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

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//===- SILoadStoreOptimizer.cpp -------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This pass tries to fuse DS instructions with close by immediate offsets.
// This will fuse operations such as
// ds_read_b32 v0, v2 offset:16
// ds_read_b32 v1, v2 offset:32
// ==>
// ds_read2_b32 v[0:1], v2, offset0:4 offset1:8
//
// The same is done for certain SMEM and VMEM opcodes, e.g.:
// s_buffer_load_dword s4, s[0:3], 4
// s_buffer_load_dword s5, s[0:3], 8
// ==>
// s_buffer_load_dwordx2 s[4:5], s[0:3], 4
//
// This pass also tries to promote constant offset to the immediate by
// adjusting the base. It tries to use a base from the nearby instructions that
// allows it to have a 13bit constant offset and then promotes the 13bit offset
// to the immediate.
// E.g.
// s_movk_i32 s0, 0x1800
// v_add_co_u32_e32 v0, vcc, s0, v2
// v_addc_co_u32_e32 v1, vcc, 0, v6, vcc
//
// s_movk_i32 s0, 0x1000
// v_add_co_u32_e32 v5, vcc, s0, v2
// v_addc_co_u32_e32 v6, vcc, 0, v6, vcc
// global_load_dwordx2 v[5:6], v[5:6], off
// global_load_dwordx2 v[0:1], v[0:1], off
// =>
// s_movk_i32 s0, 0x1000
// v_add_co_u32_e32 v5, vcc, s0, v2
// v_addc_co_u32_e32 v6, vcc, 0, v6, vcc
// global_load_dwordx2 v[5:6], v[5:6], off
// global_load_dwordx2 v[0:1], v[5:6], off offset:2048
//
// Future improvements:
//
// - This is currently missing stores of constants because loading
// the constant into the data register is placed between the stores, although
// this is arguably a scheduling problem.
//
// - Live interval recomputing seems inefficient. This currently only matches
// one pair, and recomputes live intervals and moves on to the next pair. It
// would be better to compute a list of all merges that need to occur.
//
// - With a list of instructions to process, we can also merge more. If a
// cluster of loads have offsets that are too large to fit in the 8-bit
// offsets, but are close enough to fit in the 8 bits, we can add to the base
// pointer and use the new reduced offsets.
//
//===----------------------------------------------------------------------===//
#include "AMDGPU.h"
#include "GCNSubtarget.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
#define DEBUG_TYPE "si-load-store-opt"
namespace {
enum InstClassEnum {
UNKNOWN,
DS_READ,
DS_WRITE,
S_BUFFER_LOAD_IMM,
BUFFER_LOAD,
BUFFER_STORE,
MIMG,
TBUFFER_LOAD,
TBUFFER_STORE,
};
struct AddressRegs {
unsigned char NumVAddrs = 0;
bool SBase = false;
bool SRsrc = false;
bool SOffset = false;
bool VAddr = false;
bool Addr = false;
bool SSamp = false;
};
// GFX10 image_sample instructions can have 12 vaddrs + srsrc + ssamp.
const unsigned MaxAddressRegs = 12 + 1 + 1;
class SILoadStoreOptimizer : public MachineFunctionPass {
struct CombineInfo {
MachineBasicBlock::iterator I;
unsigned EltSize;
unsigned Offset;
unsigned Width;
unsigned Format;
unsigned BaseOff;
unsigned DMask;
InstClassEnum InstClass;
unsigned CPol = 0;
bool UseST64;
int AddrIdx[MaxAddressRegs];
const MachineOperand *AddrReg[MaxAddressRegs];
unsigned NumAddresses;
unsigned Order;
bool hasSameBaseAddress(const MachineInstr &MI) {
for (unsigned i = 0; i < NumAddresses; i++) {
const MachineOperand &AddrRegNext = MI.getOperand(AddrIdx[i]);
if (AddrReg[i]->isImm() || AddrRegNext.isImm()) {
if (AddrReg[i]->isImm() != AddrRegNext.isImm() ||
AddrReg[i]->getImm() != AddrRegNext.getImm()) {
return false;
}
continue;
}
// Check same base pointer. Be careful of subregisters, which can occur
// with vectors of pointers.
if (AddrReg[i]->getReg() != AddrRegNext.getReg() ||
AddrReg[i]->getSubReg() != AddrRegNext.getSubReg()) {
return false;
}
}
return true;
}
bool hasMergeableAddress(const MachineRegisterInfo &MRI) {
for (unsigned i = 0; i < NumAddresses; ++i) {
const MachineOperand *AddrOp = AddrReg[i];
// Immediates are always OK.
if (AddrOp->isImm())
continue;
// Don't try to merge addresses that aren't either immediates or registers.
// TODO: Should be possible to merge FrameIndexes and maybe some other
// non-register
if (!AddrOp->isReg())
return false;
// TODO: We should be able to merge physical reg addreses.
if (AddrOp->getReg().isPhysical())
return false;
// If an address has only one use then there will be on other
// instructions with the same address, so we can't merge this one.
if (MRI.hasOneNonDBGUse(AddrOp->getReg()))
return false;
}
return true;
}
void setMI(MachineBasicBlock::iterator MI, const SIInstrInfo &TII,
const GCNSubtarget &STM);
};
struct BaseRegisters {
Register LoReg;
Register HiReg;
unsigned LoSubReg = 0;
unsigned HiSubReg = 0;
};
struct MemAddress {
BaseRegisters Base;
int64_t Offset = 0;
};
using MemInfoMap = DenseMap<MachineInstr *, MemAddress>;
private:
const GCNSubtarget *STM = nullptr;
const SIInstrInfo *TII = nullptr;
const SIRegisterInfo *TRI = nullptr;
MachineRegisterInfo *MRI = nullptr;
AliasAnalysis *AA = nullptr;
bool OptimizeAgain;
static bool dmasksCanBeCombined(const CombineInfo &CI,
const SIInstrInfo &TII,
const CombineInfo &Paired);
static bool offsetsCanBeCombined(CombineInfo &CI, const GCNSubtarget &STI,
CombineInfo &Paired, bool Modify = false);
static bool widthsFit(const GCNSubtarget &STI, const CombineInfo &CI,
const CombineInfo &Paired);
static unsigned getNewOpcode(const CombineInfo &CI, const CombineInfo &Paired);
static std::pair<unsigned, unsigned> getSubRegIdxs(const CombineInfo &CI,
const CombineInfo &Paired);
const TargetRegisterClass *getTargetRegisterClass(const CombineInfo &CI,
const CombineInfo &Paired);
const TargetRegisterClass *getDataRegClass(const MachineInstr &MI) const;
bool checkAndPrepareMerge(CombineInfo &CI, CombineInfo &Paired,
SmallVectorImpl<MachineInstr *> &InstsToMove);
unsigned read2Opcode(unsigned EltSize) const;
unsigned read2ST64Opcode(unsigned EltSize) const;
MachineBasicBlock::iterator mergeRead2Pair(CombineInfo &CI,
CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
unsigned write2Opcode(unsigned EltSize) const;
unsigned write2ST64Opcode(unsigned EltSize) const;
MachineBasicBlock::iterator
mergeWrite2Pair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeImagePair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeSBufferLoadImmPair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeBufferLoadPair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeBufferStorePair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeTBufferLoadPair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
MachineBasicBlock::iterator
mergeTBufferStorePair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove);
void updateBaseAndOffset(MachineInstr &I, Register NewBase,
int32_t NewOffset) const;
Register computeBase(MachineInstr &MI, const MemAddress &Addr) const;
MachineOperand createRegOrImm(int32_t Val, MachineInstr &MI) const;
Optional<int32_t> extractConstOffset(const MachineOperand &Op) const;
void processBaseWithConstOffset(const MachineOperand &Base, MemAddress &Addr) const;
/// Promotes constant offset to the immediate by adjusting the base. It
/// tries to use a base from the nearby instructions that allows it to have
/// a 13bit constant offset which gets promoted to the immediate.
bool promoteConstantOffsetToImm(MachineInstr &CI,
MemInfoMap &Visited,
SmallPtrSet<MachineInstr *, 4> &Promoted) const;
void addInstToMergeableList(const CombineInfo &CI,
std::list<std::list<CombineInfo> > &MergeableInsts) const;
std::pair<MachineBasicBlock::iterator, bool> collectMergeableInsts(
MachineBasicBlock::iterator Begin, MachineBasicBlock::iterator End,
MemInfoMap &Visited, SmallPtrSet<MachineInstr *, 4> &AnchorList,
std::list<std::list<CombineInfo>> &MergeableInsts) const;
public:
static char ID;
SILoadStoreOptimizer() : MachineFunctionPass(ID) {
initializeSILoadStoreOptimizerPass(*PassRegistry::getPassRegistry());
}
bool optimizeInstsWithSameBaseAddr(std::list<CombineInfo> &MergeList,
bool &OptimizeListAgain);
bool optimizeBlock(std::list<std::list<CombineInfo> > &MergeableInsts);
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override { return "SI Load Store Optimizer"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<AAResultsWrapperPass>();
MachineFunctionPass::getAnalysisUsage(AU);
}
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties()
.set(MachineFunctionProperties::Property::IsSSA);
}
};
static unsigned getOpcodeWidth(const MachineInstr &MI, const SIInstrInfo &TII) {
const unsigned Opc = MI.getOpcode();
if (TII.isMUBUF(Opc)) {
// FIXME: Handle d16 correctly
return AMDGPU::getMUBUFElements(Opc);
}
if (TII.isMIMG(MI)) {
uint64_t DMaskImm =
TII.getNamedOperand(MI, AMDGPU::OpName::dmask)->getImm();
return countPopulation(DMaskImm);
}
if (TII.isMTBUF(Opc)) {
return AMDGPU::getMTBUFElements(Opc);
}
switch (Opc) {
case AMDGPU::S_BUFFER_LOAD_DWORD_IMM:
return 1;
case AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM:
return 2;
case AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM:
return 4;
case AMDGPU::DS_READ_B32: LLVM_FALLTHROUGH;
case AMDGPU::DS_READ_B32_gfx9: LLVM_FALLTHROUGH;
case AMDGPU::DS_WRITE_B32: LLVM_FALLTHROUGH;
case AMDGPU::DS_WRITE_B32_gfx9:
return 1;
case AMDGPU::DS_READ_B64: LLVM_FALLTHROUGH;
case AMDGPU::DS_READ_B64_gfx9: LLVM_FALLTHROUGH;
case AMDGPU::DS_WRITE_B64: LLVM_FALLTHROUGH;
case AMDGPU::DS_WRITE_B64_gfx9:
return 2;
default:
return 0;
}
}
/// Maps instruction opcode to enum InstClassEnum.
static InstClassEnum getInstClass(unsigned Opc, const SIInstrInfo &TII) {
switch (Opc) {
default:
if (TII.isMUBUF(Opc)) {
switch (AMDGPU::getMUBUFBaseOpcode(Opc)) {
default:
return UNKNOWN;
case AMDGPU::BUFFER_LOAD_DWORD_OFFEN:
case AMDGPU::BUFFER_LOAD_DWORD_OFFEN_exact:
case AMDGPU::BUFFER_LOAD_DWORD_OFFSET:
case AMDGPU::BUFFER_LOAD_DWORD_OFFSET_exact:
return BUFFER_LOAD;
case AMDGPU::BUFFER_STORE_DWORD_OFFEN:
case AMDGPU::BUFFER_STORE_DWORD_OFFEN_exact:
case AMDGPU::BUFFER_STORE_DWORD_OFFSET:
case AMDGPU::BUFFER_STORE_DWORD_OFFSET_exact:
return BUFFER_STORE;
}
}
if (TII.isMIMG(Opc)) {
// Ignore instructions encoded without vaddr.
if (AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::vaddr) == -1 &&
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::vaddr0) == -1)
return UNKNOWN;
// TODO: Support IMAGE_GET_RESINFO and IMAGE_GET_LOD.
if (TII.get(Opc).mayStore() || !TII.get(Opc).mayLoad() ||
TII.isGather4(Opc))
return UNKNOWN;
return MIMG;
}
if (TII.isMTBUF(Opc)) {
switch (AMDGPU::getMTBUFBaseOpcode(Opc)) {
default:
return UNKNOWN;
case AMDGPU::TBUFFER_LOAD_FORMAT_X_OFFEN:
case AMDGPU::TBUFFER_LOAD_FORMAT_X_OFFEN_exact:
case AMDGPU::TBUFFER_LOAD_FORMAT_X_OFFSET:
case AMDGPU::TBUFFER_LOAD_FORMAT_X_OFFSET_exact:
return TBUFFER_LOAD;
case AMDGPU::TBUFFER_STORE_FORMAT_X_OFFEN:
case AMDGPU::TBUFFER_STORE_FORMAT_X_OFFEN_exact:
case AMDGPU::TBUFFER_STORE_FORMAT_X_OFFSET:
case AMDGPU::TBUFFER_STORE_FORMAT_X_OFFSET_exact:
return TBUFFER_STORE;
}
}
return UNKNOWN;
case AMDGPU::S_BUFFER_LOAD_DWORD_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM:
return S_BUFFER_LOAD_IMM;
case AMDGPU::DS_READ_B32:
case AMDGPU::DS_READ_B32_gfx9:
case AMDGPU::DS_READ_B64:
case AMDGPU::DS_READ_B64_gfx9:
return DS_READ;
case AMDGPU::DS_WRITE_B32:
case AMDGPU::DS_WRITE_B32_gfx9:
case AMDGPU::DS_WRITE_B64:
case AMDGPU::DS_WRITE_B64_gfx9:
return DS_WRITE;
case AMDGPU::IMAGE_BVH_INTERSECT_RAY_sa:
case AMDGPU::IMAGE_BVH64_INTERSECT_RAY_sa:
case AMDGPU::IMAGE_BVH_INTERSECT_RAY_a16_sa:
case AMDGPU::IMAGE_BVH64_INTERSECT_RAY_a16_sa:
case AMDGPU::IMAGE_BVH_INTERSECT_RAY_nsa:
case AMDGPU::IMAGE_BVH64_INTERSECT_RAY_nsa:
case AMDGPU::IMAGE_BVH_INTERSECT_RAY_a16_nsa:
case AMDGPU::IMAGE_BVH64_INTERSECT_RAY_a16_nsa:
return UNKNOWN;
}
}
/// Determines instruction subclass from opcode. Only instructions
/// of the same subclass can be merged together.
static unsigned getInstSubclass(unsigned Opc, const SIInstrInfo &TII) {
switch (Opc) {
default:
if (TII.isMUBUF(Opc))
return AMDGPU::getMUBUFBaseOpcode(Opc);
if (TII.isMIMG(Opc)) {
const AMDGPU::MIMGInfo *Info = AMDGPU::getMIMGInfo(Opc);
assert(Info);
return Info->BaseOpcode;
}
if (TII.isMTBUF(Opc))
return AMDGPU::getMTBUFBaseOpcode(Opc);
return -1;
case AMDGPU::DS_READ_B32:
case AMDGPU::DS_READ_B32_gfx9:
case AMDGPU::DS_READ_B64:
case AMDGPU::DS_READ_B64_gfx9:
case AMDGPU::DS_WRITE_B32:
case AMDGPU::DS_WRITE_B32_gfx9:
case AMDGPU::DS_WRITE_B64:
case AMDGPU::DS_WRITE_B64_gfx9:
return Opc;
case AMDGPU::S_BUFFER_LOAD_DWORD_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM:
return AMDGPU::S_BUFFER_LOAD_DWORD_IMM;
}
}
static AddressRegs getRegs(unsigned Opc, const SIInstrInfo &TII) {
AddressRegs Result;
if (TII.isMUBUF(Opc)) {
if (AMDGPU::getMUBUFHasVAddr(Opc))
Result.VAddr = true;
if (AMDGPU::getMUBUFHasSrsrc(Opc))
Result.SRsrc = true;
if (AMDGPU::getMUBUFHasSoffset(Opc))
Result.SOffset = true;
return Result;
}
if (TII.isMIMG(Opc)) {
int VAddr0Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::vaddr0);
if (VAddr0Idx >= 0) {
int SRsrcIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::srsrc);
Result.NumVAddrs = SRsrcIdx - VAddr0Idx;
} else {
Result.VAddr = true;
}
Result.SRsrc = true;
const AMDGPU::MIMGInfo *Info = AMDGPU::getMIMGInfo(Opc);
if (Info && AMDGPU::getMIMGBaseOpcodeInfo(Info->BaseOpcode)->Sampler)
Result.SSamp = true;
return Result;
}
if (TII.isMTBUF(Opc)) {
if (AMDGPU::getMTBUFHasVAddr(Opc))
Result.VAddr = true;
if (AMDGPU::getMTBUFHasSrsrc(Opc))
Result.SRsrc = true;
if (AMDGPU::getMTBUFHasSoffset(Opc))
Result.SOffset = true;
return Result;
}
switch (Opc) {
default:
return Result;
case AMDGPU::S_BUFFER_LOAD_DWORD_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM:
Result.SBase = true;
return Result;
case AMDGPU::DS_READ_B32:
case AMDGPU::DS_READ_B64:
case AMDGPU::DS_READ_B32_gfx9:
case AMDGPU::DS_READ_B64_gfx9:
case AMDGPU::DS_WRITE_B32:
case AMDGPU::DS_WRITE_B64:
case AMDGPU::DS_WRITE_B32_gfx9:
case AMDGPU::DS_WRITE_B64_gfx9:
Result.Addr = true;
return Result;
}
}
void SILoadStoreOptimizer::CombineInfo::setMI(MachineBasicBlock::iterator MI,
const SIInstrInfo &TII,
const GCNSubtarget &STM) {
I = MI;
unsigned Opc = MI->getOpcode();
InstClass = getInstClass(Opc, TII);
if (InstClass == UNKNOWN)
return;
switch (InstClass) {
case DS_READ:
EltSize =
(Opc == AMDGPU::DS_READ_B64 || Opc == AMDGPU::DS_READ_B64_gfx9) ? 8
: 4;
break;
case DS_WRITE:
EltSize =
(Opc == AMDGPU::DS_WRITE_B64 || Opc == AMDGPU::DS_WRITE_B64_gfx9) ? 8
: 4;
break;
case S_BUFFER_LOAD_IMM:
EltSize = AMDGPU::convertSMRDOffsetUnits(STM, 4);
break;
default:
EltSize = 4;
break;
}
if (InstClass == MIMG) {
DMask = TII.getNamedOperand(*I, AMDGPU::OpName::dmask)->getImm();
// Offset is not considered for MIMG instructions.
Offset = 0;
} else {
int OffsetIdx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::offset);
Offset = I->getOperand(OffsetIdx).getImm();
}
if (InstClass == TBUFFER_LOAD || InstClass == TBUFFER_STORE)
Format = TII.getNamedOperand(*I, AMDGPU::OpName::format)->getImm();
Width = getOpcodeWidth(*I, TII);
if ((InstClass == DS_READ) || (InstClass == DS_WRITE)) {
Offset &= 0xffff;
} else if (InstClass != MIMG) {
CPol = TII.getNamedOperand(*I, AMDGPU::OpName::cpol)->getImm();
}
AddressRegs Regs = getRegs(Opc, TII);
NumAddresses = 0;
for (unsigned J = 0; J < Regs.NumVAddrs; J++)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::vaddr0) + J;
if (Regs.Addr)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::addr);
if (Regs.SBase)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::sbase);
if (Regs.SRsrc)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::srsrc);
if (Regs.SOffset)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::soffset);
if (Regs.VAddr)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::vaddr);
if (Regs.SSamp)
AddrIdx[NumAddresses++] =
AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::ssamp);
assert(NumAddresses <= MaxAddressRegs);
for (unsigned J = 0; J < NumAddresses; J++)
AddrReg[J] = &I->getOperand(AddrIdx[J]);
}
} // end anonymous namespace.
INITIALIZE_PASS_BEGIN(SILoadStoreOptimizer, DEBUG_TYPE,
"SI Load Store Optimizer", false, false)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(SILoadStoreOptimizer, DEBUG_TYPE, "SI Load Store Optimizer",
false, false)
char SILoadStoreOptimizer::ID = 0;
char &llvm::SILoadStoreOptimizerID = SILoadStoreOptimizer::ID;
FunctionPass *llvm::createSILoadStoreOptimizerPass() {
return new SILoadStoreOptimizer();
}
static void moveInstsAfter(MachineBasicBlock::iterator I,
ArrayRef<MachineInstr *> InstsToMove) {
MachineBasicBlock *MBB = I->getParent();
++I;
for (MachineInstr *MI : InstsToMove) {
MI->removeFromParent();
MBB->insert(I, MI);
}
}
static void addDefsUsesToList(const MachineInstr &MI,
DenseSet<Register> &RegDefs,
DenseSet<Register> &PhysRegUses) {
for (const MachineOperand &Op : MI.operands()) {
if (Op.isReg()) {
if (Op.isDef())
RegDefs.insert(Op.getReg());
else if (Op.readsReg() && Op.getReg().isPhysical())
PhysRegUses.insert(Op.getReg());
}
}
}
static bool memAccessesCanBeReordered(MachineBasicBlock::iterator A,
MachineBasicBlock::iterator B,
AliasAnalysis *AA) {
// RAW or WAR - cannot reorder
// WAW - cannot reorder
// RAR - safe to reorder
return !(A->mayStore() || B->mayStore()) || !A->mayAlias(AA, *B, true);
}
// Add MI and its defs to the lists if MI reads one of the defs that are
// already in the list. Returns true in that case.
static bool addToListsIfDependent(MachineInstr &MI, DenseSet<Register> &RegDefs,
DenseSet<Register> &PhysRegUses,
SmallVectorImpl<MachineInstr *> &Insts) {
for (MachineOperand &Use : MI.operands()) {
// If one of the defs is read, then there is a use of Def between I and the
// instruction that I will potentially be merged with. We will need to move
// this instruction after the merged instructions.
//
// Similarly, if there is a def which is read by an instruction that is to
// be moved for merging, then we need to move the def-instruction as well.
// This can only happen for physical registers such as M0; virtual
// registers are in SSA form.
if (Use.isReg() && ((Use.readsReg() && RegDefs.count(Use.getReg())) ||
(Use.isDef() && RegDefs.count(Use.getReg())) ||
(Use.isDef() && Use.getReg().isPhysical() &&
PhysRegUses.count(Use.getReg())))) {
Insts.push_back(&MI);
addDefsUsesToList(MI, RegDefs, PhysRegUses);
return true;
}
}
return false;
}
static bool canMoveInstsAcrossMemOp(MachineInstr &MemOp,
ArrayRef<MachineInstr *> InstsToMove,
AliasAnalysis *AA) {
assert(MemOp.mayLoadOrStore());
for (MachineInstr *InstToMove : InstsToMove) {
if (!InstToMove->mayLoadOrStore())
continue;
if (!memAccessesCanBeReordered(MemOp, *InstToMove, AA))
return false;
}
return true;
}
// This function assumes that \p A and \p B have are identical except for
// size and offset, and they referecne adjacent memory.
static MachineMemOperand *combineKnownAdjacentMMOs(MachineFunction &MF,
const MachineMemOperand *A,
const MachineMemOperand *B) {
unsigned MinOffset = std::min(A->getOffset(), B->getOffset());
unsigned Size = A->getSize() + B->getSize();
// This function adds the offset parameter to the existing offset for A,
// so we pass 0 here as the offset and then manually set it to the correct
// value after the call.
MachineMemOperand *MMO = MF.getMachineMemOperand(A, 0, Size);
MMO->setOffset(MinOffset);
return MMO;
}
bool SILoadStoreOptimizer::dmasksCanBeCombined(const CombineInfo &CI,
const SIInstrInfo &TII,
const CombineInfo &Paired) {
assert(CI.InstClass == MIMG);
// Ignore instructions with tfe/lwe set.
const auto *TFEOp = TII.getNamedOperand(*CI.I, AMDGPU::OpName::tfe);
const auto *LWEOp = TII.getNamedOperand(*CI.I, AMDGPU::OpName::lwe);
if ((TFEOp && TFEOp->getImm()) || (LWEOp && LWEOp->getImm()))
return false;
// Check other optional immediate operands for equality.
unsigned OperandsToMatch[] = {AMDGPU::OpName::cpol, AMDGPU::OpName::d16,
AMDGPU::OpName::unorm, AMDGPU::OpName::da,
AMDGPU::OpName::r128, AMDGPU::OpName::a16};
for (auto op : OperandsToMatch) {
int Idx = AMDGPU::getNamedOperandIdx(CI.I->getOpcode(), op);
if (AMDGPU::getNamedOperandIdx(Paired.I->getOpcode(), op) != Idx)
return false;
if (Idx != -1 &&
CI.I->getOperand(Idx).getImm() != Paired.I->getOperand(Idx).getImm())
return false;
}
// Check DMask for overlaps.
unsigned MaxMask = std::max(CI.DMask, Paired.DMask);
unsigned MinMask = std::min(CI.DMask, Paired.DMask);
unsigned AllowedBitsForMin = llvm::countTrailingZeros(MaxMask);
if ((1u << AllowedBitsForMin) <= MinMask)
return false;
return true;
}
static unsigned getBufferFormatWithCompCount(unsigned OldFormat,
unsigned ComponentCount,
const GCNSubtarget &STI) {
if (ComponentCount > 4)
return 0;
const llvm::AMDGPU::GcnBufferFormatInfo *OldFormatInfo =
llvm::AMDGPU::getGcnBufferFormatInfo(OldFormat, STI);
if (!OldFormatInfo)
return 0;
const llvm::AMDGPU::GcnBufferFormatInfo *NewFormatInfo =
llvm::AMDGPU::getGcnBufferFormatInfo(OldFormatInfo->BitsPerComp,
ComponentCount,
OldFormatInfo->NumFormat, STI);
if (!NewFormatInfo)
return 0;
assert(NewFormatInfo->NumFormat == OldFormatInfo->NumFormat &&
NewFormatInfo->BitsPerComp == OldFormatInfo->BitsPerComp);
return NewFormatInfo->Format;
}
// Return the value in the inclusive range [Lo,Hi] that is aligned to the
// highest power of two. Note that the result is well defined for all inputs
// including corner cases like:
// - if Lo == Hi, return that value
// - if Lo == 0, return 0 (even though the "- 1" below underflows
// - if Lo > Hi, return 0 (as if the range wrapped around)
static uint32_t mostAlignedValueInRange(uint32_t Lo, uint32_t Hi) {
return Hi & maskLeadingOnes<uint32_t>(countLeadingZeros((Lo - 1) ^ Hi) + 1);
}
bool SILoadStoreOptimizer::offsetsCanBeCombined(CombineInfo &CI,
const GCNSubtarget &STI,
CombineInfo &Paired,
bool Modify) {
assert(CI.InstClass != MIMG);
// XXX - Would the same offset be OK? Is there any reason this would happen or
// be useful?
if (CI.Offset == Paired.Offset)
return false;
// This won't be valid if the offset isn't aligned.
if ((CI.Offset % CI.EltSize != 0) || (Paired.Offset % CI.EltSize != 0))
return false;
if (CI.InstClass == TBUFFER_LOAD || CI.InstClass == TBUFFER_STORE) {
const llvm::AMDGPU::GcnBufferFormatInfo *Info0 =
llvm::AMDGPU::getGcnBufferFormatInfo(CI.Format, STI);
if (!Info0)
return false;
const llvm::AMDGPU::GcnBufferFormatInfo *Info1 =
llvm::AMDGPU::getGcnBufferFormatInfo(Paired.Format, STI);
if (!Info1)
return false;
if (Info0->BitsPerComp != Info1->BitsPerComp ||
Info0->NumFormat != Info1->NumFormat)
return false;
// TODO: Should be possible to support more formats, but if format loads
// are not dword-aligned, the merged load might not be valid.
if (Info0->BitsPerComp != 32)
return false;
if (getBufferFormatWithCompCount(CI.Format, CI.Width + Paired.Width, STI) == 0)
return false;
}
uint32_t EltOffset0 = CI.Offset / CI.EltSize;
uint32_t EltOffset1 = Paired.Offset / CI.EltSize;
CI.UseST64 = false;
CI.BaseOff = 0;
// Handle all non-DS instructions.
if ((CI.InstClass != DS_READ) && (CI.InstClass != DS_WRITE)) {
return (EltOffset0 + CI.Width == EltOffset1 ||
EltOffset1 + Paired.Width == EltOffset0) &&
CI.CPol == Paired.CPol &&
(CI.InstClass == S_BUFFER_LOAD_IMM || CI.CPol == Paired.CPol);
}
// If the offset in elements doesn't fit in 8-bits, we might be able to use
// the stride 64 versions.
if ((EltOffset0 % 64 == 0) && (EltOffset1 % 64) == 0 &&
isUInt<8>(EltOffset0 / 64) && isUInt<8>(EltOffset1 / 64)) {
if (Modify) {
CI.Offset = EltOffset0 / 64;
Paired.Offset = EltOffset1 / 64;
CI.UseST64 = true;
}
return true;
}
// Check if the new offsets fit in the reduced 8-bit range.
if (isUInt<8>(EltOffset0) && isUInt<8>(EltOffset1)) {
if (Modify) {
CI.Offset = EltOffset0;
Paired.Offset = EltOffset1;
}
return true;
}
// Try to shift base address to decrease offsets.
uint32_t Min = std::min(EltOffset0, EltOffset1);
uint32_t Max = std::max(EltOffset0, EltOffset1);
const uint32_t Mask = maskTrailingOnes<uint32_t>(8) * 64;
if (((Max - Min) & ~Mask) == 0) {
if (Modify) {
// From the range of values we could use for BaseOff, choose the one that
// is aligned to the highest power of two, to maximise the chance that
// the same offset can be reused for other load/store pairs.
uint32_t BaseOff = mostAlignedValueInRange(Max - 0xff * 64, Min);
// Copy the low bits of the offsets, so that when we adjust them by
// subtracting BaseOff they will be multiples of 64.
BaseOff |= Min & maskTrailingOnes<uint32_t>(6);
CI.BaseOff = BaseOff * CI.EltSize;
CI.Offset = (EltOffset0 - BaseOff) / 64;
Paired.Offset = (EltOffset1 - BaseOff) / 64;
CI.UseST64 = true;
}
return true;
}
if (isUInt<8>(Max - Min)) {
if (Modify) {
// From the range of values we could use for BaseOff, choose the one that
// is aligned to the highest power of two, to maximise the chance that
// the same offset can be reused for other load/store pairs.
uint32_t BaseOff = mostAlignedValueInRange(Max - 0xff, Min);
CI.BaseOff = BaseOff * CI.EltSize;
CI.Offset = EltOffset0 - BaseOff;
Paired.Offset = EltOffset1 - BaseOff;
}
return true;
}
return false;
}
bool SILoadStoreOptimizer::widthsFit(const GCNSubtarget &STM,
const CombineInfo &CI,
const CombineInfo &Paired) {
const unsigned Width = (CI.Width + Paired.Width);
switch (CI.InstClass) {
default:
return (Width <= 4) && (STM.hasDwordx3LoadStores() || (Width != 3));
case S_BUFFER_LOAD_IMM:
switch (Width) {
default:
return false;
case 2:
case 4:
return true;
}
}
}
const TargetRegisterClass *
SILoadStoreOptimizer::getDataRegClass(const MachineInstr &MI) const {
if (const auto *Dst = TII->getNamedOperand(MI, AMDGPU::OpName::vdst)) {
return TRI->getRegClassForReg(*MRI, Dst->getReg());
}
if (const auto *Src = TII->getNamedOperand(MI, AMDGPU::OpName::vdata)) {
return TRI->getRegClassForReg(*MRI, Src->getReg());
}
if (const auto *Src = TII->getNamedOperand(MI, AMDGPU::OpName::data0)) {
return TRI->getRegClassForReg(*MRI, Src->getReg());
}
if (const auto *Dst = TII->getNamedOperand(MI, AMDGPU::OpName::sdst)) {
return TRI->getRegClassForReg(*MRI, Dst->getReg());
}
if (const auto *Src = TII->getNamedOperand(MI, AMDGPU::OpName::sdata)) {
return TRI->getRegClassForReg(*MRI, Src->getReg());
}
return nullptr;
}
/// This function assumes that CI comes before Paired in a basic block.
bool SILoadStoreOptimizer::checkAndPrepareMerge(
CombineInfo &CI, CombineInfo &Paired,
SmallVectorImpl<MachineInstr *> &InstsToMove) {
// Check both offsets (or masks for MIMG) can be combined and fit in the
// reduced range.
if (CI.InstClass == MIMG && !dmasksCanBeCombined(CI, *TII, Paired))
return false;
if (CI.InstClass != MIMG &&
(!widthsFit(*STM, CI, Paired) || !offsetsCanBeCombined(CI, *STM, Paired)))
return false;
const unsigned Opc = CI.I->getOpcode();
const InstClassEnum InstClass = getInstClass(Opc, *TII);
if (InstClass == UNKNOWN) {
return false;
}
const unsigned InstSubclass = getInstSubclass(Opc, *TII);
// Do not merge VMEM buffer instructions with "swizzled" bit set.
int Swizzled =
AMDGPU::getNamedOperandIdx(CI.I->getOpcode(), AMDGPU::OpName::swz);
if (Swizzled != -1 && CI.I->getOperand(Swizzled).getImm())
return false;
DenseSet<Register> RegDefsToMove;
DenseSet<Register> PhysRegUsesToMove;
addDefsUsesToList(*CI.I, RegDefsToMove, PhysRegUsesToMove);
const TargetRegisterClass *DataRC = getDataRegClass(*CI.I);
bool IsAGPR = TRI->hasAGPRs(DataRC);
MachineBasicBlock::iterator E = std::next(Paired.I);
MachineBasicBlock::iterator MBBI = std::next(CI.I);
MachineBasicBlock::iterator MBBE = CI.I->getParent()->end();
for (; MBBI != E; ++MBBI) {
if (MBBI == MBBE) {
// CombineInfo::Order is a hint on the instruction ordering within the
// basic block. This hint suggests that CI precedes Paired, which is
// true most of the time. However, moveInstsAfter() processing a
// previous list may have changed this order in a situation when it
// moves an instruction which exists in some other merge list.
// In this case it must be dependent.
return false;
}
if ((getInstClass(MBBI->getOpcode(), *TII) != InstClass) ||
(getInstSubclass(MBBI->getOpcode(), *TII) != InstSubclass)) {
// This is not a matching instruction, but we can keep looking as
// long as one of these conditions are met:
// 1. It is safe to move I down past MBBI.
// 2. It is safe to move MBBI down past the instruction that I will
// be merged into.
if (MBBI->hasUnmodeledSideEffects()) {
// We can't re-order this instruction with respect to other memory
// operations, so we fail both conditions mentioned above.
return false;
}
if (MBBI->mayLoadOrStore() &&
(!memAccessesCanBeReordered(*CI.I, *MBBI, AA) ||
!canMoveInstsAcrossMemOp(*MBBI, InstsToMove, AA))) {
// We fail condition #1, but we may still be able to satisfy condition
// #2. Add this instruction to the move list and then we will check
// if condition #2 holds once we have selected the matching instruction.
InstsToMove.push_back(&*MBBI);
addDefsUsesToList(*MBBI, RegDefsToMove, PhysRegUsesToMove);
continue;
}
// When we match I with another DS instruction we will be moving I down
// to the location of the matched instruction any uses of I will need to
// be moved down as well.
addToListsIfDependent(*MBBI, RegDefsToMove, PhysRegUsesToMove,
InstsToMove);
continue;
}
// Don't merge volatiles.
if (MBBI->hasOrderedMemoryRef())
return false;
int Swizzled =
AMDGPU::getNamedOperandIdx(MBBI->getOpcode(), AMDGPU::OpName::swz);
if (Swizzled != -1 && MBBI->getOperand(Swizzled).getImm())
return false;
// Handle a case like
// DS_WRITE_B32 addr, v, idx0
// w = DS_READ_B32 addr, idx0
// DS_WRITE_B32 addr, f(w), idx1
// where the DS_READ_B32 ends up in InstsToMove and therefore prevents
// merging of the two writes.
if (addToListsIfDependent(*MBBI, RegDefsToMove, PhysRegUsesToMove,
InstsToMove))
continue;
if (&*MBBI == &*Paired.I) {
if (TRI->hasAGPRs(getDataRegClass(*MBBI)) != IsAGPR)
return false;
// FIXME: nothing is illegal in a ds_write2 opcode with two AGPR data
// operands. However we are reporting that ds_write2 shall have
// only VGPR data so that machine copy propagation does not
// create an illegal instruction with a VGPR and AGPR sources.
// Consequenctially if we create such instruction the verifier
// will complain.
if (IsAGPR && CI.InstClass == DS_WRITE)
return false;
// We need to go through the list of instructions that we plan to
// move and make sure they are all safe to move down past the merged
// instruction.
if (canMoveInstsAcrossMemOp(*MBBI, InstsToMove, AA)) {
// Call offsetsCanBeCombined with modify = true so that the offsets are
// correct for the new instruction. This should return true, because
// this function should only be called on CombineInfo objects that
// have already been confirmed to be mergeable.
if (CI.InstClass != MIMG)
offsetsCanBeCombined(CI, *STM, Paired, true);
return true;
}
return false;
}
// We've found a load/store that we couldn't merge for some reason.
// We could potentially keep looking, but we'd need to make sure that
// it was safe to move I and also all the instruction in InstsToMove
// down past this instruction.
// check if we can move I across MBBI and if we can move all I's users
if (!memAccessesCanBeReordered(*CI.I, *MBBI, AA) ||
!canMoveInstsAcrossMemOp(*MBBI, InstsToMove, AA))
break;
}
return false;
}
unsigned SILoadStoreOptimizer::read2Opcode(unsigned EltSize) const {
if (STM->ldsRequiresM0Init())
return (EltSize == 4) ? AMDGPU::DS_READ2_B32 : AMDGPU::DS_READ2_B64;
return (EltSize == 4) ? AMDGPU::DS_READ2_B32_gfx9 : AMDGPU::DS_READ2_B64_gfx9;
}
unsigned SILoadStoreOptimizer::read2ST64Opcode(unsigned EltSize) const {
if (STM->ldsRequiresM0Init())
return (EltSize == 4) ? AMDGPU::DS_READ2ST64_B32 : AMDGPU::DS_READ2ST64_B64;
return (EltSize == 4) ? AMDGPU::DS_READ2ST64_B32_gfx9
: AMDGPU::DS_READ2ST64_B64_gfx9;
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeRead2Pair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
// Be careful, since the addresses could be subregisters themselves in weird
// cases, like vectors of pointers.
const auto *AddrReg = TII->getNamedOperand(*CI.I, AMDGPU::OpName::addr);
const auto *Dest0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdst);
const auto *Dest1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdst);
unsigned NewOffset0 = CI.Offset;
unsigned NewOffset1 = Paired.Offset;
unsigned Opc =
CI.UseST64 ? read2ST64Opcode(CI.EltSize) : read2Opcode(CI.EltSize);
unsigned SubRegIdx0 = (CI.EltSize == 4) ? AMDGPU::sub0 : AMDGPU::sub0_sub1;
unsigned SubRegIdx1 = (CI.EltSize == 4) ? AMDGPU::sub1 : AMDGPU::sub2_sub3;
if (NewOffset0 > NewOffset1) {
// Canonicalize the merged instruction so the smaller offset comes first.
std::swap(NewOffset0, NewOffset1);
std::swap(SubRegIdx0, SubRegIdx1);
}
assert((isUInt<8>(NewOffset0) && isUInt<8>(NewOffset1)) &&
(NewOffset0 != NewOffset1) && "Computed offset doesn't fit");
const MCInstrDesc &Read2Desc = TII->get(Opc);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
Register DestReg = MRI->createVirtualRegister(SuperRC);
DebugLoc DL = CI.I->getDebugLoc();
Register BaseReg = AddrReg->getReg();
unsigned BaseSubReg = AddrReg->getSubReg();
unsigned BaseRegFlags = 0;
if (CI.BaseOff) {
Register ImmReg = MRI->createVirtualRegister(&AMDGPU::SReg_32RegClass);
BuildMI(*MBB, Paired.I, DL, TII->get(AMDGPU::S_MOV_B32), ImmReg)
.addImm(CI.BaseOff);
BaseReg = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
BaseRegFlags = RegState::Kill;
TII->getAddNoCarry(*MBB, Paired.I, DL, BaseReg)
.addReg(ImmReg)
.addReg(AddrReg->getReg(), 0, BaseSubReg)
.addImm(0); // clamp bit
BaseSubReg = 0;
}
MachineInstrBuilder Read2 =
BuildMI(*MBB, Paired.I, DL, Read2Desc, DestReg)
.addReg(BaseReg, BaseRegFlags, BaseSubReg) // addr
.addImm(NewOffset0) // offset0
.addImm(NewOffset1) // offset1
.addImm(0) // gds
.cloneMergedMemRefs({&*CI.I, &*Paired.I});
(void)Read2;
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
// Copy to the old destination registers.
BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
LLVM_DEBUG(dbgs() << "Inserted read2: " << *Read2 << '\n');
return Read2;
}
unsigned SILoadStoreOptimizer::write2Opcode(unsigned EltSize) const {
if (STM->ldsRequiresM0Init())
return (EltSize == 4) ? AMDGPU::DS_WRITE2_B32 : AMDGPU::DS_WRITE2_B64;
return (EltSize == 4) ? AMDGPU::DS_WRITE2_B32_gfx9
: AMDGPU::DS_WRITE2_B64_gfx9;
}
unsigned SILoadStoreOptimizer::write2ST64Opcode(unsigned EltSize) const {
if (STM->ldsRequiresM0Init())
return (EltSize == 4) ? AMDGPU::DS_WRITE2ST64_B32
: AMDGPU::DS_WRITE2ST64_B64;
return (EltSize == 4) ? AMDGPU::DS_WRITE2ST64_B32_gfx9
: AMDGPU::DS_WRITE2ST64_B64_gfx9;
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeWrite2Pair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
// Be sure to use .addOperand(), and not .addReg() with these. We want to be
// sure we preserve the subregister index and any register flags set on them.
const MachineOperand *AddrReg =
TII->getNamedOperand(*CI.I, AMDGPU::OpName::addr);
const MachineOperand *Data0 =
TII->getNamedOperand(*CI.I, AMDGPU::OpName::data0);
const MachineOperand *Data1 =
TII->getNamedOperand(*Paired.I, AMDGPU::OpName::data0);
unsigned NewOffset0 = CI.Offset;
unsigned NewOffset1 = Paired.Offset;
unsigned Opc =
CI.UseST64 ? write2ST64Opcode(CI.EltSize) : write2Opcode(CI.EltSize);
if (NewOffset0 > NewOffset1) {
// Canonicalize the merged instruction so the smaller offset comes first.
std::swap(NewOffset0, NewOffset1);
std::swap(Data0, Data1);
}
assert((isUInt<8>(NewOffset0) && isUInt<8>(NewOffset1)) &&
(NewOffset0 != NewOffset1) && "Computed offset doesn't fit");
const MCInstrDesc &Write2Desc = TII->get(Opc);
DebugLoc DL = CI.I->getDebugLoc();
Register BaseReg = AddrReg->getReg();
unsigned BaseSubReg = AddrReg->getSubReg();
unsigned BaseRegFlags = 0;
if (CI.BaseOff) {
Register ImmReg = MRI->createVirtualRegister(&AMDGPU::SReg_32RegClass);
BuildMI(*MBB, Paired.I, DL, TII->get(AMDGPU::S_MOV_B32), ImmReg)
.addImm(CI.BaseOff);
BaseReg = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
BaseRegFlags = RegState::Kill;
TII->getAddNoCarry(*MBB, Paired.I, DL, BaseReg)
.addReg(ImmReg)
.addReg(AddrReg->getReg(), 0, BaseSubReg)
.addImm(0); // clamp bit
BaseSubReg = 0;
}
MachineInstrBuilder Write2 =
BuildMI(*MBB, Paired.I, DL, Write2Desc)
.addReg(BaseReg, BaseRegFlags, BaseSubReg) // addr
.add(*Data0) // data0
.add(*Data1) // data1
.addImm(NewOffset0) // offset0
.addImm(NewOffset1) // offset1
.addImm(0) // gds
.cloneMergedMemRefs({&*CI.I, &*Paired.I});
moveInstsAfter(Write2, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
LLVM_DEBUG(dbgs() << "Inserted write2 inst: " << *Write2 << '\n');
return Write2;
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeImagePair(CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
Register DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedDMask = CI.DMask | Paired.DMask;
unsigned DMaskIdx =
AMDGPU::getNamedOperandIdx(CI.I->getOpcode(), AMDGPU::OpName::dmask);
auto MIB = BuildMI(*MBB, Paired.I, DL, TII->get(Opcode), DestReg);
for (unsigned I = 1, E = (*CI.I).getNumOperands(); I != E; ++I) {
if (I == DMaskIdx)
MIB.addImm(MergedDMask);
else
MIB.add((*CI.I).getOperand(I));
}
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New = MIB.addMemOperand(combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
unsigned SubRegIdx0, SubRegIdx1;
std::tie(SubRegIdx0, SubRegIdx1) = getSubRegIdxs(CI, Paired);
// Copy to the old destination registers.
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
const auto *Dest0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Dest1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdata);
BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
MachineBasicBlock::iterator SILoadStoreOptimizer::mergeSBufferLoadImmPair(
CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
Register DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedOffset = std::min(CI.Offset, Paired.Offset);
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New =
BuildMI(*MBB, Paired.I, DL, TII->get(Opcode), DestReg)
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::sbase))
.addImm(MergedOffset) // offset
.addImm(CI.CPol) // cpol
.addMemOperand(combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI, Paired);
const unsigned SubRegIdx0 = std::get<0>(SubRegIdx);
const unsigned SubRegIdx1 = std::get<1>(SubRegIdx);
// Copy to the old destination registers.
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
const auto *Dest0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::sdst);
const auto *Dest1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::sdst);
BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
MachineBasicBlock::iterator SILoadStoreOptimizer::mergeBufferLoadPair(
CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
// Copy to the new source register.
Register DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedOffset = std::min(CI.Offset, Paired.Offset);
auto MIB = BuildMI(*MBB, Paired.I, DL, TII->get(Opcode), DestReg);
AddressRegs Regs = getRegs(Opcode, *TII);
if (Regs.VAddr)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New =
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(MergedOffset) // offset
.addImm(CI.CPol) // cpol
.addImm(0) // tfe
.addImm(0) // swz
.addMemOperand(combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI, Paired);
const unsigned SubRegIdx0 = std::get<0>(SubRegIdx);
const unsigned SubRegIdx1 = std::get<1>(SubRegIdx);
// Copy to the old destination registers.
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
const auto *Dest0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Dest1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdata);
BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
MachineBasicBlock::iterator SILoadStoreOptimizer::mergeTBufferLoadPair(
CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
// Copy to the new source register.
Register DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedOffset = std::min(CI.Offset, Paired.Offset);
auto MIB = BuildMI(*MBB, Paired.I, DL, TII->get(Opcode), DestReg);
AddressRegs Regs = getRegs(Opcode, *TII);
if (Regs.VAddr)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
unsigned JoinedFormat =
getBufferFormatWithCompCount(CI.Format, CI.Width + Paired.Width, *STM);
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New =
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(MergedOffset) // offset
.addImm(JoinedFormat) // format
.addImm(CI.CPol) // cpol
.addImm(0) // tfe
.addImm(0) // swz
.addMemOperand(
combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI, Paired);
const unsigned SubRegIdx0 = std::get<0>(SubRegIdx);
const unsigned SubRegIdx1 = std::get<1>(SubRegIdx);
// Copy to the old destination registers.
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
const auto *Dest0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Dest1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdata);
BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, Paired.I, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
MachineBasicBlock::iterator SILoadStoreOptimizer::mergeTBufferStorePair(
CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI, Paired);
const unsigned SubRegIdx0 = std::get<0>(SubRegIdx);
const unsigned SubRegIdx1 = std::get<1>(SubRegIdx);
// Copy to the new source register.
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
Register SrcReg = MRI->createVirtualRegister(SuperRC);
const auto *Src0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Src1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdata);
BuildMI(*MBB, Paired.I, DL, TII->get(AMDGPU::REG_SEQUENCE), SrcReg)
.add(*Src0)
.addImm(SubRegIdx0)
.add(*Src1)
.addImm(SubRegIdx1);
auto MIB = BuildMI(*MBB, Paired.I, DL, TII->get(Opcode))
.addReg(SrcReg, RegState::Kill);
AddressRegs Regs = getRegs(Opcode, *TII);
if (Regs.VAddr)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
unsigned JoinedFormat =
getBufferFormatWithCompCount(CI.Format, CI.Width + Paired.Width, *STM);
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New =
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(std::min(CI.Offset, Paired.Offset)) // offset
.addImm(JoinedFormat) // format
.addImm(CI.CPol) // cpol
.addImm(0) // tfe
.addImm(0) // swz
.addMemOperand(
combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
moveInstsAfter(MIB, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
unsigned SILoadStoreOptimizer::getNewOpcode(const CombineInfo &CI,
const CombineInfo &Paired) {
const unsigned Width = CI.Width + Paired.Width;
switch (CI.InstClass) {
default:
assert(CI.InstClass == BUFFER_LOAD || CI.InstClass == BUFFER_STORE);
// FIXME: Handle d16 correctly
return AMDGPU::getMUBUFOpcode(AMDGPU::getMUBUFBaseOpcode(CI.I->getOpcode()),
Width);
case TBUFFER_LOAD:
case TBUFFER_STORE:
return AMDGPU::getMTBUFOpcode(AMDGPU::getMTBUFBaseOpcode(CI.I->getOpcode()),
Width);
case UNKNOWN:
llvm_unreachable("Unknown instruction class");
case S_BUFFER_LOAD_IMM:
switch (Width) {
default:
return 0;
case 2:
return AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM;
case 4:
return AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM;
}
case MIMG:
assert("No overlaps" && (countPopulation(CI.DMask | Paired.DMask) == Width));
return AMDGPU::getMaskedMIMGOp(CI.I->getOpcode(), Width);
}
}
std::pair<unsigned, unsigned>
SILoadStoreOptimizer::getSubRegIdxs(const CombineInfo &CI, const CombineInfo &Paired) {
if (CI.Width == 0 || Paired.Width == 0 || CI.Width + Paired.Width > 4)
return std::make_pair(0, 0);
bool ReverseOrder;
if (CI.InstClass == MIMG) {
assert((countPopulation(CI.DMask | Paired.DMask) == CI.Width + Paired.Width) &&
"No overlaps");
ReverseOrder = CI.DMask > Paired.DMask;
} else
ReverseOrder = CI.Offset > Paired.Offset;
static const unsigned Idxs[4][4] = {
{AMDGPU::sub0, AMDGPU::sub0_sub1, AMDGPU::sub0_sub1_sub2, AMDGPU::sub0_sub1_sub2_sub3},
{AMDGPU::sub1, AMDGPU::sub1_sub2, AMDGPU::sub1_sub2_sub3, 0},
{AMDGPU::sub2, AMDGPU::sub2_sub3, 0, 0},
{AMDGPU::sub3, 0, 0, 0},
};
unsigned Idx0;
unsigned Idx1;
assert(CI.Width >= 1 && CI.Width <= 3);
assert(Paired.Width >= 1 && Paired.Width <= 3);
if (ReverseOrder) {
Idx1 = Idxs[0][Paired.Width - 1];
Idx0 = Idxs[Paired.Width][CI.Width - 1];
} else {
Idx0 = Idxs[0][CI.Width - 1];
Idx1 = Idxs[CI.Width][Paired.Width - 1];
}
return std::make_pair(Idx0, Idx1);
}
const TargetRegisterClass *
SILoadStoreOptimizer::getTargetRegisterClass(const CombineInfo &CI,
const CombineInfo &Paired) {
if (CI.InstClass == S_BUFFER_LOAD_IMM) {
switch (CI.Width + Paired.Width) {
default:
return nullptr;
case 2:
return &AMDGPU::SReg_64_XEXECRegClass;
case 4:
return &AMDGPU::SGPR_128RegClass;
case 8:
return &AMDGPU::SGPR_256RegClass;
case 16:
return &AMDGPU::SGPR_512RegClass;
}
}
unsigned BitWidth = 32 * (CI.Width + Paired.Width);
return TRI->hasAGPRs(getDataRegClass(*CI.I))
? TRI->getAGPRClassForBitWidth(BitWidth)
: TRI->getVGPRClassForBitWidth(BitWidth);
}
MachineBasicBlock::iterator SILoadStoreOptimizer::mergeBufferStorePair(
CombineInfo &CI, CombineInfo &Paired,
const SmallVectorImpl<MachineInstr *> &InstsToMove) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI, Paired);
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI, Paired);
const unsigned SubRegIdx0 = std::get<0>(SubRegIdx);
const unsigned SubRegIdx1 = std::get<1>(SubRegIdx);
// Copy to the new source register.
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI, Paired);
Register SrcReg = MRI->createVirtualRegister(SuperRC);
const auto *Src0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Src1 = TII->getNamedOperand(*Paired.I, AMDGPU::OpName::vdata);
BuildMI(*MBB, Paired.I, DL, TII->get(AMDGPU::REG_SEQUENCE), SrcReg)
.add(*Src0)
.addImm(SubRegIdx0)
.add(*Src1)
.addImm(SubRegIdx1);
auto MIB = BuildMI(*MBB, Paired.I, DL, TII->get(Opcode))
.addReg(SrcReg, RegState::Kill);
AddressRegs Regs = getRegs(Opcode, *TII);
if (Regs.VAddr)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
// It shouldn't be possible to get this far if the two instructions
// don't have a single memoperand, because MachineInstr::mayAlias()
// will return true if this is the case.
assert(CI.I->hasOneMemOperand() && Paired.I->hasOneMemOperand());
const MachineMemOperand *MMOa = *CI.I->memoperands_begin();
const MachineMemOperand *MMOb = *Paired.I->memoperands_begin();
MachineInstr *New =
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(std::min(CI.Offset, Paired.Offset)) // offset
.addImm(CI.CPol) // cpol
.addImm(0) // tfe
.addImm(0) // swz
.addMemOperand(combineKnownAdjacentMMOs(*MBB->getParent(), MMOa, MMOb));
moveInstsAfter(MIB, InstsToMove);
CI.I->eraseFromParent();
Paired.I->eraseFromParent();
return New;
}
MachineOperand
SILoadStoreOptimizer::createRegOrImm(int32_t Val, MachineInstr &MI) const {
APInt V(32, Val, true);
if (TII->isInlineConstant(V))
return MachineOperand::CreateImm(Val);
Register Reg = MRI->createVirtualRegister(&AMDGPU::SReg_32RegClass);
MachineInstr *Mov =
BuildMI(*MI.getParent(), MI.getIterator(), MI.getDebugLoc(),
TII->get(AMDGPU::S_MOV_B32), Reg)
.addImm(Val);
(void)Mov;
LLVM_DEBUG(dbgs() << " "; Mov->dump());
return MachineOperand::CreateReg(Reg, false);
}
// Compute base address using Addr and return the final register.
Register SILoadStoreOptimizer::computeBase(MachineInstr &MI,
const MemAddress &Addr) const {
MachineBasicBlock *MBB = MI.getParent();
MachineBasicBlock::iterator MBBI = MI.getIterator();
DebugLoc DL = MI.getDebugLoc();
assert((TRI->getRegSizeInBits(Addr.Base.LoReg, *MRI) == 32 ||
Addr.Base.LoSubReg) &&
"Expected 32-bit Base-Register-Low!!");
assert((TRI->getRegSizeInBits(Addr.Base.HiReg, *MRI) == 32 ||
Addr.Base.HiSubReg) &&
"Expected 32-bit Base-Register-Hi!!");
LLVM_DEBUG(dbgs() << " Re-Computed Anchor-Base:\n");
MachineOperand OffsetLo = createRegOrImm(static_cast<int32_t>(Addr.Offset), MI);
MachineOperand OffsetHi =
createRegOrImm(static_cast<int32_t>(Addr.Offset >> 32), MI);
const auto *CarryRC = TRI->getRegClass(AMDGPU::SReg_1_XEXECRegClassID);
Register CarryReg = MRI->createVirtualRegister(CarryRC);
Register DeadCarryReg = MRI->createVirtualRegister(CarryRC);
Register DestSub0 = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
Register DestSub1 = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
MachineInstr *LoHalf =
BuildMI(*MBB, MBBI, DL, TII->get(AMDGPU::V_ADD_CO_U32_e64), DestSub0)
.addReg(CarryReg, RegState::Define)
.addReg(Addr.Base.LoReg, 0, Addr.Base.LoSubReg)
.add(OffsetLo)
.addImm(0); // clamp bit
(void)LoHalf;
LLVM_DEBUG(dbgs() << " "; LoHalf->dump(););
MachineInstr *HiHalf =
BuildMI(*MBB, MBBI, DL, TII->get(AMDGPU::V_ADDC_U32_e64), DestSub1)
.addReg(DeadCarryReg, RegState::Define | RegState::Dead)
.addReg(Addr.Base.HiReg, 0, Addr.Base.HiSubReg)
.add(OffsetHi)
.addReg(CarryReg, RegState::Kill)
.addImm(0); // clamp bit
(void)HiHalf;
LLVM_DEBUG(dbgs() << " "; HiHalf->dump(););
Register FullDestReg = MRI->createVirtualRegister(TRI->getVGPR64Class());
MachineInstr *FullBase =
BuildMI(*MBB, MBBI, DL, TII->get(TargetOpcode::REG_SEQUENCE), FullDestReg)
.addReg(DestSub0)
.addImm(AMDGPU::sub0)
.addReg(DestSub1)
.addImm(AMDGPU::sub1);
(void)FullBase;
LLVM_DEBUG(dbgs() << " "; FullBase->dump(); dbgs() << "\n";);
return FullDestReg;
}
// Update base and offset with the NewBase and NewOffset in MI.
void SILoadStoreOptimizer::updateBaseAndOffset(MachineInstr &MI,
Register NewBase,
int32_t NewOffset) const {
auto Base = TII->getNamedOperand(MI, AMDGPU::OpName::vaddr);
Base->setReg(NewBase);
Base->setIsKill(false);
TII->getNamedOperand(MI, AMDGPU::OpName::offset)->setImm(NewOffset);
}
Optional<int32_t>
SILoadStoreOptimizer::extractConstOffset(const MachineOperand &Op) const {
if (Op.isImm())
return Op.getImm();
if (!Op.isReg())
return None;
MachineInstr *Def = MRI->getUniqueVRegDef(Op.getReg());
if (!Def || Def->getOpcode() != AMDGPU::S_MOV_B32 ||
!Def->getOperand(1).isImm())
return None;
return Def->getOperand(1).getImm();
}
// Analyze Base and extracts:
// - 32bit base registers, subregisters
// - 64bit constant offset
// Expecting base computation as:
// %OFFSET0:sgpr_32 = S_MOV_B32 8000
// %LO:vgpr_32, %c:sreg_64_xexec =
// V_ADD_CO_U32_e64 %BASE_LO:vgpr_32, %103:sgpr_32,
// %HI:vgpr_32, = V_ADDC_U32_e64 %BASE_HI:vgpr_32, 0, killed %c:sreg_64_xexec
// %Base:vreg_64 =
// REG_SEQUENCE %LO:vgpr_32, %subreg.sub0, %HI:vgpr_32, %subreg.sub1
void SILoadStoreOptimizer::processBaseWithConstOffset(const MachineOperand &Base,
MemAddress &Addr) const {
if (!Base.isReg())
return;
MachineInstr *Def = MRI->getUniqueVRegDef(Base.getReg());
if (!Def || Def->getOpcode() != AMDGPU::REG_SEQUENCE
|| Def->getNumOperands() != 5)
return;
MachineOperand BaseLo = Def->getOperand(1);
MachineOperand BaseHi = Def->getOperand(3);
if (!BaseLo.isReg() || !BaseHi.isReg())
return;
MachineInstr *BaseLoDef = MRI->getUniqueVRegDef(BaseLo.getReg());
MachineInstr *BaseHiDef = MRI->getUniqueVRegDef(BaseHi.getReg());
if (!BaseLoDef || BaseLoDef->getOpcode() != AMDGPU::V_ADD_CO_U32_e64 ||
!BaseHiDef || BaseHiDef->getOpcode() != AMDGPU::V_ADDC_U32_e64)
return;
const auto *Src0 = TII->getNamedOperand(*BaseLoDef, AMDGPU::OpName::src0);
const auto *Src1 = TII->getNamedOperand(*BaseLoDef, AMDGPU::OpName::src1);
auto Offset0P = extractConstOffset(*Src0);
if (Offset0P)
BaseLo = *Src1;
else {
if (!(Offset0P = extractConstOffset(*Src1)))
return;
BaseLo = *Src0;
}
Src0 = TII->getNamedOperand(*BaseHiDef, AMDGPU::OpName::src0);
Src1 = TII->getNamedOperand(*BaseHiDef, AMDGPU::OpName::src1);
if (Src0->isImm())
std::swap(Src0, Src1);
if (!Src1->isImm())
return;
uint64_t Offset1 = Src1->getImm();
BaseHi = *Src0;
Addr.Base.LoReg = BaseLo.getReg();
Addr.Base.HiReg = BaseHi.getReg();
Addr.Base.LoSubReg = BaseLo.getSubReg();
Addr.Base.HiSubReg = BaseHi.getSubReg();
Addr.Offset = (*Offset0P & 0x00000000ffffffff) | (Offset1 << 32);
}
bool SILoadStoreOptimizer::promoteConstantOffsetToImm(
MachineInstr &MI,
MemInfoMap &Visited,
SmallPtrSet<MachineInstr *, 4> &AnchorList) const {
if (!(MI.mayLoad() ^ MI.mayStore()))
return false;
// TODO: Support flat and scratch.
if (AMDGPU::getGlobalSaddrOp(MI.getOpcode()) < 0)
return false;
if (MI.mayLoad() && TII->getNamedOperand(MI, AMDGPU::OpName::vdata) != NULL)
return false;
if (AnchorList.count(&MI))
return false;
LLVM_DEBUG(dbgs() << "\nTryToPromoteConstantOffsetToImmFor "; MI.dump());
if (TII->getNamedOperand(MI, AMDGPU::OpName::offset)->getImm()) {
LLVM_DEBUG(dbgs() << " Const-offset is already promoted.\n";);
return false;
}
// Step1: Find the base-registers and a 64bit constant offset.
MachineOperand &Base = *TII->getNamedOperand(MI, AMDGPU::OpName::vaddr);
MemAddress MAddr;
if (Visited.find(&MI) == Visited.end()) {
processBaseWithConstOffset(Base, MAddr);
Visited[&MI] = MAddr;
} else
MAddr = Visited[&MI];
if (MAddr.Offset == 0) {
LLVM_DEBUG(dbgs() << " Failed to extract constant-offset or there are no"
" constant offsets that can be promoted.\n";);
return false;
}
LLVM_DEBUG(dbgs() << " BASE: {" << MAddr.Base.HiReg << ", "
<< MAddr.Base.LoReg << "} Offset: " << MAddr.Offset << "\n\n";);
// Step2: Traverse through MI's basic block and find an anchor(that has the
// same base-registers) with the highest 13bit distance from MI's offset.
// E.g. (64bit loads)
// bb:
// addr1 = &a + 4096; load1 = load(addr1, 0)
// addr2 = &a + 6144; load2 = load(addr2, 0)
// addr3 = &a + 8192; load3 = load(addr3, 0)
// addr4 = &a + 10240; load4 = load(addr4, 0)
// addr5 = &a + 12288; load5 = load(addr5, 0)
//
// Starting from the first load, the optimization will try to find a new base
// from which (&a + 4096) has 13 bit distance. Both &a + 6144 and &a + 8192
// has 13bit distance from &a + 4096. The heuristic considers &a + 8192
// as the new-base(anchor) because of the maximum distance which can
// accomodate more intermediate bases presumeably.
//
// Step3: move (&a + 8192) above load1. Compute and promote offsets from
// (&a + 8192) for load1, load2, load4.
// addr = &a + 8192
// load1 = load(addr, -4096)
// load2 = load(addr, -2048)
// load3 = load(addr, 0)
// load4 = load(addr, 2048)
// addr5 = &a + 12288; load5 = load(addr5, 0)
//
MachineInstr *AnchorInst = nullptr;
MemAddress AnchorAddr;
uint32_t MaxDist = std::numeric_limits<uint32_t>::min();
SmallVector<std::pair<MachineInstr *, int64_t>, 4> InstsWCommonBase;
MachineBasicBlock *MBB = MI.getParent();
MachineBasicBlock::iterator E = MBB->end();
MachineBasicBlock::iterator MBBI = MI.getIterator();
++MBBI;
const SITargetLowering *TLI =
static_cast<const SITargetLowering *>(STM->getTargetLowering());
for ( ; MBBI != E; ++MBBI) {
MachineInstr &MINext = *MBBI;
// TODO: Support finding an anchor(with same base) from store addresses or
// any other load addresses where the opcodes are different.
if (MINext.getOpcode() != MI.getOpcode() ||
TII->getNamedOperand(MINext, AMDGPU::OpName::offset)->getImm())
continue;
const MachineOperand &BaseNext =
*TII->getNamedOperand(MINext, AMDGPU::OpName::vaddr);
MemAddress MAddrNext;
if (Visited.find(&MINext) == Visited.end()) {
processBaseWithConstOffset(BaseNext, MAddrNext);
Visited[&MINext] = MAddrNext;
} else
MAddrNext = Visited[&MINext];
if (MAddrNext.Base.LoReg != MAddr.Base.LoReg ||
MAddrNext.Base.HiReg != MAddr.Base.HiReg ||
MAddrNext.Base.LoSubReg != MAddr.Base.LoSubReg ||
MAddrNext.Base.HiSubReg != MAddr.Base.HiSubReg)
continue;
InstsWCommonBase.push_back(std::make_pair(&MINext, MAddrNext.Offset));
int64_t Dist = MAddr.Offset - MAddrNext.Offset;
TargetLoweringBase::AddrMode AM;
AM.HasBaseReg = true;
AM.BaseOffs = Dist;
if (TLI->isLegalGlobalAddressingMode(AM) &&
(uint32_t)std::abs(Dist) > MaxDist) {
MaxDist = std::abs(Dist);
AnchorAddr = MAddrNext;
AnchorInst = &MINext;
}
}
if (AnchorInst) {
LLVM_DEBUG(dbgs() << " Anchor-Inst(with max-distance from Offset): ";
AnchorInst->dump());
LLVM_DEBUG(dbgs() << " Anchor-Offset from BASE: "
<< AnchorAddr.Offset << "\n\n");
// Instead of moving up, just re-compute anchor-instruction's base address.
Register Base = computeBase(MI, AnchorAddr);
updateBaseAndOffset(MI, Base, MAddr.Offset - AnchorAddr.Offset);
LLVM_DEBUG(dbgs() << " After promotion: "; MI.dump(););
for (auto P : InstsWCommonBase) {
TargetLoweringBase::AddrMode AM;
AM.HasBaseReg = true;
AM.BaseOffs = P.second - AnchorAddr.Offset;
if (TLI->isLegalGlobalAddressingMode(AM)) {
LLVM_DEBUG(dbgs() << " Promote Offset(" << P.second;
dbgs() << ")"; P.first->dump());
updateBaseAndOffset(*P.first, Base, P.second - AnchorAddr.Offset);
LLVM_DEBUG(dbgs() << " After promotion: "; P.first->dump());
}
}
AnchorList.insert(AnchorInst);
return true;
}
return false;
}
void SILoadStoreOptimizer::addInstToMergeableList(const CombineInfo &CI,
std::list<std::list<CombineInfo> > &MergeableInsts) const {
for (std::list<CombineInfo> &AddrList : MergeableInsts) {
if (AddrList.front().InstClass == CI.InstClass &&
AddrList.front().hasSameBaseAddress(*CI.I)) {
AddrList.emplace_back(CI);
return;
}
}
// Base address not found, so add a new list.
MergeableInsts.emplace_back(1, CI);
}
std::pair<MachineBasicBlock::iterator, bool>
SILoadStoreOptimizer::collectMergeableInsts(
MachineBasicBlock::iterator Begin, MachineBasicBlock::iterator End,
MemInfoMap &Visited, SmallPtrSet<MachineInstr *, 4> &AnchorList,
std::list<std::list<CombineInfo>> &MergeableInsts) const {
bool Modified = false;
// Sort potential mergeable instructions into lists. One list per base address.
unsigned Order = 0;
MachineBasicBlock::iterator BlockI = Begin;
for (; BlockI != End; ++BlockI) {
MachineInstr &MI = *BlockI;
// We run this before checking if an address is mergeable, because it can produce
// better code even if the instructions aren't mergeable.
if (promoteConstantOffsetToImm(MI, Visited, AnchorList))
Modified = true;
// Don't combine if volatile. We also won't be able to merge across this, so
// break the search. We can look after this barrier for separate merges.
if (MI.hasOrderedMemoryRef()) {
LLVM_DEBUG(dbgs() << "Breaking search on memory fence: " << MI);
// Search will resume after this instruction in a separate merge list.
++BlockI;
break;
}
const InstClassEnum InstClass = getInstClass(MI.getOpcode(), *TII);
if (InstClass == UNKNOWN)
continue;
CombineInfo CI;
CI.setMI(MI, *TII, *STM);
CI.Order = Order++;
if (!CI.hasMergeableAddress(*MRI))
continue;
LLVM_DEBUG(dbgs() << "Mergeable: " << MI);
addInstToMergeableList(CI, MergeableInsts);
}
// At this point we have lists of Mergeable instructions.
//
// Part 2: Sort lists by offset and then for each CombineInfo object in the
// list try to find an instruction that can be merged with I. If an instruction
// is found, it is stored in the Paired field. If no instructions are found, then
// the CombineInfo object is deleted from the list.
for (std::list<std::list<CombineInfo>>::iterator I = MergeableInsts.begin(),
E = MergeableInsts.end(); I != E;) {
std::list<CombineInfo> &MergeList = *I;
if (MergeList.size() <= 1) {
// This means we have found only one instruction with a given address
// that can be merged, and we need at least 2 instructions to do a merge,
// so this list can be discarded.
I = MergeableInsts.erase(I);
continue;
}
// Sort the lists by offsets, this way mergeable instructions will be
// adjacent to each other in the list, which will make it easier to find
// matches.
MergeList.sort(
[] (const CombineInfo &A, CombineInfo &B) {
return A.Offset < B.Offset;
});
++I;
}
return std::make_pair(BlockI, Modified);
}
// Scan through looking for adjacent LDS operations with constant offsets from
// the same base register. We rely on the scheduler to do the hard work of
// clustering nearby loads, and assume these are all adjacent.
bool SILoadStoreOptimizer::optimizeBlock(
std::list<std::list<CombineInfo> > &MergeableInsts) {
bool Modified = false;
for (std::list<std::list<CombineInfo>>::iterator I = MergeableInsts.begin(),
E = MergeableInsts.end(); I != E;) {
std::list<CombineInfo> &MergeList = *I;
bool OptimizeListAgain = false;
if (!optimizeInstsWithSameBaseAddr(MergeList, OptimizeListAgain)) {
// We weren't able to make any changes, so delete the list so we don't
// process the same instructions the next time we try to optimize this
// block.
I = MergeableInsts.erase(I);
continue;
}
Modified = true;
// We made changes, but also determined that there were no more optimization
// opportunities, so we don't need to reprocess the list
if (!OptimizeListAgain) {
I = MergeableInsts.erase(I);
continue;
}
OptimizeAgain = true;
}
return Modified;
}
bool
SILoadStoreOptimizer::optimizeInstsWithSameBaseAddr(
std::list<CombineInfo> &MergeList,
bool &OptimizeListAgain) {
if (MergeList.empty())
return false;
bool Modified = false;
for (auto I = MergeList.begin(), Next = std::next(I); Next != MergeList.end();
Next = std::next(I)) {
auto First = I;
auto Second = Next;
if ((*First).Order > (*Second).Order)
std::swap(First, Second);
CombineInfo &CI = *First;
CombineInfo &Paired = *Second;
SmallVector<MachineInstr *, 8> InstsToMove;
if (!checkAndPrepareMerge(CI, Paired, InstsToMove)) {
++I;
continue;
}
Modified = true;
LLVM_DEBUG(dbgs() << "Merging: " << *CI.I << " with: " << *Paired.I);
switch (CI.InstClass) {
default:
llvm_unreachable("unknown InstClass");
break;
case DS_READ: {
MachineBasicBlock::iterator NewMI =
mergeRead2Pair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
break;
}
case DS_WRITE: {
MachineBasicBlock::iterator NewMI =
mergeWrite2Pair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
break;
}
case S_BUFFER_LOAD_IMM: {
MachineBasicBlock::iterator NewMI =
mergeSBufferLoadImmPair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 16;
break;
}
case BUFFER_LOAD: {
MachineBasicBlock::iterator NewMI =
mergeBufferLoadPair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 4;
break;
}
case BUFFER_STORE: {
MachineBasicBlock::iterator NewMI =
mergeBufferStorePair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 4;
break;
}
case MIMG: {
MachineBasicBlock::iterator NewMI =
mergeImagePair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 4;
break;
}
case TBUFFER_LOAD: {
MachineBasicBlock::iterator NewMI =
mergeTBufferLoadPair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 4;
break;
}
case TBUFFER_STORE: {
MachineBasicBlock::iterator NewMI =
mergeTBufferStorePair(CI, Paired, InstsToMove);
CI.setMI(NewMI, *TII, *STM);
OptimizeListAgain |= (CI.Width + Paired.Width) < 4;
break;
}
}
CI.Order = Paired.Order;
if (I == Second)
I = Next;
MergeList.erase(Second);
}
return Modified;
}
bool SILoadStoreOptimizer::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
STM = &MF.getSubtarget<GCNSubtarget>();
if (!STM->loadStoreOptEnabled())
return false;
TII = STM->getInstrInfo();
TRI = &TII->getRegisterInfo();
MRI = &MF.getRegInfo();
AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
LLVM_DEBUG(dbgs() << "Running SILoadStoreOptimizer\n");
bool Modified = false;
// Contains the list of instructions for which constant offsets are being
// promoted to the IMM. This is tracked for an entire block at time.
SmallPtrSet<MachineInstr *, 4> AnchorList;
MemInfoMap Visited;
for (MachineBasicBlock &MBB : MF) {
MachineBasicBlock::iterator SectionEnd;
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E;
I = SectionEnd) {
bool CollectModified;
std::list<std::list<CombineInfo>> MergeableInsts;
// First pass: Collect list of all instructions we know how to merge in a
// subset of the block.
std::tie(SectionEnd, CollectModified) =
collectMergeableInsts(I, E, Visited, AnchorList, MergeableInsts);
Modified |= CollectModified;
do {
OptimizeAgain = false;
Modified |= optimizeBlock(MergeableInsts);
} while (OptimizeAgain);
}
Visited.clear();
AnchorList.clear();
}
return Modified;
}
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