source/reduce/remove_struct_member_reduction_opportunity.cpp - SwiftShader - Git at Google

 // Copyright (c) 2020 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.

 #include "source/reduce/remove_struct_member_reduction_opportunity.h"

 #include "source/opt/ir_context.h"

 namespace spvtools {
 namespace reduce {

 bool RemoveStructMemberReductionOpportunity::PreconditionHolds() {
   return struct_type_->NumInOperands() == original_number_of_members_;
 }

 void RemoveStructMemberReductionOpportunity::Apply() {
   std::set<opt::Instruction*> decorations_to_kill;

   // We need to remove decorations that target the removed struct member, and
   // adapt decorations that target later struct members by decrementing the
   // member identifier.  We also need to adapt composite construction
   // instructions so that no id is provided for the member being removed.
   //
   // To do this, we consider every use of the struct type.
   struct_type_->context()->get_def_use_mgr()->ForEachUse(
       struct_type_, [this, &decorations_to_kill](opt::Instruction* user,
                                                  uint32_t /*operand_index*/) {
         switch (user->opcode()) {
           case SpvOpCompositeConstruct:
           case SpvOpConstantComposite:
             // This use is constructing a composite of the struct type, so we
             // must remove the id that was provided for the member we are
             // removing.
             user->RemoveInOperand(member_index_);
             break;
           case SpvOpMemberDecorate:
             // This use is decorating a member of the struct.
             if (user->GetSingleWordInOperand(1) == member_index_) {
               // The member we are removing is being decorated, so we record
               // that we need to get rid of the decoration.
               decorations_to_kill.insert(user);
             } else if (user->GetSingleWordInOperand(1) > member_index_) {
               // A member beyond the one we are removing is being decorated, so
               // we adjust the index that identifies the member.
               user->SetInOperand(1, {user->GetSingleWordInOperand(1) - 1});
             }
             break;
           default:
             break;
         }
       });

   // Get rid of all the decorations that were found to target the member being
   // removed.
   for (auto decoration_to_kill : decorations_to_kill) {
     decoration_to_kill->context()->KillInst(decoration_to_kill);
   }

   // We now look through all instructions that access composites via sequences
   // of indices. Every time we find an index into the struct whose member is
   // being removed, and if the member being accessed comes after the member
   // being removed, we need to adjust the index accordingly.
   //
   // We go through every relevant instruction in every block of every function,
   // and invoke a helper to adjust it.
   auto context = struct_type_->context();
   for (auto& function : *context->module()) {
     for (auto& block : function) {
       for (auto& inst : block) {
         switch (inst.opcode()) {
           case SpvOpAccessChain:
           case SpvOpInBoundsAccessChain: {
             // These access chain instructions take sequences of ids for
             // indexing, starting from input operand 1.
             auto composite_type_id =
                 context->get_def_use_mgr()
                     ->GetDef(context->get_def_use_mgr()
                                  ->GetDef(inst.GetSingleWordInOperand(0))
                                  ->type_id())
                     ->GetSingleWordInOperand(1);
             AdjustAccessedIndices(composite_type_id, 1, false, context, &inst);
           } break;
           case SpvOpPtrAccessChain:
           case SpvOpInBoundsPtrAccessChain: {
             // These access chain instructions take sequences of ids for
             // indexing, starting from input operand 2.
             auto composite_type_id =
                 context->get_def_use_mgr()
                     ->GetDef(context->get_def_use_mgr()
                                  ->GetDef(inst.GetSingleWordInOperand(1))
                                  ->type_id())
                     ->GetSingleWordInOperand(1);
             AdjustAccessedIndices(composite_type_id, 2, false, context, &inst);
           } break;
           case SpvOpCompositeExtract: {
             // OpCompositeExtract uses literals for indexing, starting at input
             // operand 1.
             auto composite_type_id =
                 context->get_def_use_mgr()
                     ->GetDef(inst.GetSingleWordInOperand(0))
                     ->type_id();
             AdjustAccessedIndices(composite_type_id, 1, true, context, &inst);
           } break;
           case SpvOpCompositeInsert: {
             // OpCompositeInsert uses literals for indexing, starting at input
             // operand 2.
             auto composite_type_id =
                 context->get_def_use_mgr()
                     ->GetDef(inst.GetSingleWordInOperand(1))
                     ->type_id();
             AdjustAccessedIndices(composite_type_id, 2, true, context, &inst);
           } break;
           default:
             break;
         }
       }
     }
   }

   // Remove the member from the struct type.
   struct_type_->RemoveInOperand(member_index_);
 }

 void RemoveStructMemberReductionOpportunity::AdjustAccessedIndices(
     uint32_t composite_type_id, uint32_t first_index_input_operand,
     bool literal_indices, opt::IRContext* context,
     opt::Instruction* composite_access_instruction) const {
   // Walk the series of types that are encountered by following the
   // instruction's sequence of indices. For all types except structs, this is
   // routine: the type of the composite dictates what the next type will be
   // regardless of the specific index value.
   uint32_t next_type = composite_type_id;
   for (uint32_t i = first_index_input_operand;
        i < composite_access_instruction->NumInOperands(); i++) {
     auto type_inst = context->get_def_use_mgr()->GetDef(next_type);
     switch (type_inst->opcode()) {
       case SpvOpTypeArray:
       case SpvOpTypeMatrix:
       case SpvOpTypeRuntimeArray:
       case SpvOpTypeVector:
         next_type = type_inst->GetSingleWordInOperand(0);
         break;
       case SpvOpTypeStruct: {
         // Struct types are special becuase (a) we may need to adjust the index
         // being used, if the struct type is the one from which we are removing
         // a member, and (b) the type encountered by following the current index
         // is dependent on the value of the index.

         // Work out the member being accessed.  If literal indexing is used this
         // is simple; otherwise we need to look up the id of the constant
         // instruction being used as an index and get the value of the constant.
         uint32_t index_operand =
             composite_access_instruction->GetSingleWordInOperand(i);
         uint32_t member = literal_indices ? index_operand
                                           : context->get_def_use_mgr()
                                                 ->GetDef(index_operand)
                                                 ->GetSingleWordInOperand(0);

         // The next type we will consider is obtained by looking up the struct
         // type at |member|.
         next_type = type_inst->GetSingleWordInOperand(member);

         if (type_inst == struct_type_ && member > member_index_) {
           // The struct type is the struct from which we are removing a member,
           // and the member being accessed is beyond the member we are removing.
           // We thus need to decrement the index by 1.
           uint32_t new_in_operand;
           if (literal_indices) {
             // With literal indexing this is straightforward.
             new_in_operand = member - 1;
           } else {
             // With id-based indexing this is more tricky: we need to find or
             // create a constant instruction whose value is one less than
             // |member|, and use the id of this constant as the replacement
             // input operand.
             auto constant_inst =
                 context->get_def_use_mgr()->GetDef(index_operand);
             auto int_type = context->get_type_mgr()
                                 ->GetType(constant_inst->type_id())
                                 ->AsInteger();
             auto new_index_constant =
                 opt::analysis::IntConstant(int_type, {member - 1});
             new_in_operand = context->get_constant_mgr()
                                  ->GetDefiningInstruction(&new_index_constant)
                                  ->result_id();
           }
           composite_access_instruction->SetInOperand(i, {new_in_operand});
         }
       } break;
       default:
         assert(0 && "Unknown composite type.");
         break;
     }
   }
 }

 }  // namespace reduce
 }  // namespace spvtools
	// Copyright (c) 2020 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.

	#include "source/reduce/remove_struct_member_reduction_opportunity.h"

	#include "source/opt/ir_context.h"

	namespace spvtools {
	namespace reduce {

	bool RemoveStructMemberReductionOpportunity::PreconditionHolds() {
	return struct_type_->NumInOperands() == original_number_of_members_;
	}

	void RemoveStructMemberReductionOpportunity::Apply() {
	std::set<opt::Instruction*> decorations_to_kill;

	// We need to remove decorations that target the removed struct member, and
	// adapt decorations that target later struct members by decrementing the
	// member identifier. We also need to adapt composite construction
	// instructions so that no id is provided for the member being removed.
	//
	// To do this, we consider every use of the struct type.
	struct_type_->context()->get_def_use_mgr()->ForEachUse(
	struct_type_, [this, &decorations_to_kill](opt::Instruction* user,
	uint32_t /operand_index/) {
	switch (user->opcode()) {
	case SpvOpCompositeConstruct:
	case SpvOpConstantComposite:
	// This use is constructing a composite of the struct type, so we
	// must remove the id that was provided for the member we are
	// removing.
	user->RemoveInOperand(member_index_);
	break;
	case SpvOpMemberDecorate:
	// This use is decorating a member of the struct.
	if (user->GetSingleWordInOperand(1) == member_index_) {
	// The member we are removing is being decorated, so we record
	// that we need to get rid of the decoration.
	decorations_to_kill.insert(user);
	} else if (user->GetSingleWordInOperand(1) > member_index_) {
	// A member beyond the one we are removing is being decorated, so
	// we adjust the index that identifies the member.
	user->SetInOperand(1, {user->GetSingleWordInOperand(1) - 1});
	}
	break;
	default:
	break;
	}
	});

	// Get rid of all the decorations that were found to target the member being
	// removed.
	for (auto decoration_to_kill : decorations_to_kill) {
	decoration_to_kill->context()->KillInst(decoration_to_kill);
	}

	// We now look through all instructions that access composites via sequences
	// of indices. Every time we find an index into the struct whose member is
	// being removed, and if the member being accessed comes after the member
	// being removed, we need to adjust the index accordingly.
	//
	// We go through every relevant instruction in every block of every function,
	// and invoke a helper to adjust it.
	auto context = struct_type_->context();
	for (auto& function : *context->module()) {
	for (auto& block : function) {
	for (auto& inst : block) {
	switch (inst.opcode()) {
	case SpvOpAccessChain:
	case SpvOpInBoundsAccessChain: {
	// These access chain instructions take sequences of ids for
	// indexing, starting from input operand 1.
	auto composite_type_id =
	context->get_def_use_mgr()
	->GetDef(context->get_def_use_mgr()
	->GetDef(inst.GetSingleWordInOperand(0))
	->type_id())
	->GetSingleWordInOperand(1);
	AdjustAccessedIndices(composite_type_id, 1, false, context, &inst);
	} break;
	case SpvOpPtrAccessChain:
	case SpvOpInBoundsPtrAccessChain: {
	// These access chain instructions take sequences of ids for
	// indexing, starting from input operand 2.
	auto composite_type_id =
	context->get_def_use_mgr()
	->GetDef(context->get_def_use_mgr()
	->GetDef(inst.GetSingleWordInOperand(1))
	->type_id())
	->GetSingleWordInOperand(1);
	AdjustAccessedIndices(composite_type_id, 2, false, context, &inst);
	} break;
	case SpvOpCompositeExtract: {
	// OpCompositeExtract uses literals for indexing, starting at input
	// operand 1.
	auto composite_type_id =
	context->get_def_use_mgr()
	->GetDef(inst.GetSingleWordInOperand(0))
	->type_id();
	AdjustAccessedIndices(composite_type_id, 1, true, context, &inst);
	} break;
	case SpvOpCompositeInsert: {
	// OpCompositeInsert uses literals for indexing, starting at input
	// operand 2.
	auto composite_type_id =
	context->get_def_use_mgr()
	->GetDef(inst.GetSingleWordInOperand(1))
	->type_id();
	AdjustAccessedIndices(composite_type_id, 2, true, context, &inst);
	} break;
	default:
	break;
	}
	}
	}
	}

	// Remove the member from the struct type.
	struct_type_->RemoveInOperand(member_index_);
	}

	void RemoveStructMemberReductionOpportunity::AdjustAccessedIndices(
	uint32_t composite_type_id, uint32_t first_index_input_operand,
	bool literal_indices, opt::IRContext* context,
	opt::Instruction* composite_access_instruction) const {
	// Walk the series of types that are encountered by following the
	// instruction's sequence of indices. For all types except structs, this is
	// routine: the type of the composite dictates what the next type will be
	// regardless of the specific index value.
	uint32_t next_type = composite_type_id;
	for (uint32_t i = first_index_input_operand;
	i < composite_access_instruction->NumInOperands(); i++) {
	auto type_inst = context->get_def_use_mgr()->GetDef(next_type);
	switch (type_inst->opcode()) {
	case SpvOpTypeArray:
	case SpvOpTypeMatrix:
	case SpvOpTypeRuntimeArray:
	case SpvOpTypeVector:
	next_type = type_inst->GetSingleWordInOperand(0);
	break;
	case SpvOpTypeStruct: {
	// Struct types are special becuase (a) we may need to adjust the index
	// being used, if the struct type is the one from which we are removing
	// a member, and (b) the type encountered by following the current index
	// is dependent on the value of the index.

	// Work out the member being accessed. If literal indexing is used this
	// is simple; otherwise we need to look up the id of the constant
	// instruction being used as an index and get the value of the constant.
	uint32_t index_operand =
	composite_access_instruction->GetSingleWordInOperand(i);
	uint32_t member = literal_indices ? index_operand
	: context->get_def_use_mgr()
	->GetDef(index_operand)
	->GetSingleWordInOperand(0);

	// The next type we will consider is obtained by looking up the struct
	// type at \|member\|.
	next_type = type_inst->GetSingleWordInOperand(member);

	if (type_inst == struct_type_ && member > member_index_) {
	// The struct type is the struct from which we are removing a member,
	// and the member being accessed is beyond the member we are removing.
	// We thus need to decrement the index by 1.
	uint32_t new_in_operand;
	if (literal_indices) {
	// With literal indexing this is straightforward.
	new_in_operand = member - 1;
	} else {
	// With id-based indexing this is more tricky: we need to find or
	// create a constant instruction whose value is one less than
	// \|member\|, and use the id of this constant as the replacement
	// input operand.
	auto constant_inst =
	context->get_def_use_mgr()->GetDef(index_operand);
	auto int_type = context->get_type_mgr()
	->GetType(constant_inst->type_id())
	->AsInteger();
	auto new_index_constant =
	opt::analysis::IntConstant(int_type, {member - 1});
	new_in_operand = context->get_constant_mgr()
	->GetDefiningInstruction(&new_index_constant)
	->result_id();
	}
	composite_access_instruction->SetInOperand(i, {new_in_operand});
	}
	} break;
	default:
	assert(0 && "Unknown composite type.");
	break;
	}
	}
	}

	} // namespace reduce
	} // namespace spvtools