SPIRV-Tools/source/opt/local_single_block_elim_pass.cpp

235 lines
7.4 KiB
C++

// 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 "local_single_block_elim_pass.h"
#include "iterator.h"
namespace spvtools {
namespace opt {
namespace {
const uint32_t kStoreValIdInIdx = 1;
} // anonymous namespace
bool LocalSingleBlockLoadStoreElimPass::HasOnlySupportedRefs(uint32_t ptrId) {
if (supported_ref_ptrs_.find(ptrId) != supported_ref_ptrs_.end())
return true;
analysis::UseList* uses = def_use_mgr_->GetUses(ptrId);
assert(uses != nullptr);
for (auto u : *uses) {
SpvOp op = u.inst->opcode();
if (IsNonPtrAccessChain(op) || op == SpvOpCopyObject) {
if (!HasOnlySupportedRefs(u.inst->result_id())) return false;
} else if (op != SpvOpStore && op != SpvOpLoad && op != SpvOpName &&
!IsNonTypeDecorate(op))
return false;
}
supported_ref_ptrs_.insert(ptrId);
return true;
}
bool LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElim(
ir::Function* func) {
// Perform local store/load and load/load elimination on each block
bool modified = false;
for (auto bi = func->begin(); bi != func->end(); ++bi) {
var2store_.clear();
var2load_.clear();
pinned_vars_.clear();
for (auto ii = bi->begin(); ii != bi->end(); ++ii) {
switch (ii->opcode()) {
case SpvOpStore: {
// Verify store variable is target type
uint32_t varId;
ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
if (!IsTargetVar(varId))
continue;
if (!HasOnlySupportedRefs(varId))
continue;
// Register the store
if (ptrInst->opcode() == SpvOpVariable) {
// if not pinned, look for WAW
if (pinned_vars_.find(varId) == pinned_vars_.end()) {
auto si = var2store_.find(varId);
if (si != var2store_.end()) {
def_use_mgr_->KillInst(si->second);
}
}
var2store_[varId] = &*ii;
}
else {
assert(IsNonPtrAccessChain(ptrInst->opcode()));
var2store_.erase(varId);
}
pinned_vars_.erase(varId);
var2load_.erase(varId);
} break;
case SpvOpLoad: {
// Verify store variable is target type
uint32_t varId;
ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
if (!IsTargetVar(varId))
continue;
if (!HasOnlySupportedRefs(varId))
continue;
// Look for previous store or load
uint32_t replId = 0;
if (ptrInst->opcode() == SpvOpVariable) {
auto si = var2store_.find(varId);
if (si != var2store_.end()) {
replId = si->second->GetSingleWordInOperand(kStoreValIdInIdx);
}
else {
auto li = var2load_.find(varId);
if (li != var2load_.end()) {
replId = li->second->result_id();
}
}
}
if (replId != 0) {
// replace load's result id and delete load
ReplaceAndDeleteLoad(&*ii, replId);
modified = true;
}
else {
if (ptrInst->opcode() == SpvOpVariable)
var2load_[varId] = &*ii; // register load
pinned_vars_.insert(varId);
}
} break;
case SpvOpFunctionCall: {
// Conservatively assume all locals are redefined for now.
// TODO(): Handle more optimally
var2store_.clear();
var2load_.clear();
pinned_vars_.clear();
} break;
default:
break;
}
}
// Go back and delete useless stores in block
// TODO(greg-lunarg): Consider moving DCE into separate pass
for (auto ii = bi->begin(); ii != bi->end(); ++ii) {
if (ii->opcode() != SpvOpStore)
continue;
if (IsLiveStore(&*ii))
continue;
DCEInst(&*ii);
}
}
return modified;
}
void LocalSingleBlockLoadStoreElimPass::Initialize(ir::Module* module) {
module_ = module;
// Initialize Target Type Caches
seen_target_vars_.clear();
seen_non_target_vars_.clear();
// Clear collections
supported_ref_ptrs_.clear();
// TODO(greg-lunarg): Reuse def/use from previous passes
def_use_mgr_.reset(new analysis::DefUseManager(consumer(), module_));
// Start new ids with next availablein module
InitNextId();
// Initialize extensions whitelist
InitExtensions();
};
bool LocalSingleBlockLoadStoreElimPass::AllExtensionsSupported() const {
// If any extension not in whitelist, return false
for (auto& ei : module_->extensions()) {
const char* extName = reinterpret_cast<const char*>(
&ei.GetInOperand(0).words[0]);
if (extensions_whitelist_.find(extName) == extensions_whitelist_.end())
return false;
}
return true;
}
Pass::Status LocalSingleBlockLoadStoreElimPass::ProcessImpl() {
// Assumes logical addressing only
if (module_->HasCapability(SpvCapabilityAddresses))
return Status::SuccessWithoutChange;
// Do not process if module contains OpGroupDecorate. Additional
// support required in KillNamesAndDecorates().
// TODO(greg-lunarg): Add support for OpGroupDecorate
for (auto& ai : module_->annotations())
if (ai.opcode() == SpvOpGroupDecorate)
return Status::SuccessWithoutChange;
// If any extensions in the module are not explicitly supported,
// return unmodified.
if (!AllExtensionsSupported())
return Status::SuccessWithoutChange;
// Collect all named and decorated ids
FindNamedOrDecoratedIds();
// Process all entry point functions
ProcessFunction pfn = [this](ir::Function* fp) {
return LocalSingleBlockLoadStoreElim(fp);
};
bool modified = ProcessEntryPointCallTree(pfn, module_);
FinalizeNextId();
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElimPass() {}
Pass::Status LocalSingleBlockLoadStoreElimPass::Process(ir::Module* module) {
Initialize(module);
return ProcessImpl();
}
void LocalSingleBlockLoadStoreElimPass::InitExtensions() {
extensions_whitelist_.clear();
extensions_whitelist_.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_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
// Currently do not support extended pointer expressions
"SPV_AMD_gpu_shader_int16",
"SPV_KHR_post_depth_coverage",
"SPV_KHR_shader_atomic_counter_ops",
});
}
} // namespace opt
} // namespace spvtools