third_party_spirv-tools/source/opt/aggressive_dead_code_elim_pass.h
2017-07-10 11:45:59 -04:00

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4.9 KiB
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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.
#ifndef LIBSPIRV_OPT_AGGRESSIVE_DCE_PASS_H_
#define LIBSPIRV_OPT_AGGRESSIVE_DCE_PASS_H_
#include <algorithm>
#include <map>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include "basic_block.h"
#include "def_use_manager.h"
#include "module.h"
#include "pass.h"
namespace spvtools {
namespace opt {
// See optimizer.hpp for documentation.
class AggressiveDCEPass : public Pass {
using cbb_ptr = const ir::BasicBlock*;
public:
using GetBlocksFunction =
std::function<std::vector<ir::BasicBlock*>*(const ir::BasicBlock*)>;
AggressiveDCEPass();
const char* name() const override { return "aggressive-dce"; }
Status Process(ir::Module*) override;
private:
// Returns true if |opcode| is a non-ptr access chain op
bool IsNonPtrAccessChain(const SpvOp opcode) const;
// Given a load or store |ip|, return the pointer instruction.
// Also return the base variable's id in |varId|.
ir::Instruction* GetPtr(ir::Instruction* ip, uint32_t* varId);
// Add all store instruction which use |ptrId|, directly or indirectly,
// to the live instruction worklist.
void AddStores(uint32_t ptrId);
// Return true if variable with |varId| is function scope
bool IsLocalVar(uint32_t varId);
// Initialize combinator data structures
void InitCombinatorSets();
// Return true if core operator |op| has no side-effects. Currently returns
// true only for shader capability operations.
// TODO(greg-lunarg): Add kernel and other operators
bool IsCombinator(uint32_t op) const;
// Return true if OpExtInst |inst| has no side-effects. Currently returns
// true only for std.GLSL.450 extensions
// TODO(greg-lunarg): Add support for other extensions
bool IsCombinatorExt(ir::Instruction* inst) const;
// Return true if all extensions in this module are supported by this pass.
// Currently, no extensions are supported. glsl_std_450 extended instructions
// are allowed.
bool AllExtensionsSupported();
// Kill debug or annotation |inst| if target operand is dead.
void KillInstIfTargetDead(ir::Instruction* inst);
// For function |func|, mark all Stores to non-function-scope variables
// and block terminating instructions as live. Recursively mark the values
// they use. When complete, delete any non-live instructions. Return true
// if the function has been modified.
//
// Note: This function does not delete useless control structures. All
// existing control structures will remain. This can leave not-insignificant
// sequences of ultimately useless code.
// TODO(): Remove useless control constructs.
bool AggressiveDCE(ir::Function* func);
void Initialize(ir::Module* module);
Pass::Status ProcessImpl();
// Module this pass is processing
ir::Module* module_;
// Def-Uses for the module we are processing
std::unique_ptr<analysis::DefUseManager> def_use_mgr_;
// Map from function's result id to function
std::unordered_map<uint32_t, ir::Function*> id2function_;
// Live Instruction Worklist. An instruction is added to this list
// if it might have a side effect, either directly or indirectly.
// If we don't know, then add it to this list. Instructions are
// removed from this list as the algorithm traces side effects,
// building up the live instructions set |live_insts_|.
std::queue<ir::Instruction*> worklist_;
// Live Instructions
std::unordered_set<const ir::Instruction*> live_insts_;
// Live Local Variables
std::unordered_set<uint32_t> live_local_vars_;
// Dead instructions. Use for debug cleanup.
std::unordered_set<const ir::Instruction*> dead_insts_;
// Opcodes of shader capability core executable instructions
// without side-effect. This is a whitelist of operators
// that can safely be left unmarked as live at the beginning of
// aggressive DCE.
std::unordered_set<uint32_t> combinator_ops_shader_;
// Opcodes of GLSL_std_450 extension executable instructions
// without side-effect. This is a whitelist of operators
// that can safely be left unmarked as live at the beginning of
// aggressive DCE.
std::unordered_set<uint32_t> combinator_ops_glsl_std_450_;
// Set id for glsl_std_450 extension instructions
uint32_t glsl_std_450_id_;
};
} // namespace opt
} // namespace spvtools
#endif // LIBSPIRV_OPT_AGGRESSIVE_DCE_PASS_H_