codon/compiler/sir/analyze/dataflow/cfg.h

#pragma once

#include <iostream>
#include <list>
#include <memory>
#include <unordered_map>
#include <unordered_set>

#include "sir/analyze/analysis.h"
#include "sir/sir.h"
#include "sir/util/iterators.h"

#define DEFAULT_VISIT(x)                                                               \
  void visit(const x *v) override { defaultInsert(v); }

namespace seq {
namespace ir {
namespace analyze {
namespace dataflow {

class CFGraph;

class CFBlock : public IdMixin {
private:
  /// the in-order list of values in this block
  std::list<const Value *> values;
  /// an un-ordered list of successor blocks
  std::unordered_set<CFBlock *> successors;
  /// an un-ordered list of successor blocks
  std::unordered_set<CFBlock *> predecessors;
  /// the block's name
  std::string name;
  /// the graph
  CFGraph *graph;

public:
  /// Constructs a control-flow block.
  /// @param graph the parent graph
  /// @param name the block's name
  explicit CFBlock(CFGraph *graph, std::string name = "")
      : name(std::move(name)), graph(graph) {}

  virtual ~CFBlock() noexcept = default;

  /// @return this block's name
  std::string getName() const { return name; }

  /// @return an iterator to the first value
  auto begin() { return values.begin(); }
  /// @return an iterator beyond the last value
  auto end() { return values.end(); }
  /// @return an iterator to the first value
  auto begin() const { return values.begin(); }
  /// @return an iterator beyond the last value
  auto end() const { return values.end(); }
  /// @return a pointer to the first value
  const Value *front() const { return values.front(); }
  /// @return a pointer to the last value
  const Value *back() const { return values.back(); }

  /// Inserts a value at a given position.
  /// @param it the position
  /// @param v the new value
  /// @param an iterator to the new value
  template <typename It> auto insert(It it, const Value *v) {
    values.insert(it, v);
    reg(v);
  }
  /// Inserts a value at the back.
  /// @param v the new value
  void push_back(const Value *v) {
    values.push_back(v);
    reg(v);
  }
  /// Erases a value at the given position.
  /// @param it the position
  /// @return an iterator following the removed value
  template <typename It> auto erase(It it) { values.erase(it); }

  /// @return an iterator to the first successor
  auto successors_begin() { return successors.begin(); }
  /// @return an iterator beyond the last successor
  auto successors_end() { return successors.end(); }
  /// @return an iterator to the first successor
  auto successors_begin() const { return successors.begin(); }
  /// @return an iterator beyond the last successor
  auto successors_end() const { return successors.end(); }
  /// Inserts a successor at some position.
  /// @param v the new successor
  /// @return an iterator to the new successor
  auto successors_insert(CFBlock *v) {
    successors.insert(v);
    v->predecessors.insert(this);
  }
  /// Removes a given successor.
  /// @param v the successor to remove
  auto successors_erase(CFBlock *v) {
    successors.erase(v);
    v->predecessors.erase(this);
  }

  /// @return an iterator to the first predecessor
  auto predecessors_begin() { return predecessors.begin(); }
  /// @return an iterator beyond the last predecessor
  auto predecessors_end() { return predecessors.end(); }
  /// @return an iterator to the first predecessor
  auto predecessors_begin() const { return predecessors.begin(); }
  /// @return an iterator beyond the last predecessor
  auto predecessors_end() const { return predecessors.end(); }

  /// @return the graph
  CFGraph *getGraph() { return graph; }
  /// @return the graph
  const CFGraph *getGraph() const { return graph; }
  /// Sets the graph.
  /// @param g the new graph
  void setGraph(CFGraph *g) { graph = g; }

private:
  void reg(const Value *v);
};

class SyntheticAssignInstr : public AcceptorExtend<SyntheticAssignInstr, Instr> {
public:
  enum Kind { UNKNOWN, KNOWN, NEXT_VALUE, ADD };

private:
  /// the left-hand side
  Var *lhs;
  /// the kind of synthetic assignment
  Kind kind;
  /// any argument to the synthetic assignment
  Value *arg = nullptr;
  /// the difference
  int64_t diff = 0;

public:
  static const char NodeId;

  /// Constructs a synthetic assignment.
  /// @param lhs the variable being assigned
  /// @param arg the argument
  /// @param k the kind of assignment
  /// @param name the name of the instruction
  SyntheticAssignInstr(Var *lhs, Value *arg, Kind k = KNOWN, std::string name = "")
      : AcceptorExtend(std::move(name)), lhs(lhs), kind(k), arg(arg) {}
  /// Constructs an unknown synthetic assignment.
  /// @param lhs the variable being assigned
  /// @param name the name of the instruction
  explicit SyntheticAssignInstr(Var *lhs, std::string name = "")
      : SyntheticAssignInstr(lhs, nullptr, UNKNOWN, std::move(name)) {}
  /// Constructs an addition synthetic assignment.
  /// @param lhs the variable being assigned
  /// @param diff the difference
  /// @param name the name of the instruction
  SyntheticAssignInstr(Var *lhs, int64_t diff, std::string name = "")
      : AcceptorExtend(std::move(name)), lhs(lhs), kind(ADD), diff(diff) {}

  /// @return the variable being assigned
  Var *getLhs() { return lhs; }
  /// @return the variable being assigned
  const Var *getLhs() const { return lhs; }
  /// Sets the variable being assigned.
  /// @param v the variable
  void setLhs(Var *v) { lhs = v; }

  /// @return the argument
  Value *getArg() { return arg; }
  /// @return the argument
  const Value *getArg() const { return arg; }
  /// Sets the argument.
  /// @param v the new value
  void setArg(Value *v) { arg = v; }

  /// @return the diff
  int64_t getDiff() const { return diff; }
  /// Sets the diff.
  /// @param v the new value
  void setDiff(int64_t v) { diff = v; }

  /// @return the kind of synthetic assignment
  Kind getKind() const { return kind; }
  /// Sets the kind.
  /// @param k the new value
  void setKind(Kind k) { kind = k; }

protected:
  std::vector<Value *> doGetUsedValues() const override { return {arg}; }
  int doReplaceUsedValue(id_t id, Value *newValue) override;

  std::vector<Var *> doGetUsedVariables() const override { return {lhs}; }
  int doReplaceUsedVariable(id_t id, Var *newVar) override;
};

class SyntheticPhiInstr : public AcceptorExtend<SyntheticPhiInstr, Instr> {
public:
  class Predecessor {
  private:
    /// the predecessor block
    CFBlock *pred;
    /// the value
    Value *result;

  public:
    /// Constructs a predecessor.
    /// @param pred the predecessor block
    /// @param result the result of this predecessor.
    Predecessor(CFBlock *pred, Value *result) : pred(pred), result(result) {}

    /// @return the predecessor block
    CFBlock *getPred() { return pred; }
    /// @return the predecessor block
    const CFBlock *getPred() const { return pred; }
    /// Sets the predecessor.
    /// @param v the new value
    void setPred(CFBlock *v) { pred = v; }

    /// @return the result
    Value *getResult() { return result; }
    /// @return the result
    const Value *getResult() const { return result; }
    /// Sets the result
    /// @param v the new value
    void setResult(Value *v) { result = v; }
  };

private:
  std::list<Predecessor> preds;

public:
  static const char NodeId;

  explicit SyntheticPhiInstr(std::string name = "") : AcceptorExtend(std::move(name)) {}

  /// @return an iterator to the first instruction/flow
  auto begin() { return preds.begin(); }
  /// @return an iterator beyond the last instruction/flow
  auto end() { return preds.end(); }
  /// @return an iterator to the first instruction/flow
  auto begin() const { return preds.begin(); }
  /// @return an iterator beyond the last instruction/flow
  auto end() const { return preds.end(); }

  /// @return a pointer to the first instruction/flow
  Predecessor &front() { return preds.front(); }
  /// @return a pointer to the last instruction/flow
  Predecessor &back() { return preds.back(); }
  /// @return a pointer to the first instruction/flow
  const Predecessor &front() const { return preds.front(); }
  /// @return a pointer to the last instruction/flow
  const Predecessor &back() const { return preds.back(); }

  /// Inserts a predecessor.
  /// @param pos the position
  /// @param v the predecessor
  /// @return an iterator to the newly added predecessor
  template <typename It> auto insert(It pos, Predecessor v) {
    return preds.insert(pos, v);
  }
  /// Appends an predecessor.
  /// @param v the predecessor
  void push_back(Predecessor v) { preds.push_back(v); }

  /// Erases the item at the supplied position.
  /// @param pos the position
  /// @return the iterator beyond the removed predecessor
  template <typename It> auto erase(It pos) { return preds.erase(pos); }

  /// Emplaces a predecessor.
  /// @param args the args
  template <typename... Args> void emplace_back(Args &&...args) {
    preds.emplace_back(std::forward<Args>(args)...);
  }

protected:
  std::vector<Value *> doGetUsedValues() const override;
  int doReplaceUsedValue(id_t id, Value *newValue) override;
};

class CFGraph {
private:
  /// owned list of blocks
  std::list<std::unique_ptr<CFBlock>> blocks;
  /// the current block
  CFBlock *cur = nullptr;
  /// the function being analyzed
  const BodiedFunc *func;
  /// a list of synthetic values
  std::list<std::unique_ptr<Value>> syntheticValues;
  /// a map of synthetic values
  std::unordered_map<id_t, Value *> valueMapping;
  /// a list of synthetic variables
  std::list<std::unique_ptr<Var>> syntheticVars;
  /// a mapping from value id to block
  std::unordered_map<id_t, CFBlock *> valueLocations;

public:
  /// Constructs a control-flow graph.
  explicit CFGraph(const BodiedFunc *f);

  /// @return an iterator to the first block
  auto begin() { return util::raw_ptr_adaptor(blocks.begin()); }
  /// @return an iterator beyond the last block
  auto end() { return util::raw_ptr_adaptor(blocks.end()); }
  /// @return an iterator to the first block
  auto begin() const { return util::raw_ptr_adaptor(blocks.begin()); }
  /// @return an iterator beyond the last block
  auto end() const { return util::raw_ptr_adaptor(blocks.end()); }

  /// @return the entry block
  CFBlock *getEntryBlock() { return blocks.front().get(); }
  /// @return the entry block
  const CFBlock *getEntryBlock() const { return blocks.front().get(); }

  /// @return the entry block
  CFBlock *getCurrentBlock() { return cur; }
  /// @return the entry block
  const CFBlock *getCurrentBlock() const { return cur; }
  /// Sets the current block.
  /// @param v the new value
  void setCurrentBlock(CFBlock *v) { cur = v; }

  /// @return the function
  const BodiedFunc *getFunc() const { return func; }
  /// Sets the function.
  /// @param f the new value
  void setFunc(BodiedFunc *f) { func = f; }

  /// Gets the block containing a value.
  /// @param val the value
  /// @return the block
  CFBlock *getBlock(const Value *v) {
    auto vmIt = valueMapping.find(v->getId());
    if (vmIt != valueMapping.end())
      v = vmIt->second;

    auto it = valueLocations.find(v->getId());
    return it != valueLocations.end() ? it->second : nullptr;
  }
  /// Gets the block containing a value.
  /// @param val the value
  /// @return the block
  const CFBlock *getBlock(const Value *v) const {
    auto vmIt = valueMapping.find(v->getId());
    if (vmIt != valueMapping.end())
      v = vmIt->second;

    auto it = valueLocations.find(v->getId());
    return it != valueLocations.end() ? it->second : nullptr;
  }

  /// Creates and inserts a new block
  /// @param name the name
  /// @param setCur true if the block should be made the current one
  /// @return a newly inserted block
  CFBlock *newBlock(std::string name = "", bool setCur = false) {
    auto *ret = new CFBlock(this, std::move(name));
    blocks.emplace_back(ret);
    if (setCur)
      setCurrentBlock(ret);
    return ret;
  }

  template <typename NodeType, typename... Args> NodeType *N(Args &&...args) {
    auto *ret = new NodeType(std::forward<Args>(args)...);
    reg(ret);
    ret->setModule(func->getModule());
    return ret;
  }

  /// Remaps a value.
  /// @param id original id
  /// @param newValue the new value
  void remapValue(id_t id, Value *newValue) { valueMapping[id] = newValue; }
  /// Remaps a value.
  /// @param original the original value
  /// @param newValue the new value
  void remapValue(const Value *original, Value *newValue) {
    remapValue(original->getId(), newValue);
  }

  /// Gets a value by id.
  /// @param id the id
  /// @return the value or nullptr
  Value *getValue(id_t id) {
    auto it = valueMapping.find(id);
    return it != valueMapping.end() ? it->second : func->getModule()->getValue(id);
  }

  friend std::ostream &operator<<(std::ostream &os, const CFGraph &cfg);
  friend class CFBlock;

private:
  void reg(Var *v) { syntheticVars.emplace_back(v); }

  void reg(Value *v) {
    syntheticValues.emplace_back(v);
    valueMapping[v->getId()] = v;
  }
};

/// Builds a control-flow graph from a given function.
/// @param f the function
/// @return the control-flow graph
std::unique_ptr<CFGraph> buildCFGraph(const BodiedFunc *f);

/// Control-flow analysis result.
struct CFResult : public Result {
  /// map from function id to control-flow graph
  std::unordered_map<id_t, std::unique_ptr<CFGraph>> graphs;
};

/// Control-flow analysis that runs on all functions.
class CFAnalysis : public Analysis {
public:
  static const std::string KEY;
  std::string getKey() const override { return KEY; }

  std::unique_ptr<Result> run(const Module *m) override;
};

class CFVisitor : public util::ConstVisitor {
private:
  struct Loop {
    analyze::dataflow::CFBlock *nextIt;
    analyze::dataflow::CFBlock *end;
    id_t loopId;
    int tcIndex;

    Loop(analyze::dataflow::CFBlock *nextIt, analyze::dataflow::CFBlock *end,
         id_t loopId, int tcIndex = -1)
        : nextIt(nextIt), end(end), loopId(loopId), tcIndex(tcIndex) {}
  };

  analyze::dataflow::CFGraph *graph;
  std::vector<std::pair<analyze::dataflow::CFBlock *, analyze::dataflow::CFBlock *>>
      tryCatchStack;
  std::unordered_set<id_t> seenIds;
  std::vector<Loop> loopStack;

public:
  explicit CFVisitor(analyze::dataflow::CFGraph *graph) : graph(graph) {}

  void visit(const BodiedFunc *f) override;

  DEFAULT_VISIT(VarValue)
  DEFAULT_VISIT(PointerValue)

  void visit(const SeriesFlow *v) override;
  void visit(const IfFlow *v) override;
  void visit(const WhileFlow *v) override;
  void visit(const ForFlow *v) override;
  void visit(const ImperativeForFlow *v) override;

  void visit(const TryCatchFlow *v) override;
  void visit(const PipelineFlow *v) override;
  void visit(const dsl::CustomFlow *v) override;

  DEFAULT_VISIT(TemplatedConst<int64_t>);
  DEFAULT_VISIT(TemplatedConst<double>);
  DEFAULT_VISIT(TemplatedConst<bool>);
  DEFAULT_VISIT(TemplatedConst<std::string>);
  DEFAULT_VISIT(dsl::CustomConst);

  void visit(const AssignInstr *v) override;
  void visit(const ExtractInstr *v) override;
  void visit(const InsertInstr *v) override;
  void visit(const CallInstr *v) override;
  DEFAULT_VISIT(StackAllocInstr);
  DEFAULT_VISIT(TypePropertyInstr);
  DEFAULT_VISIT(YieldInInstr);

  void visit(const TernaryInstr *v) override;

  void visit(const BreakInstr *v) override;
  void visit(const ContinueInstr *v) override;
  void visit(const ReturnInstr *v) override;
  void visit(const YieldInstr *v) override;
  void visit(const ThrowInstr *v) override;
  void visit(const FlowInstr *v) override;
  void visit(const dsl::CustomInstr *v) override;

  template <typename NodeType> void process(const NodeType *v) {
    if (seenIds.find(v->getId()) != seenIds.end())
      return;
    seenIds.insert(v->getId());
    v->accept(*this);
  }

  void defaultInsert(const Value *v);
  void defaultJump(const CFBlock *cf, int newTcLevel = -1);

private:
  Loop &findLoop(id_t id);
};

} // namespace dataflow
} // namespace analyze
} // namespace ir
} // namespace seq

#undef DEFAULT_VISIT