[ADMGPU] SDWA peephole optimization pass.

[SamWot]

Summary

First iteration of SDWA peephole.

This pass tries to combine several instruction into one SDWA instruction. E.g. it converts:

V_LSHRREV_B32_e32 %vreg0, 16, %vreg1
V_ADD_I32_e32 %vreg2, %vreg0, %vreg3
V_LSHLREV_B32_e32 %vreg4, 16, %vreg2

Into:

V_ADD_I32_sdwa %vreg4, %vreg1, %vreg3 dst_sel:WORD_1 dst_unused:UNUSED_PAD src0_sel:WORD_1 src1_sel:DWORD

Added --amdgpu-sdwa-peephole command-line option that enables this pass. by default pass is disabled.

Pass structure:

1. Iterate over machine instruction in basic block and try to apply "SDWA patterns" to each of them. SDWA patterns match machine instruction into either source or destination SDWA operand. E.g. V_LSHRREV_B32_e32 %vreg0, 16, %vreg1 is matched to source SDWA operand %vreg1 src_sel:WORD_1.
2. Iterate over found SDWA operands and find instruction that could be potentially coverted into SDWA. E.g. for source SDWA operand potential instruction are all instruction in this basic block that uses %vreg0
3. Iterate over all potential instructions and check if they can be converted into SDWA.
4. Convert instructions to SDWA.

This review contains basic implementation of SDWA peephole pass. This pass requires additional testing fot both correctness and performance (no performance testing done).
There are several ways this pass can be improved:

1. Make this pass work on whole function not only basic block. As I can see this can be done right now without changes to pass.
2. Introduce more SDWA patterns
3. Introduce mnemonics to limit when SDWA patterns should apply

[arsenm]

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

672–675

This seems late to me, and also introduces a 3rd run of DeadMachineInstructionElim. I would expect to run this right after SIFoldOperands. You have code dealing with VOPC/vcc required uses, but that is of limited help right after the pre-RA run. I consider it a bug that we see any of those at all at this point.

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

23

Should be included last.

59

Should not need shared_ptr, unique_ptr is enough. The struct is also small enough to store values of

137

usual style is static functions without anon namespace

163

Single quotes

170

ditto

174

This function shouldn't be necessary. I think all you want to do is check the blocks have the same parent? You shouldn't be seeing situations where you're seeing instructions from multiple functions

205

I think this should be removed. There should be no cases where MRI is unavailable, so the null checks here and on its callers are unnecessary. It would be better to just pass around the one MRI reference

221

I think this is too aggressive. I would expect to restrict the number of uses to fold. In a typical case if the shift has more than one use, you are increasing code size. I would also expect a legality check here, because if there is an unfoldable user, there's no point in folding any of them.

235

I think you're going through too much trouble to loop over explicit_uses and then figuring out the operand index. In similar places we just directly query src0/src1

305–307

You could create a new virtual register and replace all uses with. If you are going through the trouble of deleting the leftover instructions yourself there's no need to run dead mi elimination again

312–314

This reasoning seems backwards to me. If you run before SIShrinkInstructions you shouldn't need to worry about the e32 case (which is part of why we try to keep things in VOP3 form until necessary)

330–333

You don't need to check this. The instruction is broken and will fail the verifier

342

For a next round patch I would expect and x, bitmask to select the low half

345–347

Ditto

369

I would expect to consolidate this with convertToSDWA and return false if it can't be converted

407–410

I think these asserts are overly aggressive

451

This should be a const reference. shared_ptr is pretty expensive

455–456

Single dbg statement, and also should be wrapped in DEBUG()

466

This check is unnecessary?

476

This doesn't seem like a problem to me. I would expect combinable patterns to be sunk down earlier

479

A better name for this might be collectSDWABitExtracts? I also think you should try folding the sources into the uses in the same loop. Once you see one of these defs, it's use is going to be later, so you don't need to collect every possible use in the block ahead of time.

You could also look at the sources for SDWA convertible instructions instead of looking at this from the other direction.

test/CodeGen/AMDGPU/sdwa-peephole.ll

1

You can replace func with GCN. This will never be shared with r600

59

The naming convention in other tests is to include the operation in the name, in this case mul, and then suffix with the llvm type, _v2i16

66

This needs a lot more tests. I would like to see a range of tests using half as well. These tests are not also stressing some of the illegal cases you check for, like SGPR operands. There should also be multiple uses tests, with some foldable and unfoldable uses.

There's also a lot of code for checking parent blocks, but these tests all only have one block.

[rampitec]

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

99

Are there plans to enable it?

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

23

It should come after llvm's includes.

179

Looks like you only need FirstBB == SecondBB.

205

Isn't MRI just always available? It is just getParentInst()->getParent()->getRegInfo(). No checks really needed. Most likely this function is not needed too.

219

Check is not needed.

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

276

I'm not sure it is always a vreg. It is better got giveup on physreg. The same for multiply defined vregs, you are running the pass late and can have multiple defs. Just bail out.

335

Should be wrapped in DEBUG().

364

Not needed.

466

>= VOLCANIC_ISLANDS?

477

Space before colon. Here and in other places.

[SamWot]

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

672–675

SDWA peephole extensively use results of SIShrinkInstructions pass. I considered placing peephole after SiFoldOperands but at that point we still have all instructions in 64-bit encoding - but they can't be encoded as SDWA. So SDWA pass would in many ways repeat work done by SiShrinkInstruction. Possibly we can move both shrink instructions and SDWA peephole earlier.

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

59

I can't store by value because it would lead to type slicing.

174

Yes, this is overkill but if I check toher thing here then why not to check that functions are also same, just for confidence?

179

This should work but I don't want to campare pointers. If internal structure of MachineFunction changes later then this would not work. Also basic block number is exactly what we need to check if this is same basic block - then why not to use it?
What I should really fix is that FirstMI->getParent()->getNumber(); should be FirstBB->getNumber().

221

I agree that we should limit number of uses. This is what I wanted to say with "Introduce mnemonics to limit when SDWA patterns should apply".
One thing that I don't know is if one instruction uses register twice would it appear in use_instructions() twice ore single time.

466

We don't yet support SDWA on gfx9.

479

This method collects not only BitExtracts but also BitInserts.

Splitting processes of finding SDWA patterns and folding sources allows to generalize finding patterns not only for source operands but also for destination operands. With that we can fold whole bunch of operands into instruction instead of folding instructions. Also I think this split makes pass much more clear and maintainable.

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

174

You do not check the module is the same? This is function pass, you do not get blocks from different functions.

179

All llvm works this way. BTW, numbers can change as well. You are taking parent basic block pointers from both instructions right here. Do you expect blocks to change in between of these two getParent() calls?

466

It then needs TODO comment here.

[arsenm]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

221

If you iterate uses you will see the same instruction for repeated uses. use_instructions skips to unique instructions

[SamWot]

Added support for subregs.
Fixed most of previous comments.

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

197

You still do not need logic more than FirstMI->getParent() == SecondMI->getParent()

219

TRI->getMatchingSuperReg() or TRI->getMatchingSuperRegClass() maybe?

232

No need to convert lanemask to integer and back.

[SamWot]

Fixed isSameBB

[SamWot]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

219

This functions work with physical registers if I understand correctly, and I need to work with virtual regs.

232

I only convert from LaneBitmask to integer. This is done because getSubRegIndexLaneMask takes integer as input.

[SamWot]

Introduced new sdwa patterns

[rampitec]

In D30038#699101, @SamWot wrote:

Introduced new sdwa patterns

I would like to see this patch fixed, submitted, and optimization enabled first, before new patterns are introduced.

[SamWot]

In D30038#699461, @rampitec wrote:

I would like to see this patch fixed, submitted, and optimization enabled first, before new patterns are introduced.

I alredy either fixed or answered on comments to previous version. Currently I'm waiting for new comments or acceptance thats why I started working on new functionality.

[SamWot]

Cleanup for remaining comments.

[SamWot]

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

99

I want first to submit this patch so that I would be able to fully test it and ensure that it doesn't break anything.

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

305–307

I have to delete instructions in that case to ensure validity of machine code. Simply intoducing new virtual registers doesn't solve this problem.
Dead code elimination is important for removing src patterns. I don't want to remove by hand because later I want to introduce more complex patterns consisting of several instructions which removal by hand might become to hard.

476

Same as for enabling pass by default: I want to submit this patch first, then extend it.

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

221

I still do not see a check for single use. Am I missing it somewhere?

[SamWot]

Add check for single use of src sdwa operand.

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

277

You only need to do:

if (PotentialMI != PotentialMO.getParent()) {
  return nullptr;

If != nullptr and continue are not needed.

312

Looks like parent will be erased anyway. I assume convertToSDWA should return status.

580

Space after comma.

580

You are working in pre-regalloc... I think you need to update LIS when you create or delete instructions.

647

There can be only one SDWA operand, right? It seems this loop may try to create more than one...

[rampitec]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

385

What will happen if instruction already comes to the pass with either SDWA or DPP in it? There can be only one such operand per instruction.

[SamWot]

Changes for latest comments

[SamWot]

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

277

Rewrote potentialToConvert function so that they should be more clear.

385

Currently instruction with SDWA or DPP would not be converted. They would not pass "isConvertibleToSDWA" check.
Later it would be nice to extend this pass so that it would accept SDWA instructions.

580

First LiveIntervalAnalysis is runnig after my pass. Liveness informatioin is inavailable for my pass.

647

No, there might be several SDWA operands for one instructions. One for each instruction operands.

[rampitec]

LGTM

lib/Target/AMDGPU/AMDGPU.h

 FunctionPass *createR600Packetizer(TargetMachine &tm);
 FunctionPass *createR600ControlFlowFinalizer(TargetMachine &tm);
 FunctionPass *createAMDGPUCFGStructurizerPass();
 
 // SI Passes
 FunctionPass *createSITypeRewriter();
 FunctionPass *createSIAnnotateControlFlowPass();
 FunctionPass *createSIFoldOperandsPass();
+FunctionPass *createSIPeepholeSDWAPass();
 FunctionPass *createSILowerI1CopiesPass();
 FunctionPass *createSIShrinkInstructionsPass();
 FunctionPass *createSILoadStoreOptimizerPass(TargetMachine &tm);
 FunctionPass *createSIWholeQuadModePass();
 FunctionPass *createSIFixControlFlowLiveIntervalsPass();
 FunctionPass *createSIFixSGPRCopiesPass();
 FunctionPass *createSIDebuggerInsertNopsPass();
 FunctionPass *createSIInsertWaitsPass();
 FunctionPass *createAMDGPUCodeGenPreparePass(const GCNTargetMachine *TM = nullptr);
 
 ModulePass *createAMDGPUAnnotateKernelFeaturesPass();
 void initializeAMDGPUAnnotateKernelFeaturesPass(PassRegistry &);
 extern char &AMDGPUAnnotateKernelFeaturesID;
 
 ModulePass *createAMDGPULowerIntrinsicsPass();
 void initializeAMDGPULowerIntrinsicsPass(PassRegistry &);
 extern char &AMDGPULowerIntrinsicsID;
 
 void initializeSIFoldOperandsPass(PassRegistry &);
 extern char &SIFoldOperandsID;
 
+void initializeSIPeepholeSDWAPass(PassRegistry &);
+extern char &SIPeepholeSDWAID;
+
 void initializeSIShrinkInstructionsPass(PassRegistry&);
 extern char &SIShrinkInstructionsID;
 
 void initializeSIFixSGPRCopiesPass(PassRegistry &);
 extern char &SIFixSGPRCopiesID;
 
 void initializeSIFixVGPRCopiesPass(PassRegistry &);
 extern char &SIFixVGPRCopiesID;

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

 
 // Option to run internalize pass.
 static cl::opt<bool> InternalizeSymbols(
   "amdgpu-internalize-symbols",
   cl::desc("Enable elimination of non-kernel functions and unused globals"),
   cl::init(false),
   cl::Hidden);
 
+static cl::opt<bool> EnableSDWAPeephole(
+  "amdgpu-sdwa-peephole",
+  cl::desc("Enable SDWA peepholer"),
+  cl::init(false));
+
 extern "C" void LLVMInitializeAMDGPUTarget() {
   // Register the target
   RegisterTargetMachine<R600TargetMachine> X(getTheAMDGPUTarget());
   RegisterTargetMachine<GCNTargetMachine> Y(getTheGCNTarget());
 
   PassRegistry *PR = PassRegistry::getPassRegistry();
   initializeSILowerI1CopiesPass(*PR);
   initializeSIFixSGPRCopiesPass(*PR);
   initializeSIFixVGPRCopiesPass(*PR);
   initializeSIFoldOperandsPass(*PR);
+  initializeSIPeepholeSDWAPass(*PR);
   initializeSIShrinkInstructionsPass(*PR);
   initializeSIFixControlFlowLiveIntervalsPass(*PR);
   initializeSILoadStoreOptimizerPass(*PR);
   initializeAMDGPUAnnotateKernelFeaturesPass(*PR);
   initializeAMDGPUAnnotateUniformValuesPass(*PR);
   initializeAMDGPULowerIntrinsicsPass(*PR);
   initializeAMDGPUPromoteAllocaPass(*PR);
   initializeAMDGPUCodeGenPreparePass(*PR);
bool GCNPassConfig::addGlobalInstructionSelect() {
   addPass(new InstructionSelect());
   return false;
 }
 
 #endif
 
 void GCNPassConfig::addPreRegAlloc() {
   addPass(createSIShrinkInstructionsPass());
+  if (EnableSDWAPeephole) {
+    addPass(&SIPeepholeSDWAID);
+    addPass(&DeadMachineInstructionElimID);
+  }
   addPass(createSIWholeQuadModePass());
 }
 
 void GCNPassConfig::addFastRegAlloc(FunctionPass *RegAllocPass) {
   // FIXME: We have to disable the verifier here because of PHIElimination +
   // TwoAddressInstructions disabling it.
 
   // This must be run immediately after phi elimination and before

lib/Target/AMDGPU/CMakeLists.txt

add_llvm_target(AMDGPUCodeGen
   SIInstrInfo.cpp
   SIISelLowering.cpp
   SILoadStoreOptimizer.cpp
   SILowerControlFlow.cpp
   SILowerI1Copies.cpp
   SIMachineFunctionInfo.cpp
   SIMachineScheduler.cpp
   SIOptimizeExecMasking.cpp
+  SIPeepholeSDWA.cpp
   SIRegisterInfo.cpp
   SIShrinkInstructions.cpp
   SITypeRewriter.cpp
   SIWholeQuadMode.cpp
   ${GLOBAL_ISEL_BUILD_FILES}
   )
 
 add_subdirectory(AsmParser)
 add_subdirectory(InstPrinter)
 add_subdirectory(Disassembler)
 add_subdirectory(TargetInfo)
 add_subdirectory(MCTargetDesc)
 add_subdirectory(Utils)

lib/Target/AMDGPU/SIInstrInfo.h

 namespace AMDGPU {
   LLVM_READONLY
   int getVOPe64(uint16_t Opcode);
 
   LLVM_READONLY
   int getVOPe32(uint16_t Opcode);
 
   LLVM_READONLY
+  int getSDWAOp(uint16_t Opcode);
+
+  LLVM_READONLY
   int getCommuteRev(uint16_t Opcode);
 
   LLVM_READONLY
   int getCommuteOrig(uint16_t Opcode);
 
   LLVM_READONLY
   int getAddr64Inst(uint16_t Opcode);
 

lib/Target/AMDGPU/SIInstrInfo.td

 def getVOPe32 : InstrMapping {
   let FilterClass = "VOP";
   let RowFields = ["OpName"];
   let ColFields = ["Size", "VOP3"];
   let KeyCol = ["8", "1"];
   let ValueCols = [["4", "0"]];
 }
 
+// Maps ordinary instructions to their SDWA counterparts
+def getSDWAOp : InstrMapping {
+  let FilterClass = "VOP";
+  let RowFields = ["OpName"];
+  let ColFields = ["AsmVariantName"];
+  let KeyCol = ["Default"];
+  let ValueCols = [["SDWA"]];
+}
+
 def getMaskedMIMGOp : InstrMapping {
   let FilterClass = "MIMG_Mask";
   let RowFields = ["Op"];
   let ColFields = ["Channels"];
   let KeyCol = ["4"];
   let ValueCols = [["1"], ["2"], ["3"] ];
 }
 

lib/Target/AMDGPU/SIPeepholeSDWA.cpp

+//===-- SIPeepholeSDWA.cpp - Peephole optimization for SDWA instructions --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This pass tries to apply several peephole SDWA patterns.
+///
+/// E.g. original:
+///   V_LSHRREV_B32_e32 %vreg0, 16, %vreg1
+///   V_ADD_I32_e32 %vreg2, %vreg0, %vreg3
+///   V_LSHLREV_B32_e32 %vreg4, 16, %vreg2
+///
+/// Replace:
+///   V_ADD_I32_sdwa %vreg4, %vreg1, %vreg3
+///       dst_sel:WORD_1 dst_unused:UNUSED_PAD src0_sel:WORD_1 src1_sel:DWORD
+///
+//===----------------------------------------------------------------------===//
+
+#include <unordered_map>
+
+#include "AMDGPU.h"
+#include "AMDGPUSubtarget.h"
+#include "SIDefines.h"
+#include "SIInstrInfo.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "si-peephole-sdwa"
+
+STATISTIC(NumSDWAPatternsFound,
+  "Number of SDWA patterns found.");
+STATISTIC(NumSDWAInstructionsPeepholed,
+  "Number of instruction converted to SDWA.");
+
+namespace {
+
+class SDWAOperand;
+
+class SIPeepholeSDWA : public MachineFunctionPass {
+private:
+  MachineRegisterInfo *MRI;
+  const SIRegisterInfo *TRI;
+  const SIInstrInfo *TII;
+
+  std::unordered_map<MachineInstr *, std::shared_ptr<SDWAOperand>> SDWAOperands;
+
+
+public:
+  static char ID;
+
+  typedef SmallVector<std::shared_ptr<SDWAOperand>, 4> SDWAOperandsVector;
+
+  SIPeepholeSDWA() : MachineFunctionPass(ID) {
+    initializeSIPeepholeSDWAPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+  void matchSDWAOperands(MachineBasicBlock &MBB);
+  bool isConvertibleToSDWA(MachineInstr &MI);
+  void convertToSDWA(MachineInstr &MI, const SDWAOperandsVector &SDWAOperands);
+
+  StringRef getPassName() const override { return "SI Peephole SDWA"; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+};
+
+class SDWAOperand {
+private:
+  MachineOperand *Target; // Operand that would be used in converted instruction
+  MachineOperand *Source; // Operand that would be replace by Target
+
+public:
+  SDWAOperand(MachineOperand *TargetOp, MachineOperand *SourceOp)
+    : Target(TargetOp), Source(SourceOp) {
+    assert(Target->isReg());
+    assert(Source->isReg());
+  }
+
+  virtual ~SDWAOperand() {}
+
+  virtual SmallVector<MachineInstr *, 4> potentialsToConvert() = 0;
+  virtual void convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) = 0;
+
+  MachineOperand *getTargetOperand() const { return Target; }
+  MachineOperand *getSourceOperand() const { return Source; }
+  MachineInstr *getParentInst() const { return Target->getParent(); }
+  MachineRegisterInfo *getMRI() const;
+};
+
+using namespace AMDGPU::SDWA;
+
+class SDWASrcOperand : public SDWAOperand {
+private:
+  SdwaSel SrcSel;
+  
+public:
+  SDWASrcOperand(MachineOperand *TargetOp, MachineOperand *SourceOp,
+                 SdwaSel SrcSel_ = DWORD)
+    : SDWAOperand(TargetOp, SourceOp), SrcSel(SrcSel_) {}
+
+  virtual SmallVector<MachineInstr *, 4> potentialsToConvert() override;
+  virtual void convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) override;
+
+  SdwaSel getSrcSel() const { return SrcSel; }
+};
+
+class SDWADstOperand : public SDWAOperand {
+private:
+  SdwaSel DstSel;
+  DstUnused DstUn;
+
+public:
+  SDWADstOperand(
+    MachineOperand *TargetOp, MachineOperand *SourceOp,
+    SdwaSel DstSel_ = DWORD,
+    DstUnused DstUn_ = UNUSED_PAD)
+    : SDWAOperand(TargetOp, SourceOp), DstSel(DstSel_), DstUn(DstUn_) {}
+
+  virtual SmallVector<MachineInstr *, 4> potentialsToConvert() override;
+  virtual void convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) override;
+
+  SdwaSel getDstSel() const { return DstSel; }
+  DstUnused getDstUnused() const { return DstUn; }
+};
+
+inline raw_ostream& operator<<(raw_ostream &OS, const SdwaSel &Sel) {
+  switch(Sel) {
+  case BYTE_0: OS << "BYTE_0"; break;
+  case BYTE_1: OS << "BYTE_1"; break;
+  case BYTE_2: OS << "BYTE_2"; break;
+  case BYTE_3: OS << "BYTE_3"; break;
+  case WORD_0: OS << "WORD_0"; break;
+  case WORD_1: OS << "WORD_1"; break;
+  case DWORD:  OS << "DWORD"; break;
+  default: llvm_unreachable("Wrong SDWA selector");
+  }
+  return OS;
+}
+
+inline raw_ostream& operator<<(raw_ostream &OS, const DstUnused &Un) {
+  switch(Un) {
+  case UNUSED_PAD: OS << "UNUSED_PAD"; break;
+  case UNUSED_SEXT: OS << "UNUSED_SEXT"; break;
+  case UNUSED_PRESERVE: OS << "UNUSED_PRESERVE"; break;
+  default: llvm_unreachable("Wrong SDWA dst_unused");
+  }
+  return OS;
+}
+
+inline raw_ostream& operator<<(raw_ostream &OS, const SDWASrcOperand &Src) {
+  OS << "SDWA src:" << *Src.getTargetOperand()
+     << " src_sel:" << Src.getSrcSel() << "\n";
+  return OS;
+}
+
+inline raw_ostream& operator<<(raw_ostream &OS, const SDWADstOperand &Dst) {
+  OS << "SDWA dst:" << *Dst.getTargetOperand()
+     << " dst_sel:" << Dst.getDstSel()
+     << " dst_unused:" << Dst.getDstUnused() << "\n";
+  return OS;
+}
+
+bool isSameBB(const MachineInstr *FirstMI, const MachineInstr *SecondMI) {
+  assert(FirstMI && SecondMI);
+  const MachineBasicBlock *FirstBB = FirstMI->getParent();
+  const MachineBasicBlock *SecondBB = SecondMI->getParent();
+  assert(FirstBB && SecondBB);
+  const MachineFunction *FirstFN = FirstBB->getParent();
+  const MachineFunction *SecondFN = SecondBB->getParent();
+  if (FirstFN && SecondFN &&
+      FirstFN->getFunctionNumber() == SecondFN->getFunctionNumber()) {
+    int FirstBBNum = FirstMI->getParent()->getNumber();
+    int SecondBBNum = SecondMI->getParent()->getNumber();
+    if (FirstBBNum >= 0 && SecondBBNum >= 0 && FirstBBNum == SecondBBNum)
+      return true;
+  }
+  return false;
+}
+
+} // End anonymous namespace.
+
+INITIALIZE_PASS(SIPeepholeSDWA, DEBUG_TYPE, "SI Peephole SDWA", false, false)
+
+char SIPeepholeSDWA::ID = 0;
+
+char &llvm::SIPeepholeSDWAID = SIPeepholeSDWA::ID;
+
+FunctionPass *llvm::createSIPeepholeSDWAPass() {
+  return new SIPeepholeSDWA();
+}
+
+
+
+MachineRegisterInfo *SDWAOperand::getMRI() const {
+  if (MachineInstr *MI = getParentInst()) {
+    if (MachineBasicBlock *MBB = getParentInst()->getParent())
+      return &MBB->getParent()->getRegInfo();
+  }
+  return nullptr;
+}
+
+SmallVector<MachineInstr*, 4> SDWASrcOperand::potentialsToConvert() {
+  // For SDWA src operand potential instructions are those that use register
+  // defined by parent instruction
+  SmallVector<MachineInstr*, 4> Potentials;
+  MachineInstr *ParentMI = getParentInst();
+  assert(ParentMI);
+  if (MachineRegisterInfo *MRI = getMRI()) {
+    for (MachineOperand Def: ParentMI->defs()) {
+      for (MachineInstr &PotentialMI: MRI->use_instructions(Def.getReg())) {
+        // Check if this instructions are in same basic block
+        if (isSameBB(ParentMI, &PotentialMI)) {
+          Potentials.push_back(&PotentialMI);
+        }
+      }
+    }
+  }
+  return Potentials;
+}
+
+void SDWASrcOperand::convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) {
+  // Find operand in instruction that matches source operand and replace it with
+  // target operand. Set corresponding src_sel
+  for (MachineOperand &Operand: MI.explicit_uses()) {
+    if (!Operand.isReg() || Operand.getReg() != getSourceOperand()->getReg()) {
+      continue;
+    }
+
+    // Find src_sel for this operand
+    MachineOperand *SrcSel = nullptr;
+    unsigned OperandIdx = MI.getOperandNo(&Operand);
+    if (AMDGPU::getNamedOperandIdx(MI.getOpcode(), AMDGPU::OpName::vdst) == -1) {
+      // for VOPC OperandIdx should be either 1 for src0 or 3 for src1
+      switch (OperandIdx) {
+      case 1: SrcSel = TII->getNamedOperand(MI, AMDGPU::OpName::src0_sel); break;
+      case 3: SrcSel = TII->getNamedOperand(MI, AMDGPU::OpName::src1_sel); break;
+      default: continue;
+      }
+    } else {
+      // for non-VOPC OperandIdx should be either 2 for src0 or 4 for src1
+      switch (OperandIdx) {
+      case 2: SrcSel = TII->getNamedOperand(MI, AMDGPU::OpName::src0_sel); break;
+      case 4: SrcSel = TII->getNamedOperand(MI, AMDGPU::OpName::src1_sel); break;
+      default: continue;
+      }
+    }
+    if (!SrcSel)
+      continue;
+
+    Operand.setReg(getTargetOperand()->getReg());
+    SrcSel->setImm(getSrcSel());
+  }
+}
+
+SmallVector<MachineInstr*, 4> SDWADstOperand::potentialsToConvert() {
+  // For SDWA dst operand potential instruction is one that defines register 
+  // that this operand uses
+  MachineInstr *ParentMI = getParentInst();
+  assert(ParentMI);
+  MachineOperand *Source = getSourceOperand();
+  assert(Source->isReg());
+
+  if (MachineRegisterInfo *MRI = getMRI()) {
+    MachineInstr *PotentialMI = MRI->getVRegDef(Source->getReg());
+    assert(PotentialMI);
+    // Check if this instructions are in same basic block
+    if (isSameBB(ParentMI, PotentialMI)) {
+      // Check that ParentMI is the only instruction that uses src register
+      int dist = std::distance(MRI->use_instr_begin(Source->getReg()),
+                               MRI->use_instr_end());
+      if (dist == 1) {
+        return SmallVector<MachineInstr*, 4>(1, PotentialMI);
+      }
+    }
+  }
+  return SmallVector<MachineInstr*, 4>();
+}
+
+void SDWADstOperand::convertToSDWA(MachineInstr &MI, const SIInstrInfo *TII) {
+  // Replace vdst operand in MI with target operand. Set dst_sel and dst_unused
+  MachineOperand *Operand = TII->getNamedOperand(MI, AMDGPU::OpName::vdst);
+  assert(
+    Operand &&
+    Operand->isReg() &&
+    Operand->getReg() == getSourceOperand()->getReg());
+  Operand->setReg(getTargetOperand()->getReg());
+  MachineOperand *DstSel= TII->getNamedOperand(MI, AMDGPU::OpName::dst_sel);
+  assert(DstSel);
+  DstSel->setImm(getDstSel());
+  MachineOperand *DstUnused= TII->getNamedOperand(MI, AMDGPU::OpName::dst_unused);
+  assert(DstUnused);
+  DstUnused->setImm(getDstUnused());
+
+  // Remove original instruction  because it would conflict with our new
+  // instruction by register definition
+  getParentInst()->eraseFromParent();
+}
+
+
+void SIPeepholeSDWA::matchSDWAOperands(MachineBasicBlock &MBB) {
+  // FIXME: It is possible to simplify this patterns because this pass is runnig
+  // after SIShrinkInstruction => we can get rid of _e64 instructions and we
+  // don't have to check for VGPRs
+  for (MachineInstr &MI : MBB) {
+    unsigned Opcode = MI.getOpcode();
+    switch(Opcode) {
+    case AMDGPU::V_LSHRREV_B32_e32:
+    case AMDGPU::V_LSHRREV_B32_e64: {
+      // from: v_lshrrev_b32_e32 v1, 16, v0
+      // to SDWA src: v0 src_sel:WORD_1
+      MachineOperand *Src0 = TII->getNamedOperand(MI, AMDGPU::OpName::src0);
+      if (!Src0->isImm() || Src0->getImm() != 16)
+        break;
+
+      MachineOperand *Src1 = TII->getNamedOperand(MI, AMDGPU::OpName::src1);
+      if (!Src1->isReg() || !TRI->isVGPR(*MRI, Src1->getReg()))
+        break;
+
+      MachineOperand *Dst =  TII->getNamedOperand(MI, AMDGPU::OpName::vdst);
+      if (!Dst->isReg() || !TRI->isVGPR(*MRI, Dst->getReg()))
+        break;
+
+      auto SDWASrc = std::make_shared<SDWASrcOperand>(Src1, Dst, WORD_1);
+      dbgs() << "Match: " << MI << "To: " << *SDWASrc;
+      SDWAOperands[&MI] = std::move(SDWASrc);
+      ++NumSDWAPatternsFound;
+      break;
+    }
+
+    case AMDGPU::V_LSHLREV_B32_e32:
+    case AMDGPU::V_LSHLREV_B32_e64: {
+      // from: v_lshlrev_b32_e32 v1, 16, v0
+      // to SDWA dst: v1 dst_sel:WORD_1 dst_unused:UNUSED_PAD
+      MachineOperand *Dst = TII->getNamedOperand(MI, AMDGPU::OpName::vdst);
+      if (!Dst->isReg() || !TRI->isVGPR(*MRI, Dst->getReg()))
+        break;
+
+      MachineOperand *Src0 = TII->getNamedOperand(MI, AMDGPU::OpName::src0);
+      if (!Src0->isImm() || Src0->getImm() != 16)
+        break;
+
+      MachineOperand *Src1 = TII->getNamedOperand(MI, AMDGPU::OpName::src1);
+      if (!Src1->isReg() || !TRI->isVGPR(*MRI, Src1->getReg()))
+        break;
+      auto SDWADst =
+        std::make_shared<SDWADstOperand>(Dst, Src1, WORD_1, UNUSED_PAD);
+      dbgs() << "Match: " << MI << "To: " << *SDWADst;
+      SDWAOperands[&MI] = std::move(SDWADst);
+      ++NumSDWAPatternsFound;
+      break;
+    }
+
+    default: continue;
+    }
+  }
+}
+
+bool SIPeepholeSDWA::isConvertibleToSDWA(MachineInstr &MI) {
+  // Check if this instruction can be converted to SDWA:
+  // 1. Does this opcode support SDWA
+  if (AMDGPU::getSDWAOp(MI.getOpcode()) == -1)
+    return false;
+
+  // 2. Are all operands - VGPRs
+  for (MachineOperand &Operand: MI.explicit_operands()) {
+    if (!Operand.isReg() || !TRI->isVGPR(*MRI, Operand.getReg()))
+      return false;
+  }
+
+  return true;
+}
+
+void SIPeepholeSDWA::convertToSDWA(MachineInstr &MI,
+                                   const SDWAOperandsVector &SDWAOperands) {
+  int SDWAOpcode = AMDGPU::getSDWAOp(MI.getOpcode());
+  assert(SDWAOpcode != -1);
+
+  const MCInstrDesc &SDWADesc = TII->get(SDWAOpcode);
+
+  // Create SDWA version of instruction MI and initialize its operands
+  MachineInstrBuilder SDWAInst =
+    BuildMI(*MI.getParent(), MI, MI.getDebugLoc(),SDWADesc);
+
+  // Copy dst, if  it is present in original then should also be present in SDWA
+  MachineOperand *Dst = TII->getNamedOperand(MI, AMDGPU::OpName::vdst);
+  if (Dst) {
+    assert(AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::vdst) != -1);
+    SDWAInst.add(*Dst);
+  } else {
+    assert(TII->isVOPC(MI));
+  }
+
+  // Copy src0, initialize src0_modifiers. All sdwa instructions has src0 and
+  // src0_modifiers (except for v_nop_sdwa, but it can't get here)
+  MachineOperand *Src0 = TII->getNamedOperand(MI, AMDGPU::OpName::src0);
+  assert(
+    Src0 &&
+    AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src0) != -1 &&
+    AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src0_modifiers) != -1);
+  SDWAInst.addImm(0);
+  SDWAInst.add(*Src0);
+
+  // Copy src1 if present, initialize src1_modifiers.
+  MachineOperand *Src1 = TII->getNamedOperand(MI, AMDGPU::OpName::src1);
+  if (Src1) {
+    assert(
+      AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src1) != -1 &&
+      AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src1_modifiers) != -1);
+    SDWAInst.addImm(0);
+    SDWAInst.add(*Src1);
+  } else {
+    assert(TII->isVOP1(MI));
+  }
+
+  // Initialize clamp.
+  assert(AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::clamp) != -1);
+  SDWAInst.addImm(0);
+
+  // Initialize dst_sel and dst_unused if present
+  if (Dst) {
+    assert(
+      AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::dst_sel) != -1 &&
+      AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::dst_unused) != -1);
+    SDWAInst.addImm(AMDGPU::SDWA::SdwaSel::DWORD);
+    SDWAInst.addImm(AMDGPU::SDWA::DstUnused::UNUSED_PAD);
+  }
+
+  // Initialize src0_sel
+  assert(AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src0_sel) != -1);
+  SDWAInst.addImm(AMDGPU::SDWA::SdwaSel::DWORD);
+
+
+  // Initialize src1_sel if present
+  if (Src1) {
+    assert(AMDGPU::getNamedOperandIdx(SDWAOpcode, AMDGPU::OpName::src1_sel) != -1);
+    SDWAInst.addImm(AMDGPU::SDWA::SdwaSel::DWORD);
+  }
+  
+  // Apply all sdwa operand pattenrs
+  for (std::shared_ptr<SDWAOperand> Operand: SDWAOperands) {
+    Operand->convertToSDWA(*SDWAInst, TII);
+  }
+
+  dbgs() << "Convert instruction:" << MI;
+  dbgs() << "Into:" << *SDWAInst << '\n';
+  ++NumSDWAInstructionsPeepholed;
+
+  MI.eraseFromParent();
+}
+
+bool SIPeepholeSDWA::runOnMachineFunction(MachineFunction &MF) {
+  const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
+
+  if (!ST.hasSDWA() ||
+      !AMDGPU::isVI(ST)) { // FIXME: We don't support SDWA anywhere other than VI
+    return false;
+  }
+
+  MRI = &MF.getRegInfo();
+  TRI = ST.getRegisterInfo();
+  TII = ST.getInstrInfo();
+
+  std::unordered_map<MachineInstr *, SDWAOperandsVector> PotentialMatches;
+
+  // FIXME: For now we only combine instructions in one basic block
+  for (MachineBasicBlock &MBB: MF) {
+    SDWAOperands.clear();
+    matchSDWAOperands(MBB);
+
+    PotentialMatches.clear();
+    for (auto OperandPair: SDWAOperands) {
+      auto Operand = OperandPair.second;
+      for (MachineInstr *PotentialMI: OperandPair.second->potentialsToConvert()) {
+        PotentialMatches[PotentialMI].push_back(Operand);
+      }
+    }
+
+    for (auto PotentialPair: PotentialMatches) {
+      MachineInstr &PotentialMI = *PotentialPair.first;
+      if (isConvertibleToSDWA(PotentialMI)) {
+        convertToSDWA(PotentialMI, PotentialPair.second);
+      }
+    }
+
+  }
+  return false;
+}

lib/Target/AMDGPU/VOPInstructions.td

class VOP_SDWA_Pseudo <string opName, VOPProfile P, list<dag> pattern=[]> :
   let mayLoad = 0;
   let mayStore = 0;
   let hasSideEffects = 0;
 
   let VALU = 1;
   let SDWA = 1;
   let Uses = [EXEC];
 
-  let SubtargetPredicate = HasSDWA;
+  let SubtargetPredicate = !if(P.HasExt, HasSDWA, DisableInst);
   let AssemblerPredicate = !if(P.HasExt, HasSDWA, DisableInst);
   let AsmVariantName = !if(P.HasExt, AMDGPUAsmVariants.SDWA,
                                      AMDGPUAsmVariants.Disable);
   let DecoderNamespace = "SDWA";
 
   VOPProfile Pfl = P;
 }
 

test/CodeGen/AMDGPU/sdwa-peephole.ll

+; RUN: llc -march=amdgcn -mcpu=fiji -verify-machineinstrs < %s | FileCheck -check-prefix=NOSDWA -check-prefix=FUNC %s
+; RUN: llc -march=amdgcn -mcpu=fiji --amdgpu-sdwa-peephole -verify-machineinstrs < %s | FileCheck -check-prefix=SDWA -check-prefix=FUNC %s
+
+; FUNC-LABEL: {{^}}shr0:
+; NOSDWA: v_lshrrev_b32_e32 v[[DST:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_add_i32_e32 v{{[0-9]+}}, vcc, v{{[0-9]+}}, v[[DST]]
+
+; SDWA: v_add_i32_sdwa v{{[0-9]+}}, vcc, v{{[0-9]+}}, v{{[0-9]+}} dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:DWORD src1_sel:WORD_1
+
+define void @shr0(i32 addrspace(1)* %out, i32 addrspace(1)* %in) {
+  %a = load i32, i32 addrspace(1)* %in, align 4
+  %shr = lshr i32 %a, 16
+  %add = add i32 %a, %shr
+  store i32 %add, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
+; FUNC-LABEL: {{^}}shr1:
+; NOSDWA: v_lshrrev_b32_e32 v[[DST:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_add_i32_e32 v{{[0-9]+}}, vcc, v{{[0-9]+}}, v[[DST]]
+
+; SDWA: v_add_i32_sdwa v{{[0-9]+}}, vcc, v{{[0-9]+}}, v{{[0-9]+}} dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:DWORD src1_sel:WORD_1
+
+define void @shr1(i32 addrspace(1)* %out, i32 addrspace(1)* %in) {
+  %a = load i32, i32 addrspace(1)* %in, align 4
+  %shr = lshr i32 %a, 16
+  %add = add i32 %shr, %a
+  store i32 %add, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
+; FUNC-LABEL: {{^}}shr01:
+; NOSDWA: v_lshrrev_b32_e32 v[[DST0:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_lshrrev_b32_e32 v[[DST1:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_add_i32_e32 v{{[0-9]+}}, vcc, v[[DST1]], v[[DST0]]
+
+; SDWA: v_add_i32_sdwa v{{[0-9]+}}, vcc, v{{[0-9]+}}, v{{[0-9]+}} dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:WORD_1 src1_sel:WORD_1
+
+define void @shr01(i32 addrspace(1)* %out, i32 addrspace(1)* %in1, i32 addrspace(1)* %in2) {
+  %a = load i32, i32 addrspace(1)* %in1, align 4
+  %b = load i32, i32 addrspace(1)* %in2, align 4
+  %shra = lshr i32 %a, 16
+  %shrb = lshr i32 %b, 16
+  %add = add i32 %shra, %shrb
+  store i32 %add, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
+; FUNC-LABEL: {{^}}vector2x16:
+; NOSDWA: v_lshrrev_b32_e32 v[[DST0:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_lshrrev_b32_e32 v[[DST1:[0-9]+]], 16, v{{[0-9]+}}
+; NOSDWA: v_mul_u32_u24_e32 v[[DST_MUL:[0-9]+]], v[[DST1]], v[[DST0]]
+; NOSDWA: v_lshlrev_b32_e32 v[[DST_SHL:[0-9]+]], 16, v[[DST_MUL]]
+; NOSDWA: v_or_b32_e32 v{{[0-9]+}}, v[[DST_SHL]], v{{[0-9]+}}
+
+; SDWA: v_mul_u32_u24_sdwa v[[DST_MUL:[0-9]+]], v{{[0-9]+}}, v{{[0-9]+}} dst_sel:WORD_1 dst_unused:UNUSED_PAD src0_sel:WORD_1 src1_sel:WORD_1
+; SDWA: v_or_b32_e32 v{{[0-9]+}}, v[[DST_MUL]], v{{[0-9]+}}
+
+define void @vector2x16(<2 x i16> addrspace(1)* %out, <2 x i16> addrspace(1)* %ina, <2 x i16> addrspace(1)* %inb) {
+entry:
+  %a = load <2 x i16>, <2 x i16> addrspace(1)* %ina, align 4
+  %b = load <2 x i16>, <2 x i16> addrspace(1)* %inb, align 4
+  %mul = mul <2 x i16> %a, %b
+  store <2 x i16> %mul, <2 x i16> addrspace(1)* %out, align 4
+  ret void
+}