin(),
 | |
|                                                MBB->pred_end());
 | |
| 
 | |
|   while (!Worklist.empty()) {
 | |
|     MachineBasicBlock *MBB = Worklist.pop_back_val();
 | |
| 
 | |
|     if (!Visited.insert(MBB).second)
 | |
|       continue;
 | |
|     if (MBB == CutOff)
 | |
|       continue;
 | |
|     if (Predicate(MBB))
 | |
|       return true;
 | |
| 
 | |
|     Worklist.append(MBB->pred_begin(), MBB->pred_end());
 | |
|   }
 | |
| 
 | |
|   return false;
 | |
| }
 | |
| 
 | |
| static bool predsHasDivergentTerminator(MachineBasicBlock *MBB,
 | |
|                                         const TargetRegisterInfo *TRI) {
 | |
|   return searchPredecessors(MBB, nullptr, [TRI](MachineBasicBlock *MBB) {
 | |
|            return hasTerminatorThatModifiesExec(*MBB, *TRI); });
 | |
| }
 | |
| 
 | |
| // Checks if there is potential path From instruction To instruction.
 | |
| // If CutOff is specified and it sits in between of that path we ignore
 | |
| // a higher portion of the path and report it is not reachable.
 | |
| static bool isReachable(const MachineInstr *From,
 | |
|                         const MachineInstr *To,
 | |
|                         const MachineBasicBlock *CutOff,
 | |
|                         MachineDominatorTree &MDT) {
 | |
|   // If either From block dominates To block or instructions are in the same
 | |
|   // block and From is higher.
 | |
|   if (MDT.dominates(From, To))
 | |
|     return true;
 | |
| 
 | |
|   const MachineBasicBlock *MBBFrom = From->getParent();
 | |
|   const MachineBasicBlock *MBBTo = To->getParent();
 | |
|   if (MBBFrom == MBBTo)
 | |
|     return false;
 | |
| 
 | |
|   // Instructions are in different blocks, do predecessor search.
 | |
|   // We should almost never get here since we do not usually produce M0 stores
 | |
|   // other than -1.
 | |
|   return searchPredecessors(MBBTo, CutOff, [MBBFrom]
 | |
|            (const MachineBasicBlock *MBB) { return MBB == MBBFrom; });
 | |
| }
 | |
| 
 | |
| // Hoist and merge identical SGPR initializations into a common predecessor.
 | |
| // This is intended to combine M0 initializations, but can work with any
 | |
| // SGPR. A VGPR cannot be processed since we cannot guarantee vector
 | |
| // executioon.
 | |
| static bool hoistAndMergeSGPRInits(unsigned Reg,
 | |
|                                    const MachineRegisterInfo &MRI,
 | |
|                                    MachineDominatorTree &MDT) {
 | |
|   // List of inits by immediate value.
 | |
|   using InitListMap = std::map<unsigned, std::list<MachineInstr *>>;
 | |
|   InitListMap Inits;
 | |
|   // List of clobbering instructions.
 | |
|   SmallVector<MachineInstr*, 8> Clobbers;
 | |
|   bool Changed = false;
 | |
| 
 | |
|   for (auto &MI : MRI.def_instructions(Reg)) {
 | |
|     MachineOperand *Imm = nullptr;
 | |
|     for (auto &MO: MI.operands()) {
 | |
|       if ((MO.isReg() && ((MO.isDef() && MO.getReg() != Reg) || !MO.isDef())) ||
 | |
|           (!MO.isImm() && !MO.isReg()) || (MO.isImm() && Imm)) {
 | |
|         Imm = nullptr;
 | |
|         break;
 | |
|       } else if (MO.isImm())
 | |
|         Imm = &MO;
 | |
|     }
 | |
|     if (Imm)
 | |
|       Inits[Imm->getImm()].push_front(&MI);
 | |
|     else
 | |
|       Clobbers.push_back(&MI);
 | |
|   }
 | |
| 
 | |
|   for (auto &Init : Inits) {
 | |
|     auto &Defs = Init.second;
 | |
| 
 | |
|     for (auto I1 = Defs.begin(), E = Defs.end(); I1 != E; ) {
 | |
|       MachineInstr *MI1 = *I1;
 | |
| 
 | |
|       for (auto I2 = std::next(I1); I2 != E; ) {
 | |
|         MachineInstr *MI2 = *I2;
 | |
| 
 | |
|         // Check any possible interference
 | |
|         auto intereferes = [&](MachineBasicBlock::iterator From,
 | |
|                                MachineBasicBlock::iterator To) -> bool {
 | |
| 
 | |
|           assert(MDT.dominates(&*To, &*From));
 | |
| 
 | |
|           auto interferes = [&MDT, From, To](MachineInstr* &Clobber) -> bool {
 | |
|             const MachineBasicBlock *MBBFrom = From->getParent();
 | |
|             const MachineBasicBlock *MBBTo = To->getParent();
 | |
|             bool MayClobberFrom = isReachable(Clobber, &*From, MBBTo, MDT);
 | |
|             bool MayClobberTo = isReachable(Clobber, &*To, MBBTo, MDT);
 | |
|             if (!MayClobberFrom && !MayClobberTo)
 | |
|               return false;
 | |
|             if ((MayClobberFrom && !MayClobberTo) ||
 | |
|                 (!MayClobberFrom && MayClobberTo))
 | |
|               return true;
 | |
|             // Both can clobber, this is not an interference only if both are
 | |
|             // dominated by Clobber and belong to the same block or if Clobber
 | |
|             // properly dominates To, given that To >> From, so it dominates
 | |
|             // both and located in a common dominator.
 | |
|             return !((MBBFrom == MBBTo &&
 | |
|                       MDT.dominates(Clobber, &*From) &&
 | |
|                       MDT.dominates(Clobber, &*To)) ||
 | |
|                      MDT.properlyDominates(Clobber->getParent(), MBBTo));
 | |
|           };
 | |
| 
 | |
|           return (llvm::any_of(Clobbers, interferes)) ||
 | |
|                  (llvm::any_of(Inits, [&](InitListMap::value_type &C) {
 | |
|                     return C.first != Init.first &&
 | |
|                            llvm::any_of(C.second, interferes);
 | |
|                   }));
 | |
|         };
 | |
| 
 | |
|         if (MDT.dominates(MI1, MI2)) {
 | |
|           if (!intereferes(MI2, MI1)) {
 | |
|             LLVM_DEBUG(dbgs()
 | |
|                        << "Erasing from "
 | |
|                        << printMBBReference(*MI2->getParent()) << " " << *MI2);
 | |
|             MI2->eraseFromParent();
 | |
|             Defs.erase(I2++);
 | |
|             Changed = true;
 | |
|             continue;
 | |
|           }
 | |
|         } else if (MDT.dominates(MI2, MI1)) {
 | |
|           if (!intereferes(MI1, MI2)) {
 | |
|             LLVM_DEBUG(dbgs()
 | |
|                        << "Erasing from "
 | |
|                        << printMBBReference(*MI1->getParent()) << " " << *MI1);
 | |
|             MI1->eraseFromParent();
 | |
|             Defs.erase(I1++);
 | |
|             Changed = true;
 | |
|             break;
 | |
|           }
 | |
|         } else {
 | |
|           auto *MBB = MDT.findNearestCommonDominator(MI1->getParent(),
 | |
|                                                      MI2->getParent());
 | |
|           if (!MBB) {
 | |
|             ++I2;
 | |
|             continue;
 | |
|           }
 | |
| 
 | |
|           MachineBasicBlock::iterator I = MBB->getFirstNonPHI();
 | |
|           if (!intereferes(MI1, I) && !intereferes(MI2, I)) {
 | |
|             LLVM_DEBUG(dbgs()
 | |
|                        << "Erasing from "
 | |
|                        << printMBBReference(*MI1->getParent()) << " " << *MI1
 | |
|                        << "and moving from "
 | |
|                        << printMBBReference(*MI2->getParent()) << " to "
 | |
|                        << printMBBReference(*I->getParent()) << " " << *MI2);
 | |
|             I->getParent()->splice(I, MI2->getParent(), MI2);
 | |
|             MI1->eraseFromParent();
 | |
|             Defs.erase(I1++);
 | |
|             Changed = true;
 | |
|             break;
 | |
|           }
 | |
|         }
 | |
|         ++I2;
 | |
|       }
 | |
|       ++I1;
 | |
|     }
 | |
|   }
 | |
| 
 | |
|   if (Changed)
 | |
|     MRI.clearKillFlags(Reg);
 | |
| 
 | |
|   return Changed;
 | |
| }
 | |
| 
 | |
| bool SIFixSGPRCopies::runOnMachineFunction(MachineFunction &MF) {
 | |
|   const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
 | |
|   MachineRegisterInfo &MRI = MF.getRegInfo();
 | |
|   const SIRegisterInfo *TRI = ST.getRegisterInfo();
 | |
|   const SIInstrInfo *TII = ST.getInstrInfo();
 | |
|   MDT = &getAnalysis<MachineDominatorTree>();
 | |
| 
 | |
|   SmallVector<MachineInstr *, 16> Worklist;
 | |
| 
 | |
|   for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
 | |
|                                                   BI != BE; ++BI) {
 | |
|     MachineBasicBlock &MBB = *BI;
 | |
|     for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
 | |
|          I != E; ++I) {
 | |
|       MachineInstr &MI = *I;
 | |
| 
 | |
|       switch (MI.getOpcode()) {
 | |
|       default:
 | |
|         continue;
 | |
|       case AMDGPU::COPY:
 | |
|       case AMDGPU::WQM:
 | |
|       case AMDGPU::WWM: {
 | |
|         // If the destination register is a physical register there isn't really
 | |
|         // much we can do to fix this.
 | |
|         if (!TargetRegisterInfo::isVirtualRegister(MI.getOperand(0).getReg()))
 | |
|           continue;
 | |
| 
 | |
|         const TargetRegisterClass *SrcRC, *DstRC;
 | |
|         std::tie(SrcRC, DstRC) = getCopyRegClasses(MI, *TRI, MRI);
 | |
|         if (isVGPRToSGPRCopy(SrcRC, DstRC, *TRI)) {
 | |
|           unsigned SrcReg = MI.getOperand(1).getReg();
 | |
|           if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) {
 | |
|             TII->moveToVALU(MI);
 | |
|             break;
 | |
|           }
 | |
| 
 | |
|           MachineInstr *DefMI = MRI.getVRegDef(SrcReg);
 | |
|           unsigned SMovOp;
 | |
|           int64_t Imm;
 | |
|           // If we are just copying an immediate, we can replace the copy with
 | |
|           // s_mov_b32.
 | |
|           if (isSafeToFoldImmIntoCopy(&MI, DefMI, TII, SMovOp, Imm)) {
 | |
|             MI.getOperand(1).ChangeToImmediate(Imm);
 | |
|             MI.addImplicitDefUseOperands(MF);
 | |
|             MI.setDesc(TII->get(SMovOp));
 | |
|             break;
 | |
|           }
 | |
|           TII->moveToVALU(MI);
 | |
|         } else if (isSGPRToVGPRCopy(SrcRC, DstRC, *TRI)) {
 | |
|           tryChangeVGPRtoSGPRinCopy(MI, TRI, TII);
 | |
|         }
 | |
| 
 | |
|         break;
 | |
|       }
 | |
|       case AMDGPU::PHI: {
 | |
|         unsigned Reg = MI.getOperand(0).getReg();
 | |
|         if (!TRI->isSGPRClass(MRI.getRegClass(Reg)))
 | |
|           break;
 | |
| 
 | |
|         // We don't need to fix the PHI if the common dominator of the
 | |
|         // two incoming blocks terminates with a uniform branch.
 | |
|         bool HasVGPROperand = phiHasVGPROperands(MI, MRI, TRI, TII);
 | |
|         if (MI.getNumExplicitOperands() == 5 && !HasVGPROperand) {
 | |
|           MachineBasicBlock *MBB0 = MI.getOperand(2).getMBB();
 | |
|           MachineBasicBlock *MBB1 = MI.getOperand(4).getMBB();
 | |
| 
 | |
|           if (!predsHasDivergentTerminator(MBB0, TRI) &&
 | |
|               !predsHasDivergentTerminator(MBB1, TRI)) {
 | |
|             LLVM_DEBUG(dbgs()
 | |
|                        << "Not fixing PHI for uniform branch: " << MI << '\n');
 | |
|             break;
 | |
|           }
 | |
|         }
 | |
| 
 | |
|         // If a PHI node defines an SGPR and any of its operands are VGPRs,
 | |
|         // then we need to move it to the VALU.
 | |
|         //
 | |
|         // Also, if a PHI node defines an SGPR and has all SGPR operands
 | |
|         // we must move it to the VALU, because the SGPR operands will
 | |
|         // all end up being assigned the same register, which means
 | |
|         // there is a potential for a conflict if different threads take
 | |
|         // different control flow paths.
 | |
|         //
 | |
|         // For Example:
 | |
|         //
 | |
|         // sgpr0 = def;
 | |
|         // ...
 | |
|         // sgpr1 = def;
 | |
|         // ...
 | |
|         // sgpr2 = PHI sgpr0, sgpr1
 | |
|         // use sgpr2;
 | |
|         //
 | |
|         // Will Become:
 | |
|         //
 | |
|         // sgpr2 = def;
 | |
|         // ...
 | |
|         // sgpr2 = def;
 | |
|         // ...
 | |
|         // use sgpr2
 | |
|         //
 | |
|         // The one exception to this rule is when one of the operands
 | |
|         // is defined by a SI_BREAK, SI_IF_BREAK, or SI_ELSE_BREAK
 | |
|         // instruction.  In this case, there we know the program will
 | |
|         // never enter the second block (the loop) without entering
 | |
|         // the first block (where the condition is computed), so there
 | |
|         // is no chance for values to be over-written.
 | |
| 
 | |
|         SmallSet<unsigned, 8> Visited;
 | |
|         if (HasVGPROperand || !phiHasBreakDef(MI, MRI, Visited)) {
 | |
|           LLVM_DEBUG(dbgs() << "Fixing PHI: " << MI);
 | |
|           TII->moveToVALU(MI);
 | |
|         }
 | |
|         break;
 | |
|       }
 | |
|       case AMDGPU::REG_SEQUENCE:
 | |
|         if (TRI->hasVGPRs(TII->getOpRegClass(MI, 0)) ||
 | |
|             !hasVGPROperands(MI, TRI)) {
 | |
|           foldVGPRCopyIntoRegSequence(MI, TRI, TII, MRI);
 | |
|           continue;
 | |
|         }
 | |
| 
 | |
|         LLVM_DEBUG(dbgs() << "Fixing REG_SEQUENCE: " << MI);
 | |
| 
 | |
|         TII->moveToVALU(MI);
 | |
|         break;
 | |
|       case AMDGPU::INSERT_SUBREG: {
 | |
|         const TargetRegisterClass *DstRC, *Src0RC, *Src1RC;
 | |
|         DstRC = MRI.getRegClass(MI.getOperand(0).getReg());
 | |
|         Src0RC = MRI.getRegClass(MI.getOperand(1).getReg());
 | |
|         Src1RC = MRI.getRegClass(MI.getOperand(2).getReg());
 | |
|         if (TRI->isSGPRClass(DstRC) &&
 | |
|             (TRI->hasVGPRs(Src0RC) || TRI->hasVGPRs(Src1RC))) {
 | |
|           LLVM_DEBUG(dbgs() << " Fixing INSERT_SUBREG: " << MI);
 | |
|           TII->moveToVALU(MI);
 | |
|         }
 | |
|         break;
 | |
|       }
 | |
|       }
 | |
|     }
 | |
|   }
 | |
| 
 | |
|   if (MF.getTarget().getOptLevel() > CodeGenOpt::None && EnableM0Merge)
 | |
|     hoistAndMergeSGPRInits(AMDGPU::M0, MRI, *MDT);
 | |
| 
 | |
|   return true;
 | |
| }
 |