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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/flatten_decoration_pass.h"
#include <cassert>
#include <memory>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include "source/opt/ir_context.h"
namespace spvtools {
namespace opt {
using Words = std::vector<uint32_t>;
using OrderedUsesMap = std::unordered_map<uint32_t, Words>;
Pass::Status FlattenDecorationPass::Process() {
bool modified = false;
// The target Id of OpDecorationGroup instructions.
// We have to track this separately from its uses, in case it
// has no uses.
std::unordered_set<uint32_t> group_ids;
// Maps a decoration group Id to its GroupDecorate targets, in order
// of appearance.
OrderedUsesMap normal_uses;
// Maps a decoration group Id to its GroupMemberDecorate targets and
// their indices, in of appearance.
OrderedUsesMap member_uses;
auto annotations = context()->annotations();
// On the first pass, record each OpDecorationGroup with its ordered uses.
// Rely on unordered_map::operator[] to create its entries on first access.
for (const auto& inst : annotations) {
switch (inst.opcode()) {
case spv::Op::OpDecorationGroup:
group_ids.insert(inst.result_id());
break;
case spv::Op::OpGroupDecorate: {
Words& words = normal_uses[inst.GetSingleWordInOperand(0)];
for (uint32_t i = 1; i < inst.NumInOperandWords(); i++) {
words.push_back(inst.GetSingleWordInOperand(i));
}
} break;
case spv::Op::OpGroupMemberDecorate: {
Words& words = member_uses[inst.GetSingleWordInOperand(0)];
for (uint32_t i = 1; i < inst.NumInOperandWords(); i++) {
words.push_back(inst.GetSingleWordInOperand(i));
}
} break;
default:
break;
}
}
// On the second pass, replace OpDecorationGroup and its uses with
// equivalent normal and struct member uses.
auto inst_iter = annotations.begin();
// We have to re-evaluate the end pointer
while (inst_iter != context()->annotations().end()) {
// Should we replace this instruction?
bool replace = false;
switch (inst_iter->opcode()) {
case spv::Op::OpDecorationGroup:
case spv::Op::OpGroupDecorate:
case spv::Op::OpGroupMemberDecorate:
replace = true;
break;
case spv::Op::OpDecorate: {
// If this decoration targets a group, then replace it
// by sets of normal and member decorations.
const uint32_t group = inst_iter->GetSingleWordOperand(0);
const auto normal_uses_iter = normal_uses.find(group);
if (normal_uses_iter != normal_uses.end()) {
for (auto target : normal_uses[group]) {
std::unique_ptr<Instruction> new_inst(inst_iter->Clone(context()));
new_inst->SetInOperand(0, Words{target});
inst_iter = inst_iter.InsertBefore(std::move(new_inst));
++inst_iter;
replace = true;
}
}
const auto member_uses_iter = member_uses.find(group);
if (member_uses_iter != member_uses.end()) {
const Words& member_id_pairs = (*member_uses_iter).second;
// The collection is a sequence of pairs.
assert((member_id_pairs.size() % 2) == 0);
for (size_t i = 0; i < member_id_pairs.size(); i += 2) {
// Make an OpMemberDecorate instruction for each (target, member)
// pair.
const uint32_t target = member_id_pairs[i];
const uint32_t member = member_id_pairs[i + 1];
std::vector<Operand> operands;
operands.push_back(Operand(SPV_OPERAND_TYPE_ID, {target}));
operands.push_back(
Operand(SPV_OPERAND_TYPE_LITERAL_INTEGER, {member}));
auto decoration_operands_iter = inst_iter->begin();
decoration_operands_iter++; // Skip the group target.
operands.insert(operands.end(), decoration_operands_iter,
inst_iter->end());
std::unique_ptr<Instruction> new_inst(new Instruction(
context(), spv::Op::OpMemberDecorate, 0, 0, operands));
inst_iter = inst_iter.InsertBefore(std::move(new_inst));
++inst_iter;
replace = true;
}
}
// If this is an OpDecorate targeting the OpDecorationGroup itself,
// remove it even if that decoration group itself is not the target of
// any OpGroupDecorate or OpGroupMemberDecorate.
if (!replace && group_ids.count(group)) {
replace = true;
}
} break;
default:
break;
}
if (replace) {
inst_iter = inst_iter.Erase();
modified = true;
} else {
// Handle the case of decorations unrelated to decoration groups.
++inst_iter;
}
}
// Remove OpName instructions which reference the removed group decorations.
// An OpDecorationGroup instruction might not have been used by an
// OpGroupDecorate or OpGroupMemberDecorate instruction.
if (!group_ids.empty()) {
for (auto debug_inst_iter = context()->debug2_begin();
debug_inst_iter != context()->debug2_end();) {
if (debug_inst_iter->opcode() == spv::Op::OpName) {
const uint32_t target = debug_inst_iter->GetSingleWordOperand(0);
if (group_ids.count(target)) {
debug_inst_iter = debug_inst_iter.Erase();
modified = true;
} else {
++debug_inst_iter;
}
}
}
}
return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
}
} // namespace opt
} // namespace spvtools
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