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 LLVM_TABLEGEN_SETTHEORY_H
48 #define LLVM_TABLEGEN_SETTHEORY_H
49 
50 #include "llvm/ADT/ArrayRef.h"
51 #include "llvm/ADT/SetVector.h"
52 #include "llvm/ADT/StringMap.h"
53 #include "llvm/Support/SMLoc.h"
54 #include <map>
55 #include <vector>
56 
57 namespace llvm {
58 
59 class DagInit;
60 class Init;
61 class Record;
62 
63 class SetTheory {
64 public:
65   typedef std::vector<Record*> RecVec;
66   typedef SmallSetVector<Record*, 16> RecSet;
67 
68   /// Operator - A callback representing a DAG operator.
69   class Operator {
70     virtual void anchor();
71   public:
~Operator()72     virtual ~Operator() {}
73 
74     /// apply - Apply this operator to Expr's arguments and insert the result
75     /// in Elts.
76     virtual void apply(SetTheory&, DagInit *Expr, RecSet &Elts,
77                        ArrayRef<SMLoc> Loc) =0;
78   };
79 
80   /// Expander - A callback function that can transform a Record representing a
81   /// set into a fully expanded list of elements. Expanders provide a way for
82   /// users to define named sets that can be used in DAG expressions.
83   class Expander {
84     virtual void anchor();
85   public:
~Expander()86     virtual ~Expander() {}
87 
88     virtual void expand(SetTheory&, Record*, RecSet &Elts) =0;
89   };
90 
91 private:
92   // Map set defs to their fully expanded contents. This serves as a memoization
93   // cache and it makes it possible to return const references on queries.
94   typedef std::map<Record*, RecVec> ExpandMap;
95   ExpandMap Expansions;
96 
97   // Known DAG operators by name.
98   StringMap<std::unique_ptr<Operator>> Operators;
99 
100   // Typed expanders by class name.
101   StringMap<std::unique_ptr<Expander>> Expanders;
102 
103 public:
104   /// Create a SetTheory instance with only the standard operators.
105   SetTheory();
106 
107   /// addExpander - Add an expander for Records with the named super class.
108   void addExpander(StringRef ClassName, std::unique_ptr<Expander>);
109 
110   /// addFieldExpander - Add an expander for ClassName that simply evaluates
111   /// FieldName in the Record to get the set elements.  That is all that is
112   /// needed for a class like:
113   ///
114   ///   class Set<dag d> {
115   ///     dag Elts = d;
116   ///   }
117   ///
118   void addFieldExpander(StringRef ClassName, StringRef FieldName);
119 
120   /// addOperator - Add a DAG operator.
121   void addOperator(StringRef Name, std::unique_ptr<Operator>);
122 
123   /// evaluate - Evaluate Expr and append the resulting set to Elts.
124   void evaluate(Init *Expr, RecSet &Elts, ArrayRef<SMLoc> Loc);
125 
126   /// evaluate - Evaluate a sequence of Inits and append to Elts.
127   template<typename Iter>
evaluate(Iter begin,Iter end,RecSet & Elts,ArrayRef<SMLoc> Loc)128   void evaluate(Iter begin, Iter end, RecSet &Elts, ArrayRef<SMLoc> Loc) {
129     while (begin != end)
130       evaluate(*begin++, Elts, Loc);
131   }
132 
133   /// expand - Expand a record into a set of elements if possible.  Return a
134   /// pointer to the expanded elements, or NULL if Set cannot be expanded
135   /// further.
136   const RecVec *expand(Record *Set);
137 };
138 
139 } // end namespace llvm
140 
141 #endif
142 
143