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// Copyright (c) 2022 The Khronos Group Inc.
// Copyright (c) 2022 LunarG Inc.
//
// 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/opt/eliminate_dead_input_components_pass.h"
#include <set>
#include <vector>
#include "source/opt/instruction.h"
#include "source/opt/ir_builder.h"
#include "source/opt/ir_context.h"
#include "source/util/bit_vector.h"
namespace {
const uint32_t kAccessChainBaseInIdx = 0;
const uint32_t kAccessChainIndex0InIdx = 1;
const uint32_t kConstantValueInIdx = 0;
const uint32_t kVariableStorageClassInIdx = 0;
} // namespace
namespace spvtools {
namespace opt {
Pass::Status EliminateDeadInputComponentsPass::Process() {
// Current functionality assumes shader capability
if (!context()->get_feature_mgr()->HasCapability(SpvCapabilityShader))
return Status::SuccessWithoutChange;
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
analysis::TypeManager* type_mgr = context()->get_type_mgr();
bool modified = false;
std::vector<std::pair<Instruction*, unsigned>> arrays_to_change;
for (auto& var : context()->types_values()) {
if (var.opcode() != SpvOpVariable) {
continue;
}
analysis::Type* var_type = type_mgr->GetType(var.type_id());
analysis::Pointer* ptr_type = var_type->AsPointer();
if (ptr_type == nullptr) {
continue;
}
if (ptr_type->storage_class() != SpvStorageClassInput) {
continue;
}
const analysis::Array* arr_type = ptr_type->pointee_type()->AsArray();
if (arr_type != nullptr) {
unsigned arr_len_id = arr_type->LengthId();
Instruction* arr_len_inst = def_use_mgr->GetDef(arr_len_id);
if (arr_len_inst->opcode() != SpvOpConstant) {
continue;
}
// SPIR-V requires array size is >= 1, so this works for signed or
// unsigned size
unsigned original_max =
arr_len_inst->GetSingleWordInOperand(kConstantValueInIdx) - 1;
unsigned max_idx = FindMaxIndex(var, original_max);
if (max_idx != original_max) {
ChangeArrayLength(var, max_idx + 1);
modified = true;
}
continue;
}
const analysis::Struct* struct_type = ptr_type->pointee_type()->AsStruct();
if (struct_type == nullptr) continue;
const auto elt_types = struct_type->element_types();
unsigned original_max = static_cast<unsigned>(elt_types.size()) - 1;
unsigned max_idx = FindMaxIndex(var, original_max);
if (max_idx != original_max) {
ChangeStructLength(var, max_idx + 1);
modified = true;
}
}
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
unsigned EliminateDeadInputComponentsPass::FindMaxIndex(Instruction& var,
unsigned original_max) {
unsigned max = 0;
bool seen_non_const_ac = false;
assert(var.opcode() == SpvOpVariable && "must be variable");
context()->get_def_use_mgr()->WhileEachUser(
var.result_id(), [&max, &seen_non_const_ac, var, this](Instruction* use) {
auto use_opcode = use->opcode();
if (use_opcode == SpvOpLoad || use_opcode == SpvOpCopyMemory ||
use_opcode == SpvOpCopyMemorySized ||
use_opcode == SpvOpCopyObject) {
seen_non_const_ac = true;
return false;
}
if (use->opcode() != SpvOpAccessChain &&
use->opcode() != SpvOpInBoundsAccessChain) {
return true;
}
// OpAccessChain with no indices currently not optimized
if (use->NumInOperands() == 1) {
seen_non_const_ac = true;
return false;
}
unsigned base_id = use->GetSingleWordInOperand(kAccessChainBaseInIdx);
USE_ASSERT(base_id == var.result_id() && "unexpected base");
unsigned idx_id = use->GetSingleWordInOperand(kAccessChainIndex0InIdx);
Instruction* idx_inst = context()->get_def_use_mgr()->GetDef(idx_id);
if (idx_inst->opcode() != SpvOpConstant) {
seen_non_const_ac = true;
return false;
}
unsigned value = idx_inst->GetSingleWordInOperand(kConstantValueInIdx);
if (value > max) max = value;
return true;
});
return seen_non_const_ac ? original_max : max;
}
void EliminateDeadInputComponentsPass::ChangeArrayLength(Instruction& arr_var,
unsigned length) {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::ConstantManager* const_mgr = context()->get_constant_mgr();
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
analysis::Pointer* ptr_type =
type_mgr->GetType(arr_var.type_id())->AsPointer();
const analysis::Array* arr_ty = ptr_type->pointee_type()->AsArray();
assert(arr_ty && "expecting array type");
uint32_t length_id = const_mgr->GetUIntConst(length);
analysis::Array new_arr_ty(arr_ty->element_type(),
arr_ty->GetConstantLengthInfo(length_id, length));
analysis::Type* reg_new_arr_ty = type_mgr->GetRegisteredType(&new_arr_ty);
analysis::Pointer new_ptr_ty(reg_new_arr_ty, SpvStorageClassInput);
analysis::Type* reg_new_ptr_ty = type_mgr->GetRegisteredType(&new_ptr_ty);
uint32_t new_ptr_ty_id = type_mgr->GetTypeInstruction(reg_new_ptr_ty);
arr_var.SetResultType(new_ptr_ty_id);
def_use_mgr->AnalyzeInstUse(&arr_var);
// Move arr_var after its new type to preserve order
USE_ASSERT(arr_var.GetSingleWordInOperand(kVariableStorageClassInIdx) !=
SpvStorageClassFunction &&
"cannot move Function variable");
Instruction* new_ptr_ty_inst = def_use_mgr->GetDef(new_ptr_ty_id);
arr_var.RemoveFromList();
arr_var.InsertAfter(new_ptr_ty_inst);
}
void EliminateDeadInputComponentsPass::ChangeStructLength(
Instruction& struct_var, unsigned length) {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::Pointer* ptr_type =
type_mgr->GetType(struct_var.type_id())->AsPointer();
const analysis::Struct* struct_ty = ptr_type->pointee_type()->AsStruct();
assert(struct_ty && "expecting struct type");
const auto orig_elt_types = struct_ty->element_types();
std::vector<const analysis::Type*> new_elt_types;
for (unsigned u = 0; u < length; ++u)
new_elt_types.push_back(orig_elt_types[u]);
analysis::Struct new_struct_ty(new_elt_types);
analysis::Type* reg_new_struct_ty =
type_mgr->GetRegisteredType(&new_struct_ty);
uint32_t new_struct_ty_id = type_mgr->GetTypeInstruction(reg_new_struct_ty);
uint32_t old_struct_ty_id = type_mgr->GetTypeInstruction(struct_ty);
analysis::DecorationManager* deco_mgr = context()->get_decoration_mgr();
deco_mgr->CloneDecorations(old_struct_ty_id, new_struct_ty_id);
analysis::Pointer new_ptr_ty(reg_new_struct_ty, SpvStorageClassInput);
analysis::Type* reg_new_ptr_ty = type_mgr->GetRegisteredType(&new_ptr_ty);
uint32_t new_ptr_ty_id = type_mgr->GetTypeInstruction(reg_new_ptr_ty);
struct_var.SetResultType(new_ptr_ty_id);
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
def_use_mgr->AnalyzeInstUse(&struct_var);
// Move struct_var after its new type to preserve order
USE_ASSERT(struct_var.GetSingleWordInOperand(kVariableStorageClassInIdx) !=
SpvStorageClassFunction &&
"cannot move Function variable");
Instruction* new_ptr_ty_inst = def_use_mgr->GetDef(new_ptr_ty_id);
struct_var.RemoveFromList();
struct_var.InsertAfter(new_ptr_ty_inst);
}
} // namespace opt
} // namespace spvtools
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