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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 currently relies on the scheduler to place loads and stores next to
// each other, and then only merges adjacent pairs of instructions. It would
// be good to be more flexible with interleaved instructions, and possibly run
// before scheduling. It 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 "AMDGPUSubtarget.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "SIInstrInfo.h"
#include "SIRegisterInfo.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <iterator>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "si-load-store-opt"
namespace {
enum InstClassEnum {
UNKNOWN,
DS_READ,
DS_WRITE,
S_BUFFER_LOAD_IMM,
BUFFER_LOAD_OFFEN = AMDGPU::BUFFER_LOAD_DWORD_OFFEN,
BUFFER_LOAD_OFFSET = AMDGPU::BUFFER_LOAD_DWORD_OFFSET,
BUFFER_STORE_OFFEN = AMDGPU::BUFFER_STORE_DWORD_OFFEN,
BUFFER_STORE_OFFSET = AMDGPU::BUFFER_STORE_DWORD_OFFSET,
BUFFER_LOAD_OFFEN_exact = AMDGPU::BUFFER_LOAD_DWORD_OFFEN_exact,
BUFFER_LOAD_OFFSET_exact = AMDGPU::BUFFER_LOAD_DWORD_OFFSET_exact,
BUFFER_STORE_OFFEN_exact = AMDGPU::BUFFER_STORE_DWORD_OFFEN_exact,
BUFFER_STORE_OFFSET_exact = AMDGPU::BUFFER_STORE_DWORD_OFFSET_exact,
};
enum RegisterEnum {
SBASE = 0x1,
SRSRC = 0x2,
SOFFSET = 0x4,
VADDR = 0x8,
ADDR = 0x10,
};
class SILoadStoreOptimizer : public MachineFunctionPass {
struct CombineInfo {
MachineBasicBlock::iterator I;
MachineBasicBlock::iterator Paired;
unsigned EltSize;
unsigned Offset0;
unsigned Offset1;
unsigned Width0;
unsigned Width1;
unsigned BaseOff;
InstClassEnum InstClass;
bool GLC0;
bool GLC1;
bool SLC0;
bool SLC1;
bool DLC0;
bool DLC1;
bool UseST64;
SmallVector<MachineInstr *, 8> InstsToMove;
};
struct BaseRegisters {
unsigned LoReg = 0;
unsigned HiReg = 0;
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 offsetsCanBeCombined(CombineInfo &CI);
static bool widthsFit(const GCNSubtarget &STM, const CombineInfo &CI);
static unsigned getNewOpcode(const CombineInfo &CI);
static std::pair<unsigned, unsigned> getSubRegIdxs(const CombineInfo &CI);
const TargetRegisterClass *getTargetRegisterClass(const CombineInfo &CI);
unsigned getOpcodeWidth(const MachineInstr &MI);
InstClassEnum getInstClass(unsigned Opc);
unsigned getRegs(unsigned Opc);
bool findMatchingInst(CombineInfo &CI);
unsigned read2Opcode(unsigned EltSize) const;
unsigned read2ST64Opcode(unsigned EltSize) const;
MachineBasicBlock::iterator mergeRead2Pair(CombineInfo &CI);
unsigned write2Opcode(unsigned EltSize) const;
unsigned write2ST64Opcode(unsigned EltSize) const;
MachineBasicBlock::iterator mergeWrite2Pair(CombineInfo &CI);
MachineBasicBlock::iterator mergeSBufferLoadImmPair(CombineInfo &CI);
MachineBasicBlock::iterator mergeBufferLoadPair(CombineInfo &CI);
MachineBasicBlock::iterator mergeBufferStorePair(CombineInfo &CI);
void updateBaseAndOffset(MachineInstr &I, unsigned NewBase,
int32_t NewOffset);
unsigned computeBase(MachineInstr &MI, const MemAddress &Addr);
MachineOperand createRegOrImm(int32_t Val, MachineInstr &MI);
Optional<int32_t> extractConstOffset(const MachineOperand &Op);
void processBaseWithConstOffset(const MachineOperand &Base, MemAddress &Addr);
/// 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);
public:
static char ID;
SILoadStoreOptimizer() : MachineFunctionPass(ID) {
initializeSILoadStoreOptimizerPass(*PassRegistry::getPassRegistry());
}
bool optimizeBlock(MachineBasicBlock &MBB);
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);
}
};
} // 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<unsigned> &RegDefs,
DenseSet<unsigned> &PhysRegUses) {
for (const MachineOperand &Op : MI.operands()) {
if (Op.isReg()) {
if (Op.isDef())
RegDefs.insert(Op.getReg());
else if (Op.readsReg() &&
TargetRegisterInfo::isPhysicalRegister(Op.getReg()))
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<unsigned> &RegDefs,
DenseSet<unsigned> &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() && TargetRegisterInfo::isPhysicalRegister(Use.getReg()) &&
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;
}
bool SILoadStoreOptimizer::offsetsCanBeCombined(CombineInfo &CI) {
// XXX - Would the same offset be OK? Is there any reason this would happen or
// be useful?
if (CI.Offset0 == CI.Offset1)
return false;
// This won't be valid if the offset isn't aligned.
if ((CI.Offset0 % CI.EltSize != 0) || (CI.Offset1 % CI.EltSize != 0))
return false;
unsigned EltOffset0 = CI.Offset0 / CI.EltSize;
unsigned EltOffset1 = CI.Offset1 / CI.EltSize;
CI.UseST64 = false;
CI.BaseOff = 0;
// Handle SMEM and VMEM instructions.
if ((CI.InstClass != DS_READ) && (CI.InstClass != DS_WRITE)) {
return (EltOffset0 + CI.Width0 == EltOffset1 ||
EltOffset1 + CI.Width1 == EltOffset0) &&
CI.GLC0 == CI.GLC1 && CI.DLC0 == CI.DLC1 &&
(CI.InstClass == S_BUFFER_LOAD_IMM || CI.SLC0 == CI.SLC1);
}
// 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)) {
CI.Offset0 = EltOffset0 / 64;
CI.Offset1 = 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)) {
CI.Offset0 = EltOffset0;
CI.Offset1 = EltOffset1;
return true;
}
// Try to shift base address to decrease offsets.
unsigned OffsetDiff = std::abs((int)EltOffset1 - (int)EltOffset0);
CI.BaseOff = std::min(CI.Offset0, CI.Offset1);
if ((OffsetDiff % 64 == 0) && isUInt<8>(OffsetDiff / 64)) {
CI.Offset0 = (EltOffset0 - CI.BaseOff / CI.EltSize) / 64;
CI.Offset1 = (EltOffset1 - CI.BaseOff / CI.EltSize) / 64;
CI.UseST64 = true;
return true;
}
if (isUInt<8>(OffsetDiff)) {
CI.Offset0 = EltOffset0 - CI.BaseOff / CI.EltSize;
CI.Offset1 = EltOffset1 - CI.BaseOff / CI.EltSize;
return true;
}
return false;
}
bool SILoadStoreOptimizer::widthsFit(const GCNSubtarget &STM,
const CombineInfo &CI) {
const unsigned Width = (CI.Width0 + CI.Width1);
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;
}
}
}
unsigned SILoadStoreOptimizer::getOpcodeWidth(const MachineInstr &MI) {
const unsigned Opc = MI.getOpcode();
if (TII->isMUBUF(MI)) {
return AMDGPU::getMUBUFDwords(Opc);
}
switch (Opc) {
default:
return 0;
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;
}
}
InstClassEnum SILoadStoreOptimizer::getInstClass(unsigned Opc) {
if (TII->isMUBUF(Opc)) {
const int baseOpcode = AMDGPU::getMUBUFBaseOpcode(Opc);
// If we couldn't identify the opcode, bail out.
if (baseOpcode == -1) {
return UNKNOWN;
}
switch (baseOpcode) {
default:
return UNKNOWN;
case AMDGPU::BUFFER_LOAD_DWORD_OFFEN:
return BUFFER_LOAD_OFFEN;
case AMDGPU::BUFFER_LOAD_DWORD_OFFSET:
return BUFFER_LOAD_OFFSET;
case AMDGPU::BUFFER_STORE_DWORD_OFFEN:
return BUFFER_STORE_OFFEN;
case AMDGPU::BUFFER_STORE_DWORD_OFFSET:
return BUFFER_STORE_OFFSET;
case AMDGPU::BUFFER_LOAD_DWORD_OFFEN_exact:
return BUFFER_LOAD_OFFEN_exact;
case AMDGPU::BUFFER_LOAD_DWORD_OFFSET_exact:
return BUFFER_LOAD_OFFSET_exact;
case AMDGPU::BUFFER_STORE_DWORD_OFFEN_exact:
return BUFFER_STORE_OFFEN_exact;
case AMDGPU::BUFFER_STORE_DWORD_OFFSET_exact:
return BUFFER_STORE_OFFSET_exact;
}
}
switch (Opc) {
default:
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_B64:
case AMDGPU::DS_READ_B32_gfx9:
case AMDGPU::DS_READ_B64_gfx9:
return DS_READ;
case AMDGPU::DS_WRITE_B32:
case AMDGPU::DS_WRITE_B64:
case AMDGPU::DS_WRITE_B32_gfx9:
case AMDGPU::DS_WRITE_B64_gfx9:
return DS_WRITE;
}
}
unsigned SILoadStoreOptimizer::getRegs(unsigned Opc) {
if (TII->isMUBUF(Opc)) {
unsigned result = 0;
if (AMDGPU::getMUBUFHasVAddr(Opc)) {
result |= VADDR;
}
if (AMDGPU::getMUBUFHasSrsrc(Opc)) {
result |= SRSRC;
}
if (AMDGPU::getMUBUFHasSoffset(Opc)) {
result |= SOFFSET;
}
return result;
}
switch (Opc) {
default:
return 0;
case AMDGPU::S_BUFFER_LOAD_DWORD_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX2_IMM:
case AMDGPU::S_BUFFER_LOAD_DWORDX4_IMM:
return SBASE;
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:
return ADDR;
}
}
bool SILoadStoreOptimizer::findMatchingInst(CombineInfo &CI) {
MachineBasicBlock *MBB = CI.I->getParent();
MachineBasicBlock::iterator E = MBB->end();
MachineBasicBlock::iterator MBBI = CI.I;
const unsigned Opc = CI.I->getOpcode();
const InstClassEnum InstClass = getInstClass(Opc);
if (InstClass == UNKNOWN) {
return false;
}
const unsigned Regs = getRegs(Opc);
unsigned AddrOpName[5] = {0};
int AddrIdx[5];
const MachineOperand *AddrReg[5];
unsigned NumAddresses = 0;
if (Regs & ADDR) {
AddrOpName[NumAddresses++] = AMDGPU::OpName::addr;
}
if (Regs & SBASE) {
AddrOpName[NumAddresses++] = AMDGPU::OpName::sbase;
}
if (Regs & SRSRC) {
AddrOpName[NumAddresses++] = AMDGPU::OpName::srsrc;
}
if (Regs & SOFFSET) {
AddrOpName[NumAddresses++] = AMDGPU::OpName::soffset;
}
if (Regs & VADDR) {
AddrOpName[NumAddresses++] = AMDGPU::OpName::vaddr;
}
for (unsigned i = 0; i < NumAddresses; i++) {
AddrIdx[i] = AMDGPU::getNamedOperandIdx(CI.I->getOpcode(), AddrOpName[i]);
AddrReg[i] = &CI.I->getOperand(AddrIdx[i]);
// We only ever merge operations with the same base address register, so
// don't bother scanning forward if there are no other uses.
if (AddrReg[i]->isReg() &&
(TargetRegisterInfo::isPhysicalRegister(AddrReg[i]->getReg()) ||
MRI->hasOneNonDBGUse(AddrReg[i]->getReg())))
return false;
}
++MBBI;
DenseSet<unsigned> RegDefsToMove;
DenseSet<unsigned> PhysRegUsesToMove;
addDefsUsesToList(*CI.I, RegDefsToMove, PhysRegUsesToMove);
for (; MBBI != E; ++MBBI) {
const bool IsDS = (InstClass == DS_READ) || (InstClass == DS_WRITE);
if ((getInstClass(MBBI->getOpcode()) != InstClass) ||
(IsDS && (MBBI->getOpcode() != Opc))) {
// This is not a matching DS 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, CI.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.
CI.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,
CI.InstsToMove);
continue;
}
// Don't merge volatiles.
if (MBBI->hasOrderedMemoryRef())
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,
CI.InstsToMove))
continue;
bool Match = true;
for (unsigned i = 0; i < NumAddresses; i++) {
const MachineOperand &AddrRegNext = MBBI->getOperand(AddrIdx[i]);
if (AddrReg[i]->isImm() || AddrRegNext.isImm()) {
if (AddrReg[i]->isImm() != AddrRegNext.isImm() ||
AddrReg[i]->getImm() != AddrRegNext.getImm()) {
Match = false;
break;
}
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()) {
Match = false;
break;
}
}
if (Match) {
int OffsetIdx =
AMDGPU::getNamedOperandIdx(CI.I->getOpcode(), AMDGPU::OpName::offset);
CI.Offset0 = CI.I->getOperand(OffsetIdx).getImm();
CI.Width0 = getOpcodeWidth(*CI.I);
CI.Offset1 = MBBI->getOperand(OffsetIdx).getImm();
CI.Width1 = getOpcodeWidth(*MBBI);
CI.Paired = MBBI;
if ((CI.InstClass == DS_READ) || (CI.InstClass == DS_WRITE)) {
CI.Offset0 &= 0xffff;
CI.Offset1 &= 0xffff;
} else {
CI.GLC0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::glc)->getImm();
CI.GLC1 = TII->getNamedOperand(*MBBI, AMDGPU::OpName::glc)->getImm();
if (CI.InstClass != S_BUFFER_LOAD_IMM) {
CI.SLC0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::slc)->getImm();
CI.SLC1 = TII->getNamedOperand(*MBBI, AMDGPU::OpName::slc)->getImm();
}
CI.DLC0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::dlc)->getImm();
CI.DLC1 = TII->getNamedOperand(*MBBI, AMDGPU::OpName::dlc)->getImm();
}
// Check both offsets fit in the reduced range.
// We also 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 (widthsFit(*STM, CI) && offsetsCanBeCombined(CI))
if (canMoveInstsAcrossMemOp(*MBBI, CI.InstsToMove, AA))
return true;
}
// 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, CI.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) {
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(*CI.Paired, AMDGPU::OpName::vdst);
unsigned NewOffset0 = CI.Offset0;
unsigned NewOffset1 = CI.Offset1;
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 =
(CI.EltSize == 4) ? &AMDGPU::VReg_64RegClass : &AMDGPU::VReg_128RegClass;
unsigned DestReg = MRI->createVirtualRegister(SuperRC);
DebugLoc DL = CI.I->getDebugLoc();
unsigned BaseReg = AddrReg->getReg();
unsigned BaseSubReg = AddrReg->getSubReg();
unsigned BaseRegFlags = 0;
if (CI.BaseOff) {
unsigned ImmReg = MRI->createVirtualRegister(&AMDGPU::SGPR_32RegClass);
BuildMI(*MBB, CI.Paired, DL, TII->get(AMDGPU::S_MOV_B32), ImmReg)
.addImm(CI.BaseOff);
BaseReg = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
BaseRegFlags = RegState::Kill;
TII->getAddNoCarry(*MBB, CI.Paired, DL, BaseReg)
.addReg(ImmReg)
.addReg(AddrReg->getReg(), 0, BaseSubReg)
.addImm(0); // clamp bit
BaseSubReg = 0;
}
MachineInstrBuilder Read2 =
BuildMI(*MBB, CI.Paired, DL, Read2Desc, DestReg)
.addReg(BaseReg, BaseRegFlags, BaseSubReg) // addr
.addImm(NewOffset0) // offset0
.addImm(NewOffset1) // offset1
.addImm(0) // gds
.cloneMergedMemRefs({&*CI.I, &*CI.Paired});
(void)Read2;
const MCInstrDesc &CopyDesc = TII->get(TargetOpcode::COPY);
// Copy to the old destination registers.
BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, CI.InstsToMove);
MachineBasicBlock::iterator Next = std::next(CI.I);
CI.I->eraseFromParent();
CI.Paired->eraseFromParent();
LLVM_DEBUG(dbgs() << "Inserted read2: " << *Read2 << '\n');
return Next;
}
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) {
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(*CI.Paired, AMDGPU::OpName::data0);
unsigned NewOffset0 = CI.Offset0;
unsigned NewOffset1 = CI.Offset1;
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();
unsigned BaseReg = AddrReg->getReg();
unsigned BaseSubReg = AddrReg->getSubReg();
unsigned BaseRegFlags = 0;
if (CI.BaseOff) {
unsigned ImmReg = MRI->createVirtualRegister(&AMDGPU::SGPR_32RegClass);
BuildMI(*MBB, CI.Paired, DL, TII->get(AMDGPU::S_MOV_B32), ImmReg)
.addImm(CI.BaseOff);
BaseReg = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
BaseRegFlags = RegState::Kill;
TII->getAddNoCarry(*MBB, CI.Paired, DL, BaseReg)
.addReg(ImmReg)
.addReg(AddrReg->getReg(), 0, BaseSubReg)
.addImm(0); // clamp bit
BaseSubReg = 0;
}
MachineInstrBuilder Write2 =
BuildMI(*MBB, CI.Paired, 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, &*CI.Paired});
moveInstsAfter(Write2, CI.InstsToMove);
MachineBasicBlock::iterator Next = std::next(CI.I);
CI.I->eraseFromParent();
CI.Paired->eraseFromParent();
LLVM_DEBUG(dbgs() << "Inserted write2 inst: " << *Write2 << '\n');
return Next;
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeSBufferLoadImmPair(CombineInfo &CI) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI);
unsigned DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedOffset = std::min(CI.Offset0, CI.Offset1);
BuildMI(*MBB, CI.Paired, DL, TII->get(Opcode), DestReg)
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::sbase))
.addImm(MergedOffset) // offset
.addImm(CI.GLC0) // glc
.addImm(CI.DLC0) // dlc
.cloneMergedMemRefs({&*CI.I, &*CI.Paired});
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI);
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(*CI.Paired, AMDGPU::OpName::sdst);
BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, CI.InstsToMove);
MachineBasicBlock::iterator Next = std::next(CI.I);
CI.I->eraseFromParent();
CI.Paired->eraseFromParent();
return Next;
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeBufferLoadPair(CombineInfo &CI) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI);
const TargetRegisterClass *SuperRC = getTargetRegisterClass(CI);
// Copy to the new source register.
unsigned DestReg = MRI->createVirtualRegister(SuperRC);
unsigned MergedOffset = std::min(CI.Offset0, CI.Offset1);
auto MIB = BuildMI(*MBB, CI.Paired, DL, TII->get(Opcode), DestReg);
const unsigned Regs = getRegs(Opcode);
if (Regs & VADDR)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(MergedOffset) // offset
.addImm(CI.GLC0) // glc
.addImm(CI.SLC0) // slc
.addImm(0) // tfe
.addImm(CI.DLC0) // dlc
.cloneMergedMemRefs({&*CI.I, &*CI.Paired});
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI);
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(*CI.Paired, AMDGPU::OpName::vdata);
BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest0) // Copy to same destination including flags and sub reg.
.addReg(DestReg, 0, SubRegIdx0);
MachineInstr *Copy1 = BuildMI(*MBB, CI.Paired, DL, CopyDesc)
.add(*Dest1)
.addReg(DestReg, RegState::Kill, SubRegIdx1);
moveInstsAfter(Copy1, CI.InstsToMove);
MachineBasicBlock::iterator Next = std::next(CI.I);
CI.I->eraseFromParent();
CI.Paired->eraseFromParent();
return Next;
}
unsigned SILoadStoreOptimizer::getNewOpcode(const CombineInfo &CI) {
const unsigned Width = CI.Width0 + CI.Width1;
switch (CI.InstClass) {
default:
return AMDGPU::getMUBUFOpcode(CI.InstClass, 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;
}
}
}
std::pair<unsigned, unsigned>
SILoadStoreOptimizer::getSubRegIdxs(const CombineInfo &CI) {
if (CI.Offset0 > CI.Offset1) {
switch (CI.Width0) {
default:
return std::make_pair(0, 0);
case 1:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub1, AMDGPU::sub0);
case 2:
return std::make_pair(AMDGPU::sub2, AMDGPU::sub0_sub1);
case 3:
return std::make_pair(AMDGPU::sub3, AMDGPU::sub0_sub1_sub2);
}
case 2:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub1_sub2, AMDGPU::sub0);
case 2:
return std::make_pair(AMDGPU::sub2_sub3, AMDGPU::sub0_sub1);
}
case 3:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub1_sub2_sub3, AMDGPU::sub0);
}
}
} else {
switch (CI.Width0) {
default:
return std::make_pair(0, 0);
case 1:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub0, AMDGPU::sub1);
case 2:
return std::make_pair(AMDGPU::sub0, AMDGPU::sub1_sub2);
case 3:
return std::make_pair(AMDGPU::sub0, AMDGPU::sub1_sub2_sub3);
}
case 2:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub0_sub1, AMDGPU::sub2);
case 2:
return std::make_pair(AMDGPU::sub0_sub1, AMDGPU::sub2_sub3);
}
case 3:
switch (CI.Width1) {
default:
return std::make_pair(0, 0);
case 1:
return std::make_pair(AMDGPU::sub0_sub1_sub2, AMDGPU::sub3);
}
}
}
}
const TargetRegisterClass *
SILoadStoreOptimizer::getTargetRegisterClass(const CombineInfo &CI) {
if (CI.InstClass == S_BUFFER_LOAD_IMM) {
switch (CI.Width0 + CI.Width1) {
default:
return nullptr;
case 2:
return &AMDGPU::SReg_64_XEXECRegClass;
case 4:
return &AMDGPU::SReg_128RegClass;
case 8:
return &AMDGPU::SReg_256RegClass;
case 16:
return &AMDGPU::SReg_512RegClass;
}
} else {
switch (CI.Width0 + CI.Width1) {
default:
return nullptr;
case 2:
return &AMDGPU::VReg_64RegClass;
case 3:
return &AMDGPU::VReg_96RegClass;
case 4:
return &AMDGPU::VReg_128RegClass;
}
}
}
MachineBasicBlock::iterator
SILoadStoreOptimizer::mergeBufferStorePair(CombineInfo &CI) {
MachineBasicBlock *MBB = CI.I->getParent();
DebugLoc DL = CI.I->getDebugLoc();
const unsigned Opcode = getNewOpcode(CI);
std::pair<unsigned, unsigned> SubRegIdx = getSubRegIdxs(CI);
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);
unsigned SrcReg = MRI->createVirtualRegister(SuperRC);
const auto *Src0 = TII->getNamedOperand(*CI.I, AMDGPU::OpName::vdata);
const auto *Src1 = TII->getNamedOperand(*CI.Paired, AMDGPU::OpName::vdata);
BuildMI(*MBB, CI.Paired, DL, TII->get(AMDGPU::REG_SEQUENCE), SrcReg)
.add(*Src0)
.addImm(SubRegIdx0)
.add(*Src1)
.addImm(SubRegIdx1);
auto MIB = BuildMI(*MBB, CI.Paired, DL, TII->get(Opcode))
.addReg(SrcReg, RegState::Kill);
const unsigned Regs = getRegs(Opcode);
if (Regs & VADDR)
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::vaddr));
MIB.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::srsrc))
.add(*TII->getNamedOperand(*CI.I, AMDGPU::OpName::soffset))
.addImm(std::min(CI.Offset0, CI.Offset1)) // offset
.addImm(CI.GLC0) // glc
.addImm(CI.SLC0) // slc
.addImm(0) // tfe
.addImm(CI.DLC0) // dlc
.cloneMergedMemRefs({&*CI.I, &*CI.Paired});
moveInstsAfter(MIB, CI.InstsToMove);
MachineBasicBlock::iterator Next = std::next(CI.I);
CI.I->eraseFromParent();
CI.Paired->eraseFromParent();
return Next;
}
MachineOperand
SILoadStoreOptimizer::createRegOrImm(int32_t Val, MachineInstr &MI) {
APInt V(32, Val, true);
if (TII->isInlineConstant(V))
return MachineOperand::CreateImm(Val);
unsigned 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.
unsigned SILoadStoreOptimizer::computeBase(MachineInstr &MI,
const MemAddress &Addr) {
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);
unsigned CarryReg = MRI->createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
unsigned DeadCarryReg =
MRI->createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
unsigned DestSub0 = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
unsigned DestSub1 = MRI->createVirtualRegister(&AMDGPU::VGPR_32RegClass);
MachineInstr *LoHalf =
BuildMI(*MBB, MBBI, DL, TII->get(AMDGPU::V_ADD_I32_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(););
unsigned FullDestReg = MRI->createVirtualRegister(&AMDGPU::VReg_64RegClass);
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,
unsigned NewBase,
int32_t NewOffset) {
TII->getNamedOperand(MI, AMDGPU::OpName::vaddr)->setReg(NewBase);
TII->getNamedOperand(MI, AMDGPU::OpName::offset)->setImm(NewOffset);
}
Optional<int32_t>
SILoadStoreOptimizer::extractConstOffset(const MachineOperand &Op) {
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_I32_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) {
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_I32_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) {
// TODO: Support flat and scratch.
if (AMDGPU::getGlobalSaddrOp(MI.getOpcode()) < 0 ||
TII->getNamedOperand(MI, AMDGPU::OpName::vdata) != NULL)
return false;
// TODO: Support Store.
if (!MI.mayLoad())
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.
unsigned 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;
}
// 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(MachineBasicBlock &MBB) {
bool Modified = false;
// Contain the list
MemInfoMap Visited;
// Contains the list of instructions for which constant offsets are being
// promoted to the IMM.
SmallPtrSet<MachineInstr *, 4> AnchorList;
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E;) {
MachineInstr &MI = *I;
if (promoteConstantOffsetToImm(MI, Visited, AnchorList))
Modified = true;
// Don't combine if volatile.
if (MI.hasOrderedMemoryRef()) {
++I;
continue;
}
const unsigned Opc = MI.getOpcode();
CombineInfo CI;
CI.I = I;
CI.InstClass = getInstClass(Opc);
switch (CI.InstClass) {
default:
break;
case DS_READ:
CI.EltSize =
(Opc == AMDGPU::DS_READ_B64 || Opc == AMDGPU::DS_READ_B64_gfx9) ? 8
: 4;
if (findMatchingInst(CI)) {
Modified = true;
I = mergeRead2Pair(CI);
} else {
++I;
}
continue;
case DS_WRITE:
CI.EltSize =
(Opc == AMDGPU::DS_WRITE_B64 || Opc == AMDGPU::DS_WRITE_B64_gfx9) ? 8
: 4;
if (findMatchingInst(CI)) {
Modified = true;
I = mergeWrite2Pair(CI);
} else {
++I;
}
continue;
case S_BUFFER_LOAD_IMM:
CI.EltSize = AMDGPU::getSMRDEncodedOffset(*STM, 4);
if (findMatchingInst(CI)) {
Modified = true;
I = mergeSBufferLoadImmPair(CI);
OptimizeAgain |= (CI.Width0 + CI.Width1) < 16;
} else {
++I;
}
continue;
case BUFFER_LOAD_OFFEN:
case BUFFER_LOAD_OFFSET:
case BUFFER_LOAD_OFFEN_exact:
case BUFFER_LOAD_OFFSET_exact:
CI.EltSize = 4;
if (findMatchingInst(CI)) {
Modified = true;
I = mergeBufferLoadPair(CI);
OptimizeAgain |= (CI.Width0 + CI.Width1) < 4;
} else {
++I;
}
continue;
case BUFFER_STORE_OFFEN:
case BUFFER_STORE_OFFSET:
case BUFFER_STORE_OFFEN_exact:
case BUFFER_STORE_OFFSET_exact:
CI.EltSize = 4;
if (findMatchingInst(CI)) {
Modified = true;
I = mergeBufferStorePair(CI);
OptimizeAgain |= (CI.Width0 + CI.Width1) < 4;
} else {
++I;
}
continue;
}
++I;
}
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();
assert(MRI->isSSA() && "Must be run on SSA");
LLVM_DEBUG(dbgs() << "Running SILoadStoreOptimizer\n");
bool Modified = false;
for (MachineBasicBlock &MBB : MF) {
do {
OptimizeAgain = false;
Modified |= optimizeBlock(MBB);
} while (OptimizeAgain);
}
return Modified;
}
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