third_party/SPIRV-Tools/source/fuzz/transformation_propagate_instruction_up.cpp

// Copyright (c) 2020 Vasyl Teliman
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "source/fuzz/transformation_propagate_instruction_up.h"

#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/instruction_descriptor.h"

namespace spvtools {
namespace fuzz {
namespace {

uint32_t GetResultIdFromLabelId(const opt::Instruction& phi_inst,
                                uint32_t label_id) {
  assert(phi_inst.opcode() == spv::Op::OpPhi && "|phi_inst| is not an OpPhi");

  for (uint32_t i = 1; i < phi_inst.NumInOperands(); i += 2) {
    if (phi_inst.GetSingleWordInOperand(i) == label_id) {
      return phi_inst.GetSingleWordInOperand(i - 1);
    }
  }

  return 0;
}

bool ContainsPointers(const opt::analysis::Type& type) {
  switch (type.kind()) {
    case opt::analysis::Type::kPointer:
      return true;
    case opt::analysis::Type::kStruct:
      return std::any_of(type.AsStruct()->element_types().begin(),
                         type.AsStruct()->element_types().end(),
                         [](const opt::analysis::Type* element_type) {
                           return ContainsPointers(*element_type);
                         });
    default:
      return false;
  }
}

bool HasValidDependencies(opt::IRContext* ir_context, opt::Instruction* inst) {
  const auto* inst_block = ir_context->get_instr_block(inst);
  assert(inst_block &&
         "This function shouldn't be applied to global instructions or function"
         "parameters");

  for (uint32_t i = 0; i < inst->NumInOperands(); ++i) {
    const auto& operand = inst->GetInOperand(i);
    if (operand.type != SPV_OPERAND_TYPE_ID) {
      // Consider only <id> operands.
      continue;
    }

    auto* dependency = ir_context->get_def_use_mgr()->GetDef(operand.words[0]);
    assert(dependency && "Operand has invalid id");

    if (ir_context->get_instr_block(dependency) == inst_block &&
        dependency->opcode() != spv::Op::OpPhi) {
      // |dependency| is "valid" if it's an OpPhi from the same basic block or
      // an instruction from a different basic block.
      return false;
    }
  }

  return true;
}

}  // namespace

TransformationPropagateInstructionUp::TransformationPropagateInstructionUp(
    protobufs::TransformationPropagateInstructionUp message)
    : message_(std::move(message)) {}

TransformationPropagateInstructionUp::TransformationPropagateInstructionUp(
    uint32_t block_id,
    const std::map<uint32_t, uint32_t>& predecessor_id_to_fresh_id) {
  message_.set_block_id(block_id);
  *message_.mutable_predecessor_id_to_fresh_id() =
      fuzzerutil::MapToRepeatedUInt32Pair(predecessor_id_to_fresh_id);
}

bool TransformationPropagateInstructionUp::IsApplicable(
    opt::IRContext* ir_context, const TransformationContext& /*unused*/) const {
  // Check that we can apply this transformation to the |block_id|.
  if (!IsApplicableToBlock(ir_context, message_.block_id())) {
    return false;
  }

  const auto predecessor_id_to_fresh_id = fuzzerutil::RepeatedUInt32PairToMap(
      message_.predecessor_id_to_fresh_id());
  for (auto id : ir_context->cfg()->preds(message_.block_id())) {
    // Each predecessor must have a fresh id in the |predecessor_id_to_fresh_id|
    // map.
    if (!predecessor_id_to_fresh_id.count(id)) {
      return false;
    }
  }

  std::vector<uint32_t> maybe_fresh_ids;
  maybe_fresh_ids.reserve(predecessor_id_to_fresh_id.size());
  for (const auto& entry : predecessor_id_to_fresh_id) {
    maybe_fresh_ids.push_back(entry.second);
  }

  // All ids must be unique and fresh.
  return !fuzzerutil::HasDuplicates(maybe_fresh_ids) &&
         std::all_of(maybe_fresh_ids.begin(), maybe_fresh_ids.end(),
                     [ir_context](uint32_t id) {
                       return fuzzerutil::IsFreshId(ir_context, id);
                     });
}

void TransformationPropagateInstructionUp::Apply(
    opt::IRContext* ir_context, TransformationContext* /*unused*/) const {
  auto* inst = GetInstructionToPropagate(ir_context, message_.block_id());
  assert(inst &&
         "The block must have at least one supported instruction to propagate");
  assert(inst->result_id() && inst->type_id() &&
         "|inst| must have a result id and a type id");

  opt::Instruction::OperandList op_phi_operands;
  const auto predecessor_id_to_fresh_id = fuzzerutil::RepeatedUInt32PairToMap(
      message_.predecessor_id_to_fresh_id());
  std::unordered_set<uint32_t> visited_predecessors;
  for (auto predecessor_id : ir_context->cfg()->preds(message_.block_id())) {
    // A block can have multiple identical predecessors.
    if (visited_predecessors.count(predecessor_id)) {
      continue;
    }

    visited_predecessors.insert(predecessor_id);

    auto new_result_id = predecessor_id_to_fresh_id.at(predecessor_id);

    // Compute InOperands for the OpPhi instruction to be inserted later.
    op_phi_operands.push_back({SPV_OPERAND_TYPE_ID, {new_result_id}});
    op_phi_operands.push_back({SPV_OPERAND_TYPE_ID, {predecessor_id}});

    // Create a clone of the |inst| to be inserted into the |predecessor_id|.
    std::unique_ptr<opt::Instruction> clone(inst->Clone(ir_context));
    clone->SetResultId(new_result_id);

    fuzzerutil::UpdateModuleIdBound(ir_context, new_result_id);

    // Adjust |clone|'s operands to account for possible dependencies on OpPhi
    // instructions from the same basic block.
    for (uint32_t i = 0; i < clone->NumInOperands(); ++i) {
      auto& operand = clone->GetInOperand(i);
      if (operand.type != SPV_OPERAND_TYPE_ID) {
        // Consider only ids.
        continue;
      }

      const auto* dependency_inst =
          ir_context->get_def_use_mgr()->GetDef(operand.words[0]);
      assert(dependency_inst && "|clone| depends on an invalid id");

      if (ir_context->get_instr_block(dependency_inst->result_id()) !=
          ir_context->cfg()->block(message_.block_id())) {
        // We don't need to adjust anything if |dependency_inst| is from a
        // different block, a global instruction or a function parameter.
        continue;
      }

      assert(dependency_inst->opcode() == spv::Op::OpPhi &&
             "Propagated instruction can depend only on OpPhis from the same "
             "basic block or instructions from different basic blocks");

      auto new_id = GetResultIdFromLabelId(*dependency_inst, predecessor_id);
      assert(new_id && "OpPhi instruction is missing a predecessor");
      operand.words[0] = new_id;
    }

    auto* insert_before_inst = fuzzerutil::GetLastInsertBeforeInstruction(
        ir_context, predecessor_id, clone->opcode());
    assert(insert_before_inst && "Can't insert |clone| into |predecessor_id");

    insert_before_inst->InsertBefore(std::move(clone));
  }

  // Insert an OpPhi instruction into the basic block of |inst|.
  ir_context->get_instr_block(inst)->begin()->InsertBefore(
      MakeUnique<opt::Instruction>(ir_context, spv::Op::OpPhi, inst->type_id(),
                                   inst->result_id(),
                                   std::move(op_phi_operands)));

  // Remove |inst| from the basic block.
  ir_context->KillInst(inst);

  // We have changed the module so most analyzes are now invalid.
  ir_context->InvalidateAnalysesExceptFor(
      opt::IRContext::Analysis::kAnalysisNone);
}

protobufs::Transformation TransformationPropagateInstructionUp::ToMessage()
    const {
  protobufs::Transformation result;
  *result.mutable_propagate_instruction_up() = message_;
  return result;
}

bool TransformationPropagateInstructionUp::IsOpcodeSupported(spv::Op opcode) {
  // TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/3605):
  //  We only support "simple" instructions that don't work with memory.
  //  We should extend this so that we support the ones that modify the memory
  //  too.
  switch (opcode) {
    case spv::Op::OpUndef:
    case spv::Op::OpAccessChain:
    case spv::Op::OpInBoundsAccessChain:
    case spv::Op::OpArrayLength:
    case spv::Op::OpVectorExtractDynamic:
    case spv::Op::OpVectorInsertDynamic:
    case spv::Op::OpVectorShuffle:
    case spv::Op::OpCompositeConstruct:
    case spv::Op::OpCompositeExtract:
    case spv::Op::OpCompositeInsert:
    case spv::Op::OpCopyObject:
    case spv::Op::OpTranspose:
    case spv::Op::OpConvertFToU:
    case spv::Op::OpConvertFToS:
    case spv::Op::OpConvertSToF:
    case spv::Op::OpConvertUToF:
    case spv::Op::OpUConvert:
    case spv::Op::OpSConvert:
    case spv::Op::OpFConvert:
    case spv::Op::OpQuantizeToF16:
    case spv::Op::OpSatConvertSToU:
    case spv::Op::OpSatConvertUToS:
    case spv::Op::OpBitcast:
    case spv::Op::OpSNegate:
    case spv::Op::OpFNegate:
    case spv::Op::OpIAdd:
    case spv::Op::OpFAdd:
    case spv::Op::OpISub:
    case spv::Op::OpFSub:
    case spv::Op::OpIMul:
    case spv::Op::OpFMul:
    case spv::Op::OpUDiv:
    case spv::Op::OpSDiv:
    case spv::Op::OpFDiv:
    case spv::Op::OpUMod:
    case spv::Op::OpSRem:
    case spv::Op::OpSMod:
    case spv::Op::OpFRem:
    case spv::Op::OpFMod:
    case spv::Op::OpVectorTimesScalar:
    case spv::Op::OpMatrixTimesScalar:
    case spv::Op::OpVectorTimesMatrix:
    case spv::Op::OpMatrixTimesVector:
    case spv::Op::OpMatrixTimesMatrix:
    case spv::Op::OpOuterProduct:
    case spv::Op::OpDot:
    case spv::Op::OpIAddCarry:
    case spv::Op::OpISubBorrow:
    case spv::Op::OpUMulExtended:
    case spv::Op::OpSMulExtended:
    case spv::Op::OpAny:
    case spv::Op::OpAll:
    case spv::Op::OpIsNan:
    case spv::Op::OpIsInf:
    case spv::Op::OpIsFinite:
    case spv::Op::OpIsNormal:
    case spv::Op::OpSignBitSet:
    case spv::Op::OpLessOrGreater:
    case spv::Op::OpOrdered:
    case spv::Op::OpUnordered:
    case spv::Op::OpLogicalEqual:
    case spv::Op::OpLogicalNotEqual:
    case spv::Op::OpLogicalOr:
    case spv::Op::OpLogicalAnd:
    case spv::Op::OpLogicalNot:
    case spv::Op::OpSelect:
    case spv::Op::OpIEqual:
    case spv::Op::OpINotEqual:
    case spv::Op::OpUGreaterThan:
    case spv::Op::OpSGreaterThan:
    case spv::Op::OpUGreaterThanEqual:
    case spv::Op::OpSGreaterThanEqual:
    case spv::Op::OpULessThan:
    case spv::Op::OpSLessThan:
    case spv::Op::OpULessThanEqual:
    case spv::Op::OpSLessThanEqual:
    case spv::Op::OpFOrdEqual:
    case spv::Op::OpFUnordEqual:
    case spv::Op::OpFOrdNotEqual:
    case spv::Op::OpFUnordNotEqual:
    case spv::Op::OpFOrdLessThan:
    case spv::Op::OpFUnordLessThan:
    case spv::Op::OpFOrdGreaterThan:
    case spv::Op::OpFUnordGreaterThan:
    case spv::Op::OpFOrdLessThanEqual:
    case spv::Op::OpFUnordLessThanEqual:
    case spv::Op::OpFOrdGreaterThanEqual:
    case spv::Op::OpFUnordGreaterThanEqual:
    case spv::Op::OpShiftRightLogical:
    case spv::Op::OpShiftRightArithmetic:
    case spv::Op::OpShiftLeftLogical:
    case spv::Op::OpBitwiseOr:
    case spv::Op::OpBitwiseXor:
    case spv::Op::OpBitwiseAnd:
    case spv::Op::OpNot:
    case spv::Op::OpBitFieldInsert:
    case spv::Op::OpBitFieldSExtract:
    case spv::Op::OpBitFieldUExtract:
    case spv::Op::OpBitReverse:
    case spv::Op::OpBitCount:
    case spv::Op::OpCopyLogical:
    case spv::Op::OpPtrEqual:
    case spv::Op::OpPtrNotEqual:
      return true;
    default:
      return false;
  }
}

opt::Instruction*
TransformationPropagateInstructionUp::GetInstructionToPropagate(
    opt::IRContext* ir_context, uint32_t block_id) {
  auto* block = ir_context->cfg()->block(block_id);
  assert(block && "|block_id| is invalid");

  for (auto& inst : *block) {
    // We look for the first instruction in the block that satisfies the
    // following rules:
    // - it's not an OpPhi
    // - it must be supported by this transformation
    // - it may depend only on instructions from different basic blocks or on
    //   OpPhi instructions from the same basic block.
    if (inst.opcode() == spv::Op::OpPhi || !IsOpcodeSupported(inst.opcode()) ||
        !inst.type_id() || !inst.result_id()) {
      continue;
    }

    const auto* inst_type = ir_context->get_type_mgr()->GetType(inst.type_id());
    assert(inst_type && "|inst| has invalid type");

    if (inst_type->AsSampledImage()) {
      // OpTypeSampledImage cannot be used as an argument to OpPhi instructions,
      // thus we cannot support this type.
      continue;
    }

    if (!ir_context->get_feature_mgr()->HasCapability(
            spv::Capability::VariablePointersStorageBuffer) &&
        ContainsPointers(*inst_type)) {
      // OpPhi supports pointer operands only with VariablePointers or
      // VariablePointersStorageBuffer capabilities.
      //
      // Note that VariablePointers capability implicitly declares
      // VariablePointersStorageBuffer capability.
      continue;
    }

    if (!HasValidDependencies(ir_context, &inst)) {
      continue;
    }

    return &inst;
  }

  return nullptr;
}

bool TransformationPropagateInstructionUp::IsApplicableToBlock(
    opt::IRContext* ir_context, uint32_t block_id) {
  // Check that |block_id| is valid.
  const auto* label_inst = ir_context->get_def_use_mgr()->GetDef(block_id);
  if (!label_inst || label_inst->opcode() != spv::Op::OpLabel) {
    return false;
  }

  // Check that |block| has predecessors.
  const auto& predecessors = ir_context->cfg()->preds(block_id);
  if (predecessors.empty()) {
    return false;
  }

  // The block must contain an instruction to propagate.
  const auto* inst_to_propagate =
      GetInstructionToPropagate(ir_context, block_id);
  if (!inst_to_propagate) {
    return false;
  }

  // We should be able to insert |inst_to_propagate| into every predecessor of
  // |block|.
  return std::all_of(predecessors.begin(), predecessors.end(),
                     [ir_context, inst_to_propagate](uint32_t predecessor_id) {
                       return fuzzerutil::GetLastInsertBeforeInstruction(
                                  ir_context, predecessor_id,
                                  inst_to_propagate->opcode()) != nullptr;
                     });
}

std::unordered_set<uint32_t> TransformationPropagateInstructionUp::GetFreshIds()
    const {
  std::unordered_set<uint32_t> result;
  for (auto& pair : message_.predecessor_id_to_fresh_id()) {
    result.insert(pair.second());
  }
  return result;
}

}  // namespace fuzz
}  // namespace spvtools