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llvm-project/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.cpp

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//===- 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 "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 <cassert>
#include <vector>
#define MAX_LANES 64
using namespace llvm;
SIMachineFunctionInfo::SIMachineFunctionInfo(const MachineFunction &MF)
: AMDGPUMachineFunction(MF),
Mode(MF.getFunction()),
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<GCNSubtarget>();
const Function &F = MF.getFunction();
FlatWorkGroupSizes = ST.getFlatWorkGroupSizes(F);
WavesPerEU = ST.getWavesPerEU(F);
Occupancy = ST.computeOccupancy(MF, getLDSSize());
CallingConv::ID CC = F.getCallingConv();
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;
ScratchWaveOffsetReg = AMDGPU::SGPR33;
// TODO: Pick a high register, and shift down, similar to a kernel.
FrameOffsetReg = AMDGPU::SGPR34;
StackPtrOffsetReg = AMDGPU::SGPR32;
ArgInfo.PrivateSegmentBuffer =
ArgDescriptor::createRegister(ScratchRSrcReg);
ArgInfo.PrivateSegmentWaveByteOffset =
ArgDescriptor::createRegister(ScratchWaveOffsetReg);
if (F.hasFnAttribute("amdgpu-implicitarg-ptr"))
ImplicitArgPtr = true;
} else {
if (F.hasFnAttribute("amdgpu-implicitarg-ptr")) {
KernargSegmentPtr = true;
MaxKernArgAlign = std::max(ST.getAlignmentForImplicitArgPtr(),
MaxKernArgAlign);
}
}
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;
const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
bool HasStackObjects = FrameInfo.hasStackObjects();
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 (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 (F.hasFnAttribute("amdgpu-kernarg-segment-ptr"))
KernargSegmentPtr = true;
if (ST.hasFlatAddressSpace() && isEntryFunction() && isAmdHsaOrMesa) {
auto hasNonSpillStackObjects = [&]() {
// Avoid expensive checking if there's no stack objects.
if (!HasStackObjects)
return false;
for (auto OI = FrameInfo.getObjectIndexBegin(),
OE = FrameInfo.getObjectIndexEnd(); OI != OE; ++OI)
if (!FrameInfo.isSpillSlotObjectIndex(OI))
return true;
// All stack objects are spill slots.
return false;
};
// TODO: This could be refined a lot. The attribute is a poor way of
// detecting calls that may require it before argument lowering.
if (hasNonSpillStackObjects() || F.hasFnAttribute("amdgpu-flat-scratch"))
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<GCNSubtarget>();
limitOccupancy(ST.getOccupancyWithLocalMemSize(getLDSSize(),
MF.getFunction()));
}
unsigned SIMachineFunctionInfo::addPrivateSegmentBuffer(
const SIRegisterInfo &TRI) {
ArgInfo.PrivateSegmentBuffer =
ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SGPR_128RegClass));
NumUserSGPRs += 4;
return ArgInfo.PrivateSegmentBuffer.getRegister();
}
unsigned SIMachineFunctionInfo::addDispatchPtr(const SIRegisterInfo &TRI) {
ArgInfo.DispatchPtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.DispatchPtr.getRegister();
}
unsigned SIMachineFunctionInfo::addQueuePtr(const SIRegisterInfo &TRI) {
ArgInfo.QueuePtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.QueuePtr.getRegister();
}
unsigned SIMachineFunctionInfo::addKernargSegmentPtr(const SIRegisterInfo &TRI) {
ArgInfo.KernargSegmentPtr
= ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.KernargSegmentPtr.getRegister();
}
unsigned SIMachineFunctionInfo::addDispatchID(const SIRegisterInfo &TRI) {
ArgInfo.DispatchID = ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.DispatchID.getRegister();
}
unsigned SIMachineFunctionInfo::addFlatScratchInit(const SIRegisterInfo &TRI) {
ArgInfo.FlatScratchInit = ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.FlatScratchInit.getRegister();
}
unsigned SIMachineFunctionInfo::addImplicitBufferPtr(const SIRegisterInfo &TRI) {
ArgInfo.ImplicitBufferPtr = ArgDescriptor::createRegister(TRI.getMatchingSuperReg(
getNextUserSGPR(), AMDGPU::sub0, &AMDGPU::SReg_64RegClass));
NumUserSGPRs += 2;
return ArgInfo.ImplicitBufferPtr.getRegister();
}
static bool 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<GCNSubtarget>();
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<SpilledReg> &SpillLanes = SGPRToVGPRSpills[FI];
// This has already been allocated.
if (!SpillLanes.empty())
return true;
const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
const SIRegisterInfo *TRI = ST.getRegisterInfo();
MachineFrameInfo &FrameInfo = MF.getFrameInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
unsigned WaveSize = ST.getWavefrontSize();
unsigned Size = FrameInfo.getObjectSize(FI);
assert(Size >= 4 && Size <= 64 && "invalid sgpr spill size");
assert(TRI->spillSGPRToVGPR() && "not spilling SGPRs to VGPRs");
int NumLanes = Size / 4;
const MCPhysReg *CSRegs = MRI.getCalleeSavedRegs();
// Make sure to handle the case where a wide SGPR spill may span between two
// VGPRs.
for (int I = 0; I < NumLanes; ++I, ++NumVGPRSpillLanes) {
unsigned LaneVGPR;
unsigned VGPRIndex = (NumVGPRSpillLanes % WaveSize);
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<int> CSRSpillFI;
if ((FrameInfo.hasCalls() || !isEntryFunction()) && CSRegs &&
isCalleeSavedReg(CSRegs, LaneVGPR)) {
CSRSpillFI = FrameInfo.CreateSpillStackObject(4, 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 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<GCNSubtarget>();
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<MCPhysReg>::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 spill hasn't been inserted yet, so keep it around.
for (auto &R : SGPRToVGPRSpills) {
if (R.first != FramePointerSaveIndex)
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)
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;
}
static yaml::StringValue regToString(unsigned Reg,
const TargetRegisterInfo &TRI) {
yaml::StringValue Dest;
{
raw_string_ostream OS(Dest.Value);
OS << printReg(Reg, &TRI);
}
return Dest;
}
static Optional<yaml::SIArgumentInfo>
convertArgumentInfo(const AMDGPUFunctionArgInfo &ArgInfo,
const TargetRegisterInfo &TRI) {
yaml::SIArgumentInfo AI;
auto convertArg = [&](Optional<yaml::SIArgument> &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)),
ScratchWaveOffsetReg(regToString(MFI.getScratchWaveOffsetReg(), 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<SIMachineFunctionInfo>::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;
}
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