SPIRV-Tools/source/opt/local_single_store_elim_pass.cpp
David Neto 760789f58d Transform multiple entry points
Don't stop just after one because of short-circuiting logical-or.
2017-06-20 15:57:47 -04:00

470 lines
15 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_store_elim_pass.h"
#include "cfa.h"
#include "iterator.h"
#include "spirv/1.0/GLSL.std.450.h"
static const int kSpvEntryPointFunctionId = 1;
static const int kSpvStorePtrId = 0;
static const int kSpvStoreValId = 1;
static const int kSpvLoadPtrId = 0;
static const int kSpvAccessChainPtrId = 0;
static const int kSpvTypePointerStorageClass = 0;
static const int kSpvTypePointerTypeId = 1;
// Universal Limit of ResultID + 1
static const int kInvalidId = 0x400000;
namespace spvtools {
namespace opt {
bool LocalSingleStoreElimPass::IsNonPtrAccessChain(const SpvOp opcode) const {
return opcode == SpvOpAccessChain || opcode == SpvOpInBoundsAccessChain;
}
bool LocalSingleStoreElimPass::IsMathType(
const ir::Instruction* typeInst) const {
switch (typeInst->opcode()) {
case SpvOpTypeInt:
case SpvOpTypeFloat:
case SpvOpTypeBool:
case SpvOpTypeVector:
case SpvOpTypeMatrix:
return true;
default:
break;
}
return false;
}
bool LocalSingleStoreElimPass::IsTargetType(
const ir::Instruction* typeInst) const {
if (IsMathType(typeInst))
return true;
if (typeInst->opcode() == SpvOpTypeArray)
return IsMathType(def_use_mgr_->GetDef(typeInst->GetSingleWordOperand(1)));
if (typeInst->opcode() != SpvOpTypeStruct)
return false;
// All struct members must be math type
int nonMathComp = 0;
typeInst->ForEachInId([&nonMathComp,this](const uint32_t* tid) {
ir::Instruction* compTypeInst = def_use_mgr_->GetDef(*tid);
if (!IsMathType(compTypeInst)) ++nonMathComp;
});
return nonMathComp == 0;
}
ir::Instruction* LocalSingleStoreElimPass::GetPtr(
ir::Instruction* ip, uint32_t* varId) {
*varId = ip->GetSingleWordInOperand(
ip->opcode() == SpvOpStore ? kSpvStorePtrId : kSpvLoadPtrId);
ir::Instruction* ptrInst = def_use_mgr_->GetDef(*varId);
ir::Instruction* varInst = ptrInst;
while (IsNonPtrAccessChain(varInst->opcode())) {
*varId = varInst->GetSingleWordInOperand(kSpvAccessChainPtrId);
varInst = def_use_mgr_->GetDef(*varId);
}
return ptrInst;
}
bool LocalSingleStoreElimPass::IsTargetVar(uint32_t varId) {
if (seen_non_target_vars_.find(varId) != seen_non_target_vars_.end())
return false;
if (seen_target_vars_.find(varId) != seen_target_vars_.end())
return true;
const ir::Instruction* varInst = def_use_mgr_->GetDef(varId);
assert(varInst->opcode() == SpvOpVariable);
const uint32_t varTypeId = varInst->type_id();
const ir::Instruction* varTypeInst = def_use_mgr_->GetDef(varTypeId);
if (varTypeInst->GetSingleWordInOperand(kSpvTypePointerStorageClass) !=
SpvStorageClassFunction) {
seen_non_target_vars_.insert(varId);
return false;
}
const uint32_t varPteTypeId =
varTypeInst->GetSingleWordInOperand(kSpvTypePointerTypeId);
ir::Instruction* varPteTypeInst = def_use_mgr_->GetDef(varPteTypeId);
if (!IsTargetType(varPteTypeInst)) {
seen_non_target_vars_.insert(varId);
return false;
}
seen_target_vars_.insert(varId);
return true;
}
bool LocalSingleStoreElimPass::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)) {
if (!HasOnlySupportedRefs(u.inst->result_id()))
return false;
}
else if (op != SpvOpStore && op != SpvOpLoad && op != SpvOpName)
return false;
}
supported_ref_ptrs_.insert(ptrId);
return true;
}
void LocalSingleStoreElimPass::SingleStoreAnalyze(ir::Function* func) {
ssa_var2store_.clear();
non_ssa_vars_.clear();
store2idx_.clear();
store2blk_.clear();
for (auto bi = func->begin(); bi != func->end(); ++bi) {
uint32_t instIdx = 0;
for (auto ii = bi->begin(); ii != bi->end(); ++ii, ++instIdx) {
switch (ii->opcode()) {
case SpvOpStore: {
// Verify store variable is target type
uint32_t varId;
ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
if (non_ssa_vars_.find(varId) != non_ssa_vars_.end())
continue;
if (!HasOnlySupportedRefs(varId)) {
non_ssa_vars_.insert(varId);
continue;
}
if (IsNonPtrAccessChain(ptrInst->opcode())) {
non_ssa_vars_.insert(varId);
ssa_var2store_.erase(varId);
continue;
}
// Verify target type and function storage class
if (!IsTargetVar(varId)) {
non_ssa_vars_.insert(varId);
continue;
}
// Ignore variables with multiple stores
if (ssa_var2store_.find(varId) != ssa_var2store_.end()) {
non_ssa_vars_.insert(varId);
ssa_var2store_.erase(varId);
continue;
}
// Remember pointer to variable's store and it's
// ordinal position in block
ssa_var2store_[varId] = &*ii;
store2idx_[&*ii] = instIdx;
store2blk_[&*ii] = &*bi;
} break;
default:
break;
} // switch
}
}
}
void LocalSingleStoreElimPass::ReplaceAndDeleteLoad(
ir::Instruction* loadInst, uint32_t replId) {
(void) def_use_mgr_->ReplaceAllUsesWith(loadInst->result_id(), replId);
DCEInst(loadInst);
}
LocalSingleStoreElimPass::GetBlocksFunction
LocalSingleStoreElimPass::AugmentedCFGSuccessorsFunction() const {
return [this](const ir::BasicBlock* block) {
auto asmi = augmented_successors_map_.find(block);
if (asmi != augmented_successors_map_.end())
return &(*asmi).second;
auto smi = successors_map_.find(block);
return &(*smi).second;
};
}
LocalSingleStoreElimPass::GetBlocksFunction
LocalSingleStoreElimPass::AugmentedCFGPredecessorsFunction() const {
return [this](const ir::BasicBlock* block) {
auto apmi = augmented_predecessors_map_.find(block);
if (apmi != augmented_predecessors_map_.end())
return &(*apmi).second;
auto pmi = predecessors_map_.find(block);
return &(*pmi).second;
};
}
void LocalSingleStoreElimPass::CalculateImmediateDominators(
ir::Function* func) {
// Compute CFG
vector<ir::BasicBlock*> ordered_blocks;
predecessors_map_.clear();
successors_map_.clear();
for (auto& blk : *func) {
ordered_blocks.push_back(&blk);
blk.ForEachSuccessorLabel([&blk, &ordered_blocks, this](uint32_t sbid) {
successors_map_[&blk].push_back(label2block_[sbid]);
predecessors_map_[label2block_[sbid]].push_back(&blk);
});
}
// Compute Augmented CFG
augmented_successors_map_.clear();
augmented_predecessors_map_.clear();
successors_map_[&pseudo_exit_block_] = {};
predecessors_map_[&pseudo_entry_block_] = {};
auto succ_func = [this](const ir::BasicBlock* b)
{ return &successors_map_[b]; };
auto pred_func = [this](const ir::BasicBlock* b)
{ return &predecessors_map_[b]; };
CFA<ir::BasicBlock>::ComputeAugmentedCFG(
ordered_blocks,
&pseudo_entry_block_,
&pseudo_exit_block_,
&augmented_successors_map_,
&augmented_predecessors_map_,
succ_func,
pred_func);
// Compute Dominators
vector<const ir::BasicBlock*> postorder;
auto ignore_block = [](cbb_ptr) {};
auto ignore_edge = [](cbb_ptr, cbb_ptr) {};
spvtools::CFA<ir::BasicBlock>::DepthFirstTraversal(
ordered_blocks[0], AugmentedCFGSuccessorsFunction(),
ignore_block, [&](cbb_ptr b) { postorder.push_back(b); },
ignore_edge);
auto edges = spvtools::CFA<ir::BasicBlock>::CalculateDominators(
postorder, AugmentedCFGPredecessorsFunction());
idom_.clear();
for (auto edge : edges)
idom_[edge.first] = edge.second;
}
bool LocalSingleStoreElimPass::Dominates(
ir::BasicBlock* blk0, uint32_t idx0,
ir::BasicBlock* blk1, uint32_t idx1) {
if (blk0 == blk1)
return idx0 <= idx1;
ir::BasicBlock* b = blk1;
while (idom_[b] != b) {
b = idom_[b];
if (b == blk0)
return true;
}
return false;
}
bool LocalSingleStoreElimPass::SingleStoreProcess(ir::Function* func) {
CalculateImmediateDominators(func);
bool modified = false;
for (auto bi = func->begin(); bi != func->end(); ++bi) {
uint32_t instIdx = 0;
for (auto ii = bi->begin(); ii != bi->end(); ++ii, ++instIdx) {
if (ii->opcode() != SpvOpLoad)
continue;
uint32_t varId;
ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
// Skip access chain loads
if (IsNonPtrAccessChain(ptrInst->opcode()))
continue;
if (ptrInst->opcode() != SpvOpVariable)
continue;
const auto vsi = ssa_var2store_.find(varId);
if (vsi == ssa_var2store_.end())
continue;
if (non_ssa_vars_.find(varId) != non_ssa_vars_.end())
continue;
// store must dominate load
if (!Dominates(store2blk_[vsi->second], store2idx_[vsi->second], &*bi, instIdx))
continue;
// Use store value as replacement id
uint32_t replId = vsi->second->GetSingleWordInOperand(kSpvStoreValId);
// replace all instances of the load's id with the SSA value's id
ReplaceAndDeleteLoad(&*ii, replId);
modified = true;
}
}
return modified;
}
bool LocalSingleStoreElimPass::HasLoads(uint32_t varId) const {
analysis::UseList* uses = def_use_mgr_->GetUses(varId);
if (uses == nullptr)
return false;
for (auto u : *uses) {
SpvOp op = u.inst->opcode();
// TODO(): The following is slightly conservative. Could be
// better handling of non-store/name.
if (IsNonPtrAccessChain(op) || op == SpvOpCopyObject) {
if (HasLoads(u.inst->result_id()))
return true;
}
else if (op != SpvOpStore && op != SpvOpName)
return true;
}
return false;
}
bool LocalSingleStoreElimPass::IsLiveVar(uint32_t varId) const {
// non-function scope vars are live
const ir::Instruction* varInst = def_use_mgr_->GetDef(varId);
assert(varInst->opcode() == SpvOpVariable);
const uint32_t varTypeId = varInst->type_id();
const ir::Instruction* varTypeInst = def_use_mgr_->GetDef(varTypeId);
if (varTypeInst->GetSingleWordInOperand(kSpvTypePointerStorageClass) !=
SpvStorageClassFunction)
return true;
// test if variable is loaded from
return HasLoads(varId);
}
bool LocalSingleStoreElimPass::IsLiveStore(ir::Instruction* storeInst) {
// get store's variable
uint32_t varId;
(void) GetPtr(storeInst, &varId);
return IsLiveVar(varId);
}
void LocalSingleStoreElimPass::AddStores(
uint32_t ptr_id, std::queue<ir::Instruction*>* insts) {
analysis::UseList* uses = def_use_mgr_->GetUses(ptr_id);
if (uses != nullptr) {
for (auto u : *uses) {
if (IsNonPtrAccessChain(u.inst->opcode()))
AddStores(u.inst->result_id(), insts);
else if (u.inst->opcode() == SpvOpStore)
insts->push(u.inst);
}
}
}
void LocalSingleStoreElimPass::DCEInst(ir::Instruction* inst) {
std::queue<ir::Instruction*> deadInsts;
deadInsts.push(inst);
while (!deadInsts.empty()) {
ir::Instruction* di = deadInsts.front();
// Don't delete labels
if (di->opcode() == SpvOpLabel) {
deadInsts.pop();
continue;
}
// Remember operands
std::queue<uint32_t> ids;
di->ForEachInId([&ids](uint32_t* iid) {
ids.push(*iid);
});
uint32_t varId = 0;
// Remember variable if dead load
if (di->opcode() == SpvOpLoad)
(void) GetPtr(di, &varId);
def_use_mgr_->KillInst(di);
// For all operands with no remaining uses, add their instruction
// to the dead instruction queue.
while (!ids.empty()) {
uint32_t id = ids.front();
analysis::UseList* uses = def_use_mgr_->GetUses(id);
if (uses == nullptr)
deadInsts.push(def_use_mgr_->GetDef(id));
ids.pop();
}
// if a load was deleted and it was the variable's
// last load, add all its stores to dead queue
if (varId != 0 && !IsLiveVar(varId))
AddStores(varId, &deadInsts);
deadInsts.pop();
}
}
bool LocalSingleStoreElimPass::SingleStoreDCE() {
bool modified = false;
for (auto v : ssa_var2store_) {
// check that it hasn't already been DCE'd
if (v.second->opcode() != SpvOpStore)
continue;
if (non_ssa_vars_.find(v.first) != non_ssa_vars_.end())
continue;
if (!IsLiveStore(v.second)) {
DCEInst(v.second);
modified = true;
}
}
return modified;
}
bool LocalSingleStoreElimPass::LocalSingleStoreElim(ir::Function* func) {
bool modified = false;
SingleStoreAnalyze(func);
if (ssa_var2store_.empty())
return false;
modified |= SingleStoreProcess(func);
modified |= SingleStoreDCE();
return modified;
}
void LocalSingleStoreElimPass::Initialize(ir::Module* module) {
module_ = module;
// Initialize function and block maps
id2function_.clear();
label2block_.clear();
for (auto& fn : *module_) {
id2function_[fn.result_id()] = &fn;
for (auto& blk : fn) {
uint32_t bid = blk.id();
label2block_[bid] = &blk;
}
}
// Initialize Target Type Caches
seen_target_vars_.clear();
seen_non_target_vars_.clear();
// Initialize Supported Ref Pointer Cache
supported_ref_ptrs_.clear();
// TODO: Reuse def/use (and other state) from previous passes
def_use_mgr_.reset(new analysis::DefUseManager(consumer(), module_));
// Initialize next unused Id
next_id_ = module_->id_bound();
};
Pass::Status LocalSingleStoreElimPass::ProcessImpl() {
// Assumes logical addressing only
if (module_->HasCapability(SpvCapabilityAddresses))
return Status::SuccessWithoutChange;
bool modified = false;
// Call Mem2Reg on all remaining functions.
for (auto& e : module_->entry_points()) {
ir::Function* fn =
id2function_[e.GetSingleWordOperand(kSpvEntryPointFunctionId)];
modified = LocalSingleStoreElim(fn) || modified;
}
FinalizeNextId(module_);
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
LocalSingleStoreElimPass::LocalSingleStoreElimPass()
: module_(nullptr), def_use_mgr_(nullptr),
pseudo_entry_block_(std::unique_ptr<ir::Instruction>(
new ir::Instruction(SpvOpLabel, 0, 0, {}))),
pseudo_exit_block_(std::unique_ptr<ir::Instruction>(
new ir::Instruction(SpvOpLabel, 0, kInvalidId, {}))),
next_id_(0) {}
Pass::Status LocalSingleStoreElimPass::Process(ir::Module* module) {
Initialize(module);
return ProcessImpl();
}
} // namespace opt
} // namespace spvtools