DirectXShaderCompiler/lib/DxilPIXPasses/DxilPIXMeshShaderOutputInstrumentation.cpp

///////////////////////////////////////////////////////////////////////////////
//                                                                           //
// DxilAddPixelHitInstrumentation.cpp                                        //
// Copyright (C) Microsoft Corporation. All rights reserved.                 //
// This file is distributed under the University of Illinois Open Source     //
// License. See LICENSE.TXT for details.                                     //
//                                                                           //
// Provides a pass to add instrumentation to retrieve mesh shader output.    //
// Used by PIX.                                                              //
//                                                                           //
///////////////////////////////////////////////////////////////////////////////

#include "dxc/DXIL/DxilOperations.h"
#include "dxc/DXIL/DxilUtil.h"

#include "dxc/DXIL/DxilInstructions.h"
#include "dxc/DXIL/DxilModule.h"
#include "dxc/DxilPIXPasses/DxilPIXPasses.h"
#include "dxc/HLSL/DxilGenerationPass.h"
#include "dxc/HLSL/DxilSpanAllocator.h"

#include "llvm/IR/PassManager.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Transforms/Utils/Local.h"
#include <deque>

#ifdef _WIN32
#include <winerror.h>
#endif

#include "PixPassHelpers.h"

// Keep these in sync with the same-named value in the debugger application's
// WinPixShaderUtils.h

constexpr uint64_t DebugBufferDumpingGroundSize = 64 * 1024;
// The actual max size per record is much smaller than this, but it never
// hurts to be generous.
constexpr size_t CounterOffsetBeyondUsefulData = DebugBufferDumpingGroundSize / 2;

// Keep these in sync with the same-named values in PIX's MeshShaderOutput.cpp
constexpr uint32_t triangleIndexIndicator = 1;
constexpr uint32_t int32ValueIndicator = 2;
constexpr uint32_t floatValueIndicator = 3;
constexpr uint32_t int16ValueIndicator = 4;
constexpr uint32_t float16ValueIndicator = 5;

using namespace llvm;
using namespace hlsl;

class DxilPIXMeshShaderOutputInstrumentation : public ModulePass 
{
public:
  static char ID; // Pass identification, replacement for typeid
  explicit DxilPIXMeshShaderOutputInstrumentation() : ModulePass(ID) {}
  const char *getPassName() const override {
    return "DXIL mesh shader output instrumentation";
  }
  void applyOptions(PassOptions O) override;
  bool runOnModule(Module &M) override;

private:
  CallInst *m_OutputUAV = nullptr;
  int m_RemainingReservedSpaceInBytes = 0;
  Constant *m_OffsetMask = nullptr;

  uint64_t m_UAVSize = 1024 * 1024;

  struct BuilderContext {
    Module &M;
    DxilModule &DM;
    LLVMContext &Ctx;
    OP *HlslOP;
    IRBuilder<> &Builder;
  };

  Value *insertInstructionsToCalculateFlattenedGroupIdXandY(BuilderContext &BC);
  Value *insertInstructionsToCalculateGroupIdZ(BuilderContext &BC);
  Value *reserveDebugEntrySpace(BuilderContext &BC, uint32_t SpaceInBytes);
  uint32_t UAVDumpingGroundOffset();
  Value *writeDwordAndReturnNewOffset(BuilderContext &BC, Value *TheOffset,
                                      Value *TheValue);
  template <typename... T> void Instrument(BuilderContext &BC, T... values);
};

void DxilPIXMeshShaderOutputInstrumentation::applyOptions(PassOptions O) 
{
  GetPassOptionUInt64(O, "UAVSize", &m_UAVSize, 1024 * 1024);
}

uint32_t DxilPIXMeshShaderOutputInstrumentation::UAVDumpingGroundOffset() 
{
  return static_cast<uint32_t>(m_UAVSize - DebugBufferDumpingGroundSize);
}

Value *DxilPIXMeshShaderOutputInstrumentation::
    insertInstructionsToCalculateFlattenedGroupIdXandY(BuilderContext &BC)
{
  Constant *Zero32Arg = BC.HlslOP->GetU32Const(0);
  Constant *One32Arg = BC.HlslOP->GetU32Const(1);

  auto GroupIdFunc =
      BC.HlslOP->GetOpFunc(DXIL::OpCode::GroupId, Type::getInt32Ty(BC.Ctx));
  Constant *Opcode = BC.HlslOP->GetU32Const((unsigned)DXIL::OpCode::GroupId);
  auto GroupIdX =
      BC.Builder.CreateCall(GroupIdFunc, {Opcode, Zero32Arg}, "GroupIdX");
  auto GroupIdY =
      BC.Builder.CreateCall(GroupIdFunc, {Opcode, One32Arg}, "GroupIdY");

  // Spec requires that no group id index is greater than 64k, so we can 
  // combine two into one 32-bit value:
  auto YShifted =
      BC.Builder.CreateShl(GroupIdY, 16);
  return BC.Builder.CreateAdd(YShifted, GroupIdX);
}

Value *DxilPIXMeshShaderOutputInstrumentation::
    insertInstructionsToCalculateGroupIdZ(BuilderContext &BC) 
{
  Constant *Two32Arg = BC.HlslOP->GetU32Const(2);
  auto GroupIdFunc =
      BC.HlslOP->GetOpFunc(DXIL::OpCode::GroupId, Type::getInt32Ty(BC.Ctx));
  Constant *Opcode = BC.HlslOP->GetU32Const((unsigned)DXIL::OpCode::GroupId);

  return BC.Builder.CreateCall(GroupIdFunc, {Opcode, Two32Arg}, "GroupIdZ");
}

Value *DxilPIXMeshShaderOutputInstrumentation::reserveDebugEntrySpace(
    BuilderContext &BC, uint32_t SpaceInBytes) 
{
  
  // Check the previous caller didn't reserve too much space:
  assert(m_RemainingReservedSpaceInBytes == 0);
  
  // Check that the caller didn't ask for so much memory that it will 
  // overwrite the offset counter:
  assert(m_RemainingReservedSpaceInBytes < (int)CounterOffsetBeyondUsefulData);

  m_RemainingReservedSpaceInBytes = SpaceInBytes;

  // Insert the UAV increment instruction:
  Function *AtomicOpFunc =
      BC.HlslOP->GetOpFunc(OP::OpCode::AtomicBinOp, Type::getInt32Ty(BC.Ctx));
  Constant *AtomicBinOpcode =
      BC.HlslOP->GetU32Const((unsigned)OP::OpCode::AtomicBinOp);
  Constant *AtomicAdd =
      BC.HlslOP->GetU32Const((unsigned)DXIL::AtomicBinOpCode::Add);
  Constant *OffsetArg =
      BC.HlslOP->GetU32Const(UAVDumpingGroundOffset() + CounterOffsetBeyondUsefulData);
  UndefValue *UndefArg = UndefValue::get(Type::getInt32Ty(BC.Ctx));

  Constant *Increment = BC.HlslOP->GetU32Const(SpaceInBytes);

  auto *PreviousValue = BC.Builder.CreateCall(
      AtomicOpFunc,
      {
          AtomicBinOpcode, // i32, ; opcode
          m_OutputUAV,     // %dx.types.Handle, ; resource handle
          AtomicAdd, // i32, ; binary operation code : EXCHANGE, IADD, AND, OR,
                     // XOR, IMIN, IMAX, UMIN, UMAX
          OffsetArg, // i32, ; coordinate c0: index in bytes
          UndefArg,  // i32, ; coordinate c1 (unused)
          UndefArg,  // i32, ; coordinate c2 (unused)
          Increment, // i32); increment value
      },
      "UAVIncResult");

  return BC.Builder.CreateAnd(PreviousValue, m_OffsetMask, "MaskedForUAVLimit");
}

Value *DxilPIXMeshShaderOutputInstrumentation::writeDwordAndReturnNewOffset(
    BuilderContext &BC, Value *TheOffset, Value *TheValue) 
{

  Function *StoreValue =
      BC.HlslOP->GetOpFunc(OP::OpCode::BufferStore, Type::getInt32Ty(BC.Ctx));
  Constant *StoreValueOpcode =
      BC.HlslOP->GetU32Const((unsigned)DXIL::OpCode::BufferStore);
  UndefValue *Undef32Arg = UndefValue::get(Type::getInt32Ty(BC.Ctx));
  Constant *WriteMask_X = BC.HlslOP->GetI8Const(1);

  (void)BC.Builder.CreateCall(
      StoreValue,
      {StoreValueOpcode, // i32 opcode
       m_OutputUAV,      // %dx.types.Handle, ; resource handle
       TheOffset,        // i32 c0: index in bytes into UAV
       Undef32Arg,       // i32 c1: unused
       TheValue,
       Undef32Arg, // unused values
       Undef32Arg, // unused values
       Undef32Arg, // unused values
       WriteMask_X});

  m_RemainingReservedSpaceInBytes -= sizeof(uint32_t);
  assert(m_RemainingReservedSpaceInBytes >=
         0); // or else the caller didn't reserve enough space

  return BC.Builder.CreateAdd(
      TheOffset,
      BC.HlslOP->GetU32Const(static_cast<unsigned int>(sizeof(uint32_t))));
}

template <typename... T>
void DxilPIXMeshShaderOutputInstrumentation::Instrument(BuilderContext &BC,
                                                        T... values)
{
  llvm::SmallVector<llvm::Value *, 10> Values(
      {static_cast<llvm::Value *>(values)...});
  const uint32_t DwordCount = Values.size();
  llvm::Value *byteOffset =
      reserveDebugEntrySpace(BC, DwordCount * sizeof(uint32_t));
  for (llvm::Value *V : Values)
  {
    byteOffset = writeDwordAndReturnNewOffset(BC, byteOffset, V);
  }
}

bool DxilPIXMeshShaderOutputInstrumentation::runOnModule(Module &M)
{
  DxilModule &DM = M.GetOrCreateDxilModule();
  LLVMContext &Ctx = M.getContext();
  OP *HlslOP = DM.GetOP();

  Instruction *firstInsertionPt =
      dxilutil::FirstNonAllocaInsertionPt(DM.GetEntryFunction());
  IRBuilder<> Builder(firstInsertionPt);

  BuilderContext BC{M, DM, Ctx, HlslOP, Builder};

  m_OffsetMask = BC.HlslOP->GetU32Const(UAVDumpingGroundOffset() - 1);

  m_OutputUAV = PIXPassHelpers::CreateUAV(DM, Builder, 0, "PIX_DebugUAV_Handle");

  auto GroupIdXandY = insertInstructionsToCalculateFlattenedGroupIdXandY(BC);
  auto GroupIdZ = insertInstructionsToCalculateGroupIdZ(BC);

  auto F = HlslOP->GetOpFunc(DXIL::OpCode::EmitIndices, Type::getVoidTy(Ctx));
  auto FunctionUses = F->uses();
  for (auto FI = FunctionUses.begin(); FI != FunctionUses.end();)
  {
    auto &FunctionUse = *FI++;
    auto FunctionUser = FunctionUse.getUser();

    auto Call = cast<CallInst>(FunctionUser);

    IRBuilder<> Builder2(Call);
    BuilderContext BC2{M, DM, Ctx, HlslOP, Builder2};

    Instrument(BC2, BC2.HlslOP->GetI32Const(triangleIndexIndicator),
               GroupIdXandY, GroupIdZ, Call->getOperand(1),
               Call->getOperand(2), Call->getOperand(3), Call->getOperand(4));
  }

  struct OutputType
  {
    Type *type;
    uint32_t tag;
  };
  SmallVector<OutputType, 4> StoreVertexOutputOverloads
  {
    {Type::getInt32Ty(Ctx), int32ValueIndicator},
    {Type::getInt16Ty(Ctx), int16ValueIndicator}, 
    {Type::getFloatTy(Ctx), floatValueIndicator},
    {Type::getHalfTy(Ctx), float16ValueIndicator}
  };

  for (auto const &Overload : StoreVertexOutputOverloads)
  {
    F = HlslOP->GetOpFunc(DXIL::OpCode::StoreVertexOutput, Overload.type);
    FunctionUses = F->uses();
    for (auto FI = FunctionUses.begin(); FI != FunctionUses.end();)
    {
      auto &FunctionUse = *FI++;
      auto FunctionUser = FunctionUse.getUser();

      auto Call = cast<CallInst>(FunctionUser);

      IRBuilder<> Builder2(Call);
      BuilderContext BC2{M, DM, Ctx, HlslOP, Builder2};

      // Expand column index to 32 bits:
      auto ColumnIndex = BC2.Builder.CreateCast(
       Instruction::ZExt, 
        Call->getOperand(3), 
        Type::getInt32Ty(Ctx));

      // Coerce actual value to int32 
      Value *CoercedValue = Call->getOperand(4);

      if (Overload.tag == floatValueIndicator) 
      {
        CoercedValue = BC2.Builder.CreateCast(
          Instruction::BitCast,
          CoercedValue, 
          Type::getInt32Ty(Ctx));
      }
      else if (Overload.tag == float16ValueIndicator) 
      {
        auto * HalfInt = BC2.Builder.CreateCast(
          Instruction::BitCast, 
          CoercedValue, 
          Type::getInt16Ty(Ctx));

        CoercedValue = BC2.Builder.CreateCast(
          Instruction::ZExt, 
          HalfInt, 
          Type::getInt32Ty(Ctx));
      }
      else if (Overload.tag == int16ValueIndicator) 
      {
        CoercedValue = BC2.Builder.CreateCast(
          Instruction::ZExt,
          CoercedValue,
          Type::getInt32Ty(Ctx));
      }

      Instrument(
        BC2, 
        BC2.HlslOP->GetI32Const(Overload.tag),
        GroupIdXandY,
        GroupIdZ, 
        Call->getOperand(1),
        Call->getOperand(2),
        ColumnIndex,
        CoercedValue,
        Call->getOperand(5));
    }
  }

  DM.ReEmitDxilResources();

  return true;
}

char DxilPIXMeshShaderOutputInstrumentation::ID = 0;

ModulePass *llvm::createDxilDxilPIXMeshShaderOutputInstrumentation()
{
  return new DxilPIXMeshShaderOutputInstrumentation();
}

INITIALIZE_PASS(DxilPIXMeshShaderOutputInstrumentation,
                "hlsl-dxil-pix-meshshader-output-instrumentation",
                "DXIL mesh shader output instrumentation for PIX", false, false)