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SPIRV-Tools/source/opt/scalar_replacement_pass.cpp
Diego Novillo 9559cdbdf0
Fix #2609 - Handle out-of-bounds scalar replacements. (#2767) 
* Fix #2609 - Handle out-of-bounds scalar replacements.

When SROA tries to do a replacement for an OpAccessChain that is exactly
one element out of bounds, the code was trying to access its internal
array of replacements and segfaulting.

This protects the code from doing this, and it additionally fixes the
way SROA works by not returning failure when it refuses to do a
replacement.  Instead of failing the optimization pass, SROA will now
simply refuse to do the replacement and keep going.

Additionally, this patch fixes the SROA logic to now return a proper status so we can
correctly state that the pass made no changes to the IR if it only found
invalid references.
2019-07-26 12:33:40 -04:00

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// Copyright (c) 2017 Google 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/scalar_replacement_pass.h"
#include <algorithm>
#include <queue>
#include <tuple>
#include <utility>
#include "source/enum_string_mapping.h"
#include "source/extensions.h"
#include "source/opt/reflect.h"
#include "source/opt/types.h"
#include "source/util/make_unique.h"
namespace spvtools {
namespace opt {
Pass::Status ScalarReplacementPass::Process() {
Status status = Status::SuccessWithoutChange;
for (auto& f : *get_module()) {
Status functionStatus = ProcessFunction(&f);
if (functionStatus == Status::Failure)
return functionStatus;
else if (functionStatus == Status::SuccessWithChange)
status = functionStatus;
}
return status;
}
Pass::Status ScalarReplacementPass::ProcessFunction(Function* function) {
std::queue<Instruction*> worklist;
BasicBlock& entry = *function->begin();
for (auto iter = entry.begin(); iter != entry.end(); ++iter) {
// Function storage class OpVariables must appear as the first instructions
// of the entry block.
if (iter->opcode() != SpvOpVariable) break;
Instruction* varInst = &*iter;
if (CanReplaceVariable(varInst)) {
worklist.push(varInst);
}
}
Status status = Status::SuccessWithoutChange;
while (!worklist.empty()) {
Instruction* varInst = worklist.front();
worklist.pop();
Status var_status = ReplaceVariable(varInst, &worklist);
if (var_status == Status::Failure)
return var_status;
else if (var_status == Status::SuccessWithChange)
status = var_status;
}
return status;
}
Pass::Status ScalarReplacementPass::ReplaceVariable(
Instruction* inst, std::queue<Instruction*>* worklist) {
std::vector<Instruction*> replacements;
if (!CreateReplacementVariables(inst, &replacements)) {
return Status::Failure;
}
std::vector<Instruction*> dead;
if (get_def_use_mgr()->WhileEachUser(
inst, [this, &replacements, &dead](Instruction* user) {
if (!IsAnnotationInst(user->opcode())) {
switch (user->opcode()) {
case SpvOpLoad:
ReplaceWholeLoad(user, replacements);
dead.push_back(user);
break;
case SpvOpStore:
ReplaceWholeStore(user, replacements);
dead.push_back(user);
break;
case SpvOpAccessChain:
case SpvOpInBoundsAccessChain:
if (ReplaceAccessChain(user, replacements))
dead.push_back(user);
else
return false;
break;
case SpvOpName:
case SpvOpMemberName:
break;
default:
assert(false && "Unexpected opcode");
break;
}
}
return true;
}))
dead.push_back(inst);
// If there are no dead instructions to clean up, return with no changes.
if (dead.empty()) return Status::SuccessWithoutChange;
// Clean up some dead code.
while (!dead.empty()) {
Instruction* toKill = dead.back();
dead.pop_back();
context()->KillInst(toKill);
}
// Attempt to further scalarize.
for (auto var : replacements) {
if (var->opcode() == SpvOpVariable) {
if (get_def_use_mgr()->NumUsers(var) == 0) {
context()->KillInst(var);
} else if (CanReplaceVariable(var)) {
worklist->push(var);
}
}
}
return Status::SuccessWithChange;
}
void ScalarReplacementPass::ReplaceWholeLoad(
Instruction* load, const std::vector<Instruction*>& replacements) {
// Replaces the load of the entire composite with a load from each replacement
// variable followed by a composite construction.
BasicBlock* block = context()->get_instr_block(load);
std::vector<Instruction*> loads;
loads.reserve(replacements.size());
BasicBlock::iterator where(load);
for (auto var : replacements) {
// Create a load of each replacement variable.
if (var->opcode() != SpvOpVariable) {
loads.push_back(var);
continue;
}
Instruction* type = GetStorageType(var);
uint32_t loadId = TakeNextId();
std::unique_ptr<Instruction> newLoad(
new Instruction(context(), SpvOpLoad, type->result_id(), loadId,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_ID, {var->result_id()}}}));
// Copy memory access attributes which start at index 1. Index 0 is the
// pointer to load.
for (uint32_t i = 1; i < load->NumInOperands(); ++i) {
Operand copy(load->GetInOperand(i));
newLoad->AddOperand(std::move(copy));
}
where = where.InsertBefore(std::move(newLoad));
get_def_use_mgr()->AnalyzeInstDefUse(&*where);
context()->set_instr_block(&*where, block);
loads.push_back(&*where);
}
// Construct a new composite.
uint32_t compositeId = TakeNextId();
where = load;
std::unique_ptr<Instruction> compositeConstruct(new Instruction(
context(), SpvOpCompositeConstruct, load->type_id(), compositeId, {}));
for (auto l : loads) {
Operand op(SPV_OPERAND_TYPE_ID,
std::initializer_list<uint32_t>{l->result_id()});
compositeConstruct->AddOperand(std::move(op));
}
where = where.InsertBefore(std::move(compositeConstruct));
get_def_use_mgr()->AnalyzeInstDefUse(&*where);
context()->set_instr_block(&*where, block);
context()->ReplaceAllUsesWith(load->result_id(), compositeId);
}
void ScalarReplacementPass::ReplaceWholeStore(
Instruction* store, const std::vector<Instruction*>& replacements) {
// Replaces a store to the whole composite with a series of extract and stores
// to each element.
uint32_t storeInput = store->GetSingleWordInOperand(1u);
BasicBlock* block = context()->get_instr_block(store);
BasicBlock::iterator where(store);
uint32_t elementIndex = 0;
for (auto var : replacements) {
// Create the extract.
if (var->opcode() != SpvOpVariable) {
elementIndex++;
continue;
}
Instruction* type = GetStorageType(var);
uint32_t extractId = TakeNextId();
std::unique_ptr<Instruction> extract(new Instruction(
context(), SpvOpCompositeExtract, type->result_id(), extractId,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_ID, {storeInput}},
{SPV_OPERAND_TYPE_LITERAL_INTEGER, {elementIndex++}}}));
auto iter = where.InsertBefore(std::move(extract));
get_def_use_mgr()->AnalyzeInstDefUse(&*iter);
context()->set_instr_block(&*iter, block);
// Create the store.
std::unique_ptr<Instruction> newStore(
new Instruction(context(), SpvOpStore, 0, 0,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_ID, {var->result_id()}},
{SPV_OPERAND_TYPE_ID, {extractId}}}));
// Copy memory access attributes which start at index 2. Index 0 is the
// pointer and index 1 is the data.
for (uint32_t i = 2; i < store->NumInOperands(); ++i) {
Operand copy(store->GetInOperand(i));
newStore->AddOperand(std::move(copy));
}
iter = where.InsertBefore(std::move(newStore));
get_def_use_mgr()->AnalyzeInstDefUse(&*iter);
context()->set_instr_block(&*iter, block);
}
}
bool ScalarReplacementPass::ReplaceAccessChain(
Instruction* chain, const std::vector<Instruction*>& replacements) {
// Replaces the access chain with either another access chain (with one fewer
// indexes) or a direct use of the replacement variable.
uint32_t indexId = chain->GetSingleWordInOperand(1u);
const Instruction* index = get_def_use_mgr()->GetDef(indexId);
uint64_t indexValue = GetConstantInteger(index);
if (indexValue >= replacements.size()) {
// Out of bounds access, this is illegal IR. Notice that OpAccessChain
// indexing is 0-based, so we should also reject index == size-of-array.
return false;
} else {
const Instruction* var = replacements[static_cast<size_t>(indexValue)];
if (chain->NumInOperands() > 2) {
// Replace input access chain with another access chain.
BasicBlock::iterator chainIter(chain);
uint32_t replacementId = TakeNextId();
std::unique_ptr<Instruction> replacementChain(new Instruction(
context(), chain->opcode(), chain->type_id(), replacementId,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_ID, {var->result_id()}}}));
// Add the remaining indexes.
for (uint32_t i = 2; i < chain->NumInOperands(); ++i) {
Operand copy(chain->GetInOperand(i));
replacementChain->AddOperand(std::move(copy));
}
auto iter = chainIter.InsertBefore(std::move(replacementChain));
get_def_use_mgr()->AnalyzeInstDefUse(&*iter);
context()->set_instr_block(&*iter, context()->get_instr_block(chain));
context()->ReplaceAllUsesWith(chain->result_id(), replacementId);
} else {
// Replace with a use of the variable.
context()->ReplaceAllUsesWith(chain->result_id(), var->result_id());
}
}
return true;
}
bool ScalarReplacementPass::CreateReplacementVariables(
Instruction* inst, std::vector<Instruction*>* replacements) {
Instruction* type = GetStorageType(inst);
std::unique_ptr<std::unordered_set<uint64_t>> components_used =
GetUsedComponents(inst);
uint32_t elem = 0;
switch (type->opcode()) {
case SpvOpTypeStruct:
type->ForEachInOperand(
[this, inst, &elem, replacements, &components_used](uint32_t* id) {
if (!components_used || components_used->count(elem)) {
CreateVariable(*id, inst, elem, replacements);
} else {
replacements->push_back(CreateNullConstant(*id));
}
elem++;
});
break;
case SpvOpTypeArray:
for (uint32_t i = 0; i != GetArrayLength(type); ++i) {
if (!components_used || components_used->count(i)) {
CreateVariable(type->GetSingleWordInOperand(0u), inst, i,
replacements);
} else {
replacements->push_back(
CreateNullConstant(type->GetSingleWordInOperand(0u)));
}
}
break;
case SpvOpTypeMatrix:
case SpvOpTypeVector:
for (uint32_t i = 0; i != GetNumElements(type); ++i) {
CreateVariable(type->GetSingleWordInOperand(0u), inst, i, replacements);
}
break;
default:
assert(false && "Unexpected type.");
break;
}
TransferAnnotations(inst, replacements);
return std::find(replacements->begin(), replacements->end(), nullptr) ==
replacements->end();
}
void ScalarReplacementPass::TransferAnnotations(
const Instruction* source, std::vector<Instruction*>* replacements) {
// Only transfer invariant and restrict decorations on the variable. There are
// no type or member decorations that are necessary to transfer.
for (auto inst :
get_decoration_mgr()->GetDecorationsFor(source->result_id(), false)) {
assert(inst->opcode() == SpvOpDecorate);
uint32_t decoration = inst->GetSingleWordInOperand(1u);
if (decoration == SpvDecorationInvariant ||
decoration == SpvDecorationRestrict) {
for (auto var : *replacements) {
std::unique_ptr<Instruction> annotation(
new Instruction(context(), SpvOpDecorate, 0, 0,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_ID, {var->result_id()}},
{SPV_OPERAND_TYPE_DECORATION, {decoration}}}));
for (uint32_t i = 2; i < inst->NumInOperands(); ++i) {
Operand copy(inst->GetInOperand(i));
annotation->AddOperand(std::move(copy));
}
context()->AddAnnotationInst(std::move(annotation));
get_def_use_mgr()->AnalyzeInstUse(&*--context()->annotation_end());
}
}
}
}
void ScalarReplacementPass::CreateVariable(
uint32_t typeId, Instruction* varInst, uint32_t index,
std::vector<Instruction*>* replacements) {
uint32_t ptrId = GetOrCreatePointerType(typeId);
uint32_t id = TakeNextId();
std::unique_ptr<Instruction> variable(new Instruction(
context(), SpvOpVariable, ptrId, id,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_STORAGE_CLASS, {SpvStorageClassFunction}}}));
BasicBlock* block = context()->get_instr_block(varInst);
block->begin().InsertBefore(std::move(variable));
Instruction* inst = &*block->begin();
// If varInst was initialized, make sure to initialize its replacement.
GetOrCreateInitialValue(varInst, index, inst);
get_def_use_mgr()->AnalyzeInstDefUse(inst);
context()->set_instr_block(inst, block);
replacements->push_back(inst);
}
uint32_t ScalarReplacementPass::GetOrCreatePointerType(uint32_t id) {
auto iter = pointee_to_pointer_.find(id);
if (iter != pointee_to_pointer_.end()) return iter->second;
analysis::Type* pointeeTy;
std::unique_ptr<analysis::Pointer> pointerTy;
std::tie(pointeeTy, pointerTy) =
context()->get_type_mgr()->GetTypeAndPointerType(id,
SpvStorageClassFunction);
uint32_t ptrId = 0;
if (pointeeTy->IsUniqueType()) {
// Non-ambiguous type, just ask the type manager for an id.
ptrId = context()->get_type_mgr()->GetTypeInstruction(pointerTy.get());
pointee_to_pointer_[id] = ptrId;
return ptrId;
}
// Ambiguous type. We must perform a linear search to try and find the right
// type.
for (auto global : context()->types_values()) {
if (global.opcode() == SpvOpTypePointer &&
global.GetSingleWordInOperand(0u) == SpvStorageClassFunction &&
global.GetSingleWordInOperand(1u) == id) {
if (get_decoration_mgr()->GetDecorationsFor(id, false).empty()) {
// Only reuse a decoration-less pointer of the correct type.
ptrId = global.result_id();
break;
}
}
}
if (ptrId != 0) {
pointee_to_pointer_[id] = ptrId;
return ptrId;
}
ptrId = TakeNextId();
context()->AddType(MakeUnique<Instruction>(
context(), SpvOpTypePointer, 0, ptrId,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_STORAGE_CLASS, {SpvStorageClassFunction}},
{SPV_OPERAND_TYPE_ID, {id}}}));
Instruction* ptr = &*--context()->types_values_end();
get_def_use_mgr()->AnalyzeInstDefUse(ptr);
pointee_to_pointer_[id] = ptrId;
// Register with the type manager if necessary.
context()->get_type_mgr()->RegisterType(ptrId, *pointerTy);
return ptrId;
}
void ScalarReplacementPass::GetOrCreateInitialValue(Instruction* source,
uint32_t index,
Instruction* newVar) {
assert(source->opcode() == SpvOpVariable);
if (source->NumInOperands() < 2) return;
uint32_t initId = source->GetSingleWordInOperand(1u);
uint32_t storageId = GetStorageType(newVar)->result_id();
Instruction* init = get_def_use_mgr()->GetDef(initId);
uint32_t newInitId = 0;
// TODO(dnovillo): Refactor this with constant propagation.
if (init->opcode() == SpvOpConstantNull) {
// Initialize to appropriate NULL.
auto iter = type_to_null_.find(storageId);
if (iter == type_to_null_.end()) {
newInitId = TakeNextId();
type_to_null_[storageId] = newInitId;
context()->AddGlobalValue(
MakeUnique<Instruction>(context(), SpvOpConstantNull, storageId,
newInitId, std::initializer_list<Operand>{}));
Instruction* newNull = &*--context()->types_values_end();
get_def_use_mgr()->AnalyzeInstDefUse(newNull);
} else {
newInitId = iter->second;
}
} else if (IsSpecConstantInst(init->opcode())) {
// Create a new constant extract.
newInitId = TakeNextId();
context()->AddGlobalValue(MakeUnique<Instruction>(
context(), SpvOpSpecConstantOp, storageId, newInitId,
std::initializer_list<Operand>{
{SPV_OPERAND_TYPE_SPEC_CONSTANT_OP_NUMBER, {SpvOpCompositeExtract}},
{SPV_OPERAND_TYPE_ID, {init->result_id()}},
{SPV_OPERAND_TYPE_LITERAL_INTEGER, {index}}}));
Instruction* newSpecConst = &*--context()->types_values_end();
get_def_use_mgr()->AnalyzeInstDefUse(newSpecConst);
} else if (init->opcode() == SpvOpConstantComposite) {
// Get the appropriate index constant.
newInitId = init->GetSingleWordInOperand(index);
Instruction* element = get_def_use_mgr()->GetDef(newInitId);
if (element->opcode() == SpvOpUndef) {
// Undef is not a valid initializer for a variable.
newInitId = 0;
}
} else {
assert(false);
}
if (newInitId != 0) {
newVar->AddOperand({SPV_OPERAND_TYPE_ID, {newInitId}});
}
}
uint64_t ScalarReplacementPass::GetIntegerLiteral(const Operand& op) const {
assert(op.words.size() <= 2);
uint64_t len = 0;
for (uint32_t i = 0; i != op.words.size(); ++i) {
len |= (op.words[i] << (32 * i));
}
return len;
}
uint64_t ScalarReplacementPass::GetConstantInteger(
const Instruction* constant) const {
assert(get_def_use_mgr()->GetDef(constant->type_id())->opcode() ==
SpvOpTypeInt);
assert(constant->opcode() == SpvOpConstant ||
constant->opcode() == SpvOpConstantNull);
if (constant->opcode() == SpvOpConstantNull) {
return 0;
}
const Operand& op = constant->GetInOperand(0u);
return GetIntegerLiteral(op);
}
uint64_t ScalarReplacementPass::GetArrayLength(
const Instruction* arrayType) const {
assert(arrayType->opcode() == SpvOpTypeArray);
const Instruction* length =
get_def_use_mgr()->GetDef(arrayType->GetSingleWordInOperand(1u));
return GetConstantInteger(length);
}
uint64_t ScalarReplacementPass::GetNumElements(const Instruction* type) const {
assert(type->opcode() == SpvOpTypeVector ||
type->opcode() == SpvOpTypeMatrix);
const Operand& op = type->GetInOperand(1u);
assert(op.words.size() <= 2);
uint64_t len = 0;
for (size_t i = 0; i != op.words.size(); ++i) {
len |= (static_cast<uint64_t>(op.words[i]) << (32ull * i));
}
return len;
}
bool ScalarReplacementPass::IsSpecConstant(uint32_t id) const {
const Instruction* inst = get_def_use_mgr()->GetDef(id);
assert(inst);
return spvOpcodeIsSpecConstant(inst->opcode());
}
Instruction* ScalarReplacementPass::GetStorageType(
const Instruction* inst) const {
assert(inst->opcode() == SpvOpVariable);
uint32_t ptrTypeId = inst->type_id();
uint32_t typeId =
get_def_use_mgr()->GetDef(ptrTypeId)->GetSingleWordInOperand(1u);
return get_def_use_mgr()->GetDef(typeId);
}
bool ScalarReplacementPass::CanReplaceVariable(
const Instruction* varInst) const {
assert(varInst->opcode() == SpvOpVariable);
// Can only replace function scope variables.
if (varInst->GetSingleWordInOperand(0u) != SpvStorageClassFunction)
return false;
if (!CheckTypeAnnotations(get_def_use_mgr()->GetDef(varInst->type_id())))
return false;
const Instruction* typeInst = GetStorageType(varInst);
return CheckType(typeInst) && CheckAnnotations(varInst) && CheckUses(varInst);
}
bool ScalarReplacementPass::CheckType(const Instruction* typeInst) const {
if (!CheckTypeAnnotations(typeInst)) return false;
switch (typeInst->opcode()) {
case SpvOpTypeStruct:
// Don't bother with empty structs or very large structs.
if (typeInst->NumInOperands() == 0 ||
IsLargerThanSizeLimit(typeInst->NumInOperands()))
return false;
return true;
case SpvOpTypeArray:
if (IsSpecConstant(typeInst->GetSingleWordInOperand(1u))) {
return false;
}
if (IsLargerThanSizeLimit(GetArrayLength(typeInst))) {
return false;
}
return true;
// TODO(alanbaker): Develop some heuristics for when this should be
// re-enabled.
//// Specifically including matrix and vector in an attempt to reduce the
//// number of vector registers required.
// case SpvOpTypeMatrix:
// case SpvOpTypeVector:
// if (IsLargerThanSizeLimit(GetNumElements(typeInst))) return false;
// return true;
case SpvOpTypeRuntimeArray:
default:
return false;
}
}
bool ScalarReplacementPass::CheckTypeAnnotations(
const Instruction* typeInst) const {
for (auto inst :
get_decoration_mgr()->GetDecorationsFor(typeInst->result_id(), false)) {
uint32_t decoration;
if (inst->opcode() == SpvOpDecorate) {
decoration = inst->GetSingleWordInOperand(1u);
} else {
assert(inst->opcode() == SpvOpMemberDecorate);
decoration = inst->GetSingleWordInOperand(2u);
}
switch (decoration) {
case SpvDecorationRowMajor:
case SpvDecorationColMajor:
case SpvDecorationArrayStride:
case SpvDecorationMatrixStride:
case SpvDecorationCPacked:
case SpvDecorationInvariant:
case SpvDecorationRestrict:
case SpvDecorationOffset:
case SpvDecorationAlignment:
case SpvDecorationAlignmentId:
case SpvDecorationMaxByteOffset:
break;
default:
return false;
}
}
return true;
}
bool ScalarReplacementPass::CheckAnnotations(const Instruction* varInst) const {
for (auto inst :
get_decoration_mgr()->GetDecorationsFor(varInst->result_id(), false)) {
assert(inst->opcode() == SpvOpDecorate);
uint32_t decoration = inst->GetSingleWordInOperand(1u);
switch (decoration) {
case SpvDecorationInvariant:
case SpvDecorationRestrict:
case SpvDecorationAlignment:
case SpvDecorationAlignmentId:
case SpvDecorationMaxByteOffset:
break;
default:
return false;
}
}
return true;
}
bool ScalarReplacementPass::CheckUses(const Instruction* inst) const {
VariableStats stats = {0, 0};
bool ok = CheckUses(inst, &stats);
// TODO(alanbaker/greg-lunarg): Add some meaningful heuristics about when
// SRoA is costly, such as when the structure has many (unaccessed?)
// members.
return ok;
}
bool ScalarReplacementPass::CheckUses(const Instruction* inst,
VariableStats* stats) const {
bool ok = true;
get_def_use_mgr()->ForEachUse(
inst, [this, stats, &ok](const Instruction* user, uint32_t index) {
// Annotations are check as a group separately.
if (!IsAnnotationInst(user->opcode())) {
switch (user->opcode()) {
case SpvOpAccessChain:
case SpvOpInBoundsAccessChain:
if (index == 2u && user->NumInOperands() > 1) {
uint32_t id = user->GetSingleWordInOperand(1u);
const Instruction* opInst = get_def_use_mgr()->GetDef(id);
if (!IsCompileTimeConstantInst(opInst->opcode())) {
ok = false;
} else {
if (!CheckUsesRelaxed(user)) ok = false;
}
stats->num_partial_accesses++;
} else {
ok = false;
}
break;
case SpvOpLoad:
if (!CheckLoad(user, index)) ok = false;
stats->num_full_accesses++;
break;
case SpvOpStore:
if (!CheckStore(user, index)) ok = false;
stats->num_full_accesses++;
break;
case SpvOpName:
case SpvOpMemberName:
break;
default:
ok = false;
break;
}
}
});
return ok;
}
bool ScalarReplacementPass::CheckUsesRelaxed(const Instruction* inst) const {
bool ok = true;
get_def_use_mgr()->ForEachUse(
inst, [this, &ok](const Instruction* user, uint32_t index) {
switch (user->opcode()) {
case SpvOpAccessChain:
case SpvOpInBoundsAccessChain:
if (index != 2u) {
ok = false;
} else {
if (!CheckUsesRelaxed(user)) ok = false;
}
break;
case SpvOpLoad:
if (!CheckLoad(user, index)) ok = false;
break;
case SpvOpStore:
if (!CheckStore(user, index)) ok = false;
break;
default:
ok = false;
break;
}
});
return ok;
}
bool ScalarReplacementPass::CheckLoad(const Instruction* inst,
uint32_t index) const {
if (index != 2u) return false;
if (inst->NumInOperands() >= 2 &&
inst->GetSingleWordInOperand(1u) & SpvMemoryAccessVolatileMask)
return false;
return true;
}
bool ScalarReplacementPass::CheckStore(const Instruction* inst,
uint32_t index) const {
if (index != 0u) return false;
if (inst->NumInOperands() >= 3 &&
inst->GetSingleWordInOperand(2u) & SpvMemoryAccessVolatileMask)
return false;
return true;
}
bool ScalarReplacementPass::IsLargerThanSizeLimit(uint64_t length) const {
if (max_num_elements_ == 0) {
return false;
}
return length > max_num_elements_;
}
std::unique_ptr<std::unordered_set<uint64_t>>
ScalarReplacementPass::GetUsedComponents(Instruction* inst) {
std::unique_ptr<std::unordered_set<uint64_t>> result(
new std::unordered_set<uint64_t>());
analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
def_use_mgr->WhileEachUser(inst, [&result, def_use_mgr,
this](Instruction* use) {
switch (use->opcode()) {
case SpvOpLoad: {
// Look for extract from the load.
std::vector<uint32_t> t;
if (def_use_mgr->WhileEachUser(use, [&t](Instruction* use2) {
if (use2->opcode() != SpvOpCompositeExtract) {
return false;
}
t.push_back(use2->GetSingleWordInOperand(1));
return true;
})) {
result->insert(t.begin(), t.end());
return true;
} else {
result.reset(nullptr);
return false;
}
}
case SpvOpName:
case SpvOpMemberName:
case SpvOpStore:
// No components are used.
return true;
case SpvOpAccessChain:
case SpvOpInBoundsAccessChain: {
// Add the first index it if is a constant.
// TODO: Could be improved by checking if the address is used in a load.
analysis::ConstantManager* const_mgr = context()->get_constant_mgr();
uint32_t index_id = use->GetSingleWordInOperand(1);
const analysis::Constant* index_const =
const_mgr->FindDeclaredConstant(index_id);
if (index_const) {
const analysis::Integer* index_type =
index_const->type()->AsInteger();
assert(index_type);
if (index_type->width() == 32) {
result->insert(index_const->GetU32());
return true;
} else if (index_type->width() == 64) {
result->insert(index_const->GetU64());
return true;
}
result.reset(nullptr);
return false;
} else {
// Could be any element. Assuming all are used.
result.reset(nullptr);
return false;
}
}
default:
// We do not know what is happening. Have to assume the worst.
result.reset(nullptr);
return false;
}
});
return result;
}
Instruction* ScalarReplacementPass::CreateNullConstant(uint32_t type_id) {
analysis::TypeManager* type_mgr = context()->get_type_mgr();
analysis::ConstantManager* const_mgr = context()->get_constant_mgr();
const analysis::Type* type = type_mgr->GetType(type_id);
const analysis::Constant* null_const = const_mgr->GetConstant(type, {});
Instruction* null_inst =
const_mgr->GetDefiningInstruction(null_const, type_id);
if (null_inst != nullptr) {
context()->UpdateDefUse(null_inst);
}
return null_inst;
}
} // namespace opt
} // namespace spvtools
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