diff options
Diffstat (limited to 'third_party/courgette/adjustment_method.cc')
| -rw-r--r-- | third_party/courgette/adjustment_method.cc | 703 |
1 files changed, 0 insertions, 703 deletions
diff --git a/third_party/courgette/adjustment_method.cc b/third_party/courgette/adjustment_method.cc deleted file mode 100644 index 8f6caef..0000000 --- a/third_party/courgette/adjustment_method.cc +++ /dev/null @@ -1,703 +0,0 @@ -// Copyright (c) 2009 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "third_party/courgette/adjustment_method.h"
-
-#include <algorithm>
-#include <list>
-#include <map>
-#include <set>
-#include <string>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/logging.h"
-#include "base/string_util.h"
-
-#include "third_party/courgette/assembly_program.h"
-#include "third_party/courgette/courgette.h"
-#include "third_party/courgette/encoded_program.h"
-#include "third_party/courgette/image_info.h"
-
-namespace courgette {
-
-// We have three discretionary information logging levels for algorithm
-// development. For now just configure with #defines.
-// TODO(sra): make dependent of some configurable setting.
-#define NO_LOG DLOG_IF(INFO, false)
-// #define ALOG1 LOG(INFO)
-// #define ALOG2 LOG(INFO)
-// #define ALOG3 LOG(INFO)
-#define ALOG1 NO_LOG
-#define ALOG2 NO_LOG
-#define ALOG3 NO_LOG
-
-////////////////////////////////////////////////////////////////////////////////
-
-class NullAdjustmentMethod : public AdjustmentMethod {
- bool Adjust(const AssemblyProgram& model, AssemblyProgram* program) {
- return true;
- }
-};
-
-////////////////////////////////////////////////////////////////////////////////
-
-// The purpose of adjustment is to assign indexes to Labels of a program 'p' to
-// make the sequence of indexes similar to a 'model' program 'm'. Labels
-// themselves don't have enough information to do this job, so we work with a
-// LabelInfo surrogate for each label.
-//
-class LabelInfo {
- public:
- Label* label_; // The label that this info a surrogate for.
-
- // Information used only in debugging messages.
- uint32 is_model_ : 1; // Is the label in the model?
- uint32 debug_index_ : 31; // An unique small number for naming the label.
-
- uint32 refs_; // Number of times this Label is referenced.
-
- LabelInfo* assignment_; // Label from other program corresponding to this.
-
- // LabelInfos are in a doubly linked list ordered by address (label_->rva_) so
- // we can quickly find Labels adjacent in address order.
- LabelInfo* next_addr_; // Label(Info) at next highest address.
- LabelInfo* prev_addr_; // Label(Info) at next lowest address.
-
- std::vector<uint32> positions_; // Offsets into the trace of references.
-
- // Just a no-argument constructor and copy constructor. Actual LabelInfo
- // objects are allocated in std::pair structs in a std::map.
- LabelInfo()
- : label_(NULL), is_model_(false), debug_index_(0), refs_(0),
- assignment_(NULL),
- next_addr_(NULL),
- prev_addr_(NULL) {}
-
- private:
- void operator=(const LabelInfo*); // Disallow assignment only.
-
- // Public compiler generated copy constructor is needed to constuct
- // std::pair<Label*, LabelInfo> so that fresh LabelInfos can be allocated
- // inside a std::map.
-};
-
-struct OrderLabelInfoByAddressAscending {
- bool operator()(const LabelInfo* a, const LabelInfo* b) const {
- return a->label_->rva_ < b->label_->rva_;
- }
-};
-
-static std::string ToString(LabelInfo* info) {
- std::string s;
- StringAppendF(&s, "%c%d", "pm"[info->is_model_], info->debug_index_);
- if (info->label_->index_ != Label::kNoIndex)
- StringAppendF(&s, " (%d)", info->label_->index_);
-
- StringAppendF(&s, " #%u", info->refs_);
- return s;
-}
-
-// General graph matching is exponential, essentially trying all permutations.
-// The exponential algorithm can be made faster by avoiding consideration of
-// impossible or unlikely matches. We can make the matching practical by eager
-// matching - by looking for likely matches and commiting to them, and using the
-// committed assignment as the basis for further matching.
-//
-// The basic eager graph-matching assignment is based on several ideas:
-//
-// * The strongest match will be for parts of the program that have not
-// changed. If part of a program has not changed, then the number of
-// references to a label will be the same, and corresponding pairs of
-// adjacent labels will have the same RVA difference.
-//
-// * Some assignments are 'obvious' if you look at the distribution. Example:
-// if both the program and the model have a label that is referred to much
-// more often than the next most refered-to label, it is likely the two
-// labels correspond.
-//
-// * If a label from the program corresponds to a label in the model, it is
-// likely that the labels near the corresponding labels also match. A
-// conservative way of extending the match is to assign only those labels
-// which have exactly the same address offset and reference count.
-//
-// * If two labels correspond, then we can try to match up the references
-// before and after the labels in the reference stream. For this to be
-// practical, the number of references has to be small, e.g. each label has
-// exactly one reference.
-//
-
-// Note: we also tried a completely different approach: random assignment
-// followed by simulated annealing. This produced similar results. The results
-// were not as good for very small differences because the simulated annealing
-// never quite hit the groove. And simulated annealing was several orders of
-// magnitude slower.
-
-
-// TRIE node for suffix strings in the label reference sequence.
-//
-// We dynamically build a trie for both the program and model, growing the trie
-// as necessary. The trie node for a (possibly) empty string of label
-// references contains the distribution of labels following the string. The
-// roots node (for the empty string) thus contains the simple distribution of
-// labels within the label reference stream.
-
-struct Node {
- Node(LabelInfo* in_edge, Node* prev)
- : in_edge_(in_edge), prev_(prev), count_(0),
- in_queue_(false) {
- length_ = 1 + (prev_ ? prev_->length_ : 0);
- }
- LabelInfo* in_edge_; //
- Node* prev_; // Node at shorter length.
- int count_; // Frequency of this path in Trie.
- int length_;
- typedef std::map<LabelInfo*, Node*> Edges;
- Edges edges_;
- std::vector<int> places_; // Indexes into sequence of this item.
- std::list<Node*> edges_in_frequency_order;
-
- bool in_queue_;
- bool Extended() const { return edges_.size() > 0; }
-
- uint32 Weight() const {
- return edges_in_frequency_order.front()->count_;
- }
-};
-
-static std::string ToString(Node* node) {
- std::vector<std::string> prefix;
- for (Node* n = node; n->prev_; n = n->prev_)
- prefix.push_back(ToString(n->in_edge_));
-
- std::string s;
- s += "{";
- const char* sep = "";
- while (!prefix.empty()) {
- s += sep;
- sep = ",";
- s += prefix.back();
- prefix.pop_back();
- }
-
- s += StringPrintf("%u", node->count_);
- s += " @";
- s += Uint64ToString(node->edges_in_frequency_order.size());
- s += "}";
- return s;
-}
-
-typedef std::vector<LabelInfo*> Trace;
-
-struct OrderNodeByCountDecreasing {
- bool operator()(Node* a, Node* b) const {
- if (a->count_ != b->count_)
- return (a->count_) > (b->count_);
- return a->places_.at(0) < b->places_.at(0); // Prefer first occuring.
- }
-};
-
-struct OrderNodeByWeightDecreasing {
- bool operator()(Node* a, Node* b) const {
- // (Maybe tie-break on total count, followed by lowest assigned node indexes
- // in path.)
- uint32 a_weight = a->Weight();
- uint32 b_weight = b->Weight();
- if (a_weight != b_weight)
- return a_weight > b_weight;
- if (a->length_ != b->length_)
- return a->length_ > b->length_; // Prefer longer.
- return a->places_.at(0) < b->places_.at(0); // Prefer first occuring.
- }
-};
-
-typedef std::set<Node*, OrderNodeByWeightDecreasing> NodeQueue;
-
-class AssignmentProblem {
- public:
- AssignmentProblem(const Trace& model,
- const Trace& problem)
- : m_trace_(model),
- p_trace_(problem) {
- }
-
- ~AssignmentProblem() {
- for (size_t i = 0; i < all_nodes_.size(); ++i)
- delete all_nodes_[i];
- }
-
- bool Solve() {
- m_root_ = MakeRootNode(m_trace_);
- p_root_ = MakeRootNode(p_trace_);
- AddToQueue(p_root_);
-
- while (!worklist_.empty()) {
- Node* node = *worklist_.begin();
- node->in_queue_ = false;
- worklist_.erase(node);
- TrySolveNode(node);
- }
-
- ALOG1 << unsolved_.size() << " unsolved items";
- return true;
- }
-
- private:
- void AddToQueue(Node* node) {
- if (node->length_ >= 10) {
- ALOG3 << "Length clipped " << ToString(node->prev_);
- return;
- }
- if (node->in_queue_) {
- LOG(ERROR) << "Double add " << ToString(node);
- return;
- }
- // just to be sure data for prioritizing is available
- ExtendNode(node, p_trace_);
- // SkipCommittedLabels(node);
- if (node->edges_in_frequency_order.empty())
- return;
- node->in_queue_ = true;
- worklist_.insert(node);
- }
-
- void SkipCommittedLabels(Node* node) {
- ExtendNode(node, p_trace_);
- uint32 skipped = 0;
- while (!node->edges_in_frequency_order.empty() &&
- node->edges_in_frequency_order.front()->in_edge_->assignment_) {
- ++skipped;
- node->edges_in_frequency_order.pop_front();
- }
- if (skipped > 0)
- ALOG3 << "Skipped " << skipped << " at " << ToString(node);
- }
-
- void TrySolveNode(Node* p_node) {
- Node* front = p_node->edges_in_frequency_order.front();
- if (front->in_edge_->assignment_) {
- p_node->edges_in_frequency_order.pop_front();
- AddToQueue(front);
- AddToQueue(p_node);
- return;
- }
-
- // Compare frequencies of unassigned edges, and either make
- // assignment(s) or move node to unsolved list
-
- Node* m_node = FindModelNode(p_node);
-
- if (m_node == NULL) {
- ALOG1 << "Can't find model node";
- unsolved_.insert(p_node);
- return;
- }
- ExtendNode(m_node, m_trace_);
-
- // Lets just try greedy
-
- SkipCommittedLabels(m_node);
- if (m_node->edges_in_frequency_order.empty()) {
- ALOG3 << "Punting, no elements left in model vs "
- << p_node->edges_in_frequency_order.size();
- unsolved_.insert(p_node);
- return;
- }
- Node* m_match = m_node->edges_in_frequency_order.front();
- Node* p_match = p_node->edges_in_frequency_order.front();
-
- if (p_match->count_ > 1.1 * m_match->count_ ||
- m_match->count_ > 1.1 * p_match->count_) {
- ALOG2 << "Tricky distribution "
- << p_match->count_ << ":" << m_match->count_ << " "
- << ToString(p_match) << " vs " << ToString(m_match);
- return;
- }
-
- m_node->edges_in_frequency_order.pop_front();
- p_node->edges_in_frequency_order.pop_front();
-
- LabelInfo* p_label_info = p_match->in_edge_;
- LabelInfo* m_label_info = m_match->in_edge_;
- int m_index = p_label_info->label_->index_;
- if (m_index != Label::kNoIndex) {
- ALOG1 << "Cant use unassigned label from model " << m_index;
- unsolved_.insert(p_node);
- return;
- }
-
- Assign(p_label_info, m_label_info);
-
- AddToQueue(p_match); // find matches within new match
- AddToQueue(p_node); // and more matches within this node
- }
-
- void Assign(LabelInfo* p_info, LabelInfo* m_info) {
- AssignOne(p_info, m_info);
- ALOG3 << "Assign " << ToString(p_info) << " := " << ToString(m_info);
- // Now consider unassigned adjacent addresses
- TryExtendAssignment(p_info, m_info);
- }
-
- void AssignOne(LabelInfo* p_info, LabelInfo* m_info) {
- p_info->label_->index_ = m_info->label_->index_;
-
- // Mark as assigned
- m_info->assignment_ = p_info;
- p_info->assignment_ = m_info;
- }
-
- void TryExtendAssignment(LabelInfo* p_info, LabelInfo* m_info) {
- RVA m_rva_base = m_info->label_->rva_;
- RVA p_rva_base = p_info->label_->rva_;
-
- LabelInfo* m_info_next = m_info->next_addr_;
- LabelInfo* p_info_next = p_info->next_addr_;
- for ( ; m_info_next && p_info_next; ) {
- if (m_info_next->assignment_)
- break;
-
- RVA m_rva = m_info_next->label_->rva_;
- RVA p_rva = p_info_next->label_->rva_;
-
- if (m_rva - m_rva_base != p_rva - p_rva_base) {
- // previous label was pointing to something that is different size
- break;
- }
- LabelInfo* m_info_next_next = m_info_next->next_addr_;
- LabelInfo* p_info_next_next = p_info_next->next_addr_;
- if (m_info_next_next && p_info_next_next) {
- RVA m_rva_next = m_info_next_next->label_->rva_;
- RVA p_rva_next = p_info_next_next->label_->rva_;
- if (m_rva_next - m_rva != p_rva_next - p_rva) {
- // Since following labels are no longer in address lockstep, assume
- // this address has a difference.
- break;
- }
- }
-
- // The label has inconsistent numbers of references, it is probably not
- // the same thing.
- if (m_info_next->refs_ != p_info_next->refs_) {
- break;
- }
-
- ALOG3 << " Extending assignment -> "
- << ToString(p_info_next) << " := " << ToString(m_info_next);
-
- AssignOne(p_info_next, m_info_next);
-
- if (p_info_next->refs_ == m_info_next->refs_ &&
- p_info_next->refs_ == 1) {
- TryExtendSequence(p_info_next->positions_[0],
- m_info_next->positions_[0]);
- TryExtendSequenceBackwards(p_info_next->positions_[0],
- m_info_next->positions_[0]);
- }
-
- p_info_next = p_info_next_next;
- m_info_next = m_info_next_next;
- }
-
- LabelInfo* m_info_prev = m_info->prev_addr_;
- LabelInfo* p_info_prev = p_info->prev_addr_;
- for ( ; m_info_prev && p_info_prev; ) {
- if (m_info_prev->assignment_)
- break;
-
- RVA m_rva = m_info_prev->label_->rva_;
- RVA p_rva = p_info_prev->label_->rva_;
-
- if (m_rva - m_rva_base != p_rva - p_rva_base) {
- // previous label was pointing to something that is different size
- break;
- }
- LabelInfo* m_info_prev_prev = m_info_prev->prev_addr_;
- LabelInfo* p_info_prev_prev = p_info_prev->prev_addr_;
-
- // The the label has inconsistent numbers of references, it is
- // probably not the same thing
- if (m_info_prev->refs_ != p_info_prev->refs_) {
- break;
- }
-
- AssignOne(p_info_prev, m_info_prev);
- ALOG3 << " Extending assignment <- " << ToString(p_info_prev) << " := "
- << ToString(m_info_prev);
-
- p_info_prev = p_info_prev_prev;
- m_info_prev = m_info_prev_prev;
- }
- }
-
- uint32 TryExtendSequence(uint32 p_pos_start, uint32 m_pos_start) {
- uint32 p_pos = p_pos_start + 1;
- uint32 m_pos = m_pos_start + 1;
-
- while (p_pos < p_trace_.size() && m_pos < m_trace_.size()) {
- LabelInfo* p_info = p_trace_[p_pos];
- LabelInfo* m_info = m_trace_[m_pos];
-
- // To match, either (1) both are assigned or (2) both are unassigned.
- if ((p_info->assignment_ == NULL) != (m_info->assignment_ == NULL))
- break;
-
- // If they are assigned, it needs to be consistent (same index).
- if (p_info->assignment_ && m_info->assignment_) {
- if (p_info->label_->index_ != m_info->label_->index_)
- break;
- ++p_pos;
- ++m_pos;
- continue;
- }
-
- if (p_info->refs_ != m_info->refs_)
- break;
-
- AssignOne(p_info, m_info);
- ALOG3 << " Extending assignment seq"
- << "[+" << p_pos - p_pos_start << "]"
- << " -> "
- << ToString(p_info) << " := " << ToString(m_info);
-
- ++p_pos;
- ++m_pos;
- }
-
- return p_pos - p_pos_start;
- }
-
- uint32 TryExtendSequenceBackwards(uint32 p_pos_start, uint32 m_pos_start) {
- if (p_pos_start == 0 || m_pos_start == 0)
- return 0;
-
- uint32 p_pos = p_pos_start - 1;
- uint32 m_pos = m_pos_start - 1;
-
- while (p_pos > 0 && m_pos > 0) {
- LabelInfo* p_info = p_trace_[p_pos];
- LabelInfo* m_info = m_trace_[m_pos];
-
- if ((p_info->assignment_ == NULL) != (m_info->assignment_ == NULL))
- break;
-
- if (p_info->assignment_ && m_info->assignment_) {
- if (p_info->label_->index_ != m_info->label_->index_)
- break;
- --p_pos;
- --m_pos;
- continue;
- }
-
- if (p_info->refs_ != m_info->refs_)
- break;
-
- AssignOne(p_info, m_info);
- ALOG3 << " Extending assignment seq"
- << "[-" << p_pos_start - p_pos << "]"
- << " <- "
- << ToString(p_info) << " := " << ToString(m_info);
-
- --p_pos;
- --m_pos;
- }
-
- return p_pos - p_pos_start;
- }
-
- Node* FindModelNode(Node* node) {
- if (node->prev_ == NULL)
- return m_root_;
-
- Node* m_parent = FindModelNode(node->prev_);
- if (m_parent == NULL) {
- return NULL;
- }
-
- ExtendNode(m_parent, m_trace_);
-
- LabelInfo* p_label = node->in_edge_;
- LabelInfo* m_label = p_label->assignment_;
- if (m_label == NULL) {
- ALOG1 << "Expected assigned prefix";
- return NULL;
- }
-
- Node::Edges::iterator e = m_parent->edges_.find(m_label);
- if (e == m_parent->edges_.end()) {
- ALOG2 << "Expected defined edge in parent";
- return NULL;
- }
-
- return e->second;
- }
-
- Node* MakeRootNode(const Trace& trace) {
- Node* node = new Node(NULL, NULL);
- all_nodes_.push_back(node);
- for (size_t i = 0; i < trace.size(); ++i) {
- ++node->count_;
- node->places_.push_back(i);
- }
- return node;
- }
-
- void ExtendNode(Node* node, const Trace& trace) {
- // Make sure trie is filled in at this node.
- if (node->Extended())
- return;
- for (size_t i = 0; i < node->places_.size(); ++i) {
- uint32 index = node->places_.at(i);
- if (index < trace.size()) {
- LabelInfo* item = trace.at(index);
- Node*& slot = node->edges_[item];
- if (slot == NULL) {
- slot = new Node(item, node);
- all_nodes_.push_back(slot);
- node->edges_in_frequency_order.push_back(slot);
- }
- slot->places_.push_back(index + 1);
- ++slot->count_;
- }
- }
- node->edges_in_frequency_order.sort(OrderNodeByCountDecreasing());
- }
-
- const Trace& m_trace_;
- const Trace& p_trace_;
- Node* m_root_;
- Node* p_root_;
-
- NodeQueue worklist_;
- NodeQueue unsolved_;
-
- std::vector<Node*> all_nodes_;
-
- DISALLOW_COPY_AND_ASSIGN(AssignmentProblem);
-};
-
-class GraphAdjuster : public AdjustmentMethod {
- public:
- GraphAdjuster() {}
- ~GraphAdjuster() {}
-
- bool Adjust(const AssemblyProgram& model, AssemblyProgram* program) {
- LOG(INFO) << "GraphAdjuster::Adjust";
- prog_ = program;
- model_ = &model;
- debug_label_index_gen_ = 0;
- return Finish();
- }
-
- bool Finish() {
- prog_->UnassignIndexes();
- CollectTraces(model_, &model_abs32_, &model_rel32_, true);
- CollectTraces(prog_, &prog_abs32_, &prog_rel32_, false);
- Solve(model_abs32_, prog_abs32_);
- Solve(model_rel32_, prog_rel32_);
- prog_->AssignRemainingIndexes();
- return true;
- }
-
- private:
-
- void CollectTraces(const AssemblyProgram* program, Trace* abs32, Trace* rel32,
- bool is_model) {
- const std::vector<Instruction*>& instructions = program->instructions();
- for (size_t i = 0; i < instructions.size(); ++i) {
- Instruction* instruction = instructions.at(i);
- if (Label* label = program->InstructionAbs32Label(instruction))
- ReferenceLabel(abs32, label, is_model);
- if (Label* label = program->InstructionRel32Label(instruction))
- ReferenceLabel(rel32, label, is_model);
- }
- // TODO(sra): we could simply append all the labels in index order to
- // incorporate some costing for entropy (bigger deltas) that will be
- // introduced into the label address table by non-monotonic ordering. This
- // would have some knock-on effects to parts of the algorithm that work on
- // single-occurence labels.
- }
-
- void Solve(const Trace& model, const Trace& problem) {
- LinkLabelInfos(model);
- LinkLabelInfos(problem);
- AssignmentProblem a(model, problem);
- a.Solve();
- }
-
- void LinkLabelInfos(const Trace& trace) {
- typedef std::set<LabelInfo*, OrderLabelInfoByAddressAscending> Ordered;
- Ordered ordered;
- for (Trace::const_iterator p = trace.begin(); p != trace.end(); ++p)
- ordered.insert(*p);
- LabelInfo* prev = NULL;
- for (Ordered::iterator p = ordered.begin(); p != ordered.end(); ++p) {
- LabelInfo* curr = *p;
- if (prev) prev->next_addr_ = curr;
- curr->prev_addr_ = prev;
- prev = curr;
-
- if (curr->positions_.size() != curr->refs_)
- NOTREACHED();
- }
- }
-
- void ReferenceLabel(Trace* trace, Label* label, bool is_model) {
- trace->push_back(MakeLabelInfo(label, is_model, trace->size()));
- }
-
- LabelInfo* MakeLabelInfo(Label* label, bool is_model, uint32 position) {
- LabelInfo& slot = label_infos_[label];
- if (slot.label_ == NULL) {
- slot.label_ = label;
- slot.is_model_ = is_model;
- slot.debug_index_ = ++debug_label_index_gen_;
- }
- slot.positions_.push_back(position);
- ++slot.refs_;
- return &slot;
- }
-
- AssemblyProgram* prog_; // Program to be adjusted, owned by caller.
- const AssemblyProgram* model_; // Program to be mimicked, owned by caller.
-
- Trace model_abs32_;
- Trace model_rel32_;
- Trace prog_abs32_;
- Trace prog_rel32_;
-
- int debug_label_index_gen_;
-
- // Note LabelInfo is allocated inside map, so the LabelInfo lifetimes are
- // managed by the map.
- std::map<Label*, LabelInfo> label_infos_;
-
- private:
- DISALLOW_COPY_AND_ASSIGN(GraphAdjuster);
-};
-
-
-////////////////////////////////////////////////////////////////////////////////
-
-void AdjustmentMethod::Destroy() { delete this; }
-
-AdjustmentMethod* AdjustmentMethod::MakeNullAdjustmentMethod() {
- return new NullAdjustmentMethod();
-}
-
-AdjustmentMethod* AdjustmentMethod::MakeProductionAdjustmentMethod() {
- return new GraphAdjuster();
-}
-
-Status Adjust(const AssemblyProgram& model, AssemblyProgram* program) {
- AdjustmentMethod* method = AdjustmentMethod::MakeProductionAdjustmentMethod();
- bool ok = method->Adjust(model, program);
- method->Destroy();
- if (ok)
- return C_OK;
- else
- return C_ADJUSTMENT_FAILED;
-}
-
-} // namespace courgette
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