// 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.

// This file is specifically named spvtools_fuzz.proto so that the string
// 'spvtools_fuzz' appears in the names of global-scope symbols that protoc
// generates when targeting C++.  This is to reduce the potential for name
// clashes with other globally-scoped symbols.

syntax = "proto3";

package spvtools.fuzz.protobufs;

message UInt32Pair {

  // A pair of uint32s; useful for defining mappings.

  uint32 first = 1;

  uint32 second = 2;

}

message InstructionDescriptor {

  // Describes an instruction in some block of a function with respect to a
  // base instruction.

  // The id of an instruction after which the instruction being described is
  // believed to be located.  It might be the using instruction itself.
  uint32 base_instruction_result_id = 1;

  // The opcode for the instruction being described.
  uint32 target_instruction_opcode = 2;

  // The number of matching opcodes to skip over when searching from the base
  // instruction to the instruction being described.
  uint32 num_opcodes_to_ignore = 3;

}

message IdUseDescriptor {

  // Describes a use of an id as an input operand to an instruction in some
  // block of a function.

  // Example:
  //   - id_of_interest = 42
  //   - enclosing_instruction = (
  //         base_instruction_result_id = 50,
  //         target_instruction_opcode = OpStore
  //         num_opcodes_to_ignore = 7
  //     )
  //   - in_operand_index = 1
  // represents a use of id 42 as input operand 1 to an OpStore instruction,
  // such that the OpStore instruction can be found in the same basic block as
  // the instruction with result id 50, and in particular is the 8th OpStore
  // instruction found from instruction 50 onwards (i.e. 7 OpStore
  // instructions are skipped).

  // An id that we would like to be able to find a use of.
  uint32 id_of_interest = 1;

  // The input operand index at which the use is expected.
  InstructionDescriptor enclosing_instruction = 2;

  uint32 in_operand_index = 3;

}

message DataDescriptor {

  // Represents a data element that can be accessed from an id, by walking the
  // type hierarchy via a sequence of 0 or more indices.
  //
  // Very similar to a UniformBufferElementDescriptor, except that a
  // DataDescriptor is rooted at the id of a scalar or composite.

  // The object being accessed - a scalar or composite
  uint32 object = 1;

  // 0 or more indices, used to index into a composite object
  repeated uint32 index = 2;

}

message UniformBufferElementDescriptor {

  // Represents a data element inside a uniform buffer.  The element is
  // specified via (a) the result id of a uniform variable in which the element
  // is contained, and (b) a series of indices that need to be followed to get
  // to the element (via fields and array/vector indices).
  //
  // Example: suppose there is a uniform variable with descriptor set 7 and
  // binding 9, and that the uniform variable has the following type (using
  // GLSL-like syntax):
  //
  // struct S {
  //   float f;
  //   vec3 g;
  //   int4 h[10];
  // };
  //
  // Then:
  // - (7, 9, [0]) describes the 'f' field.
  // - (7, 9, [1,1]) describes the y component of the 'g' field.
  // - (7, 9, [2,7,3]) describes the w component of element 7 of the 'h' field

  // The descriptor set and binding associated with a uniform variable.
  uint32 descriptor_set = 1;
  uint32 binding = 2;

  // An ordered sequence of indices through composite structures in the
  // uniform buffer.
  repeated uint32 index = 3;

}

message InstructionOperand {

  // Represents an operand to a SPIR-V instruction.

  // The type of the operand.
  uint32 operand_type = 1;

  // The data associated with the operand.  For most operands (e.g. ids,
  // storage classes and literals) this will be a single word.
  repeated uint32 operand_data = 2;

}

message Instruction {

  // Represents a SPIR-V instruction.

  // The instruction's opcode (e.g. OpLabel).
  uint32 opcode = 1;

  // The id of the instruction's result type; 0 if there is no result type.
  uint32 result_type_id = 2;

  // The id of the instruction's result; 0 if there is no result.
  uint32 result_id = 3;

  // Zero or more input operands.
  repeated InstructionOperand input_operand = 4;

}

message FactSequence {
  repeated Fact fact = 1;
}

message Fact {
  oneof fact {
    // Order the fact options by numeric id (rather than alphabetically).
    FactConstantUniform constant_uniform_fact = 1;
    FactDataSynonym data_synonym_fact = 2;
    FactBlockIsDead block_is_dead_fact = 3;
    FactFunctionIsLivesafe function_is_livesafe_fact = 4;
    FactValueOfVariableIsArbitrary value_of_variable_is_arbitrary = 5;
  }
}

// Keep fact message types in alphabetical order:

message FactConstantUniform {

  // Records the fact that a uniform buffer element is guaranteed to be equal
  // to a particular constant value.  spirv-fuzz can use such guarantees to
  // obfuscate code, e.g. to manufacture an expression that will (due to the
  // guarantee) evaluate to a particular value at runtime but in a manner that
  // cannot be predicted at compile-time.

  // An element of a uniform buffer
  UniformBufferElementDescriptor uniform_buffer_element_descriptor = 1;

  // The words of the associated constant
  repeated uint32 constant_word = 2;

}

message FactDataSynonym {

  // Records the fact that the data held in two data descriptors are guaranteed
  // to be equal.  spirv-fuzz can use this to replace uses of one piece of data
  // with a known-to-be-equal piece of data.

  // Data descriptors guaranteed to hold identical data.
  DataDescriptor data1 = 1;

  DataDescriptor data2 = 2;

}

message FactBlockIsDead {

  // Records the fact that a block is guaranteed to be dynamically unreachable.
  // This is useful because it informs the fuzzer that rather arbitrary changes
  // can be made to this block.

  uint32 block_id = 1;
}

message FactFunctionIsLivesafe {

  // Records the fact that a function is guaranteed to be "livesafe", meaning
  // that it will not make out-of-bounds accesses, does not contain reachable
  // OpKill or OpUnreachable instructions, does not contain loops that will
  // execute for large numbers of iterations, and only invokes other livesafe
  // functions.

  uint32 function_id = 1;
}

message FactValueOfVariableIsArbitrary {

  // Records the fact that the value stored in the variable or function
  // parameter with the given id can be arbitrary: the module's observable
  // behaviour does not depend on it.  This means that arbitrary stores can be
  // made to the variable, and that nothing can be guaranteed about values
  // loaded from the variable.

  // The result id of an OpVariable instruction, or an OpFunctionParameter
  // instruction with pointer type
  uint32 variable_id = 1;
}

message AccessChainClampingInfo {

  // When making a function livesafe it is necessary to clamp the indices that
  // occur as operands to access chain instructions so that they are guaranteed
  // to be in bounds.  This message type allows an access chain instruction to
  // have an associated sequence of ids that are reserved for comparing an
  // access chain index with a bound (e.g. an array size), and selecting
  // between the access chain index (if it is within bounds) and the bound (if
  // it is not).
  //
  // This allows turning an instruction of the form:
  //
  // %result = OpAccessChain %type %object ... %index ...
  //
  // into:
  //
  // %t1 = OpULessThanEqual %bool %index %bound_minus_one
  // %t2 = OpSelect %int_type %t1 %index %bound_minus_one
  // %result = OpAccessChain %type %object ... %t2 ...

  // The result id of an OpAccessChain or OpInBoundsAccessChain instruction.
  uint32 access_chain_id = 1;

  // A series of pairs of fresh ids, one per access chain index, for the results
  // of a compare instruction and a select instruction, serving the roles of %t1
  // and %t2 in the above example.
  repeated UInt32Pair compare_and_select_ids = 2;

}

message LoopLimiterInfo {

  // Structure capturing the information required to manipulate a loop limiter
  // at a loop header.

  // The header for the loop.
  uint32 loop_header_id = 1;

  // A fresh id into which the loop limiter's current value can be loaded.
  uint32 load_id = 2;

  // A fresh id that can be used to increment the loaded value by 1.
  uint32 increment_id = 3;

  // A fresh id that can be used to compare the loaded value with the loop
  // limit.
  uint32 compare_id = 4;

  // A fresh id that can be used to compute the conjunction or disjunction of
  // an original loop exit condition with |compare_id|, if the loop's back edge
  // block can conditionally exit the loop.
  uint32 logical_op_id = 5;

  // A sequence of ids suitable for extending OpPhi instructions of the loop
  // merge block if it did not previously have an incoming edge from the loop
  // back edge block.
  repeated uint32 phi_id = 6;

}

message TransformationSequence {
  repeated Transformation transformation = 1;
}

message Transformation {
  oneof transformation {
    // Order the transformation options by numeric id (rather than
    // alphabetically).
    TransformationMoveBlockDown move_block_down = 1;
    TransformationSplitBlock split_block = 2;
    TransformationAddConstantBoolean add_constant_boolean = 3;
    TransformationAddConstantScalar add_constant_scalar = 4;
    TransformationAddTypeBoolean add_type_boolean = 5;
    TransformationAddTypeFloat add_type_float = 6;
    TransformationAddTypeInt add_type_int = 7;
    TransformationAddDeadBreak add_dead_break = 8;
    TransformationReplaceBooleanConstantWithConstantBinary
      replace_boolean_constant_with_constant_binary = 9;
    TransformationAddTypePointer add_type_pointer = 10;
    TransformationReplaceConstantWithUniform replace_constant_with_uniform = 11;
    TransformationAddDeadContinue add_dead_continue = 12;
    TransformationCopyObject copy_object = 13;
    TransformationReplaceIdWithSynonym replace_id_with_synonym = 14;
    TransformationSetSelectionControl set_selection_control = 15;
    TransformationCompositeConstruct composite_construct = 16;
    TransformationSetLoopControl set_loop_control = 17;
    TransformationSetFunctionControl set_function_control = 18;
    TransformationAddNoContractionDecoration add_no_contraction_decoration = 19;
    TransformationSetMemoryOperandsMask set_memory_operands_mask = 20;
    TransformationCompositeExtract composite_extract = 21;
    TransformationVectorShuffle vector_shuffle = 22;
    TransformationOutlineFunction outline_function = 23;
    TransformationMergeBlocks merge_blocks = 24;
    TransformationAddTypeVector add_type_vector = 25;
    TransformationAddTypeArray add_type_array = 26;
    TransformationAddTypeMatrix add_type_matrix = 27;
    TransformationAddTypeStruct add_type_struct = 28;
    TransformationAddTypeFunction add_type_function = 29;
    TransformationAddConstantComposite add_constant_composite = 30;
    TransformationAddGlobalVariable add_global_variable = 31;
    TransformationAddGlobalUndef add_global_undef = 32;
    TransformationAddFunction add_function = 33;
    TransformationAddDeadBlock add_dead_block = 34;
    // Add additional option using the next available number.
  }
}

// Keep transformation message types in alphabetical order:

message TransformationAddConstantBoolean {

  // Supports adding the constants true and false to a module, which may be
  // necessary in order to enable other transformations if they are not present.

  uint32 fresh_id = 1;
  bool is_true = 2;

}

message TransformationAddConstantComposite {

  // Adds a constant of the given composite type to the module.

  // Fresh id for the composite
  uint32 fresh_id = 1;

  // A composite type id
  uint32 type_id = 2;

  // Constituent ids for the composite
  repeated uint32 constituent_id = 3;

}

message TransformationAddConstantScalar {

  // Adds a constant of the given scalar type.

  // Id for the constant
  uint32 fresh_id = 1;

  // Id for the scalar type of the constant
  uint32 type_id = 2;

  // Value of the constant
  repeated uint32 word = 3;

}

message TransformationAddDeadBlock {

  // Adds a new block to the module that is statically reachable from an
  // existing block, but dynamically unreachable.

  // Fresh id for the dead block
  uint32 fresh_id = 1;

  // Id of an existing block terminated with OpBranch, such that this OpBranch
  // can be replaced with an OpBranchConditional to its exiting successor or
  // the dead block
  uint32 existing_block = 2;

  // Determines whether the condition associated with the OpBranchConditional
  // is true or false
  bool condition_value = 3;

}

message TransformationAddDeadBreak {

  // A transformation that turns a basic block that unconditionally branches to
  // its successor into a block that potentially breaks out of a structured
  // control flow construct, but in such a manner that the break cannot actually
  // be taken.

  // The block to break from
  uint32 from_block = 1;

  // The merge block to break to
  uint32 to_block = 2;

  // Determines whether the break condition is true or false
  bool break_condition_value = 3;

  // A sequence of ids suitable for extending OpPhi instructions as a result of
  // the new break edge
  repeated uint32 phi_id = 4;

}

message TransformationAddDeadContinue {

  // A transformation that turns a basic block appearing in a loop and that
  // unconditionally branches to its successor into a block that potentially
  // branches to the continue target of the loop, but in such a manner that the
  // continue branch cannot actually be taken.

  // The block to continue from
  uint32 from_block = 1;

  // Determines whether the continue condition is true or false
  bool continue_condition_value = 2;

  // A sequence of ids suitable for extending OpPhi instructions as a result of
  // the new break edge
  repeated uint32 phi_id = 3;

}

message TransformationAddFunction {

  // Adds a SPIR-V function to the module.

  // The series of instructions that comprise the function.
  repeated Instruction instruction = 1;

  // True if and only if the given function should be made livesafe (see
  // FactFunctionIsLivesafe for definition).
  bool is_livesafe = 2;

  // Fresh id for a new variable that will serve as a "loop limiter" for the
  // function; only relevant if |is_livesafe| holds.
  uint32 loop_limiter_variable_id = 3;

  // Id of an existing unsigned integer constant providing the maximum value
  // that the loop limiter can reach before the loop is broken from; only
  // relevant if |is_livesafe| holds.
  uint32 loop_limit_constant_id = 4;

  // Fresh ids for each loop in the function that allow the loop limiter to be
  // manipulated; only relevant if |is_livesafe| holds.
  repeated LoopLimiterInfo loop_limiter_info = 5;

  // Id of an existing global value with the same return type as the function
  // that can be used to replace OpKill and OpReachable instructions with
  // ReturnValue instructions.  Ignored if the function has void return type.
  uint32 kill_unreachable_return_value_id = 6;

  // A mapping (represented as a sequence) from every access chain result id in
  // the function to the ids required to clamp its indices to ensure they are in
  // bounds.
  repeated AccessChainClampingInfo access_chain_clamping_info = 7;

}

message TransformationAddGlobalUndef {

  // Adds an undefined value of a given type to the module at global scope.

  // Fresh id for the undefined value
  uint32 fresh_id = 1;

  // The type of the undefined value
  uint32 type_id = 2;

}

message TransformationAddGlobalVariable {

  // Adds a global variable of the given type to the module, with Private
  // storage class and optionally with an initializer.

  // Fresh id for the global variable
  uint32 fresh_id = 1;

  // The type of the global variable
  uint32 type_id = 2;

  // Optional initializer; 0 if there is no initializer
  uint32 initializer_id = 3;

  // True if and only if the value of the variable should be regarded, in
  // general, as totally unknown and subject to change (even if, due to an
  // initializer, the original value is known).  This is the case for variables
  // added when a module is donated, for example, and means that stores to such
  // variables can be performed in an arbitrary fashion.
  bool value_is_arbitrary = 4;

}

message TransformationAddNoContractionDecoration {

  // Applies OpDecorate NoContraction to the given result id

  // Result id to be decorated
  uint32 result_id = 1;

}

message TransformationAddTypeArray {

  // Adds an array type of the given element type and size to the module

  // Fresh id for the array type
  uint32 fresh_id = 1;

  // The array's element type
  uint32 element_type_id = 2;

  // The array's size
  uint32 size_id = 3;

}

message TransformationAddTypeBoolean {

  // Adds OpTypeBool to the module

  // Id to be used for the type
  uint32 fresh_id = 1;

}

message TransformationAddTypeFloat {

  // Adds OpTypeFloat to the module with the given width

  // Id to be used for the type
  uint32 fresh_id = 1;

  // Floating-point width
  uint32 width = 2;

}

message TransformationAddTypeFunction {

  // Adds a function type to the module

  // Fresh id for the function type
  uint32 fresh_id = 1;

  // The function's return type
  uint32 return_type_id = 2;

  // The function's argument types
  repeated uint32 argument_type_id = 3;

}

message TransformationAddTypeInt {

  // Adds OpTypeInt to the module with the given width and signedness

  // Id to be used for the type
  uint32 fresh_id = 1;

  // Integer width
  uint32 width = 2;

  // True if and only if this is a signed type
  bool is_signed = 3;

}

message TransformationAddTypeMatrix {

  // Adds a matrix type to the module

  // Fresh id for the matrix type
  uint32 fresh_id = 1;

  // The matrix's column type, which must be a floating-point vector (as per
  // the "data rules" in the SPIR-V specification).
  uint32 column_type_id = 2;

  // The matrix's column count
  uint32 column_count = 3;

}

message TransformationAddTypePointer {

  // Adds OpTypePointer to the module, with the given storage class and base
  // type

  // Id to be used for the type
  uint32 fresh_id = 1;

  // Pointer storage class
  uint32 storage_class = 2;

  // Id of the base type for the pointer
  uint32 base_type_id = 3;

}

message TransformationAddTypeStruct {

  // Adds a struct type to the module

  // Fresh id for the struct type
  uint32 fresh_id = 1;

  // The struct's member types
  repeated uint32 member_type_id = 3;

}

message TransformationAddTypeVector {

  // Adds a vector type to the module

  // Fresh id for the vector type
  uint32 fresh_id = 1;

  // The vector's component type
  uint32 component_type_id = 2;

  // The vector's component count
  uint32 component_count = 3;

}

message TransformationCompositeConstruct {

  // A transformation that introduces an OpCompositeConstruct instruction to
  // make a composite object.

  // Id of the type of the composite that is to be constructed
  uint32 composite_type_id = 1;

  // Ids of the objects that will form the components of the composite
  repeated uint32 component = 2;

  // A descriptor for an instruction in a block before which the new
  // OpCompositeConstruct instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 3;

  // A fresh id for the composite object
  uint32 fresh_id = 4;

}

message TransformationCompositeExtract {

  // A transformation that adds an instruction to extract an element from a
  // composite.

  // A descriptor for an instruction in a block before which the new
  // OpCompositeExtract instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 1;

  // Result id for the extract operation.
  uint32 fresh_id = 2;

  // Id of the composite from which data is to be extracted.
  uint32 composite_id = 3;

  // Indices that indicate which part of the composite should be extracted.
  repeated uint32 index = 4;

}

message TransformationCopyObject {

  // A transformation that introduces an OpCopyObject instruction to make a
  // copy of an object.

  // Id of the object to be copied
  uint32 object = 1;

  // A descriptor for an instruction in a block before which the new
  // OpCopyObject instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 2;

  // A fresh id for the copied object
  uint32 fresh_id = 3;

}

message TransformationMergeBlocks {

  // A transformation that merges a block with its predecessor.

  // The id of the block that is to be merged with its predecessor; the merged
  // block will have the *predecessor's* id.
  uint32 block_id = 1;

}

message TransformationMoveBlockDown {

  // A transformation that moves a basic block to be one position lower in
  // program order.

  // The id of the block to move down.
  uint32 block_id = 1;
}

message TransformationOutlineFunction {

  // A transformation that outlines a single-entry single-exit region of a
  // control flow graph into a separate function, and replaces the region with
  // a call to that function.

  // Id of the entry block of the single-entry single-exit region to be outlined
  uint32 entry_block = 1;

  // Id of the exit block of the single-entry single-exit region to be outlined
  uint32 exit_block = 2;

  // Id of a struct that will store the return values of the new function
  uint32 new_function_struct_return_type_id = 3;

  // A fresh id for the type of the outlined function
  uint32 new_function_type_id = 4;

  // A fresh id for the outlined function itself
  uint32 new_function_id = 5;

  // A fresh id to represent the block in the outlined function that represents
  // the first block of the outlined region.
  uint32 new_function_region_entry_block = 6;

  // A fresh id for the result of the OpFunctionCall instruction that will call
  // the outlined function
  uint32 new_caller_result_id = 7;

  // A fresh id to capture the return value of the outlined function - the
  // argument to OpReturn
  uint32 new_callee_result_id = 8;

  // Ids defined outside the region and used inside the region will become
  // parameters to the outlined function.  This is a mapping from used ids to
  // fresh parameter ids.
  repeated UInt32Pair input_id_to_fresh_id = 9;

  // Ids defined inside the region and used outside the region will become
  // fresh ids defined by the outlined function, which get copied into the
  // function's struct return value and then copied into their destination ids
  // by the caller.  This is a mapping from original ids to corresponding fresh
  // ids.
  repeated UInt32Pair output_id_to_fresh_id = 10;

}

message TransformationReplaceBooleanConstantWithConstantBinary {

  // A transformation to capture replacing a use of a boolean constant with
  // binary operation on two constant values

  // A descriptor for the boolean constant id we would like to replace
  IdUseDescriptor id_use_descriptor = 1;

  // Id for the constant to be used on the LHS of the comparision
  uint32 lhs_id = 2;

  // Id for the constant to be used on the RHS of the comparision
  uint32 rhs_id = 3;

  // Opcode for binary operator
  uint32 opcode = 4;

  // Id that will store the result of the binary operation instruction
  uint32 fresh_id_for_binary_operation = 5;

}

message TransformationReplaceConstantWithUniform {

  // Replaces a use of a constant id with the result of a load from an
  // element of uniform buffer known to hold the same value as the constant

  // A descriptor for the id we would like to replace
  IdUseDescriptor id_use_descriptor = 1;

  // Uniform descriptor to identify which uniform value to choose
  UniformBufferElementDescriptor uniform_descriptor = 2;

  // Id that will store the result of an access chain
  uint32 fresh_id_for_access_chain = 3;

  // Id that will store the result of a load
  uint32 fresh_id_for_load = 4;

}

message TransformationReplaceIdWithSynonym {

  // Replaces a use of an id with an id that is known to be synonymous, e.g.
  // because it was obtained via applying OpCopyObject

  // The id use that is to be replaced
  IdUseDescriptor id_use_descriptor = 1;

  // The synonymous id
  uint32 synonymous_id = 2;

}

message TransformationSetFunctionControl {

  // A transformation that sets the function control operand of an OpFunction
  // instruction.

  // The result id of an OpFunction instruction
  uint32 function_id = 1;

  // The value to which the 'function control' operand should be set.
  uint32 function_control = 2;

}

message TransformationSetLoopControl {

  // A transformation that sets the loop control operand of an OpLoopMerge
  // instruction.

  // The id of a basic block that should contain OpLoopMerge
  uint32 block_id = 1;

  // The value to which the 'loop control' operand should be set.
  // This must be a legal loop control mask.
  uint32 loop_control = 2;

  // Provides a peel count value for the loop.  Used if and only if the
  // PeelCount bit is set.  Must be zero if the PeelCount bit is not set (can
  // still be zero if this bit is set).
  uint32 peel_count = 3;

  // Provides a partial count value for the loop.  Used if and only if the
  // PartialCount bit is set.  Must be zero if the PartialCount bit is not set
  // (can still be zero if this bit is set).
  uint32 partial_count = 4;

}

message TransformationSetMemoryOperandsMask {

  // A transformation that sets the memory operands mask of a memory access
  // instruction.

  // A descriptor for a memory access instruction, e.g. an OpLoad
  InstructionDescriptor memory_access_instruction = 1;

  // A mask of memory operands to be applied to the instruction.  It must be the
  // same as the original mask, except that Volatile can be added, and
  // Nontemporal can be added or removed.
  uint32 memory_operands_mask = 2;

  // Some memory access instructions allow more than one mask to be specified;
  // this field indicates which mask should be set
  uint32 memory_operands_mask_index = 3;

}

message TransformationSetSelectionControl {

  // A transformation that sets the selection control operand of an
  // OpSelectionMerge instruction.

  // The id of a basic block that should contain OpSelectionMerge
  uint32 block_id = 1;

  // The value to which the 'selection control' operand should be set.
  // Although technically 'selection control' is a literal mask that can be
  // some combination of 'None', 'Flatten' and 'DontFlatten', the combination
  // 'Flatten | DontFlatten' does not make sense and is not allowed here.
  uint32 selection_control = 2;

}

message TransformationSplitBlock {

  // A transformation that splits a basic block into two basic blocks

  // A descriptor for an instruction such that the block containing the
  // described instruction should be split right before the instruction.
  InstructionDescriptor instruction_to_split_before = 1;

  // An id that must not yet be used by the module to which this transformation
  // is applied.  Rather than having the transformation choose a suitable id on
  // application, we require the id to be given upfront in order to facilitate
  // reducing fuzzed shaders by removing transformations.  The reason is that
  // future transformations may refer to the fresh id introduced by this
  // transformation, and if we end up changing what that id is, due to removing
  // earlier transformations, it may inhibit later transformations from
  // applying.
  uint32 fresh_id = 2;

}

message TransformationVectorShuffle {

  // A transformation that adds a vector shuffle instruction.

  // A descriptor for an instruction in a block before which the new
  // OpVectorShuffle instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 1;

  // Result id for the shuffle operation.
  uint32 fresh_id = 2;

  // Id of the first vector operand.
  uint32 vector1 = 3;

  // Id of the second vector operand.
  uint32 vector2 = 4;

  // Indices that indicate which components of the input vectors should be used.
  repeated uint32 component = 5;

}