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// Copyright (c) 2017 The Khronos Group Inc.
// Copyright (c) 2017 Valve Corporation
// Copyright (c) 2017 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/local_single_store_elim_pass.h"
#include "source/cfa.h"
#include "source/util/string_utils.h"
namespace spvtools {
namespace opt {
namespace {
constexpr uint32_t kStoreValIdInIdx = 1;
constexpr uint32_t kVariableInitIdInIdx = 1;
} // namespace
bool LocalSingleStoreElimPass::LocalSingleStoreElim(Function* func) {
bool modified = false;
// Check all function scope variables in |func|.
BasicBlock* entry_block = &*func->begin();
for (Instruction& inst : *entry_block) {
if (inst.opcode() != spv::Op::OpVariable) {
break;
}
modified |= ProcessVariable(&inst);
}
return modified;
}
bool LocalSingleStoreElimPass::AllExtensionsSupported() const {
// If any extension not in allowlist, return false
for (auto& ei : get_module()->extensions()) {
const std::string extName = ei.GetInOperand(0).AsString();
if (extensions_allowlist_.find(extName) == extensions_allowlist_.end())
return false;
}
// only allow NonSemantic.Shader.DebugInfo.100, we cannot safely optimise
// around unknown extended
// instruction sets even if they are non-semantic
for (auto& inst : context()->module()->ext_inst_imports()) {
assert(inst.opcode() == spv::Op::OpExtInstImport &&
"Expecting an import of an extension's instruction set.");
const std::string extension_name = inst.GetInOperand(0).AsString();
if (spvtools::utils::starts_with(extension_name, "NonSemantic.") &&
extension_name != "NonSemantic.Shader.DebugInfo.100") {
return false;
}
}
return true;
}
Pass::Status LocalSingleStoreElimPass::ProcessImpl() {
// Assumes relaxed logical addressing only (see instruction.h)
if (context()->get_feature_mgr()->HasCapability(spv::Capability::Addresses))
return Status::SuccessWithoutChange;
// Do not process if any disallowed extensions are enabled
if (!AllExtensionsSupported()) return Status::SuccessWithoutChange;
// Process all entry point functions
ProcessFunction pfn = [this](Function* fp) {
return LocalSingleStoreElim(fp);
};
bool modified = context()->ProcessReachableCallTree(pfn);
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
LocalSingleStoreElimPass::LocalSingleStoreElimPass() = default;
Pass::Status LocalSingleStoreElimPass::Process() {
InitExtensionAllowList();
return ProcessImpl();
}
void LocalSingleStoreElimPass::InitExtensionAllowList() {
extensions_allowlist_.insert({"SPV_AMD_shader_explicit_vertex_parameter",
"SPV_AMD_shader_trinary_minmax",
"SPV_AMD_gcn_shader",
"SPV_KHR_shader_ballot",
"SPV_AMD_shader_ballot",
"SPV_AMD_gpu_shader_half_float",
"SPV_KHR_shader_draw_parameters",
"SPV_KHR_subgroup_vote",
"SPV_KHR_8bit_storage",
"SPV_KHR_16bit_storage",
"SPV_KHR_device_group",
"SPV_KHR_multiview",
"SPV_NVX_multiview_per_view_attributes",
"SPV_NV_viewport_array2",
"SPV_NV_stereo_view_rendering",
"SPV_NV_sample_mask_override_coverage",
"SPV_NV_geometry_shader_passthrough",
"SPV_AMD_texture_gather_bias_lod",
"SPV_KHR_storage_buffer_storage_class",
"SPV_KHR_variable_pointers",
"SPV_AMD_gpu_shader_int16",
"SPV_KHR_post_depth_coverage",
"SPV_KHR_shader_atomic_counter_ops",
"SPV_EXT_shader_stencil_export",
"SPV_EXT_shader_viewport_index_layer",
"SPV_AMD_shader_image_load_store_lod",
"SPV_AMD_shader_fragment_mask",
"SPV_EXT_fragment_fully_covered",
"SPV_AMD_gpu_shader_half_float_fetch",
"SPV_GOOGLE_decorate_string",
"SPV_GOOGLE_hlsl_functionality1",
"SPV_NV_shader_subgroup_partitioned",
"SPV_EXT_descriptor_indexing",
"SPV_NV_fragment_shader_barycentric",
"SPV_NV_compute_shader_derivatives",
"SPV_NV_shader_image_footprint",
"SPV_NV_shading_rate",
"SPV_NV_mesh_shader",
"SPV_EXT_mesh_shader",
"SPV_NV_ray_tracing",
"SPV_KHR_ray_query",
"SPV_EXT_fragment_invocation_density",
"SPV_EXT_physical_storage_buffer",
"SPV_KHR_physical_storage_buffer",
"SPV_KHR_terminate_invocation",
"SPV_KHR_subgroup_uniform_control_flow",
"SPV_KHR_integer_dot_product",
"SPV_EXT_shader_image_int64",
"SPV_KHR_non_semantic_info",
"SPV_KHR_uniform_group_instructions",
"SPV_KHR_fragment_shader_barycentric",
"SPV_KHR_vulkan_memory_model",
"SPV_NV_bindless_texture",
"SPV_EXT_shader_atomic_float_add",
"SPV_EXT_fragment_shader_interlock",
"SPV_NV_compute_shader_derivatives"});
}
bool LocalSingleStoreElimPass::ProcessVariable(Instruction* var_inst) {
std::vector<Instruction*> users;
FindUses(var_inst, &users);
Instruction* store_inst = FindSingleStoreAndCheckUses(var_inst, users);
if (store_inst == nullptr) {
return false;
}
bool all_rewritten;
bool modified = RewriteLoads(store_inst, users, &all_rewritten);
// If all uses are rewritten and the variable has a DebugDeclare and the
// variable is not an aggregate, add a DebugValue after the store and remove
// the DebugDeclare.
uint32_t var_id = var_inst->result_id();
if (all_rewritten &&
context()->get_debug_info_mgr()->IsVariableDebugDeclared(var_id)) {
const analysis::Type* var_type =
context()->get_type_mgr()->GetType(var_inst->type_id());
const analysis::Type* store_type = var_type->AsPointer()->pointee_type();
if (!(store_type->AsStruct() || store_type->AsArray())) {
modified |= RewriteDebugDeclares(store_inst, var_id);
}
}
return modified;
}
bool LocalSingleStoreElimPass::RewriteDebugDeclares(Instruction* store_inst,
uint32_t var_id) {
uint32_t value_id = store_inst->GetSingleWordInOperand(1);
bool modified = context()->get_debug_info_mgr()->AddDebugValueForVariable(
store_inst, var_id, value_id, store_inst);
modified |= context()->get_debug_info_mgr()->KillDebugDeclares(var_id);
return modified;
}
Instruction* LocalSingleStoreElimPass::FindSingleStoreAndCheckUses(
Instruction* var_inst, const std::vector<Instruction*>& users) const {
// Make sure there is exactly 1 store.
Instruction* store_inst = nullptr;
// If |var_inst| has an initializer, then that will count as a store.
if (var_inst->NumInOperands() > 1) {
store_inst = var_inst;
}
for (Instruction* user : users) {
switch (user->opcode()) {
case spv::Op::OpStore:
// Since we are in the relaxed addressing mode, the use has to be the
// base address of the store, and not the value being store. Otherwise,
// we would have a pointer to a pointer to function scope memory, which
// is not allowed.
if (store_inst == nullptr) {
store_inst = user;
} else {
// More than 1 store.
return nullptr;
}
break;
case spv::Op::OpAccessChain:
case spv::Op::OpInBoundsAccessChain:
if (FeedsAStore(user)) {
// Has a partial store. Cannot propagate that.
return nullptr;
}
break;
case spv::Op::OpLoad:
case spv::Op::OpImageTexelPointer:
case spv::Op::OpName:
case spv::Op::OpCopyObject:
break;
case spv::Op::OpExtInst: {
auto dbg_op = user->GetCommonDebugOpcode();
if (dbg_op == CommonDebugInfoDebugDeclare ||
dbg_op == CommonDebugInfoDebugValue) {
break;
}
return nullptr;
}
default:
if (!user->IsDecoration()) {
// Don't know if this instruction modifies the variable.
// Conservatively assume it is a store.
return nullptr;
}
break;
}
}
return store_inst;
}
void LocalSingleStoreElimPass::FindUses(
const Instruction* var_inst, std::vector<Instruction*>* users) const {
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
def_use_mgr->ForEachUser(var_inst, [users, this](Instruction* user) {
users->push_back(user);
if (user->opcode() == spv::Op::OpCopyObject) {
FindUses(user, users);
}
});
}
bool LocalSingleStoreElimPass::FeedsAStore(Instruction* inst) const {
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
return !def_use_mgr->WhileEachUser(inst, [this](Instruction* user) {
switch (user->opcode()) {
case spv::Op::OpStore:
return false;
case spv::Op::OpAccessChain:
case spv::Op::OpInBoundsAccessChain:
case spv::Op::OpCopyObject:
return !FeedsAStore(user);
case spv::Op::OpLoad:
case spv::Op::OpImageTexelPointer:
case spv::Op::OpName:
return true;
default:
// Don't know if this instruction modifies the variable.
// Conservatively assume it is a store.
return user->IsDecoration();
}
});
}
bool LocalSingleStoreElimPass::RewriteLoads(
Instruction* store_inst, const std::vector<Instruction*>& uses,
bool* all_rewritten) {
BasicBlock* store_block = context()->get_instr_block(store_inst);
DominatorAnalysis* dominator_analysis =
context()->GetDominatorAnalysis(store_block->GetParent());
uint32_t stored_id;
if (store_inst->opcode() == spv::Op::OpStore)
stored_id = store_inst->GetSingleWordInOperand(kStoreValIdInIdx);
else
stored_id = store_inst->GetSingleWordInOperand(kVariableInitIdInIdx);
*all_rewritten = true;
bool modified = false;
for (Instruction* use : uses) {
if (use->opcode() == spv::Op::OpStore) continue;
auto dbg_op = use->GetCommonDebugOpcode();
if (dbg_op == CommonDebugInfoDebugDeclare ||
dbg_op == CommonDebugInfoDebugValue)
continue;
if (use->opcode() == spv::Op::OpLoad &&
dominator_analysis->Dominates(store_inst, use)) {
modified = true;
context()->KillNamesAndDecorates(use->result_id());
context()->ReplaceAllUsesWith(use->result_id(), stored_id);
context()->KillInst(use);
} else {
*all_rewritten = false;
}
}
return modified;
}
} // namespace opt
} // namespace spvtools