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 
22 namespace 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, const Value *L, const Value *R)
37           : Engine(Engine) {
38         Engine.consumer.enterContext(L, R);
39       }
40 
41       ~Context() {
42         Engine.consumer.exitContext();
43       }
44 
45     private:
46       DifferenceEngine &Engine;
47     };
48 
49     /// An oracle for answering whether two values are equivalent as
50     /// operands.
51     class Oracle {
52       virtual void anchor();
53     public:
54       virtual bool operator()(const Value *L, const Value *R) = 0;
55 
56     protected:
57       virtual ~Oracle() {}
58     };
59 
60     DifferenceEngine(Consumer &consumer)
61       : consumer(consumer), globalValueOracle(nullptr) {}
62 
63     void diff(const Module *L, const Module *R);
64     void diff(const Function *L, const Function *R);
65     void log(StringRef text) {
66       consumer.log(text);
67     }
68     LogBuilder logf(StringRef text) {
69       return LogBuilder(consumer, text);
70     }
71     Consumer& getConsumer() const { return consumer; }
72 
73     /// Installs an oracle to decide whether two global values are
74     /// equivalent as operands.  Without an oracle, global values are
75     /// considered equivalent as operands precisely when they have the
76     /// same name.
77     void setGlobalValueOracle(Oracle *oracle) {
78       globalValueOracle = oracle;
79     }
80 
81     /// Determines whether two global values are equivalent.
82     bool equivalentAsOperands(const GlobalValue *L, const GlobalValue *R);
83 
84   private:
85     Consumer &consumer;
86     Oracle *globalValueOracle;
87   };
88 }
89 
90 #endif
91