utils/TableGen/SetTheory.h

   1 //===- SetTheory.h - Generate ordered sets from DAG expressions -*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the SetTheory class that computes ordered sets of
  11 // Records from DAG expressions.  Operators for standard set operations are
  12 // predefined, and it is possible to add special purpose set operators as well.
  13 //
  14 // The user may define named sets as Records of predefined classes. Set
  15 // expanders can be added to a SetTheory instance to teach it how to find the
  16 // elements of such a named set.
  17 //
  18 // These are the predefined operators. The argument lists can be individual
  19 // elements (defs), other sets (defs of expandable classes), lists, or DAG
  20 // expressions that are evaluated recursively.
  21 //
  22 // - (add S1, S2 ...) Union sets. This is also how sets are created from element
  23 //   lists.
  24 //
  25 // - (sub S1, S2, ...) Set difference. Every element in S1 except for the
  26 //   elements in S2, ...
  27 //
  28 // - (and S1, S2) Set intersection. Every element in S1 that is also in S2.
  29 //
  30 // - (shl S, N) Shift left. Remove the first N elements from S.
  31 //
  32 // - (trunc S, N) Truncate. The first N elements of S.
  33 //
  34 // - (rotl S, N) Rotate left. Same as (add (shl S, N), (trunc S, N)).
  35 //
  36 // - (rotr S, N) Rotate right.
  37 //
  38 // - (decimate S, N) Decimate S by picking every N'th element, starting with
  39 //   the first one. For instance, (decimate S, 2) returns the even elements of
  40 //   S.
  41 //
  42 // - (sequence "Format", From, To) Generate a sequence of defs with printf.
  43 //   For instance, (sequence "R%u", 0, 3) -> [ R0, R1, R2, R3 ]
  44 //
  45 //===----------------------------------------------------------------------===//
  46
  47 #ifndef SETTHEORY_H
  48 #define SETTHEORY_H
  49
  50 #include "llvm/ADT/StringMap.h"
  51 #include "llvm/ADT/SetVector.h"
  52 #include <map>
  53 #include <vector>
  54
  55 namespace llvm {
  56
  57 class DagInit;
  58 struct Init;
  59 class Record;
  60 class RecordKeeper;
  61
  62 class SetTheory {
  63 public:
  64   typedef std::vector<Record*> RecVec;
  65   typedef SmallSetVector<Record*, 16> RecSet;
  66
  67   /// Operator - A callback representing a DAG operator.
  68   struct Operator {
  69     virtual ~Operator() {}
  70
  71     /// apply - Apply this operator to Expr's arguments and insert the result
  72     /// in Elts.
  73     virtual void apply(SetTheory&, DagInit *Expr, RecSet &Elts) =0;
  74   };
  75
  76   /// Expander - A callback function that can transform a Record representing a
  77   /// set into a fully expanded list of elements. Expanders provide a way for
  78   /// users to define named sets that can be used in DAG expressions.
  79   struct Expander {
  80     virtual ~Expander() {}
  81
  82     virtual void expand(SetTheory&, Record*, RecSet &Elts) =0;
  83   };
  84
  85 private:
  86   // Map set defs to their fully expanded contents. This serves as a memoization
  87   // cache and it makes it possible to return const references on queries.
  88   typedef std::map<Record*, RecVec> ExpandMap;
  89   ExpandMap Expansions;
  90
  91   // Known DAG operators by name.
  92   StringMap<Operator*> Operators;
  93
  94   // Typed expanders by class name.
  95   StringMap<Expander*> Expanders;
  96
  97 public:
  98   /// Create a SetTheory instance with only the standard operators.
  99   SetTheory();
 100
 101   /// addExpander - Add an expander for Records with the named super class.
 102   void addExpander(StringRef ClassName, Expander*);
 103
 104   /// addFieldExpander - Add an expander for ClassName that simply evaluates
 105   /// FieldName in the Record to get the set elements.  That is all that is
 106   /// needed for a class like:
 107   ///
 108   ///   class Set<dag d> {
 109   ///     dag Elts = d;
 110   ///   }
 111   ///
 112   void addFieldExpander(StringRef ClassName, StringRef FieldName);
 113
 114   /// addOperator - Add a DAG operator.
 115   void addOperator(StringRef Name, Operator*);
 116
 117   /// evaluate - Evaluate Expr and append the resulting set to Elts.
 118   void evaluate(Init *Expr, RecSet &Elts);
 119
 120   /// evaluate - Evaluate a sequence of Inits and append to Elts.
 121   template<typename Iter>
 122   void evaluate(Iter begin, Iter end, RecSet &Elts) {
 123     while (begin != end)
 124       evaluate(*begin++, Elts);
 125   }
 126
 127   /// expand - Expand a record into a set of elements if possible.  Return a
 128   /// pointer to the expanded elements, or NULL if Set cannot be expanded
 129   /// further.
 130   const RecVec *expand(Record *Set);
 131 };
 132
 133 } // end namespace llvm
 134
 135 #endif
 136