aboutsummaryrefslogtreecommitdiffstats
path: root/libyul/optimiser/EquivalentFunctionDetector.h
blob: 329fd385ed01b46c383bad8ee35821524208615d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * Optimiser component that combines syntactically equivalent functions.
 */
#pragma once

#include <libyul/optimiser/ASTWalker.h>
#include <libyul/AsmDataForward.h>

namespace yul
{

/**
 * Optimiser component that detects syntactically equivalent functions.
 *
 * Prerequisite: Disambiguator
 */
class EquivalentFunctionDetector: public ASTWalker
{
public:
    static std::map<YulString, FunctionDefinition const*> run(Block& _block)
    {
        EquivalentFunctionDetector detector{};
        detector(_block);
        return std::move(detector.m_duplicates);
    }

    using ASTWalker::operator();
    void operator()(FunctionDefinition const& _fun) override;

private:
    EquivalentFunctionDetector() = default;
    /**
     * Fast heuristic to detect distinct, resp. potentially equal functions.
     *
     * Defines a partial order on function definitions. If two functions
     * are comparable (one is "less" than the other), they are distinct.
     * If not (neither is "less" than the other), they are *potentially* equal.
     */
    class RoughHeuristic
    {
    public:
        RoughHeuristic(FunctionDefinition const& _fun): m_fun(_fun) {}
        bool operator<(RoughHeuristic const& _rhs) const;
    private:
        std::size_t codeSize() const;
        FunctionDefinition const& m_fun;
        mutable boost::optional<std::size_t> m_codeSize;
        // In case the heuristic doesn't turn out to be good enough, we might want to define a hash function for code blocks.
    };
    std::map<RoughHeuristic, std::vector<FunctionDefinition const*>> m_candidates;
    std::map<YulString, FunctionDefinition const*> m_duplicates;
};


}