text: // Copyright (c) 2019 Google LLC
  //
  // 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.
  
  #ifndef SOURCE_FUZZ_FUZZER_PASS_H_
  #define SOURCE_FUZZ_FUZZER_PASS_H_
  
  #include <functional>
  #include <vector>
  
  #include "source/fuzz/fuzzer_context.h"
  #include "source/fuzz/protobufs/spirvfuzz_protobufs.h"
  #include "source/fuzz/transformation.h"
  #include "source/fuzz/transformation_context.h"
  #include "source/opt/ir_context.h"
  
  namespace spvtools {
  namespace fuzz {
  
  // Interface for applying a pass of transformations to a module.
  class FuzzerPass {
   public:
    FuzzerPass(opt::IRContext* ir_context,
               TransformationContext* transformation_context,
               FuzzerContext* fuzzer_context,
               protobufs::TransformationSequence* transformations);
  
    virtual ~FuzzerPass();
  
    // Applies the pass to the module |ir_context_|, assuming and updating
    // information from |transformation_context_|, and using |fuzzer_context_| to
    // guide the process.  Appends to |transformations_| all transformations that
    // were applied during the pass.
    virtual void Apply() = 0;
  
   protected:
    opt::IRContext* GetIRContext() const { return ir_context_; }
  
    TransformationContext* GetTransformationContext() const {
      return transformation_context_;
    }
  
    FuzzerContext* GetFuzzerContext() const { return fuzzer_context_; }
  
    protobufs::TransformationSequence* GetTransformations() const {
      return transformations_;
    }
  
    // Returns all instructions that are *available* at |inst_it|, which is
    // required to be inside block |block| of function |function| - that is, all
    // instructions at global scope and all instructions that strictly dominate
    // |inst_it|.
    //
    // Filters said instructions to return only those that satisfy the
    // |instruction_is_relevant| predicate.  This, for instance, could ignore all
    // instructions that have a particular decoration.
    std::vector<opt::Instruction*> FindAvailableInstructions(
        opt::Function* function, opt::BasicBlock* block,
        const opt::BasicBlock::iterator& inst_it,
        std::function<bool(opt::IRContext*, opt::Instruction*)>
            instruction_is_relevant) const;
  
    // A helper method that iterates through each instruction in each block, at
    // all times tracking an instruction descriptor that allows the latest
    // instruction to be located even if it has no result id.
    //
    // The code to manipulate the instruction descriptor is a bit fiddly.  The
    // point of this method is to avoiding having to duplicate it in multiple
    // transformation passes.
    //
    // The function |action| is invoked for each instruction |inst_it| in block
    // |block| of function |function| that is encountered.  The
    // |instruction_descriptor| parameter to the function object allows |inst_it|
    // to be identified.
    //
    // In most intended use cases, the job of |action| is to randomly decide
    // whether to try to apply some transformation, and then - if selected - to
    // attempt to apply it.
    void ForEachInstructionWithInstructionDescriptor(
        std::function<
            void(opt::Function* function, opt::BasicBlock* block,
                 opt::BasicBlock::iterator inst_it,
                 const protobufs::InstructionDescriptor& instruction_descriptor)>
            action);
  
    // A generic helper for applying a transformation that should be applicable
    // by construction, and adding it to the sequence of applied transformations.
    void ApplyTransformation(const Transformation& transformation) {
      assert(transformation.IsApplicable(GetIRContext(),
                                         *GetTransformationContext()) &&
             "Transformation should be applicable by construction.");
      transformation.Apply(GetIRContext(), GetTransformationContext());
      *GetTransformations()->add_transformation() = transformation.ToMessage();
    }
  
    // A generic helper for applying a transformation only if it is applicable.
    // If it is applicable, the transformation is applied and then added to the
    // sequence of applied transformations and the function returns true.
    // Otherwise, the function returns false.
    bool MaybeApplyTransformation(const Transformation& transformation) {
      if (transformation.IsApplicable(GetIRContext(),
                                      *GetTransformationContext())) {
        transformation.Apply(GetIRContext(), GetTransformationContext());
        *GetTransformations()->add_transformation() = transformation.ToMessage();
        return true;
      }
      return false;
    }
  
    // Returns the id of an OpTypeBool instruction.  If such an instruction does
    // not exist, a transformation is applied to add it.
    uint32_t FindOrCreateBoolType();
  
    // Returns the id of an OpTypeInt instruction, with width and signedness
    // specified by |width| and |is_signed|, respectively.  If such an instruction
    // does not exist, a transformation is applied to add it.
    uint32_t FindOrCreateIntegerType(uint32_t width, bool is_signed);
  
    // Returns the id of an OpTypeFloat instruction, with width specified by
    // |width|.  If such an instruction does not exist, a transformation is
    // applied to add it.
    uint32_t FindOrCreateFloatType(uint32_t width);
  
    // Returns the id of an OpTypeFunction %<return_type_id> %<...argument_id>
    // instruction. If such an instruction doesn't exist, a transformation
    // is applied to create a new one.
    uint32_t FindOrCreateFunctionType(uint32_t return_type_id,
                                      const std::vector<uint32_t>& argument_id);
  
    // Returns the id of an OpTypeVector instruction, with |component_type_id|
    // (which must already exist) as its base type, and |component_count|
    // elements (which must be in the range [2, 4]).  If such an instruction does
    // not exist, a transformation is applied to add it.
    uint32_t FindOrCreateVectorType(uint32_t component_type_id,
                                    uint32_t component_count);
  
    // Returns the id of an OpTypeMatrix instruction, with |column_count| columns
    // and |row_count| rows (each of which must be in the range [2, 4]).  If the
    // float and vector types required to build this matrix type or the matrix
    // type itself do not exist, transformations are applied to add them.
    uint32_t FindOrCreateMatrixType(uint32_t column_count, uint32_t row_count);
  
    // Returns the id of an OpTypeStruct instruction with |component_type_ids| as
    // type ids for struct's components. If no such a struct type exists,
    // transformations are applied to add it. |component_type_ids| may not contain
    // a result id of an OpTypeFunction.
    uint32_t FindOrCreateStructType(
        const std::vector<uint32_t>& component_type_ids);
  
    // Returns the id of a pointer type with base type |base_type_id| (which must
    // already exist) and storage class |storage_class|.  A transformation is
    // applied to add the pointer if it does not already exist.
    uint32_t FindOrCreatePointerType(uint32_t base_type_id,
                                     SpvStorageClass storage_class);
  
    // Returns the id of an OpTypePointer instruction, with a integer base
    // type of width and signedness specified by |width| and |is_signed|,
    // respectively.  If the pointer type or required integer base type do not
    // exist, transformations are applied to add them.
    uint32_t FindOrCreatePointerToIntegerType(uint32_t width, bool is_signed,
                                              SpvStorageClass storage_class);
  
    // Returns the id of an OpConstant instruction, with a integer type of
    // width and signedness specified by |width| and |is_signed|, respectively,
    // with |words| as its value.  If either the required integer type or the
    // constant do not exist, transformations are applied to add them.
    uint32_t FindOrCreateIntegerConstant(const std::vector<uint32_t>& words,
                                         uint32_t width, bool is_signed);
  
    // Returns the id of an OpConstant instruction, with a floating-point
    // type of width specified by |width|, with |words| as its value.  If either
    // the required floating-point type or the constant do not exist,
    // transformations are applied to add them.
    uint32_t FindOrCreateFloatConstant(const std::vector<uint32_t>& words,
                                       uint32_t width);
  
    // Returns the id of an OpConstantTrue or OpConstantFalse instruction,
    // according to |value|.  If either the required instruction or the bool
    // type do not exist, transformations are applied to add them.
    uint32_t FindOrCreateBoolConstant(bool value);
  
    // Returns the id of an OpConstant instruction of type with |type_id|
    // that consists of |words|. If that instruction doesn't exist,
    // transformations are applied to add it. |type_id| must be a valid
    // result id of either scalar or boolean OpType* instruction that exists
    // in the module.
    uint32_t FindOrCreateConstant(const std::vector<uint32_t>& words,
                                  uint32_t type_id);
  
    // Returns the id of an OpConstantComposite
    uint32_t FindOrCreateCompositeConstant(
        const std::vector<uint32_t>& component_ids, uint32_t type_id);
  
    // Returns the result id of an instruction of the form:
    //   %id = OpUndef %|type_id|
    // If no such instruction exists, a transformation is applied to add it.
    uint32_t FindOrCreateGlobalUndef(uint32_t type_id);
  
    // Returns the id of an OpNullConstant instruction of type |type_id|. If
    // that instruction doesn't exist, it is added through a transformation.
    // |type_id| must be a valid result id of an OpType* instruction that exists
    // in the module.
    uint32_t FindOrCreateNullConstant(uint32_t type_id);
  
    // Define a *basic type* to be an integer, boolean or floating-point type,
    // or a matrix, vector, struct or fixed-size array built from basic types.  In
    // particular, a basic type cannot contain an opaque type (such as an image),
    // or a runtime-sized array.
    //
    // Yields a pair, (basic_type_ids, basic_type_ids_to_pointers), such that:
    // - basic_type_ids captures every basic type declared in the module.
    // - basic_type_ids_to_pointers maps every such basic type to the sequence
    //   of all pointer types that have storage class |storage_class| and the
    //   given basic type as their pointee type.  The sequence may be empty for
    //   some basic types if no pointers to those types are defined for the given
    //   storage class, and the sequence will have multiple elements if there are
    //   repeated pointer declarations for the same basic type and storage class.
    std::pair<std::vector<uint32_t>, std::map<uint32_t, std::vector<uint32_t>>>
    GetAvailableBasicTypesAndPointers(SpvStorageClass storage_class) const;
  
    // Given a type id, |scalar_or_composite_type_id|, which must correspond to
    // some scalar or composite type, returns the result id of an instruction
    // defining a constant of the given type that is zero or false at everywhere.
    // If such an instruction does not yet exist, transformations are applied to
    // add it.
    //
    // Examples:
    // --------------+-------------------------------
    //   TYPE        | RESULT is id corresponding to
    // --------------+-------------------------------
    //   bool        | false
    // --------------+-------------------------------
    //   bvec4       | (false, false, false, false)
    // --------------+-------------------------------
    //   float       | 0.0
    // --------------+-------------------------------
    //   vec2        | (0.0, 0.0)
    // --------------+-------------------------------
    //   int[3]      | [0, 0, 0]
    // --------------+-------------------------------
    //   struct S {  |
    //     int i;    | S(0, false, (0u, 0u))
    //     bool b;   |
    //     uint2 u;  |
    //   }           |
    // --------------+-------------------------------
    uint32_t FindOrCreateZeroConstant(uint32_t scalar_or_composite_type_id);
  
   private:
    // Array, matrix and vector are *homogeneous* composite types in the sense
    // that every component of one of these types has the same type.  Given a
    // homogeneous composite type instruction, |composite_type_instruction|,
    // returns the id of a composite constant instruction for which every element
    // is zero/false.  If such an instruction does not yet exist, transformations
    // are applied to add it.
    uint32_t GetZeroConstantForHomogeneousComposite(
        const opt::Instruction& composite_type_instruction,
        uint32_t component_type_id, uint32_t num_components);
  
    // Helper to find an existing composite constant instruction of the given
    // composite type with the given constant components, or to apply
    // transformations to create such an instruction if it does not yet exist.
    // Parameter |composite_type_instruction| must be a composite type
    // instruction.  The parameters |constants| and |constant_ids| must have the
    // same size, and it must be the case that for each i, |constant_ids[i]| is
    // the result id of an instruction that defines |constants[i]|.
    uint32_t FindOrCreateCompositeConstant(
        const opt::Instruction& composite_type_instruction,
        const std::vector<const opt::analysis::Constant*>& constants,
        const std::vector<uint32_t>& constant_ids);
  
    opt::IRContext* ir_context_;
    TransformationContext* transformation_context_;
    FuzzerContext* fuzzer_context_;
    protobufs::TransformationSequence* transformations_;
  };
  
  }  // namespace fuzz
  }  // namespace spvtools
  
  #endif  // SOURCE_FUZZ_FUZZER_PASS_H_
  