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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 "local_ssa_elim_pass.h"
#include "cfa.h"
#include "iterator.h"
namespace spvtools {
namespace opt {
bool LocalMultiStoreElimPass::EliminateMultiStoreLocal(ir::Function* func) {
// Add Phi instructions to the function.
if (InsertPhiInstructions(func) == Status::SuccessWithoutChange) return false;
// Remove all target variable stores.
bool modified = false;
for (auto bi = func->begin(); bi != func->end(); ++bi) {
std::vector<ir::Instruction*> dead_instructions;
for (auto ii = bi->begin(); ii != bi->end(); ++ii) {
if (ii->opcode() != SpvOpStore) continue;
uint32_t varId;
(void)GetPtr(&*ii, &varId);
if (!IsTargetVar(varId)) continue;
assert(!HasLoads(varId));
dead_instructions.push_back(&*ii);
modified = true;
}
while (!dead_instructions.empty()) {
ir::Instruction* inst = dead_instructions.back();
dead_instructions.pop_back();
DCEInst(inst, [&dead_instructions](ir::Instruction* other_inst) {
auto i = std::find(dead_instructions.begin(), dead_instructions.end(),
other_inst);
if (i != dead_instructions.end()) {
dead_instructions.erase(i);
}
});
}
}
return modified;
}
void LocalMultiStoreElimPass::Initialize(ir::IRContext* c) {
InitializeProcessing(c);
// Initialize extension whitelist
InitExtensions();
};
bool LocalMultiStoreElimPass::AllExtensionsSupported() const {
// If any extension not in whitelist, return false
for (auto& ei : get_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 LocalMultiStoreElimPass::ProcessImpl() {
// Assumes all control flow structured.
// TODO(greg-lunarg): Do SSA rewrite for non-structured control flow
if (!context()->get_feature_mgr()->HasCapability(SpvCapabilityShader))
return Status::SuccessWithoutChange;
// Assumes relaxed logical addressing only (see instruction.h)
// TODO(greg-lunarg): Add support for physical addressing
if (context()->get_feature_mgr()->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 : get_module()->annotations())
if (ai.opcode() == SpvOpGroupDecorate) return Status::SuccessWithoutChange;
// Do not process if any disallowed extensions are enabled
if (!AllExtensionsSupported()) return Status::SuccessWithoutChange;
// Process functions
ProcessFunction pfn = [this](ir::Function* fp) {
return EliminateMultiStoreLocal(fp);
};
bool modified = ProcessEntryPointCallTree(pfn, get_module());
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
LocalMultiStoreElimPass::LocalMultiStoreElimPass() {}
Pass::Status LocalMultiStoreElimPass::Process(ir::IRContext* c) {
Initialize(c);
return ProcessImpl();
}
void LocalMultiStoreElimPass::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
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