//===- SIMachineFunctionInfo.cpp - SI Machine Function Info ---------------===// // // 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 // //===----------------------------------------------------------------------===// #include "SIMachineFunctionInfo.h" #include "AMDGPUArgumentUsageInfo.h" #include "AMDGPUTargetMachine.h" #include "AMDGPUSubtarget.h" #include "SIRegisterInfo.h" #include "MCTargetDesc/AMDGPUMCTargetDesc.h" #include "Utils/AMDGPUBaseInfo.h" #include "llvm/ADT/Optional.h" #include "llvm/CodeGen/MachineBasicBlock.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/IR/CallingConv.h" #include "llvm/IR/Function.h" #include #include #define MAX_LANES 64 using namespace llvm; SIMachineFunctionInfo::SIMachineFunctionInfo(const MachineFunction &MF) : AMDGPUMachineFunction(MF), PrivateSegmentBuffer(false), DispatchPtr(false), QueuePtr(false), KernargSegmentPtr(false), DispatchID(false), FlatScratchInit(false), WorkGroupIDX(false), WorkGroupIDY(false), WorkGroupIDZ(false), WorkGroupInfo(false), PrivateSegmentWaveByteOffset(false), WorkItemIDX(false), WorkItemIDY(false), WorkItemIDZ(false), ImplicitBufferPtr(false), ImplicitArgPtr(false), GITPtrHigh(0xffffffff), HighBitsOf32BitAddress(0), GDSSize(0) { const GCNSubtarget &ST = MF.getSubtarget(); const Function &F = MF.getFunction(); FlatWorkGroupSizes = ST.getFlatWorkGroupSizes(F); WavesPerEU = ST.getWavesPerEU(F); Occupancy = ST.computeOccupancy(F, getLDSSize()); CallingConv::ID CC = F.getCallingConv(); // FIXME: Should have analysis or something rather than attribute to detect // calls. const bool HasCalls = F.hasFnAttribute("amdgpu-calls"); // Enable all kernel inputs if we have the fixed ABI. Don't bother if we don't // have any calls. const bool UseFixedABI = AMDGPUTargetMachine::EnableFixedFunctionABI && (!isEntryFunction() || HasCalls); if (CC == CallingConv::AMDGPU_KERNEL || CC == CallingConv::SPIR_KERNEL) { if (!F.arg_empty()) KernargSegmentPtr = true; WorkGroupIDX = true; WorkItemIDX = true; } else if (CC == CallingConv::AMDGPU_PS) { PSInputAddr = AMDGPU::getInitialPSInputAddr(F); } if (!isEntryFunction()) { // Non-entry functions have no special inputs for now, other registers // required for scratch access. ScratchRSrcReg = AMDGPU::SGPR0_SGPR1_SGPR2_SGPR3; // TODO: Pick a high register, and shift down, similar to a kernel. FrameOffsetReg = AMDGPU::SGPR33; StackPtrOffsetReg = AMDGPU::SGPR32; ArgInfo.PrivateSegmentBuffer = ArgDescriptor::createRegister(ScratchRSrcReg); if (F.hasFnAttribute("amdgpu-implicitarg-ptr")) ImplicitArgPtr = true; } else { if (F.hasFnAttribute("amdgpu-implicitarg-ptr")) { KernargSegmentPtr = true; MaxKernArgAlign = std::max(ST.getAlignmentForImplicitArgPtr(), MaxKernArgAlign); } } if (UseFixedABI) { WorkGroupIDX = true; WorkGroupIDY = true; WorkGroupIDZ = true; WorkItemIDX = true; WorkItemIDY = true; WorkItemIDZ = true; ImplicitArgPtr = true; } else { if (F.hasFnAttribute("amdgpu-work-group-id-x")) WorkGroupIDX = true; if (F.hasFnAttribute("amdgpu-work-group-id-y")) WorkGroupIDY = true; if (F.hasFnAttribute("amdgpu-work-group-id-z")) WorkGroupIDZ = true; if (F.hasFnAttribute("amdgpu-work-item-id-x")) WorkItemIDX = true; if (F.hasFnAttribute("amdgpu-work-item-id-y")) WorkItemIDY = true; if (F.hasFnAttribute("amdgpu-work-item-id-z")) WorkItemIDZ = true; } bool HasStackObjects = F.hasFnAttribute("amdgpu-stack-objects"); if (isEntryFunction()) { // X, XY, and XYZ are the only supported combinations, so make sure Y is // enabled if Z is. if (WorkItemIDZ) WorkItemIDY = true; PrivateSegmentWaveByteOffset = true; // HS and GS always have the scratch wave offset in SGPR5 on GFX9. if (ST.getGeneration() >= AMDGPUSubtarget::GFX9 && (CC == CallingConv::AMDGPU_HS || CC == CallingConv::AMDGPU_GS)) ArgInfo.PrivateSegmentWaveByteOffset = ArgDescriptor::createRegister(AMDGPU::SGPR5); } bool isAmdHsaOrMesa = ST.isAmdHsaOrMesa(F); if (isAmdHsaOrMesa) { PrivateSegmentBuffer = true; if (UseFixedABI) { DispatchPtr = true; QueuePtr = true; // FIXME: We don't need this? DispatchID = true; } else { if (F.hasFnAttribute("amdgpu-dispatch-ptr")) DispatchPtr = true; if (F.hasFnAttribute("amdgpu-queue-ptr")) QueuePtr = true; if (F.hasFnAttribute("amdgpu-dispatch-id")) DispatchID = true; } } else if (ST.isMesaGfxShader(F)) { ImplicitBufferPtr = true; } if (UseFixedABI || F.hasFnAttribute("amdgpu-kernarg-segment-ptr")) KernargSegmentPtr = true; if (ST.hasFlatAddressSpace() && isEntryFunction() && isAmdHsaOrMesa) { // TODO: This could be refined a lot. The attribute is a poor way of // detecting calls or stack objects that may require it before argument // lowering. if (HasCalls || HasStackObjects) FlatScratchInit = true; } Attribute A = F.getFnAttribute("amdgpu-git-ptr-high"); StringRef S = A.getValueAsString(); if (!S.empty()) S.consumeInteger(0, GITPtrHigh); A = F.getFnAttribute("amdgpu-32bit-address-high-bits"); S = A.getValueAsString(); if (!S.empty()) S.consumeInteger(0, HighBitsOf32BitAddress); S = F.getFnAttribute("amdgpu-gds-size").getValueAsString(); if (!S.empty()) S.consumeInteger(0, GDSSize); } void SIMachineFunctionInfo::limitOccupancy(const MachineFunction &MF) { limitOccupancy(getMaxWavesPerEU()); const GCNSubtarget& ST = MF.getSubtarget(); limitOccupancy(ST.getOccupancyWithLocalMemSize(getLDSSize(), MF.getFunction())); } Register SIMachineFunctionInfo::addPrivateSegmentBuffer( const SIRegisterInfo &TRI) { ArgInfo.PrivateSegmentBuffer = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SGPR_128RegClass)); NumUserSGPRs += 4; return ArgInfo.PrivateSegmentBuffer.getRegister(); } Register SIMachineFunctionInfo::addDispatchPtr(const SIRegisterInfo &TRI) { ArgInfo.DispatchPtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.DispatchPtr.getRegister(); } Register SIMachineFunctionInfo::addQueuePtr(const SIRegisterInfo &TRI) { ArgInfo.QueuePtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.QueuePtr.getRegister(); } Register SIMachineFunctionInfo::addKernargSegmentPtr(const SIRegisterInfo &TRI) { ArgInfo.KernargSegmentPtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.KernargSegmentPtr.getRegister(); } Register SIMachineFunctionInfo::addDispatchID(const SIRegisterInfo &TRI) { ArgInfo.DispatchID = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.DispatchID.getRegister(); } Register SIMachineFunctionInfo::addFlatScratchInit(const SIRegisterInfo &TRI) { ArgInfo.FlatScratchInit = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.FlatScratchInit.getRegister(); } Register SIMachineFunctionInfo::addImplicitBufferPtr(const SIRegisterInfo &TRI) { ArgInfo.ImplicitBufferPtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg( getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass)); NumUserSGPRs += 2; return ArgInfo.ImplicitBufferPtr.getRegister(); } bool SIMachineFunctionInfo::isCalleeSavedReg(const MCPhysReg *CSRegs, MCPhysReg Reg) { for (unsigned I = 0; CSRegs[I]; ++I) { if (CSRegs[I] == Reg) return true; } return false; } /// \p returns true if \p NumLanes slots are available in VGPRs already used for /// SGPR spilling. // // FIXME: This only works after processFunctionBeforeFrameFinalized bool SIMachineFunctionInfo::haveFreeLanesForSGPRSpill(const MachineFunction &MF, unsigned NumNeed) const { const GCNSubtarget &ST = MF.getSubtarget(); unsigned WaveSize = ST.getWavefrontSize(); return NumVGPRSpillLanes + NumNeed <= WaveSize * SpillVGPRs.size(); } /// Reserve a slice of a VGPR to support spilling for FrameIndex \p FI. bool SIMachineFunctionInfo::allocateSGPRSpillToVGPR(MachineFunction &MF, int FI) { std::vector &SpillLanes = SGPRToVGPRSpills[FI]; // This has already been allocated. if (!SpillLanes.empty()) return true; const GCNSubtarget &ST = MF.getSubtarget(); const SIRegisterInfo *TRI = ST.getRegisterInfo(); MachineFrameInfo &FrameInfo = MF.getFrameInfo(); MachineRegisterInfo &MRI = MF.getRegInfo(); unsigned WaveSize = ST.getWavefrontSize(); SIMachineFunctionInfo *FuncInfo = MF.getInfo(); unsigned Size = FrameInfo.getObjectSize(FI); unsigned NumLanes = Size / 4; if (NumLanes > WaveSize) return false; assert(Size >= 4 && "invalid sgpr spill size"); assert(TRI->spillSGPRToVGPR() && "not spilling SGPRs to VGPRs"); const MCPhysReg *CSRegs = MRI.getCalleeSavedRegs(); // Make sure to handle the case where a wide SGPR spill may span between two // VGPRs. for (unsigned I = 0; I < NumLanes; ++I, ++NumVGPRSpillLanes) { Register LaneVGPR; unsigned VGPRIndex = (NumVGPRSpillLanes % WaveSize); // Reserve a VGPR (when NumVGPRSpillLanes = 0, WaveSize, 2*WaveSize, ..) and // when one of the two conditions is true: // 1. One reserved VGPR being tracked by VGPRReservedForSGPRSpill is not yet // reserved. // 2. All spill lanes of reserved VGPR(s) are full and another spill lane is // required. if (FuncInfo->VGPRReservedForSGPRSpill && NumVGPRSpillLanes < WaveSize) { assert(FuncInfo->VGPRReservedForSGPRSpill == SpillVGPRs.back().VGPR); LaneVGPR = FuncInfo->VGPRReservedForSGPRSpill; } else if (VGPRIndex == 0) { LaneVGPR = TRI->findUnusedRegister(MRI, &AMDGPU::VGPR_32RegClass, MF); if (LaneVGPR == AMDGPU::NoRegister) { // We have no VGPRs left for spilling SGPRs. Reset because we will not // partially spill the SGPR to VGPRs. SGPRToVGPRSpills.erase(FI); NumVGPRSpillLanes -= I; return false; } Optional CSRSpillFI; if ((FrameInfo.hasCalls() || !isEntryFunction()) && CSRegs && isCalleeSavedReg(CSRegs, LaneVGPR)) { CSRSpillFI = FrameInfo.CreateSpillStackObject(4, Align(4)); } SpillVGPRs.push_back(SGPRSpillVGPRCSR(LaneVGPR, CSRSpillFI)); // Add this register as live-in to all blocks to avoid machine verifer // complaining about use of an undefined physical register. for (MachineBasicBlock &BB : MF) BB.addLiveIn(LaneVGPR); } else { LaneVGPR = SpillVGPRs.back().VGPR; } SpillLanes.push_back(SpilledReg(LaneVGPR, VGPRIndex)); } return true; } /// Reserve a VGPR for spilling of SGPRs bool SIMachineFunctionInfo::reserveVGPRforSGPRSpills(MachineFunction &MF) { const GCNSubtarget &ST = MF.getSubtarget(); const SIRegisterInfo *TRI = ST.getRegisterInfo(); SIMachineFunctionInfo *FuncInfo = MF.getInfo(); Register LaneVGPR = TRI->findUnusedRegister( MF.getRegInfo(), &AMDGPU::VGPR_32RegClass, MF, true); SpillVGPRs.push_back(SGPRSpillVGPRCSR(LaneVGPR, None)); FuncInfo->VGPRReservedForSGPRSpill = LaneVGPR; return true; } /// Reserve AGPRs or VGPRs to support spilling for FrameIndex \p FI. /// Either AGPR is spilled to VGPR to vice versa. /// Returns true if a \p FI can be eliminated completely. bool SIMachineFunctionInfo::allocateVGPRSpillToAGPR(MachineFunction &MF, int FI, bool isAGPRtoVGPR) { MachineRegisterInfo &MRI = MF.getRegInfo(); MachineFrameInfo &FrameInfo = MF.getFrameInfo(); const GCNSubtarget &ST = MF.getSubtarget(); assert(ST.hasMAIInsts() && FrameInfo.isSpillSlotObjectIndex(FI)); auto &Spill = VGPRToAGPRSpills[FI]; // This has already been allocated. if (!Spill.Lanes.empty()) return Spill.FullyAllocated; unsigned Size = FrameInfo.getObjectSize(FI); unsigned NumLanes = Size / 4; Spill.Lanes.resize(NumLanes, AMDGPU::NoRegister); const TargetRegisterClass &RC = isAGPRtoVGPR ? AMDGPU::VGPR_32RegClass : AMDGPU::AGPR_32RegClass; auto Regs = RC.getRegisters(); auto &SpillRegs = isAGPRtoVGPR ? SpillAGPR : SpillVGPR; const SIRegisterInfo *TRI = ST.getRegisterInfo(); Spill.FullyAllocated = true; // FIXME: Move allocation logic out of MachineFunctionInfo and initialize // once. BitVector OtherUsedRegs; OtherUsedRegs.resize(TRI->getNumRegs()); const uint32_t *CSRMask = TRI->getCallPreservedMask(MF, MF.getFunction().getCallingConv()); if (CSRMask) OtherUsedRegs.setBitsInMask(CSRMask); // TODO: Should include register tuples, but doesn't matter with current // usage. for (MCPhysReg Reg : SpillAGPR) OtherUsedRegs.set(Reg); for (MCPhysReg Reg : SpillVGPR) OtherUsedRegs.set(Reg); SmallVectorImpl::const_iterator NextSpillReg = Regs.begin(); for (unsigned I = 0; I < NumLanes; ++I) { NextSpillReg = std::find_if( NextSpillReg, Regs.end(), [&MRI, &OtherUsedRegs](MCPhysReg Reg) { return MRI.isAllocatable(Reg) && !MRI.isPhysRegUsed(Reg) && !OtherUsedRegs[Reg]; }); if (NextSpillReg == Regs.end()) { // Registers exhausted Spill.FullyAllocated = false; break; } OtherUsedRegs.set(*NextSpillReg); SpillRegs.push_back(*NextSpillReg); Spill.Lanes[I] = *NextSpillReg++; } return Spill.FullyAllocated; } void SIMachineFunctionInfo::removeDeadFrameIndices(MachineFrameInfo &MFI) { // The FP & BP spills haven't been inserted yet, so keep them around. for (auto &R : SGPRToVGPRSpills) { if (R.first != FramePointerSaveIndex && R.first != BasePointerSaveIndex) MFI.RemoveStackObject(R.first); } // All other SPGRs must be allocated on the default stack, so reset the stack // ID. for (int i = MFI.getObjectIndexBegin(), e = MFI.getObjectIndexEnd(); i != e; ++i) if (i != FramePointerSaveIndex && i != BasePointerSaveIndex) MFI.setStackID(i, TargetStackID::Default); for (auto &R : VGPRToAGPRSpills) { if (R.second.FullyAllocated) MFI.RemoveStackObject(R.first); } } MCPhysReg SIMachineFunctionInfo::getNextUserSGPR() const { assert(NumSystemSGPRs == 0 && "System SGPRs must be added after user SGPRs"); return AMDGPU::SGPR0 + NumUserSGPRs; } MCPhysReg SIMachineFunctionInfo::getNextSystemSGPR() const { return AMDGPU::SGPR0 + NumUserSGPRs + NumSystemSGPRs; } Register SIMachineFunctionInfo::getGITPtrLoReg(const MachineFunction &MF) const { const GCNSubtarget &ST = MF.getSubtarget(); if (!ST.isAmdPalOS()) return Register(); Register GitPtrLo = AMDGPU::SGPR0; // Low GIT address passed in if (ST.hasMergedShaders()) { switch (MF.getFunction().getCallingConv()) { case CallingConv::AMDGPU_HS: case CallingConv::AMDGPU_GS: // Low GIT address is passed in s8 rather than s0 for an LS+HS or // ES+GS merged shader on gfx9+. GitPtrLo = AMDGPU::SGPR8; return GitPtrLo; default: return GitPtrLo; } } return GitPtrLo; } static yaml::StringValue regToString(Register Reg, const TargetRegisterInfo &TRI) { yaml::StringValue Dest; { raw_string_ostream OS(Dest.Value); OS << printReg(Reg, &TRI); } return Dest; } static Optional convertArgumentInfo(const AMDGPUFunctionArgInfo &ArgInfo, const TargetRegisterInfo &TRI) { yaml::SIArgumentInfo AI; auto convertArg = [&](Optional &A, const ArgDescriptor &Arg) { if (!Arg) return false; // Create a register or stack argument. yaml::SIArgument SA = yaml::SIArgument::createArgument(Arg.isRegister()); if (Arg.isRegister()) { raw_string_ostream OS(SA.RegisterName.Value); OS << printReg(Arg.getRegister(), &TRI); } else SA.StackOffset = Arg.getStackOffset(); // Check and update the optional mask. if (Arg.isMasked()) SA.Mask = Arg.getMask(); A = SA; return true; }; bool Any = false; Any |= convertArg(AI.PrivateSegmentBuffer, ArgInfo.PrivateSegmentBuffer); Any |= convertArg(AI.DispatchPtr, ArgInfo.DispatchPtr); Any |= convertArg(AI.QueuePtr, ArgInfo.QueuePtr); Any |= convertArg(AI.KernargSegmentPtr, ArgInfo.KernargSegmentPtr); Any |= convertArg(AI.DispatchID, ArgInfo.DispatchID); Any |= convertArg(AI.FlatScratchInit, ArgInfo.FlatScratchInit); Any |= convertArg(AI.PrivateSegmentSize, ArgInfo.PrivateSegmentSize); Any |= convertArg(AI.WorkGroupIDX, ArgInfo.WorkGroupIDX); Any |= convertArg(AI.WorkGroupIDY, ArgInfo.WorkGroupIDY); Any |= convertArg(AI.WorkGroupIDZ, ArgInfo.WorkGroupIDZ); Any |= convertArg(AI.WorkGroupInfo, ArgInfo.WorkGroupInfo); Any |= convertArg(AI.PrivateSegmentWaveByteOffset, ArgInfo.PrivateSegmentWaveByteOffset); Any |= convertArg(AI.ImplicitArgPtr, ArgInfo.ImplicitArgPtr); Any |= convertArg(AI.ImplicitBufferPtr, ArgInfo.ImplicitBufferPtr); Any |= convertArg(AI.WorkItemIDX, ArgInfo.WorkItemIDX); Any |= convertArg(AI.WorkItemIDY, ArgInfo.WorkItemIDY); Any |= convertArg(AI.WorkItemIDZ, ArgInfo.WorkItemIDZ); if (Any) return AI; return None; } yaml::SIMachineFunctionInfo::SIMachineFunctionInfo( const llvm::SIMachineFunctionInfo& MFI, const TargetRegisterInfo &TRI) : ExplicitKernArgSize(MFI.getExplicitKernArgSize()), MaxKernArgAlign(MFI.getMaxKernArgAlign()), LDSSize(MFI.getLDSSize()), IsEntryFunction(MFI.isEntryFunction()), NoSignedZerosFPMath(MFI.hasNoSignedZerosFPMath()), MemoryBound(MFI.isMemoryBound()), WaveLimiter(MFI.needsWaveLimiter()), HighBitsOf32BitAddress(MFI.get32BitAddressHighBits()), ScratchRSrcReg(regToString(MFI.getScratchRSrcReg(), TRI)), FrameOffsetReg(regToString(MFI.getFrameOffsetReg(), TRI)), StackPtrOffsetReg(regToString(MFI.getStackPtrOffsetReg(), TRI)), ArgInfo(convertArgumentInfo(MFI.getArgInfo(), TRI)), Mode(MFI.getMode()) {} void yaml::SIMachineFunctionInfo::mappingImpl(yaml::IO &YamlIO) { MappingTraits::mapping(YamlIO, *this); } bool SIMachineFunctionInfo::initializeBaseYamlFields( const yaml::SIMachineFunctionInfo &YamlMFI) { ExplicitKernArgSize = YamlMFI.ExplicitKernArgSize; MaxKernArgAlign = assumeAligned(YamlMFI.MaxKernArgAlign); LDSSize = YamlMFI.LDSSize; HighBitsOf32BitAddress = YamlMFI.HighBitsOf32BitAddress; IsEntryFunction = YamlMFI.IsEntryFunction; NoSignedZerosFPMath = YamlMFI.NoSignedZerosFPMath; MemoryBound = YamlMFI.MemoryBound; WaveLimiter = YamlMFI.WaveLimiter; return false; } // Remove VGPR which was reserved for SGPR spills if there are no spilled SGPRs bool SIMachineFunctionInfo::removeVGPRForSGPRSpill(Register ReservedVGPR, MachineFunction &MF) { for (auto *i = SpillVGPRs.begin(); i < SpillVGPRs.end(); i++) { if (i->VGPR == ReservedVGPR) { SpillVGPRs.erase(i); for (MachineBasicBlock &MBB : MF) { MBB.removeLiveIn(ReservedVGPR); MBB.sortUniqueLiveIns(); } this->VGPRReservedForSGPRSpill = AMDGPU::NoRegister; return true; } } return false; }