// 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;
    FactPointeeValueIsIrrelevant pointee_value_is_irrelevant_fact = 5;
    FactIdEquation id_equation_fact = 6;
    FactIdIsIrrelevant id_is_irrelevant = 7;
  }
}

// Keep fact message types in alphabetical order:

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 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 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 FactIdEquation {

  // Records the fact that the equation:
  //
  // lhs_id = opcode rhs_id[0] rhs_id[1] ... rhs_id[N-1]
  //
  // holds; e.g. that the equation:
  //
  // %12 = OpIAdd %13 %14
  //
  // holds in the case where lhs_id is 12, rhs_id is [13, 14], and the opcode is
  // OpIAdd.

  // The left-hand-side of the equation.
  uint32 lhs_id = 1;

  // A SPIR-V opcode, from a restricted set of instructions for which equation
  // facts make sense.
  uint32 opcode = 2;

  // The operands to the right-hand-side of the equation.
  repeated uint32 rhs_id = 3;

}

message FactIdIsIrrelevant {

  // Records a fact that |result_id| is irrelevant (i.e. it's usage doesn't
  // change the semantics of the module). This implies that a use of this id
  // can later be replaced with some other id of the same type, or the
  // definition of |result_id| can be changed so that it yields a different value.

  // An irrelevant id.
  uint32 result_id = 1;

}

message FactPointeeValueIsIrrelevant {

  // Records the fact that value of the data pointed to by a pointer id does
  // not influence the observable behaviour of the module.  This means that
  // arbitrary stores can be made through the pointer, and that nothing can be
  // guaranteed about the values that are loaded via the pointer.

  // A result id of pointer type
  uint32 pointer_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 SideEffectWrapperInfo {
  // When flattening a conditional branch, it is necessary to enclose
  // instructions that have side effects inside conditionals, so that
  // they are only executed if the condition holds. Otherwise, there
  // might be unintended changes in memory, or crashes that would not
  // originally happen.
  // For example, the instruction %id = OpLoad %type %ptr, found in
  // the true branch of the conditional, will be enclosed in a new
  // conditional (assuming that the block containing it can be split
  // around it) as follows:
  //
  //   [previous instructions in the block]
  //                        OpSelectionMerge %merge_block_id None
  //                        OpBranchConditional %cond %execute_block_id %alternative_block_id
  //    %execute_block_id = OpLabel
  //    %actual_result_id = OpLoad %type %ptr
  //                       OpBranch %merge_block_id
  //  %alternative_block_id = OpLabel
  // %placeholder_result_id = OpCopyObject %type %value_to_copy_id
  //                       OpBranch %merge_block_id
  //     %merge_block_id = OpLabel
  //                 %id = OpPhi %type %actual_result_id %execute_block_id %placeholder_result_id %alternative_block_id
  //   [following instructions from the original block]
  //
  // If the instruction does not have a result id, this is simplified.
  // For example, OpStore %ptr %value, found in the true branch of a
  // conditional, is enclosed as follows:
  //
  //   [previous instructions in the block]
  //                       OpSelectionMerge %merge_block None
  //                       OpBranchConditional %cond %execute_block_id %merge_block_id
  //   %execute_block_id = OpLabel
  //                       OpStore %ptr %value
  //                       OpBranch %merge_block_id
  //     %merge_block_id = OpLabel
  //   [following instructions from the original block]
  //
  // The same happens if the instruction is found in the false branch
  // of the conditional being flattened, except that the label ids in
  // the OpBranchConditional are swapped.


  // An instruction descriptor for identifying the instruction to be
  // enclosed inside a conditional. An instruction descriptor is
  // necessary because the instruction might not have a result id.
  InstructionDescriptor instruction = 1;

  // A fresh id for the new merge block.
  uint32 merge_block_id = 2;

  // A fresh id for the new block where the actual instruction is
  // executed.
  uint32 execute_block_id = 3;

  // The following fields are only needed if the original instruction has a
  // result id. They can be set to 0 if not needed.

  // A fresh id for the result id of the instruction (the original
  // one is used by the OpPhi instruction).
  uint32 actual_result_id = 4;

  // A fresh id for the new block where the placeholder instruction
  // is placed.
  uint32 alternative_block_id = 5;

  // A fresh id for the placeholder instruction.
  uint32 placeholder_result_id = 6;

  // An id present in the module, available to use at this point in
  // the program and with the same type as the original instruction,
  // that can be used to create a placeholder OpCopyObject
  // instruction.
  uint32 value_to_copy_id = 7;
}

message ReturnMergingInfo {
  // TransformationMergeFunctionReturns needs to modify each merge block of
  // loops containing return instructions, by:
  // - adding instructions to decide whether the function is returning
  // - adding instructions to pass on the return value of the function,
  //   if it is returning
  // - changing the branch instruction (which must be an unconditional branch)
  //   to a conditional branch that, if the function is returning, branches to
  //   the merge block of the innermost loop that contains this merge block
  //   (which can be the new merge block introduced by the transformation).
  //
  // One such merge block of the form:
  //  %block = OpLabel
  //   %phi1 = OpPhi %type1 %val1_1 %pred1 %val1_2 %pred2
  //   %phi2 = OpPhi %type2 %val2_1 %pred1 %val2_2 %pred2
  //           OpBranch %next
  //
  // is transformed into:
  //               %block = OpLabel
  //     %is_returning_id = OpPhi %bool %false %pred1 %false %pred2 %true %ret_bb1 %is_bb2_returning %mer_bb2
  // %maybe_return_val_id = OpPhi %return_type %any_returnable_val %pred1 %any_returnable_val %pred2
  //                                            %ret_val1 %ret_bb1 %ret_val2 %mer_bb2
  //                %phi1 = OpPhi %type1 %val1_1 %pred1 %val1_2 %pred2
  //                                     %any_suitable_id_1 %ret_bb1 %any_suitable_id_1 %mer_bb2
  //                %phi2 = OpPhi %type2 %val2_1 %pred1 %val2_2 %pred2
  //                                     %any_suitable_id_1 %ret_bb1 %any_suitable_id_1 %mer_bb2
  //                        OpBranchConditional %is_returning_id %innermost_loop_merge %next
  //
  // where %ret_bb1 is a block that originally contains a return instruction and %mer_bb2 is the merge block of an inner
  // loop, from where the function might be returning.
  //
  // Note that the block is required to only have OpLabel, OpPhi or OpBranch instructions.

  // The id of the merge block that needs to be modified.
  uint32 merge_block_id = 1;

  // A fresh id for a boolean OpPhi whose value will be true iff the function
  // is returning. This will be used to decide whether to break out of the loop
  // or to use the original branch of the function. This value will also be
  // used by the merge block of the enclosing loop (if there is one) if the
  // function is returning from this block.
  uint32 is_returning_id = 2;

  // A fresh id that will get the value being returned, if the function is
  // returning. If the function return type is void, this is ignored.
  uint32 maybe_return_val_id = 3;

  // A mapping from each existing OpPhi id to a suitable id of the same type
  // available to use before the instruction.
  repeated UInt32Pair opphi_to_suitable_id = 4;
}

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;
    TransformationReplaceIdWithSynonym replace_id_with_synonym = 13;
    TransformationSetSelectionControl set_selection_control = 14;
    TransformationCompositeConstruct composite_construct = 15;
    TransformationSetLoopControl set_loop_control = 16;
    TransformationSetFunctionControl set_function_control = 17;
    TransformationAddNoContractionDecoration add_no_contraction_decoration = 18;
    TransformationSetMemoryOperandsMask set_memory_operands_mask = 19;
    TransformationCompositeExtract composite_extract = 20;
    TransformationVectorShuffle vector_shuffle = 21;
    TransformationOutlineFunction outline_function = 22;
    TransformationMergeBlocks merge_blocks = 23;
    TransformationAddTypeVector add_type_vector = 24;
    TransformationAddTypeArray add_type_array = 25;
    TransformationAddTypeMatrix add_type_matrix = 26;
    TransformationAddTypeStruct add_type_struct = 27;
    TransformationAddTypeFunction add_type_function = 28;
    TransformationAddConstantComposite add_constant_composite = 29;
    TransformationAddGlobalVariable add_global_variable = 30;
    TransformationAddGlobalUndef add_global_undef = 31;
    TransformationAddFunction add_function = 32;
    TransformationAddDeadBlock add_dead_block = 33;
    TransformationAddLocalVariable add_local_variable = 34;
    TransformationLoad load = 35;
    TransformationStore store = 36;
    TransformationFunctionCall function_call = 37;
    TransformationAccessChain access_chain = 38;
    TransformationEquationInstruction equation_instruction = 39;
    TransformationSwapCommutableOperands swap_commutable_operands = 40;
    TransformationPermuteFunctionParameters permute_function_parameters = 41;
    TransformationToggleAccessChainInstruction toggle_access_chain_instruction = 42;
    TransformationAddConstantNull add_constant_null = 43;
    TransformationComputeDataSynonymFactClosure compute_data_synonym_fact_closure = 44;
    TransformationAdjustBranchWeights adjust_branch_weights = 45;
    TransformationPushIdThroughVariable push_id_through_variable = 46;
    TransformationAddSpecConstantOp add_spec_constant_op = 47;
    TransformationReplaceLinearAlgebraInstruction replace_linear_algebra_instruction = 48;
    TransformationSwapConditionalBranchOperands swap_conditional_branch_operands = 49;
    TransformationPermutePhiOperands permute_phi_operands = 50;
    TransformationAddParameter add_parameter = 51;
    TransformationAddCopyMemory add_copy_memory = 52;
    TransformationInvertComparisonOperator invert_comparison_operator = 53;
    TransformationAddImageSampleUnusedComponents add_image_sample_unused_components = 54;
    TransformationReplaceParameterWithGlobal replace_parameter_with_global = 55;
    TransformationRecordSynonymousConstants record_synonymous_constants = 56;
    TransformationAddSynonym add_synonym = 57;
    TransformationAddRelaxedDecoration add_relaxed_decoration = 58;
    TransformationReplaceParamsWithStruct replace_params_with_struct = 59;
    TransformationReplaceCopyObjectWithStoreLoad replace_copy_object_with_store_load = 60;
    TransformationReplaceCopyMemoryWithLoadStore replace_copy_memory_with_load_store = 61;
    TransformationReplaceLoadStoreWithCopyMemory replace_load_store_with_copy_memory = 62;
    TransformationAddLoopPreheader add_loop_preheader = 63;
    TransformationMoveInstructionDown move_instruction_down = 64;
    TransformationMakeVectorOperationDynamic make_vector_operation_dynamic = 65;
    TransformationReplaceAddSubMulWithCarryingExtended replace_add_sub_mul_with_carrying_extended = 66;
    TransformationPropagateInstructionUp propagate_instruction_up = 67;
    TransformationCompositeInsert composite_insert = 68;
    TransformationInlineFunction inline_function = 69;
    TransformationAddOpPhiSynonym add_opphi_synonym = 70;
    TransformationMutatePointer mutate_pointer = 71;
    TransformationReplaceIrrelevantId replace_irrelevant_id = 72;
    TransformationReplaceOpPhiIdFromDeadPredecessor replace_opphi_id_from_dead_predecessor = 73;
    TransformationReplaceOpSelectWithConditionalBranch replace_opselect_with_conditional_branch = 74;
    TransformationDuplicateRegionWithSelection duplicate_region_with_selection = 75;
    TransformationFlattenConditionalBranch flatten_conditional_branch = 76;
    TransformationAddBitInstructionSynonym add_bit_instruction_synonym = 77;
    TransformationAddLoopToCreateIntConstantSynonym add_loop_to_create_int_constant_synonym = 78;
    TransformationWrapRegionInSelection wrap_region_in_selection = 79;
    TransformationAddEarlyTerminatorWrapper add_early_terminator_wrapper = 80;
    TransformationPropagateInstructionDown propagate_instruction_down = 81;
    TransformationReplaceBranchFromDeadBlockWithExit replace_branch_from_dead_block_with_exit = 82;
    TransformationWrapEarlyTerminatorInFunction wrap_early_terminator_in_function = 83;
    TransformationMergeFunctionReturns merge_function_returns = 84;
    // Add additional option using the next available number.
  }
}

// Keep transformation message types in alphabetical order:

message TransformationAccessChain {

  // Adds an access chain instruction based on a given pointer and indices.

  // When accessing a struct, the corresponding indices must be 32-bit integer constants.
  // For any other composite, the indices can be any 32-bit integer, and the transformation
  // adds two instructions for each such index to clamp it to the bound, as follows:
  //
  // %t1 = OpULessThanEqual %bool %index %bound_minus_one
  // %t2 = OpSelect %int_type %t1 %index %bound_minus_one

  // Result id for the access chain
  uint32 fresh_id = 1;

  // The pointer from which the access chain starts
  uint32 pointer_id = 2;

  // Zero or more access chain indices
  repeated uint32 index_id = 3;

  // A descriptor for an instruction in a block before which the new
  // OpAccessChain instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 4;

  // Additional fresh ids, required to clamp index variables. A pair is needed
  // for each access to a non-struct composite.
  repeated UInt32Pair fresh_ids_for_clamping = 5;

}

message TransformationAddBitInstructionSynonym {

  // A transformation that adds synonyms for bit instructions by evaluating
  // each bit with the corresponding operation. There is a SPIR-V code example in the
  // header file of the transformation class that can help understand the transformation.

  // This transformation is only applicable if the described instruction has one of the following opcodes.
  // Supported:
  //   OpBitwiseOr
  //   OpBitwiseXor
  //   OpBitwiseAnd
  //   OpNot
  // To be supported in the future:
  //   OpShiftRightLogical
  //   OpShiftRightArithmetic
  //   OpShiftLeftLogical
  //   OpBitReverse
  //   OpBitCount

  // The bit instruction result id.
  uint32 instruction_result_id = 1;

  // The fresh ids required to apply the transformation.
  repeated uint32 fresh_ids = 2;

}

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.
  // Also, creates an IdIsIrrelevant fact about |fresh_id| if |is_irrelevant| is true.

  uint32 fresh_id = 1;
  bool is_true = 2;

  // If the constant should be marked as irrelevant.
  bool is_irrelevant = 3;

}

message TransformationAddConstantComposite {

  // Adds a constant of the given composite type to the module.
  // Also, creates an IdIsIrrelevant fact about |fresh_id| if
  // |is_irrelevant| is true.

  // 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;

  // If the constant should be marked as irrelevant.
  bool is_irrelevant = 4;

}

message TransformationAddConstantNull {

  // Adds a null constant.

  // Id for the constant
  uint32 fresh_id = 1;

  // Type of the constant
  uint32 type_id = 2;

}

message TransformationAddConstantScalar {

  // Adds a constant of the given scalar type.
  // Also, creates an IdIsIrrelevant fact about
  // |fresh_id| if |is_irrelevant| is true.

  // 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;

  // If the constant should be marked as irrelevant.
  bool is_irrelevant = 4;

}

message TransformationAddCopyMemory {

  // Adds an OpCopyMemory instruction into the module.
  // Creates either a global or a local variable (based on
  // |storage_class| field) to copy the target into.

  // OpCopyMemory will be inserted before this instruction.
  InstructionDescriptor instruction_descriptor = 1;

  // Fresh id to copy memory into.
  uint32 fresh_id = 2;

  // Source to copy memory from.
  uint32 source_id = 3;

  // Storage class for the target variable. Can be either Function or Private.
  uint32 storage_class = 4;

  // Result id for the variable's initializer operand. Its type must be equal to
  // variable's pointee type.
  uint32 initializer_id = 5;

}

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 TransformationAddEarlyTerminatorWrapper {

  // Adds a function to the module containing a single block with a single non-
  // label instruction that is either OpKill, OpUnreachable, or
  // OpTerminateInvocation.  The purpose of this is to allow such instructions
  // to be subsequently replaced with wrapper functions, which can then enable
  // transformations (such as inlining) that are hard in the direct presence
  // of these instructions.

  // Fresh id for the function.
  uint32 function_fresh_id = 1;

  // Fresh id for the single basic block in the function.
  uint32 label_fresh_id = 2;

  // One of OpKill, OpUnreachable, OpTerminateInvocation.  If additional early
  // termination instructions are added to SPIR-V they should also be handled
  // here.
  uint32 opcode = 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.
  // Only relevant if |is_livesafe| holds.
  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; only relevant if |is_livesafe| holds.
  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 or
  // Workgroup storage class, and optionally (for the Private case) with an
  // initializer.

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

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

  uint32 storage_class = 3;

  // Initial value of the variable
  uint32 initializer_id = 4;

  // True if and only if the behaviour of the module should not depend on the
  // value of the variable, in which case stores to the variable can be
  // performed in an arbitrary fashion.
  bool value_is_irrelevant = 5;

}

message TransformationAddImageSampleUnusedComponents {

  // A transformation that adds unused components to an image sample coordinate.

  // An vector id with the original coordinate and the unused components.
  uint32 coordinate_with_unused_components_id = 1;

  // A descriptor for an image sample instruction.
  InstructionDescriptor instruction_descriptor = 2;

}

message TransformationAddLocalVariable {

  // Adds a local variable of the given type (which must be a pointer with
  // Function storage class) to the given function, initialized to the given
  // id.

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

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

  // The id of the function to which the local variable should be added
  uint32 function_id = 3;

  // Initial value of the variable
  uint32 initializer_id = 4;

  // True if and only if the behaviour of the module should not depend on the
  // value of the variable, in which case stores to the variable can be
  // performed in an arbitrary fashion.
  bool value_is_irrelevant = 5;

}

message TransformationAddLoopPreheader {

  // A transformation that adds a loop preheader block before the given loop header.

  // The id of the loop header block
  uint32 loop_header_block = 1;

  // A fresh id for the preheader block
  uint32 fresh_id = 2;

  // Fresh ids for splitting the OpPhi instructions in the header.
  // A new OpPhi instruction in the preheader is needed for each OpPhi instruction in the header,
  // if the header has more than one predecessor outside of the loop.
  // This allows turning instructions of the form:
  //
  //   %loop_header_block = OpLabel
  //                 %id1 = OpPhi %type %val1 %pred1_id %val2 %pred2_id %val3 %backedge_block_id
  //
  // into:
  //            %fresh_id = OpLabel
  //             %phi_id1 = OpPhi %type %val1 %pred1_id %val2 %pred2_id
  //                        OpBranch %header_id
  //   %loop_header_block = OpLabel
  //                 %id1 = OpPhi %type %phi_id1 %fresh_id %val3 %backedge_block_id
  repeated uint32 phi_id = 3;

}

message TransformationAddLoopToCreateIntConstantSynonym {
  // A transformation that uses a loop to create a synonym for an integer
  // constant C (scalar or vector) using an initial value I, a step value S and
  // a number of iterations N such that C = I - N * S. For each iteration, S is
  // subtracted from the total.
  // The loop can be made up of one or two blocks, and it is inserted before a
  // block with a single predecessor. In the one-block case, it is of the form:
  //
  //            %loop_id = OpLabel
  //             %ctr_id = OpPhi %int %int_0 %pred %incremented_ctr_id %loop_id
  //            %temp_id = OpPhi %type_of_I %I %pred %eventual_syn_id %loop_id
  //    %eventual_syn_id = OpISub %type_of_I %temp_id %step_val_id
  // %incremented_ctr_id = OpIAdd %int %ctr_id %int_1
  //            %cond_id = OpSLessThan %bool %incremented_ctr_id %num_iterations_id
  //                       OpLoopMerge %block_after_loop_id %loop_id None
  //                       OpBranchConditional %cond_id %loop_id %block_after_loop_id
  //
  // A new OpPhi instruction is then added to %block_after_loop_id, as follows:
  //
  //  %block_after_loop_id = OpLabel
  //               %syn_id = OpPhi %type_of_I %eventual_syn_id %loop_id
  //
  // This can be translated, assuming that N > 0, to:
  // int syn = I;
  // for (int ctr = 0; ctr < N; ctr++) syn = syn - S;
  //
  // All existing OpPhi instructions in %block_after_loop_id are also updated
  // to reflect the fact that its predecessor is now %loop_id.

  // The following are existing ids.

  // The id of the integer constant C that we want a synonym of.
  uint32 constant_id = 1;

  // The id of the initial value integer constant I.
  uint32 initial_val_id = 2;

  // The id of the step value integer constant S.
  uint32 step_val_id = 3;

  // The id of the integer scalar constant, its value being the number of
  // iterations N.
  uint32 num_iterations_id = 4;

  // The label id of the block before which the loop must be inserted.
  uint32 block_after_loop_id = 5;


  // The following are fresh ids.

  // A fresh id for the synonym.
  uint32 syn_id = 6;

  // A fresh id for the label of the loop,
  uint32 loop_id = 7;

  // A fresh id for the counter.
  uint32 ctr_id = 8;

  // A fresh id taking the value I - S * ctr at the ctr-th iteration.
  uint32 temp_id = 9;

  // A fresh id taking the value I - S * (ctr + 1) at the ctr-th iteration, and
  // thus I - S * N at the last iteration.
  uint32 eventual_syn_id = 10;

  // A fresh id for the incremented counter.
  uint32 incremented_ctr_id = 11;

  // A fresh id for the loop condition.
  uint32 cond_id = 12;

  // The instructions in the loop can also be laid out in two basic blocks, as follows:
  //
  //  %loop_id = OpLabel
  //   %ctr_id = OpPhi %int %int_0 %pred %incremented_ctr_id %loop_id
  //  %temp_id = OpPhi %type_of_I %I %pred %eventual_syn_id %loop_id
  //             OpLoopMerge %block_after_loop_id %additional_block_id None
  //             OpBranch %additional_block_id
  //
  //  %additional_block_id = OpLabel
  //      %eventual_syn_id = OpISub %type_of_I %temp_id %step_val_id
  //   %incremented_ctr_id = OpIAdd %int %ctr_id %int_1
  //              %cond_id = OpSLessThan %bool %incremented_ctr_id %num_iterations_id
  //                         OpBranchConditional %cond_id %loop_id %block_after_loop_id

  // A fresh id for the additional block. If this is 0, it means that only one
  // block is to be created.
  uint32 additional_block_id = 13;
}

message TransformationAddNoContractionDecoration {

  // Applies OpDecorate NoContraction to the given result id

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

}

message TransformationAddOpPhiSynonym {

  // Adds an OpPhi instruction at the start of a block with n predecessors (pred_1, pred_2, ..., pred_n)
  // and n related ids (id_1, id_2, ..., id_n) which are pairwise synonymous.
  // The instruction will be of the form:
  //       %fresh_id = OpPhi %type %id_1 %pred_1 %id_2 %pred_2 ... %id_n %pred_n
  // and fresh_id will be recorded as being synonymous with all the other ids.

  // Label id of the block
  uint32 block_id = 1;

  // Pairs (pred_i, id_i)
  repeated UInt32Pair pred_to_id = 2;

  // Fresh id for the new instruction
  uint32 fresh_id = 3;
}

message TransformationAddParameter {

  // Adds a new parameter into the function.

  // Result id of the function to add parameters to.
  uint32 function_id = 1;

  // Fresh id for a new parameter.
  uint32 parameter_fresh_id = 2;

  // Type id for a new parameter.
  uint32 parameter_type_id = 3;

  // A map that maps from the OpFunctionCall id to the id that will be passed as the new
  // parameter at that call site. It must have the same type as that of the new parameter.
  repeated UInt32Pair call_parameter_ids = 4;

  // A fresh id for a new function type. This might not be used
  // if a required function type already exists or if we can change
  // the old function type.
  uint32 function_type_fresh_id = 5;

}

message TransformationAddRelaxedDecoration {

  // Applies OpDecorate RelaxedPrecision to the given result id

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

}

message TransformationAddSpecConstantOp {

  // Adds OpSpecConstantOp into the module.

  // Result id for the new instruction.
  uint32 fresh_id = 1;

  // Type id for the new instruction.
  uint32 type_id = 2;

  // Opcode operand of the OpSpecConstantOp instruction.
  uint32 opcode = 3;

  // Operands of the |opcode| instruction.
  repeated InstructionOperand operand = 4;

}

message TransformationAddSynonym {

  // Adds a |synonymous_instruction| before |insert_before| instruction with
  // and creates a fact that |result_id| and the result id of |synonymous_instruction|
  // are synonymous.

  // Result id of the first synonym.
  uint32 result_id = 1;

  // Type of the synonym to apply. Some types might produce instructions
  // with commutative operands. Such types do not specify the order of the
  // operands since we have a special transformation to swap commutable operands.
  //
  // TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/3499):
  //  Consider adding more types here.
  enum SynonymType {
    // New synonym is derived by adding zero to the |result_id|.
    ADD_ZERO = 0;

    // New synonym is derived by subtracting zero from the |result_id|.
    SUB_ZERO = 1;

    // New synonym is derived by multiplying |result_id| by one.
    MUL_ONE = 2;

    // New synonym is derived by applying OpCopyObject instruction to |result_id|.
    COPY_OBJECT = 3;

    // New synonym is derived by applying OpLogicalOr to |result_id| with the second
    // operand being 'false'.
    LOGICAL_OR = 4;

    // New synonym is derived by applying OpLogicalAnd to |result_id| with the second
    // operand being 'true'.
    LOGICAL_AND = 5;
  }

  // Type of the synonym to create. See SynonymType for more details.
  SynonymType synonym_type = 2;

  // Fresh result id for a created synonym.
  uint32 synonym_fresh_id = 3;

  // An instruction to insert a new synonym before.
  InstructionDescriptor insert_before = 4;

}

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 TransformationAdjustBranchWeights {

  // A transformation that adjusts the branch weights
  // of a branch conditional instruction.

  // A descriptor for a branch conditional instruction.
  InstructionDescriptor instruction_descriptor = 1;

  // Branch weights of a branch conditional instruction.
  UInt32Pair branch_weights = 2;

}

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 TransformationCompositeInsert {

  // A transformation that adds an instruction OpCompositeInsert which creates
  // a new composite from an existing composite, with an element inserted.

  // A descriptor for an instruction before which the new instruction
  // OpCompositeInsert should be inserted.
  InstructionDescriptor instruction_to_insert_before = 1;

  // Result id of the inserted OpCompositeInsert instruction.
  uint32 fresh_id = 2;

  // Id of the composite used as the basis for the insertion.
  uint32 composite_id = 3;

  // Id of the object to be inserted.
  uint32 object_id = 4;

  // Indices that indicate which part of the composite should be inserted into.
  repeated uint32 index = 5;

}

message TransformationComputeDataSynonymFactClosure {

  // A transformation that impacts the fact manager only, forcing a computation
  // of the closure of data synonym facts, so that e.g. if the components of
  // vectors v and w are known to be pairwise synonymous, it is deduced that v
  // and w are themselves synonymous.

  // When searching equivalence classes for implied facts, equivalence classes
  // larger than this size will be skipped.
  uint32 maximum_equivalence_class_size = 1;

}

message TransformationDuplicateRegionWithSelection {

  // A transformation that inserts a conditional statement with a boolean expression
  // of arbitrary value and duplicates a given single-entry, single-exit region, so
  // that it is present in each conditional branch and will be executed regardless
  // of which branch will be taken.

  // Fresh id for a label of the new entry block.
  uint32 new_entry_fresh_id = 1;

  // Id for a boolean expression.
  uint32 condition_id = 2;

  // Fresh id for a label of the merge block of the conditional.
  uint32 merge_label_fresh_id = 3;

  // Block id of the entry block of the original region.
  uint32 entry_block_id = 4;

  // Block id of the exit block of the original region.
  uint32 exit_block_id = 5;

  // Map that maps from a label in the original region to the corresponding label
  // in the duplicated region.
  repeated UInt32Pair original_label_to_duplicate_label = 6;

  // Map that maps from a result id in the original region to the corresponding
  // result id in the duplicated region.
  repeated UInt32Pair original_id_to_duplicate_id = 7;

  // Map that maps from a result id in the original region to the result id of the
  // corresponding OpPhi instruction.
  repeated UInt32Pair original_id_to_phi_id = 8;
}

message TransformationEquationInstruction {

  // A transformation that adds an instruction to the module that defines an
  // equation between its result id and input operand ids, such that the
  // equation is guaranteed to hold at any program point where all ids involved
  // are available (i.e. at any program point dominated by the instruction).

  // The result id of the new instruction
  uint32 fresh_id = 1;

  // The instruction's opcode
  uint32 opcode = 2;

  // The input operands to the instruction
  repeated uint32 in_operand_id = 3;

  // A descriptor for an instruction in a block before which the new
  // instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 4;

}

message TransformationFlattenConditionalBranch {

  // A transformation that takes a selection construct with a header
  // containing an OpBranchConditional instruction and flattens it.
  // For example, something of the form:
  //
  // %1 = OpLabel
  //      [header instructions]
  //      OpSelectionMerge %4 None
  //      OpBranchConditional %cond %2 %3
  // %2 = OpLabel
  //      [true branch instructions]
  //      OpBranch %4
  // %3 = OpLabel
  //      [false branch instructions]
  //      OpBranch %4
  // %4 = OpLabel
  //      ...
  //
  // becomes:
  //
  // %1 = OpLabel
  //      [header instructions]
  //      OpBranch %2
  // %2 = OpLabel
  //      [true branch instructions]
  //      OpBranch %3
  // %3 = OpLabel
  //      [false branch instructions]
  //      OpBranch %4
  // %4 = OpLabel
  //      ...
  //
  // If all of the instructions in the true or false branches have
  // no side effects, this is semantics-preserving.
  // Side-effecting instructions will instead be enclosed by smaller
  // conditionals. For more details, look at the definition for the
  // SideEffectWrapperInfo message.
  //
  // Nested conditionals or loops are not supported. The false branch
  // could also be executed before the true branch, depending on the
  // |true_branch_first| field.

  // The label id of the header block
  uint32 header_block_id = 1;

  // A boolean field deciding the order in which the original branches
  // will be laid out: the true branch will be laid out first iff this
  // field is true.
  bool true_branch_first = 2;

  // A list of instructions with side effects, which must be enclosed
  // inside smaller conditionals before flattening the main one, and
  // the corresponding fresh ids and module ids needed.
  repeated SideEffectWrapperInfo side_effect_wrapper_info = 3;
}

message TransformationFunctionCall {

  // A transformation that introduces an OpFunctionCall instruction.  The call
  // must not make the module's call graph cyclic.  Beyond that, if the call
  // is in a dead block it can be to any function with arbitrary suitably-typed
  // arguments; otherwise it must be to a livesafe function, with injected
  // variables as pointer arguments and arbitrary non-pointer arguments.

  // A fresh id for the result of the call
  uint32 fresh_id = 1;

  // Id of the function to be called
  uint32 callee_id = 2;

  // Ids for arguments to the function
  repeated uint32 argument_id = 3;

  // A descriptor for an instruction in a block before which the new
  // OpFunctionCall instruction should be inserted
  InstructionDescriptor instruction_to_insert_before = 4;

}

message TransformationInlineFunction {

  // This transformation inlines a function by mapping the function instructions to fresh ids.

  // Result id of the function call instruction.
  uint32 function_call_id = 1;

  // For each result id defined by the called function,
  // this map provides an associated fresh id that can
  // be used in the inlined version of the function call.
  repeated UInt32Pair result_id_map = 2;

}

message TransformationInvertComparisonOperator {

  // For some instruction with result id |operator_id| that
  // represents a binary comparison operator (e.g. <, >, <=), this transformation
  // will replace that instruction's result id with |fresh_id|,
  // invert the opcode (< will become >=) and insert OpLogicalNot
  // instruction with result id |operator_id| below.

  // Result id of the instruction to invert.
  uint32 operator_id = 1;

  // Fresh id that will be used by the operator after the inversion.
  uint32 fresh_id = 2;

}

message TransformationLoad {

  // Transformation that adds an OpLoad instruction from a pointer into an id.

  // The result of the load instruction
  uint32 fresh_id = 1;

  // The pointer to be loaded from
  uint32 pointer_id = 2;

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

}

message TransformationMakeVectorOperationDynamic {

  // A transformation that replaces the OpCompositeExtract and OpCompositeInsert
  // instructions with the OpVectorExtractDynamic and OpVectorInsertDynamic instructions.

  // The composite instruction result id.
  uint32 instruction_result_id = 1;

  // The OpCompositeExtract/Insert instructions accept integer literals as indices to the composite object.
  // However, the OpVectorInsert/ExtractDynamic instructions require its single index to be an integer instruction.
  // This is the result id of the integer instruction.
  uint32 constant_index_id = 2;

}

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 TransformationMergeFunctionReturns {

  // A transformation that modifies a function so that it does not return early,
  // so it only has one return statement (ignoring unreachable blocks).
  //
  // The function is enclosed inside an outer loop, that is only executed once,
  // and whose merge block is the new return block of the function.
  //
  // Each return instruction is replaced by:
  //     OpBranch %innermost_loop_merge
  // where %innermost_loop_merge is the innermost loop containing the return
  // instruction.
  //
  // Each merge block whose associated loop contains return instructions is
  // changed so that it branches to the merge block of the loop containing it,
  // as explained in the comments to the ReturnMergingInfo message.
  //
  // The new return block (the merge block of the new outer loop) will be of
  // the following form (if the return type is not void):
  //  %outer_return_id = OpLabel
  //   %return_val_id = OpPhi %return_type %val1 %block_1 %val2 %block_2 ...
  //                    OpReturnValue %return_val_id
  // where %block_k is either a return block that, in the original function, is
  // outside of any loops, or the merge block of a loop that contains return
  // instructions and is not, originally, nested inside another loop, and
  // %block_k is the corresponding return value.
  // If the function has void type, there will be no OpPhi instruction and the
  // last instruction will be OpReturn.

  // The id of the function to which the transformation is being applied.
  uint32 function_id = 1;

  // A fresh id for the header of the new outer loop.
  uint32 outer_header_id = 2;

  // A fresh id for the new return block of the function,
  // i.e. the merge block of the new outer loop.
  uint32 outer_return_id = 3;

  // A fresh id for the value that will be returned.
  // This is ignored if the function has void return type.
  uint32 return_val_id = 4;

  // An existing id of the same type as the return value, which is
  // available to use at the end of the entry block.
  // This is ignored if the function has void return type or if no
  // loops in the function contain a return instruction.
  // If the function is not void, the transformation will add an
  // OpPhi instruction to each merge block whose associated loop
  // contains at least a return instruction. The value associated
  // with existing predecessors from which the function cannot be
  // returning will be this id, used as a placeholder.
  uint32 any_returnable_val_id = 5;

  // The information needed to modify the merge blocks of
  // loops containing return instructions.
  repeated ReturnMergingInfo return_merging_info = 6;
}

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 TransformationMoveInstructionDown {

  // Swaps |instruction| with the next instruction in the block.

  // The instruction to move down.
  InstructionDescriptor instruction = 1;

}

message TransformationMutatePointer {

  // Backs up value of the pointer, writes into the pointer and
  // restores the original value.

  // Result id of the pointer instruction to mutate.
  uint32 pointer_id = 1;

  // Fresh id for the OpLoad instruction.
  uint32 fresh_id = 2;

  // Instruction to insert backup, mutation and restoration code before.
  InstructionDescriptor insert_before = 3;

}

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 TransformationPermuteFunctionParameters {

  // A transformation that, given a non-entry-point function taking n
  // parameters and a permutation of the set [0, n-1]:
  //   - Introduces a new function type that is the same as the original
  //     function's type but with the order of arguments permuted
  //     (only if it doesn't already exist)
  //   - Changes the type of the function to this type
  //   - Adjusts all calls to the function so that their arguments are permuted

  // Function, whose parameters will be permuted
  uint32 function_id = 1;

  // Fresh id for a new type of the function. This might not be used
  // if a required function type already exists or if we can change
  // the old function type.
  uint32 function_type_fresh_id = 2;

  // An array of size |n|, where |n| is a number of arguments to a function
  // with |function_id|. For each i: 0 <= permutation[i] < n.
  //
  // i-th element of this array contains a position for an i-th
  // function's argument (i.e. i-th argument will be permutation[i]-th
  // after running this transformation)
  repeated uint32 permutation = 3;

}

message TransformationPermutePhiOperands {

  // Permutes operands of some OpPhi instruction.

  // Result id of the instruction to apply the transformation to.
  uint32 result_id = 1;

  // A sequence of numbers in the range [0, n/2 - 1] where |n| is the number
  // of operands of the OpPhi instruction with |result_id|.
  repeated uint32 permutation = 2;

}

message TransformationPropagateInstructionDown {

  // Propagates an instruction from |block_id| into its successors.
  // Concretely, the transformation clones the propagated instruction
  // into some of the successors of |block_id| and removes the original
  // instruction. Additionally, an OpPhi instruction may be added to make sure
  // that the transformation can be applied in various scenarios.
  //
  // Note that the instruction might not be propagated down into every successor
  // of |block_id| since it might make the module invalid.

  // Id of the block to propagate an instruction from. The decision on what
  // instruction to propagate is made based on whether the instruction interacts
  // with memory, whether that instruction is used in its block etc (see the
  // transformation class for more details).
  uint32 block_id = 1;

  // A fresh id for an OpPhi instruction. This might not be used by the
  // transformation since an OpPhi instruction is created only if needed
  // (e.g. an instruction is propagated into divergent blocks).
  uint32 phi_fresh_id = 2;

  // A map from the id of some successor of the |block_id| to the fresh id.
  // The map contains a fresh id for at least every successor of the |block_id|.
  // Every fresh id in the map corresponds to the result id of the clone,
  // propagated into the corresponding successor block. This transformation
  // might use overflow ids if they are available and this field doesn't account
  // for every successor of |block_id|.
  repeated UInt32Pair successor_id_to_fresh_id = 3;

}

message TransformationPropagateInstructionUp {

  // Propagates an instruction in the block into the block's predecessors.
  // Concretely, this transformation clones some particular instruction from
  // the |block_id| into every block's predecessor and replaces the original
  // instruction with OpPhi. Take a look at the transformation class to learn
  // more about how we choose what instruction to propagate.

  // Id of the block to propagate an instruction from.
  uint32 block_id = 1;

  // A map from the id of some predecessor of the |block_id| to the fresh id.
  // The map contains a fresh id for at least every predecessor of the |block_id|.
  // The instruction is propagated by creating a number of clones - one clone for
  // each predecessor. Fresh ids from this field are used as result ids of cloned
  // instructions.
  repeated UInt32Pair predecessor_id_to_fresh_id = 2;

}

message TransformationPushIdThroughVariable {

  // A transformation that makes |value_synonym_id| and |value_id| to be
  // synonymous by storing |value_id| into |variable_id| and
  // loading |variable_id| to |value_synonym_id|.

  // The value to be stored.
  uint32 value_id = 1;

  // A fresh id for the result of the load instruction.
  uint32 value_synonym_id = 2;

  // A fresh id for the variable to be stored to.
  uint32 variable_id = 3;

  // Constant to initialize the variable from.
  uint32 initializer_id = 4;

  // The variable storage class (global or local).
  uint32 variable_storage_class = 5;

  // A descriptor for an instruction which the new OpStore
  // and OpLoad instructions might be inserted before.
  InstructionDescriptor instruction_descriptor = 6;

}

message TransformationRecordSynonymousConstants {

  // A transformation that, given the IDs to two synonymous constants,
  // records the fact that they are synonymous. The module is not changed.
  // Two constants are synonymous if:
  // - they have the same type (ignoring the presence of integer sign)
  // - they have the same opcode (one of OpConstant, OpConstantTrue,
  //   OpConstantFalse, OpConstantNull)
  // - they have the same value
  // If the types are the same, OpConstantNull is equivalent to
  // OpConstantFalse or OpConstant with value zero.

  // The id of a constant
  uint32 constant1_id = 1;

  // The id of the synonym
  uint32 constant2_id = 2;

}

message TransformationReplaceAddSubMulWithCarryingExtended {

  // Replaces OpIAdd with OpIAddCarry, OpISub with OpISubBorrow, OpIMul
  // with OpUMulExtended or OpSMulExtended (depending on the signedness
  // of the operands) and stores the result into a |struct_fresh_id|.
  // In the original instruction the result type id and the type ids of
  // the operands must be the same. Then the transformation extracts
  // the first element of the result into the original |result_id|.
  // This value is the same as the result of the original instruction.

  // The fresh id of the intermediate result.
  uint32 struct_fresh_id = 1;

  // The result id of the original instruction.
  uint32 result_id = 2;

}

message TransformationReplaceBranchFromDeadBlockWithExit {

  // Given a dead block that ends with OpBranch, replaces OpBranch with an
  // "exit" instruction; one of OpReturn/OpReturnValue, OpKill (in a fragment
  // shader) or OpUnreachable.

  // The dead block whose terminator is to be replaced.
  uint32 block_id = 1;

  // The opcode of the new terminator.
  uint32 opcode = 2;

  // Ignored unless opcode is OpReturnValue, in which case this field provides
  // a suitable result id to be returned.
  uint32 return_value_id = 3;

}

message TransformationReplaceParameterWithGlobal {

  // Removes parameter with result id |parameter_id| from its function
  // and creates a global variable to pass its value to the function instead.

  // Fresh id for a new function type. This might not be used if a required
  // function type already exists or if we can change the old function type.
  uint32 function_type_fresh_id = 2;

  // Result id of the OpFunctionParameter instruction to remove.
  uint32 parameter_id = 3;

  // Fresh id of a global variable used to pass parameter's value to the function.
  uint32 global_variable_fresh_id = 4;

}

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 TransformationReplaceCopyMemoryWithLoadStore {

  // A transformation that replaces instructions OpCopyMemory with loading
  // the source variable to an intermediate value and storing this value into the
  // target variable of the original OpCopyMemory instruction.

  // The intermediate value.
  uint32 fresh_id = 1;

  // The instruction descriptor to OpCopyMemory. It is necessary, because
  // OpCopyMemory doesn't have a result id.
  InstructionDescriptor copy_memory_instruction_descriptor = 2;
}

message TransformationReplaceCopyObjectWithStoreLoad {

  // A transformation that replaces instruction OpCopyObject with
  // storing into a new variable and immediately loading from this
  // variable to |result_id| of the original OpCopyObject instruction.

  // The result id of initial OpCopyObject instruction
  uint32 copy_object_result_id = 1;

  // A fresh id for the variable to be stored to.
  uint32 fresh_variable_id = 2;

  // The variable storage class (Function or Private).
  uint32 variable_storage_class = 3;

  // Constant to initialize the variable with.
  uint32 variable_initializer_id = 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 TransformationReplaceIrrelevantId {

  // Replaces an irrelevant id with another id of the same type.

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

  // The replacement id
  uint32 replacement_id = 2;
}

message TransformationReplaceLinearAlgebraInstruction {

  // Replaces a linear algebra instruction with its
  // mathematical definition.

  // The fresh ids needed to apply the transformation.
  repeated uint32 fresh_ids = 1;

  // A descriptor for a linear algebra instruction.
  InstructionDescriptor instruction_descriptor = 2;

}

message TransformationReplaceLoadStoreWithCopyMemory {
  // A transformation that takes a pair of instruction descriptors
  // to OpLoad and OpStore that have the same intermediate value
  // and replaces the OpStore with an equivalent OpCopyMemory.

  // The instruction descriptor to OpLoad
  InstructionDescriptor load_instruction_descriptor = 1;

  // The instruction descriptor to OpStore
  InstructionDescriptor store_instruction_descriptor = 2;
}

message TransformationReplaceOpPhiIdFromDeadPredecessor {

  // Replaces one of the ids used by an OpPhi instruction, when
  // the corresponding predecessor is dead, with any available id
  // of the correct type.

  // The result id of the OpPhi instruction.
  uint32 opphi_id = 1;

  // The label id of one of the predecessors of the block containing
  // the OpPhi instruction, corresponding to the id that we want to
  // replace.
  uint32 pred_label_id = 2;

  // The id that, after the transformation, will be associated with
  // the given predecessor.
  uint32 replacement_id = 3;

}

message TransformationReplaceOpSelectWithConditionalBranch {

  // A transformation that takes an OpSelect instruction with a
  // scalar boolean condition and replaces it with a conditional
  // branch and an OpPhi instruction.
  // The OpSelect instruction must be the first instruction in its
  // block, which must have a unique predecessor. The block will
  // become the merge block of a new construct, while its predecessor
  // will become the header.
  // Given the original OpSelect instruction:
  //   %id = OpSelect %type %cond %then %else
  // The branching instruction of the header will be:
  //         OpBranchConditional %cond %true_block_id %false_block_id
  // and the OpSelect instruction will be turned into:
  //   %id = OpPhi %type %then %true_block_id %else %false_block_id
  // At most one of |true_block_id| and |false_block_id| can be zero. In
  // that case, there will be no such block and all references to it
  // will be replaced by %merge_block (where %merge_block is the
  // block containing the OpSelect instruction).

  // The result id of the OpSelect instruction.
  uint32 select_id = 1;

  // A fresh id for the new block that the predecessor of the block
  // containing |select_id| will branch to if the condition holds.
  uint32 true_block_id = 2;

  // A fresh id for the new block that the predecessor of the block
  // containing |select_id| will branch to if the condition does not
  // hold.
  uint32 false_block_id = 3;
}

message TransformationReplaceParamsWithStruct {

  // Replaces parameters of the function with a struct containing
  // values of those parameters.

  // Result ids of parameters to replace.
  repeated uint32 parameter_id = 1;

  // Fresh id for a new function type. This might be unused if the required type
  // already exists in the module or if we can change the old type.
  uint32 fresh_function_type_id = 2;

  // Fresh id for a new struct function parameter to be used as a replacement.
  uint32 fresh_parameter_id = 3;

  // Fresh ids for struct objects containing values of replaced parameters.
  // This field contains a fresh id for at least every result id of a relevant
  // OpFunctionCall instruction.
  repeated UInt32Pair caller_id_to_fresh_composite_id = 4;

}

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 TransformationStore {

  // Transformation that adds an OpStore instruction of an id to a pointer.

  // The pointer to be stored to
  uint32 pointer_id = 1;

  // The value to be stored
  uint32 value_id = 2;

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

}

message TransformationSwapCommutableOperands {

  // A transformation that swaps the operands of a commutative instruction.

  // A descriptor for a commutative instruction
  InstructionDescriptor instruction_descriptor = 1;

}

message TransformationSwapConditionalBranchOperands {

  // Swaps label ids in OpBranchConditional instruction.
  // Additionally, inverts the guard and swaps branch weights
  // if present.

  // Descriptor of the instruction to swap operands of.
  InstructionDescriptor instruction_descriptor = 1;

  // Fresh result id for the OpLogicalNot instruction, used
  // to invert the guard.
  uint32 fresh_id = 2;

}

message TransformationToggleAccessChainInstruction {

  // A transformation that toggles an access chain instruction.

  // A descriptor for an access chain instruction
  InstructionDescriptor instruction_descriptor = 1;

}

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;

}

message TransformationWrapEarlyTerminatorInFunction {

  // Replaces an early terminator - OpKill, OpReachable or OpTerminateInvocation
  // - with a call to a wrapper function for the terminator.

  // A fresh id for a new OpFunctionCall instruction.
  uint32 fresh_id = 1;

  // A descriptor for an OpKill, OpUnreachable or OpTerminateInvocation
  // instruction.
  InstructionDescriptor early_terminator_instruction = 2;

  // An id with the same type as the enclosing function's return type that is
  // available at the early terminator.  This is used to change the terminator
  // to OpReturnValue.  Ignored if the enclosing function has void return type,
  // in which case OpReturn can be used as the new terminator.
  uint32 returned_value_id = 3;

}

message TransformationWrapRegionInSelection {

  // Transforms a single-entry-single-exit region R into
  // if (|branch_condition|) { R } else { R }
  // The entry block for R becomes a selection header and
  // the exit block - a selection merge.
  //
  // Note that the region R is not duplicated. Thus, the effect of
  // this transformation can be represented as follows:
  //              entry
  //  entry        / \
  //    |          \ /
  //    R   -->     R
  //    |           |
  //   exit        exit

  // This behaviour is different from TransformationDuplicateRegionWithSelection
  // that copies the blocks in R.

  // The entry block for the region R.
  uint32 region_entry_block_id = 1;

  // The exit block for the region R.
  uint32 region_exit_block_id = 2;

  // Boolean value for the condition expression.
  bool branch_condition = 3;

}