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//===- SetTheory.h - Generate ordered sets from DAG expressions -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the SetTheory class that computes ordered sets of
// Records from DAG expressions. Operators for standard set operations are
// predefined, and it is possible to add special purpose set operators as well.
//
// The user may define named sets as Records of predefined classes. Set
// expanders can be added to a SetTheory instance to teach it how to find the
// elements of such a named set.
//
// These are the predefined operators. The argument lists can be individual
// elements (defs), other sets (defs of expandable classes), lists, or DAG
// expressions that are evaluated recursively.
//
// - (add S1, S2 ...) Union sets. This is also how sets are created from element
// lists.
//
// - (sub S1, S2, ...) Set difference. Every element in S1 except for the
// elements in S2, ...
//
// - (and S1, S2) Set intersection. Every element in S1 that is also in S2.
//
// - (shl S, N) Shift left. Remove the first N elements from S.
//
// - (trunc S, N) Truncate. The first N elements of S.
//
// - (rotl S, N) Rotate left. Same as (add (shl S, N), (trunc S, N)).
//
// - (rotr S, N) Rotate right.
//
// - (decimate S, N) Decimate S by picking every N'th element, starting with
// the first one. For instance, (decimate S, 2) returns the even elements of
// S.
//
// - (sequence "Format", From, To, [Stride]) Generate a sequence of defs with
// printf. For instance, (sequence "R%u", 0, 3) -> [ R0, R1, R2, R3 ] and
// (sequence "R%u", 20, 30, 5) -> [ R20, R25, R30 ].
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TABLEGEN_SETTHEORY_H
#define LLVM_TABLEGEN_SETTHEORY_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/SMLoc.h"
#include <map>
#include <memory>
#include <vector>
namespace llvm {
class DagInit;
class Init;
class Record;
class SetTheory {
public:
using RecVec = std::vector<Record *>;
using RecSet = SmallSetVector<Record *, 16>;
/// Operator - A callback representing a DAG operator.
class Operator {
virtual void anchor();
public:
virtual ~Operator() = default;
/// apply - Apply this operator to Expr's arguments and insert the result
/// in Elts.
virtual void apply(SetTheory&, DagInit *Expr, RecSet &Elts,
ArrayRef<SMLoc> Loc) = 0;
};
/// Expander - A callback function that can transform a Record representing a
/// set into a fully expanded list of elements. Expanders provide a way for
/// users to define named sets that can be used in DAG expressions.
class Expander {
virtual void anchor();
public:
virtual ~Expander() = default;
virtual void expand(SetTheory&, Record*, RecSet &Elts) = 0;
};
private:
// Map set defs to their fully expanded contents. This serves as a memoization
// cache and it makes it possible to return const references on queries.
using ExpandMap = std::map<Record *, RecVec>;
ExpandMap Expansions;
// Known DAG operators by name.
StringMap<std::unique_ptr<Operator>> Operators;
// Typed expanders by class name.
StringMap<std::unique_ptr<Expander>> Expanders;
public:
/// Create a SetTheory instance with only the standard operators.
SetTheory();
/// addExpander - Add an expander for Records with the named super class.
void addExpander(StringRef ClassName, std::unique_ptr<Expander>);
/// addFieldExpander - Add an expander for ClassName that simply evaluates
/// FieldName in the Record to get the set elements. That is all that is
/// needed for a class like:
///
/// class Set<dag d> {
/// dag Elts = d;
/// }
///
void addFieldExpander(StringRef ClassName, StringRef FieldName);
/// addOperator - Add a DAG operator.
void addOperator(StringRef Name, std::unique_ptr<Operator>);
/// evaluate - Evaluate Expr and append the resulting set to Elts.
void evaluate(Init *Expr, RecSet &Elts, ArrayRef<SMLoc> Loc);
/// evaluate - Evaluate a sequence of Inits and append to Elts.
template<typename Iter>
void evaluate(Iter begin, Iter end, RecSet &Elts, ArrayRef<SMLoc> Loc) {
while (begin != end)
evaluate(*begin++, Elts, Loc);
}
/// expand - Expand a record into a set of elements if possible. Return a
/// pointer to the expanded elements, or NULL if Set cannot be expanded
/// further.
const RecVec *expand(Record *Set);
};
} // end namespace llvm
#endif // LLVM_TABLEGEN_SETTHEORY_H
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