//===-- AMDGPUSubtarget.cpp - AMDGPU Subtarget Information ----------------===// // // 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 /// Implements the AMDGPU specific subclass of TargetSubtarget. // //===----------------------------------------------------------------------===// #include "AMDGPUSubtarget.h" #include "AMDGPUCallLowering.h" #include "AMDGPUInstructionSelector.h" #include "AMDGPULegalizerInfo.h" #include "AMDGPURegisterBankInfo.h" #include "AMDGPUTargetMachine.h" #include "GCNSubtarget.h" #include "R600Subtarget.h" #include "SIMachineFunctionInfo.h" #include "Utils/AMDGPUBaseInfo.h" #include "llvm/ADT/SmallString.h" #include "llvm/CodeGen/GlobalISel/InlineAsmLowering.h" #include "llvm/CodeGen/MachineScheduler.h" #include "llvm/CodeGen/TargetFrameLowering.h" #include "llvm/IR/DiagnosticInfo.h" #include "llvm/IR/IntrinsicsAMDGPU.h" #include "llvm/IR/IntrinsicsR600.h" #include "llvm/IR/MDBuilder.h" #include "llvm/MC/MCSubtargetInfo.h" #include using namespace llvm; #define DEBUG_TYPE "amdgpu-subtarget" #define GET_SUBTARGETINFO_TARGET_DESC #define GET_SUBTARGETINFO_CTOR #define AMDGPUSubtarget GCNSubtarget #include "AMDGPUGenSubtargetInfo.inc" #undef AMDGPUSubtarget static cl::opt EnablePowerSched( "amdgpu-enable-power-sched", cl::desc("Enable scheduling to minimize mAI power bursts"), cl::init(false)); static cl::opt EnableVGPRIndexMode( "amdgpu-vgpr-index-mode", cl::desc("Use GPR indexing mode instead of movrel for vector indexing"), cl::init(false)); static cl::opt UseAA("amdgpu-use-aa-in-codegen", cl::desc("Enable the use of AA during codegen."), cl::init(true)); static cl::opt NSAThreshold("amdgpu-nsa-threshold", cl::desc("Number of addresses from which to enable MIMG NSA."), cl::init(3), cl::Hidden); GCNSubtarget::~GCNSubtarget() = default; GCNSubtarget & GCNSubtarget::initializeSubtargetDependencies(const Triple &TT, StringRef GPU, StringRef FS) { // Determine default and user-specified characteristics // // We want to be able to turn these off, but making this a subtarget feature // for SI has the unhelpful behavior that it unsets everything else if you // disable it. // // Similarly we want enable-prt-strict-null to be on by default and not to // unset everything else if it is disabled SmallString<256> FullFS("+promote-alloca,+load-store-opt,+enable-ds128,"); // Turn on features that HSA ABI requires. Also turn on FlatForGlobal by default if (isAmdHsaOS()) FullFS += "+flat-for-global,+unaligned-access-mode,+trap-handler,"; FullFS += "+enable-prt-strict-null,"; // This is overridden by a disable in FS // Disable mutually exclusive bits. if (FS.contains_insensitive("+wavefrontsize")) { if (!FS.contains_insensitive("wavefrontsize16")) FullFS += "-wavefrontsize16,"; if (!FS.contains_insensitive("wavefrontsize32")) FullFS += "-wavefrontsize32,"; if (!FS.contains_insensitive("wavefrontsize64")) FullFS += "-wavefrontsize64,"; } FullFS += FS; ParseSubtargetFeatures(GPU, /*TuneCPU*/ GPU, FullFS); // Implement the "generic" processors, which acts as the default when no // generation features are enabled (e.g for -mcpu=''). HSA OS defaults to // the first amdgcn target that supports flat addressing. Other OSes defaults // to the first amdgcn target. if (Gen == AMDGPUSubtarget::INVALID) { Gen = TT.getOS() == Triple::AMDHSA ? AMDGPUSubtarget::SEA_ISLANDS : AMDGPUSubtarget::SOUTHERN_ISLANDS; } if (!hasFeature(AMDGPU::FeatureWavefrontSize32) && !hasFeature(AMDGPU::FeatureWavefrontSize64)) { // If there is no default wave size it must be a generation before gfx10, // these have FeatureWavefrontSize64 in their definition already. For gfx10+ // set wave32 as a default. ToggleFeature(AMDGPU::FeatureWavefrontSize32); } // We don't support FP64 for EG/NI atm. assert(!hasFP64() || (getGeneration() >= AMDGPUSubtarget::SOUTHERN_ISLANDS)); // Targets must either support 64-bit offsets for MUBUF instructions, and/or // support flat operations, otherwise they cannot access a 64-bit global // address space assert(hasAddr64() || hasFlat()); // Unless +-flat-for-global is specified, turn on FlatForGlobal for targets // that do not support ADDR64 variants of MUBUF instructions. Such targets // cannot use a 64 bit offset with a MUBUF instruction to access the global // address space if (!hasAddr64() && !FS.contains("flat-for-global") && !FlatForGlobal) { ToggleFeature(AMDGPU::FeatureFlatForGlobal); FlatForGlobal = true; } // Unless +-flat-for-global is specified, use MUBUF instructions for global // address space access if flat operations are not available. if (!hasFlat() && !FS.contains("flat-for-global") && FlatForGlobal) { ToggleFeature(AMDGPU::FeatureFlatForGlobal); FlatForGlobal = false; } // Set defaults if needed. if (MaxPrivateElementSize == 0) MaxPrivateElementSize = 4; if (LDSBankCount == 0) LDSBankCount = 32; if (TT.getArch() == Triple::amdgcn) { if (LocalMemorySize == 0) LocalMemorySize = 32768; // Do something sensible for unspecified target. if (!HasMovrel && !HasVGPRIndexMode) HasMovrel = true; } AddressableLocalMemorySize = LocalMemorySize; if (AMDGPU::isGFX10Plus(*this) && !getFeatureBits().test(AMDGPU::FeatureCuMode)) LocalMemorySize *= 2; // Don't crash on invalid devices. if (WavefrontSizeLog2 == 0) WavefrontSizeLog2 = 5; HasFminFmaxLegacy = getGeneration() < AMDGPUSubtarget::VOLCANIC_ISLANDS; HasSMulHi = getGeneration() >= AMDGPUSubtarget::GFX9; TargetID.setTargetIDFromFeaturesString(FS); LLVM_DEBUG(dbgs() << "xnack setting for subtarget: " << TargetID.getXnackSetting() << '\n'); LLVM_DEBUG(dbgs() << "sramecc setting for subtarget: " << TargetID.getSramEccSetting() << '\n'); return *this; } void GCNSubtarget::checkSubtargetFeatures(const Function &F) const { LLVMContext &Ctx = F.getContext(); if (hasFeature(AMDGPU::FeatureWavefrontSize32) == hasFeature(AMDGPU::FeatureWavefrontSize64)) { Ctx.diagnose(DiagnosticInfoUnsupported( F, "must specify exactly one of wavefrontsize32 and wavefrontsize64")); } } AMDGPUSubtarget::AMDGPUSubtarget(Triple TT) : TargetTriple(std::move(TT)) {} bool AMDGPUSubtarget::useRealTrue16Insts() const { return hasTrue16BitInsts() && EnableRealTrue16Insts; } GCNSubtarget::GCNSubtarget(const Triple &TT, StringRef GPU, StringRef FS, const GCNTargetMachine &TM) : // clang-format off AMDGPUGenSubtargetInfo(TT, GPU, /*TuneCPU*/ GPU, FS), AMDGPUSubtarget(TT), TargetTriple(TT), TargetID(*this), InstrItins(getInstrItineraryForCPU(GPU)), InstrInfo(initializeSubtargetDependencies(TT, GPU, FS)), TLInfo(TM, *this), FrameLowering(TargetFrameLowering::StackGrowsUp, getStackAlignment(), 0) { // clang-format on MaxWavesPerEU = AMDGPU::IsaInfo::getMaxWavesPerEU(this); EUsPerCU = AMDGPU::IsaInfo::getEUsPerCU(this); CallLoweringInfo = std::make_unique(*getTargetLowering()); InlineAsmLoweringInfo = std::make_unique(getTargetLowering()); Legalizer = std::make_unique(*this, TM); RegBankInfo = std::make_unique(*this); InstSelector = std::make_unique(*this, *RegBankInfo, TM); } unsigned GCNSubtarget::getConstantBusLimit(unsigned Opcode) const { if (getGeneration() < GFX10) return 1; switch (Opcode) { case AMDGPU::V_LSHLREV_B64_e64: case AMDGPU::V_LSHLREV_B64_gfx10: case AMDGPU::V_LSHLREV_B64_e64_gfx11: case AMDGPU::V_LSHLREV_B64_e32_gfx12: case AMDGPU::V_LSHLREV_B64_e64_gfx12: case AMDGPU::V_LSHL_B64_e64: case AMDGPU::V_LSHRREV_B64_e64: case AMDGPU::V_LSHRREV_B64_gfx10: case AMDGPU::V_LSHRREV_B64_e64_gfx11: case AMDGPU::V_LSHRREV_B64_e64_gfx12: case AMDGPU::V_LSHR_B64_e64: case AMDGPU::V_ASHRREV_I64_e64: case AMDGPU::V_ASHRREV_I64_gfx10: case AMDGPU::V_ASHRREV_I64_e64_gfx11: case AMDGPU::V_ASHRREV_I64_e64_gfx12: case AMDGPU::V_ASHR_I64_e64: return 1; } return 2; } /// This list was mostly derived from experimentation. bool GCNSubtarget::zeroesHigh16BitsOfDest(unsigned Opcode) const { switch (Opcode) { case AMDGPU::V_CVT_F16_F32_e32: case AMDGPU::V_CVT_F16_F32_e64: case AMDGPU::V_CVT_F16_U16_e32: case AMDGPU::V_CVT_F16_U16_e64: case AMDGPU::V_CVT_F16_I16_e32: case AMDGPU::V_CVT_F16_I16_e64: case AMDGPU::V_RCP_F16_e64: case AMDGPU::V_RCP_F16_e32: case AMDGPU::V_RSQ_F16_e64: case AMDGPU::V_RSQ_F16_e32: case AMDGPU::V_SQRT_F16_e64: case AMDGPU::V_SQRT_F16_e32: case AMDGPU::V_LOG_F16_e64: case AMDGPU::V_LOG_F16_e32: case AMDGPU::V_EXP_F16_e64: case AMDGPU::V_EXP_F16_e32: case AMDGPU::V_SIN_F16_e64: case AMDGPU::V_SIN_F16_e32: case AMDGPU::V_COS_F16_e64: case AMDGPU::V_COS_F16_e32: case AMDGPU::V_FLOOR_F16_e64: case AMDGPU::V_FLOOR_F16_e32: case AMDGPU::V_CEIL_F16_e64: case AMDGPU::V_CEIL_F16_e32: case AMDGPU::V_TRUNC_F16_e64: case AMDGPU::V_TRUNC_F16_e32: case AMDGPU::V_RNDNE_F16_e64: case AMDGPU::V_RNDNE_F16_e32: case AMDGPU::V_FRACT_F16_e64: case AMDGPU::V_FRACT_F16_e32: case AMDGPU::V_FREXP_MANT_F16_e64: case AMDGPU::V_FREXP_MANT_F16_e32: case AMDGPU::V_FREXP_EXP_I16_F16_e64: case AMDGPU::V_FREXP_EXP_I16_F16_e32: case AMDGPU::V_LDEXP_F16_e64: case AMDGPU::V_LDEXP_F16_e32: case AMDGPU::V_LSHLREV_B16_e64: case AMDGPU::V_LSHLREV_B16_e32: case AMDGPU::V_LSHRREV_B16_e64: case AMDGPU::V_LSHRREV_B16_e32: case AMDGPU::V_ASHRREV_I16_e64: case AMDGPU::V_ASHRREV_I16_e32: case AMDGPU::V_ADD_U16_e64: case AMDGPU::V_ADD_U16_e32: case AMDGPU::V_SUB_U16_e64: case AMDGPU::V_SUB_U16_e32: case AMDGPU::V_SUBREV_U16_e64: case AMDGPU::V_SUBREV_U16_e32: case AMDGPU::V_MUL_LO_U16_e64: case AMDGPU::V_MUL_LO_U16_e32: case AMDGPU::V_ADD_F16_e64: case AMDGPU::V_ADD_F16_e32: case AMDGPU::V_SUB_F16_e64: case AMDGPU::V_SUB_F16_e32: case AMDGPU::V_SUBREV_F16_e64: case AMDGPU::V_SUBREV_F16_e32: case AMDGPU::V_MUL_F16_e64: case AMDGPU::V_MUL_F16_e32: case AMDGPU::V_MAX_F16_e64: case AMDGPU::V_MAX_F16_e32: case AMDGPU::V_MIN_F16_e64: case AMDGPU::V_MIN_F16_e32: case AMDGPU::V_MAX_U16_e64: case AMDGPU::V_MAX_U16_e32: case AMDGPU::V_MIN_U16_e64: case AMDGPU::V_MIN_U16_e32: case AMDGPU::V_MAX_I16_e64: case AMDGPU::V_MAX_I16_e32: case AMDGPU::V_MIN_I16_e64: case AMDGPU::V_MIN_I16_e32: case AMDGPU::V_MAD_F16_e64: case AMDGPU::V_MAD_U16_e64: case AMDGPU::V_MAD_I16_e64: case AMDGPU::V_FMA_F16_e64: case AMDGPU::V_DIV_FIXUP_F16_e64: // On gfx10, all 16-bit instructions preserve the high bits. return getGeneration() <= AMDGPUSubtarget::GFX9; case AMDGPU::V_MADAK_F16: case AMDGPU::V_MADMK_F16: case AMDGPU::V_MAC_F16_e64: case AMDGPU::V_MAC_F16_e32: case AMDGPU::V_FMAMK_F16: case AMDGPU::V_FMAAK_F16: case AMDGPU::V_FMAC_F16_e64: case AMDGPU::V_FMAC_F16_e32: // In gfx9, the preferred handling of the unused high 16-bits changed. Most // instructions maintain the legacy behavior of 0ing. Some instructions // changed to preserving the high bits. return getGeneration() == AMDGPUSubtarget::VOLCANIC_ISLANDS; case AMDGPU::V_MAD_MIXLO_F16: case AMDGPU::V_MAD_MIXHI_F16: default: return false; } } // Returns the maximum per-workgroup LDS allocation size (in bytes) that still // allows the given function to achieve an occupancy of NWaves waves per // SIMD / EU, taking into account only the function's *maximum* workgroup size. unsigned AMDGPUSubtarget::getMaxLocalMemSizeWithWaveCount(unsigned NWaves, const Function &F) const { const unsigned WaveSize = getWavefrontSize(); const unsigned WorkGroupSize = getFlatWorkGroupSizes(F).second; const unsigned WavesPerWorkgroup = std::max(1u, (WorkGroupSize + WaveSize - 1) / WaveSize); const unsigned WorkGroupsPerCU = std::max(1u, (NWaves * getEUsPerCU()) / WavesPerWorkgroup); return getLocalMemorySize() / WorkGroupsPerCU; } // FIXME: Should return min,max range. // // Returns the maximum occupancy, in number of waves per SIMD / EU, that can // be achieved when only the given function is running on the machine; and // taking into account the overall number of wave slots, the (maximum) workgroup // size, and the per-workgroup LDS allocation size. unsigned AMDGPUSubtarget::getOccupancyWithLocalMemSize(uint32_t Bytes, const Function &F) const { const unsigned MaxWorkGroupSize = getFlatWorkGroupSizes(F).second; const unsigned MaxWorkGroupsPerCu = getMaxWorkGroupsPerCU(MaxWorkGroupSize); if (!MaxWorkGroupsPerCu) return 0; const unsigned WaveSize = getWavefrontSize(); // FIXME: Do we need to account for alignment requirement of LDS rounding the // size up? // Compute restriction based on LDS usage unsigned NumGroups = getLocalMemorySize() / (Bytes ? Bytes : 1u); // This can be queried with more LDS than is possible, so just assume the // worst. if (NumGroups == 0) return 1; NumGroups = std::min(MaxWorkGroupsPerCu, NumGroups); // Round to the number of waves per CU. const unsigned MaxGroupNumWaves = divideCeil(MaxWorkGroupSize, WaveSize); unsigned MaxWaves = NumGroups * MaxGroupNumWaves; // Number of waves per EU (SIMD). MaxWaves = divideCeil(MaxWaves, getEUsPerCU()); // Clamp to the maximum possible number of waves. MaxWaves = std::min(MaxWaves, getMaxWavesPerEU()); // FIXME: Needs to be a multiple of the group size? //MaxWaves = MaxGroupNumWaves * (MaxWaves / MaxGroupNumWaves); assert(MaxWaves > 0 && MaxWaves <= getMaxWavesPerEU() && "computed invalid occupancy"); return MaxWaves; } unsigned AMDGPUSubtarget::getOccupancyWithLocalMemSize(const MachineFunction &MF) const { const auto *MFI = MF.getInfo(); return getOccupancyWithLocalMemSize(MFI->getLDSSize(), MF.getFunction()); } std::pair AMDGPUSubtarget::getDefaultFlatWorkGroupSize(CallingConv::ID CC) const { switch (CC) { case CallingConv::AMDGPU_VS: case CallingConv::AMDGPU_LS: case CallingConv::AMDGPU_HS: case CallingConv::AMDGPU_ES: case CallingConv::AMDGPU_GS: case CallingConv::AMDGPU_PS: return std::pair(1, getWavefrontSize()); default: return std::pair(1u, getMaxFlatWorkGroupSize()); } } std::pair AMDGPUSubtarget::getFlatWorkGroupSizes( const Function &F) const { // Default minimum/maximum flat work group sizes. std::pair Default = getDefaultFlatWorkGroupSize(F.getCallingConv()); // Requested minimum/maximum flat work group sizes. std::pair Requested = AMDGPU::getIntegerPairAttribute( F, "amdgpu-flat-work-group-size", Default); // Make sure requested minimum is less than requested maximum. if (Requested.first > Requested.second) return Default; // Make sure requested values do not violate subtarget's specifications. if (Requested.first < getMinFlatWorkGroupSize()) return Default; if (Requested.second > getMaxFlatWorkGroupSize()) return Default; return Requested; } std::pair AMDGPUSubtarget::getEffectiveWavesPerEU( std::pair Requested, std::pair FlatWorkGroupSizes) const { // Default minimum/maximum number of waves per execution unit. std::pair Default(1, getMaxWavesPerEU()); // If minimum/maximum flat work group sizes were explicitly requested using // "amdgpu-flat-workgroup-size" attribute, then set default minimum/maximum // number of waves per execution unit to values implied by requested // minimum/maximum flat work group sizes. unsigned MinImpliedByFlatWorkGroupSize = getWavesPerEUForWorkGroup(FlatWorkGroupSizes.second); Default.first = MinImpliedByFlatWorkGroupSize; // Make sure requested minimum is less than requested maximum. if (Requested.second && Requested.first > Requested.second) return Default; // Make sure requested values do not violate subtarget's specifications. if (Requested.first < getMinWavesPerEU() || Requested.second > getMaxWavesPerEU()) return Default; // Make sure requested values are compatible with values implied by requested // minimum/maximum flat work group sizes. if (Requested.first < MinImpliedByFlatWorkGroupSize) return Default; return Requested; } std::pair AMDGPUSubtarget::getWavesPerEU( const Function &F, std::pair FlatWorkGroupSizes) const { // Default minimum/maximum number of waves per execution unit. std::pair Default(1, getMaxWavesPerEU()); // Requested minimum/maximum number of waves per execution unit. std::pair Requested = AMDGPU::getIntegerPairAttribute(F, "amdgpu-waves-per-eu", Default, true); return getEffectiveWavesPerEU(Requested, FlatWorkGroupSizes); } static unsigned getReqdWorkGroupSize(const Function &Kernel, unsigned Dim) { auto Node = Kernel.getMetadata("reqd_work_group_size"); if (Node && Node->getNumOperands() == 3) return mdconst::extract(Node->getOperand(Dim))->getZExtValue(); return std::numeric_limits::max(); } bool AMDGPUSubtarget::isMesaKernel(const Function &F) const { return isMesa3DOS() && !AMDGPU::isShader(F.getCallingConv()); } unsigned AMDGPUSubtarget::getMaxWorkitemID(const Function &Kernel, unsigned Dimension) const { unsigned ReqdSize = getReqdWorkGroupSize(Kernel, Dimension); if (ReqdSize != std::numeric_limits::max()) return ReqdSize - 1; return getFlatWorkGroupSizes(Kernel).second - 1; } bool AMDGPUSubtarget::isSingleLaneExecution(const Function &Func) const { for (int I = 0; I < 3; ++I) { if (getMaxWorkitemID(Func, I) > 0) return false; } return true; } bool AMDGPUSubtarget::makeLIDRangeMetadata(Instruction *I) const { Function *Kernel = I->getParent()->getParent(); unsigned MinSize = 0; unsigned MaxSize = getFlatWorkGroupSizes(*Kernel).second; bool IdQuery = false; // If reqd_work_group_size is present it narrows value down. if (auto *CI = dyn_cast(I)) { const Function *F = CI->getCalledFunction(); if (F) { unsigned Dim = UINT_MAX; switch (F->getIntrinsicID()) { case Intrinsic::amdgcn_workitem_id_x: case Intrinsic::r600_read_tidig_x: IdQuery = true; [[fallthrough]]; case Intrinsic::r600_read_local_size_x: Dim = 0; break; case Intrinsic::amdgcn_workitem_id_y: case Intrinsic::r600_read_tidig_y: IdQuery = true; [[fallthrough]]; case Intrinsic::r600_read_local_size_y: Dim = 1; break; case Intrinsic::amdgcn_workitem_id_z: case Intrinsic::r600_read_tidig_z: IdQuery = true; [[fallthrough]]; case Intrinsic::r600_read_local_size_z: Dim = 2; break; default: break; } if (Dim <= 3) { unsigned ReqdSize = getReqdWorkGroupSize(*Kernel, Dim); if (ReqdSize != std::numeric_limits::max()) MinSize = MaxSize = ReqdSize; } } } if (!MaxSize) return false; // Range metadata is [Lo, Hi). For ID query we need to pass max size // as Hi. For size query we need to pass Hi + 1. if (IdQuery) MinSize = 0; else ++MaxSize; APInt Lower{32, MinSize}; APInt Upper{32, MaxSize}; if (auto *CI = dyn_cast(I)) { ConstantRange Range(Lower, Upper); CI->addRangeRetAttr(Range); } else { MDBuilder MDB(I->getContext()); MDNode *MaxWorkGroupSizeRange = MDB.createRange(Lower, Upper); I->setMetadata(LLVMContext::MD_range, MaxWorkGroupSizeRange); } return true; } unsigned AMDGPUSubtarget::getImplicitArgNumBytes(const Function &F) const { assert(AMDGPU::isKernel(F.getCallingConv())); // We don't allocate the segment if we know the implicit arguments weren't // used, even if the ABI implies we need them. if (F.hasFnAttribute("amdgpu-no-implicitarg-ptr")) return 0; if (isMesaKernel(F)) return 16; // Assume all implicit inputs are used by default const Module *M = F.getParent(); unsigned NBytes = AMDGPU::getAMDHSACodeObjectVersion(*M) >= AMDGPU::AMDHSA_COV5 ? 256 : 56; return F.getFnAttributeAsParsedInteger("amdgpu-implicitarg-num-bytes", NBytes); } uint64_t AMDGPUSubtarget::getExplicitKernArgSize(const Function &F, Align &MaxAlign) const { assert(F.getCallingConv() == CallingConv::AMDGPU_KERNEL || F.getCallingConv() == CallingConv::SPIR_KERNEL); const DataLayout &DL = F.getDataLayout(); uint64_t ExplicitArgBytes = 0; MaxAlign = Align(1); for (const Argument &Arg : F.args()) { const bool IsByRef = Arg.hasByRefAttr(); Type *ArgTy = IsByRef ? Arg.getParamByRefType() : Arg.getType(); Align Alignment = DL.getValueOrABITypeAlignment( IsByRef ? Arg.getParamAlign() : std::nullopt, ArgTy); uint64_t AllocSize = DL.getTypeAllocSize(ArgTy); ExplicitArgBytes = alignTo(ExplicitArgBytes, Alignment) + AllocSize; MaxAlign = std::max(MaxAlign, Alignment); } return ExplicitArgBytes; } unsigned AMDGPUSubtarget::getKernArgSegmentSize(const Function &F, Align &MaxAlign) const { if (F.getCallingConv() != CallingConv::AMDGPU_KERNEL && F.getCallingConv() != CallingConv::SPIR_KERNEL) return 0; uint64_t ExplicitArgBytes = getExplicitKernArgSize(F, MaxAlign); unsigned ExplicitOffset = getExplicitKernelArgOffset(); uint64_t TotalSize = ExplicitOffset + ExplicitArgBytes; unsigned ImplicitBytes = getImplicitArgNumBytes(F); if (ImplicitBytes != 0) { const Align Alignment = getAlignmentForImplicitArgPtr(); TotalSize = alignTo(ExplicitArgBytes, Alignment) + ImplicitBytes; MaxAlign = std::max(MaxAlign, Alignment); } // Being able to dereference past the end is useful for emitting scalar loads. return alignTo(TotalSize, 4); } AMDGPUDwarfFlavour AMDGPUSubtarget::getAMDGPUDwarfFlavour() const { return getWavefrontSize() == 32 ? AMDGPUDwarfFlavour::Wave32 : AMDGPUDwarfFlavour::Wave64; } void GCNSubtarget::overrideSchedPolicy(MachineSchedPolicy &Policy, unsigned NumRegionInstrs) const { // Track register pressure so the scheduler can try to decrease // pressure once register usage is above the threshold defined by // SIRegisterInfo::getRegPressureSetLimit() Policy.ShouldTrackPressure = true; // Enabling both top down and bottom up scheduling seems to give us less // register spills than just using one of these approaches on its own. Policy.OnlyTopDown = false; Policy.OnlyBottomUp = false; // Enabling ShouldTrackLaneMasks crashes the SI Machine Scheduler. if (!enableSIScheduler()) Policy.ShouldTrackLaneMasks = true; } void GCNSubtarget::mirFileLoaded(MachineFunction &MF) const { if (isWave32()) { // Fix implicit $vcc operands after MIParser has verified that they match // the instruction definitions. for (auto &MBB : MF) { for (auto &MI : MBB) InstrInfo.fixImplicitOperands(MI); } } } bool GCNSubtarget::hasMadF16() const { return InstrInfo.pseudoToMCOpcode(AMDGPU::V_MAD_F16_e64) != -1; } bool GCNSubtarget::useVGPRIndexMode() const { return !hasMovrel() || (EnableVGPRIndexMode && hasVGPRIndexMode()); } bool GCNSubtarget::useAA() const { return UseAA; } unsigned GCNSubtarget::getOccupancyWithNumSGPRs(unsigned SGPRs) const { return AMDGPU::IsaInfo::getOccupancyWithNumSGPRs(SGPRs, getMaxWavesPerEU(), getGeneration()); } unsigned GCNSubtarget::getOccupancyWithNumVGPRs(unsigned NumVGPRs) const { return AMDGPU::IsaInfo::getNumWavesPerEUWithNumVGPRs(this, NumVGPRs); } unsigned GCNSubtarget::getBaseReservedNumSGPRs(const bool HasFlatScratch) const { if (getGeneration() >= AMDGPUSubtarget::GFX10) return 2; // VCC. FLAT_SCRATCH and XNACK are no longer in SGPRs. if (HasFlatScratch || HasArchitectedFlatScratch) { if (getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS) return 6; // FLAT_SCRATCH, XNACK, VCC (in that order). if (getGeneration() == AMDGPUSubtarget::SEA_ISLANDS) return 4; // FLAT_SCRATCH, VCC (in that order). } if (isXNACKEnabled()) return 4; // XNACK, VCC (in that order). return 2; // VCC. } unsigned GCNSubtarget::getReservedNumSGPRs(const MachineFunction &MF) const { const SIMachineFunctionInfo &MFI = *MF.getInfo(); return getBaseReservedNumSGPRs(MFI.getUserSGPRInfo().hasFlatScratchInit()); } unsigned GCNSubtarget::getReservedNumSGPRs(const Function &F) const { // In principle we do not need to reserve SGPR pair used for flat_scratch if // we know flat instructions do not access the stack anywhere in the // program. For now assume it's needed if we have flat instructions. const bool KernelUsesFlatScratch = hasFlatAddressSpace(); return getBaseReservedNumSGPRs(KernelUsesFlatScratch); } unsigned GCNSubtarget::computeOccupancy(const Function &F, unsigned LDSSize, unsigned NumSGPRs, unsigned NumVGPRs) const { unsigned Occupancy = std::min(getMaxWavesPerEU(), getOccupancyWithLocalMemSize(LDSSize, F)); if (NumSGPRs) Occupancy = std::min(Occupancy, getOccupancyWithNumSGPRs(NumSGPRs)); if (NumVGPRs) Occupancy = std::min(Occupancy, getOccupancyWithNumVGPRs(NumVGPRs)); return Occupancy; } unsigned GCNSubtarget::getBaseMaxNumSGPRs( const Function &F, std::pair WavesPerEU, unsigned PreloadedSGPRs, unsigned ReservedNumSGPRs) const { // Compute maximum number of SGPRs function can use using default/requested // minimum number of waves per execution unit. unsigned MaxNumSGPRs = getMaxNumSGPRs(WavesPerEU.first, false); unsigned MaxAddressableNumSGPRs = getMaxNumSGPRs(WavesPerEU.first, true); // Check if maximum number of SGPRs was explicitly requested using // "amdgpu-num-sgpr" attribute. if (F.hasFnAttribute("amdgpu-num-sgpr")) { unsigned Requested = F.getFnAttributeAsParsedInteger("amdgpu-num-sgpr", MaxNumSGPRs); // Make sure requested value does not violate subtarget's specifications. if (Requested && (Requested <= ReservedNumSGPRs)) Requested = 0; // If more SGPRs are required to support the input user/system SGPRs, // increase to accommodate them. // // FIXME: This really ends up using the requested number of SGPRs + number // of reserved special registers in total. Theoretically you could re-use // the last input registers for these special registers, but this would // require a lot of complexity to deal with the weird aliasing. unsigned InputNumSGPRs = PreloadedSGPRs; if (Requested && Requested < InputNumSGPRs) Requested = InputNumSGPRs; // Make sure requested value is compatible with values implied by // default/requested minimum/maximum number of waves per execution unit. if (Requested && Requested > getMaxNumSGPRs(WavesPerEU.first, false)) Requested = 0; if (WavesPerEU.second && Requested && Requested < getMinNumSGPRs(WavesPerEU.second)) Requested = 0; if (Requested) MaxNumSGPRs = Requested; } if (hasSGPRInitBug()) MaxNumSGPRs = AMDGPU::IsaInfo::FIXED_NUM_SGPRS_FOR_INIT_BUG; return std::min(MaxNumSGPRs - ReservedNumSGPRs, MaxAddressableNumSGPRs); } unsigned GCNSubtarget::getMaxNumSGPRs(const MachineFunction &MF) const { const Function &F = MF.getFunction(); const SIMachineFunctionInfo &MFI = *MF.getInfo(); return getBaseMaxNumSGPRs(F, MFI.getWavesPerEU(), MFI.getNumPreloadedSGPRs(), getReservedNumSGPRs(MF)); } static unsigned getMaxNumPreloadedSGPRs() { using USI = GCNUserSGPRUsageInfo; // Max number of user SGPRs const unsigned MaxUserSGPRs = USI::getNumUserSGPRForField(USI::PrivateSegmentBufferID) + USI::getNumUserSGPRForField(USI::DispatchPtrID) + USI::getNumUserSGPRForField(USI::QueuePtrID) + USI::getNumUserSGPRForField(USI::KernargSegmentPtrID) + USI::getNumUserSGPRForField(USI::DispatchIdID) + USI::getNumUserSGPRForField(USI::FlatScratchInitID) + USI::getNumUserSGPRForField(USI::ImplicitBufferPtrID); // Max number of system SGPRs const unsigned MaxSystemSGPRs = 1 + // WorkGroupIDX 1 + // WorkGroupIDY 1 + // WorkGroupIDZ 1 + // WorkGroupInfo 1; // private segment wave byte offset // Max number of synthetic SGPRs const unsigned SyntheticSGPRs = 1; // LDSKernelId return MaxUserSGPRs + MaxSystemSGPRs + SyntheticSGPRs; } unsigned GCNSubtarget::getMaxNumSGPRs(const Function &F) const { return getBaseMaxNumSGPRs(F, getWavesPerEU(F), getMaxNumPreloadedSGPRs(), getReservedNumSGPRs(F)); } unsigned GCNSubtarget::getBaseMaxNumVGPRs( const Function &F, std::pair WavesPerEU) const { // Compute maximum number of VGPRs function can use using default/requested // minimum number of waves per execution unit. unsigned MaxNumVGPRs = getMaxNumVGPRs(WavesPerEU.first); // Check if maximum number of VGPRs was explicitly requested using // "amdgpu-num-vgpr" attribute. if (F.hasFnAttribute("amdgpu-num-vgpr")) { unsigned Requested = F.getFnAttributeAsParsedInteger("amdgpu-num-vgpr", MaxNumVGPRs); if (hasGFX90AInsts()) Requested *= 2; // Make sure requested value is compatible with values implied by // default/requested minimum/maximum number of waves per execution unit. if (Requested && Requested > getMaxNumVGPRs(WavesPerEU.first)) Requested = 0; if (WavesPerEU.second && Requested && Requested < getMinNumVGPRs(WavesPerEU.second)) Requested = 0; if (Requested) MaxNumVGPRs = Requested; } return MaxNumVGPRs; } unsigned GCNSubtarget::getMaxNumVGPRs(const Function &F) const { return getBaseMaxNumVGPRs(F, getWavesPerEU(F)); } unsigned GCNSubtarget::getMaxNumVGPRs(const MachineFunction &MF) const { const Function &F = MF.getFunction(); const SIMachineFunctionInfo &MFI = *MF.getInfo(); return getBaseMaxNumVGPRs(F, MFI.getWavesPerEU()); } void GCNSubtarget::adjustSchedDependency( SUnit *Def, int DefOpIdx, SUnit *Use, int UseOpIdx, SDep &Dep, const TargetSchedModel *SchedModel) const { if (Dep.getKind() != SDep::Kind::Data || !Dep.getReg() || !Def->isInstr() || !Use->isInstr()) return; MachineInstr *DefI = Def->getInstr(); MachineInstr *UseI = Use->getInstr(); if (DefI->isBundle()) { const SIRegisterInfo *TRI = getRegisterInfo(); auto Reg = Dep.getReg(); MachineBasicBlock::const_instr_iterator I(DefI->getIterator()); MachineBasicBlock::const_instr_iterator E(DefI->getParent()->instr_end()); unsigned Lat = 0; for (++I; I != E && I->isBundledWithPred(); ++I) { if (I->modifiesRegister(Reg, TRI)) Lat = InstrInfo.getInstrLatency(getInstrItineraryData(), *I); else if (Lat) --Lat; } Dep.setLatency(Lat); } else if (UseI->isBundle()) { const SIRegisterInfo *TRI = getRegisterInfo(); auto Reg = Dep.getReg(); MachineBasicBlock::const_instr_iterator I(UseI->getIterator()); MachineBasicBlock::const_instr_iterator E(UseI->getParent()->instr_end()); unsigned Lat = InstrInfo.getInstrLatency(getInstrItineraryData(), *DefI); for (++I; I != E && I->isBundledWithPred() && Lat; ++I) { if (I->readsRegister(Reg, TRI)) break; --Lat; } Dep.setLatency(Lat); } else if (Dep.getLatency() == 0 && Dep.getReg() == AMDGPU::VCC_LO) { // Work around the fact that SIInstrInfo::fixImplicitOperands modifies // implicit operands which come from the MCInstrDesc, which can fool // ScheduleDAGInstrs::addPhysRegDataDeps into treating them as implicit // pseudo operands. Dep.setLatency(InstrInfo.getSchedModel().computeOperandLatency( DefI, DefOpIdx, UseI, UseOpIdx)); } } namespace { struct FillMFMAShadowMutation : ScheduleDAGMutation { const SIInstrInfo *TII; ScheduleDAGMI *DAG; FillMFMAShadowMutation(const SIInstrInfo *tii) : TII(tii) {} bool isSALU(const SUnit *SU) const { const MachineInstr *MI = SU->getInstr(); return MI && TII->isSALU(*MI) && !MI->isTerminator(); } bool isVALU(const SUnit *SU) const { const MachineInstr *MI = SU->getInstr(); return MI && TII->isVALU(*MI); } // Link as many SALU instructions in chain as possible. Return the size // of the chain. Links up to MaxChain instructions. unsigned linkSALUChain(SUnit *From, SUnit *To, unsigned MaxChain, SmallPtrSetImpl &Visited) const { SmallVector Worklist({To}); unsigned Linked = 0; while (!Worklist.empty() && MaxChain-- > 0) { SUnit *SU = Worklist.pop_back_val(); if (!Visited.insert(SU).second) continue; LLVM_DEBUG(dbgs() << "Inserting edge from\n" ; DAG->dumpNode(*From); dbgs() << "to\n"; DAG->dumpNode(*SU); dbgs() << '\n'); if (SU != From && From != &DAG->ExitSU && DAG->canAddEdge(SU, From)) if (DAG->addEdge(SU, SDep(From, SDep::Artificial))) ++Linked; for (SDep &SI : From->Succs) { SUnit *SUv = SI.getSUnit(); if (SUv != From && SU != &DAG->ExitSU && isVALU(SUv) && DAG->canAddEdge(SUv, SU)) DAG->addEdge(SUv, SDep(SU, SDep::Artificial)); } for (SDep &SI : SU->Succs) { SUnit *Succ = SI.getSUnit(); if (Succ != SU && isSALU(Succ)) Worklist.push_back(Succ); } } return Linked; } void apply(ScheduleDAGInstrs *DAGInstrs) override { const GCNSubtarget &ST = DAGInstrs->MF.getSubtarget(); if (!ST.hasMAIInsts()) return; DAG = static_cast(DAGInstrs); const TargetSchedModel *TSchedModel = DAGInstrs->getSchedModel(); if (!TSchedModel || DAG->SUnits.empty()) return; // Scan for MFMA long latency instructions and try to add a dependency // of available SALU instructions to give them a chance to fill MFMA // shadow. That is desirable to fill MFMA shadow with SALU instructions // rather than VALU to prevent power consumption bursts and throttle. auto LastSALU = DAG->SUnits.begin(); auto E = DAG->SUnits.end(); SmallPtrSet Visited; for (SUnit &SU : DAG->SUnits) { MachineInstr &MAI = *SU.getInstr(); if (!TII->isMAI(MAI) || MAI.getOpcode() == AMDGPU::V_ACCVGPR_WRITE_B32_e64 || MAI.getOpcode() == AMDGPU::V_ACCVGPR_READ_B32_e64) continue; unsigned Lat = TSchedModel->computeInstrLatency(&MAI) - 1; LLVM_DEBUG(dbgs() << "Found MFMA: "; DAG->dumpNode(SU); dbgs() << "Need " << Lat << " instructions to cover latency.\n"); // Find up to Lat independent scalar instructions as early as // possible such that they can be scheduled after this MFMA. for ( ; Lat && LastSALU != E; ++LastSALU) { if (Visited.count(&*LastSALU)) continue; if (&SU == &DAG->ExitSU || &SU == &*LastSALU || !isSALU(&*LastSALU) || !DAG->canAddEdge(&*LastSALU, &SU)) continue; Lat -= linkSALUChain(&SU, &*LastSALU, Lat, Visited); } } } }; } // namespace void GCNSubtarget::getPostRAMutations( std::vector> &Mutations) const { Mutations.push_back(std::make_unique(&InstrInfo)); } std::unique_ptr GCNSubtarget::createFillMFMAShadowMutation(const TargetInstrInfo *TII) const { return EnablePowerSched ? std::make_unique(&InstrInfo) : nullptr; } unsigned GCNSubtarget::getNSAThreshold(const MachineFunction &MF) const { if (getGeneration() >= AMDGPUSubtarget::GFX12) return 0; // Not MIMG encoding. if (NSAThreshold.getNumOccurrences() > 0) return std::max(NSAThreshold.getValue(), 2u); int Value = MF.getFunction().getFnAttributeAsParsedInteger( "amdgpu-nsa-threshold", -1); if (Value > 0) return std::max(Value, 2); return 3; } const AMDGPUSubtarget &AMDGPUSubtarget::get(const MachineFunction &MF) { if (MF.getTarget().getTargetTriple().getArch() == Triple::amdgcn) return static_cast(MF.getSubtarget()); return static_cast(MF.getSubtarget()); } const AMDGPUSubtarget &AMDGPUSubtarget::get(const TargetMachine &TM, const Function &F) { if (TM.getTargetTriple().getArch() == Triple::amdgcn) return static_cast(TM.getSubtarget(F)); return static_cast( TM.getSubtarget(F)); } GCNUserSGPRUsageInfo::GCNUserSGPRUsageInfo(const Function &F, const GCNSubtarget &ST) : ST(ST) { const CallingConv::ID CC = F.getCallingConv(); const bool IsKernel = CC == CallingConv::AMDGPU_KERNEL || CC == CallingConv::SPIR_KERNEL; // FIXME: Should have analysis or something rather than attribute to detect // calls. const bool HasCalls = F.hasFnAttribute("amdgpu-calls"); // FIXME: This attribute is a hack, we just need an analysis on the function // to look for allocas. const bool HasStackObjects = F.hasFnAttribute("amdgpu-stack-objects"); if (IsKernel && (!F.arg_empty() || ST.getImplicitArgNumBytes(F) != 0)) KernargSegmentPtr = true; bool IsAmdHsaOrMesa = ST.isAmdHsaOrMesa(F); if (IsAmdHsaOrMesa && !ST.enableFlatScratch()) PrivateSegmentBuffer = true; else if (ST.isMesaGfxShader(F)) ImplicitBufferPtr = true; if (!AMDGPU::isGraphics(CC)) { if (!F.hasFnAttribute("amdgpu-no-dispatch-ptr")) DispatchPtr = true; // FIXME: Can this always be disabled with < COv5? if (!F.hasFnAttribute("amdgpu-no-queue-ptr")) QueuePtr = true; if (!F.hasFnAttribute("amdgpu-no-dispatch-id")) DispatchID = true; } // 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 (ST.hasFlatAddressSpace() && AMDGPU::isEntryFunctionCC(CC) && (IsAmdHsaOrMesa || ST.enableFlatScratch()) && (HasCalls || HasStackObjects || ST.enableFlatScratch()) && !ST.flatScratchIsArchitected()) { FlatScratchInit = true; } if (hasImplicitBufferPtr()) NumUsedUserSGPRs += getNumUserSGPRForField(ImplicitBufferPtrID); if (hasPrivateSegmentBuffer()) NumUsedUserSGPRs += getNumUserSGPRForField(PrivateSegmentBufferID); if (hasDispatchPtr()) NumUsedUserSGPRs += getNumUserSGPRForField(DispatchPtrID); if (hasQueuePtr()) NumUsedUserSGPRs += getNumUserSGPRForField(QueuePtrID); if (hasKernargSegmentPtr()) NumUsedUserSGPRs += getNumUserSGPRForField(KernargSegmentPtrID); if (hasDispatchID()) NumUsedUserSGPRs += getNumUserSGPRForField(DispatchIdID); if (hasFlatScratchInit()) NumUsedUserSGPRs += getNumUserSGPRForField(FlatScratchInitID); if (hasPrivateSegmentSize()) NumUsedUserSGPRs += getNumUserSGPRForField(PrivateSegmentSizeID); } void GCNUserSGPRUsageInfo::allocKernargPreloadSGPRs(unsigned NumSGPRs) { assert(NumKernargPreloadSGPRs + NumSGPRs <= AMDGPU::getMaxNumUserSGPRs(ST)); NumKernargPreloadSGPRs += NumSGPRs; NumUsedUserSGPRs += NumSGPRs; } unsigned GCNUserSGPRUsageInfo::getNumFreeUserSGPRs() { return AMDGPU::getMaxNumUserSGPRs(ST) - NumUsedUserSGPRs; } SmallVector AMDGPUSubtarget::getMaxNumWorkGroups(const Function &F) const { return AMDGPU::getIntegerVecAttribute(F, "amdgpu-max-num-workgroups", 3); }