1//===-- DifferenceEngine.h - Module comparator ------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This header defines the interface to the LLVM difference engine,
10// which structurally compares functions within a module.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_TOOLS_LLVM_DIFF_DIFFERENCEENGINE_H
15#define LLVM_TOOLS_LLVM_DIFF_DIFFERENCEENGINE_H
16
17#include "DiffConsumer.h"
18#include "DiffLog.h"
19#include "llvm/ADT/StringRef.h"
20#include <utility>
21
22namespace llvm {
23  class Function;
24  class GlobalValue;
25  class Instruction;
26  class LLVMContext;
27  class Module;
28  class Twine;
29  class Value;
30
31  /// A class for performing structural comparisons of LLVM assembly.
32  class DifferenceEngine {
33  public:
34    /// A RAII object for recording the current context.
35    struct Context {
36      Context(DifferenceEngine &Engine, Value *L, Value *R) : Engine(Engine) {
37        Engine.consumer.enterContext(L, R);
38      }
39
40      ~Context() {
41        Engine.consumer.exitContext();
42      }
43
44    private:
45      DifferenceEngine &Engine;
46    };
47
48    /// An oracle for answering whether two values are equivalent as
49    /// operands.
50    class Oracle {
51      virtual void anchor();
52    public:
53      virtual bool operator()(Value *L, Value *R) = 0;
54
55    protected:
56      virtual ~Oracle() {}
57    };
58
59    DifferenceEngine(Consumer &consumer)
60      : consumer(consumer), globalValueOracle(nullptr) {}
61
62    void diff(Module *L, Module *R);
63    void diff(Function *L, Function *R);
64    void log(StringRef text) {
65      consumer.log(text);
66    }
67    LogBuilder logf(StringRef text) {
68      return LogBuilder(consumer, text);
69    }
70    Consumer& getConsumer() const { return consumer; }
71
72    /// Installs an oracle to decide whether two global values are
73    /// equivalent as operands.  Without an oracle, global values are
74    /// considered equivalent as operands precisely when they have the
75    /// same name.
76    void setGlobalValueOracle(Oracle *oracle) {
77      globalValueOracle = oracle;
78    }
79
80    /// Determines whether two global values are equivalent.
81    bool equivalentAsOperands(GlobalValue *L, GlobalValue *R);
82
83  private:
84    Consumer &consumer;
85    Oracle *globalValueOracle;
86  };
87}
88
89#endif
90