1 //===-- DifferenceEngine.h - Module comparator ------------------*- 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 header defines the interface to the LLVM difference engine,
11 // which structurally compares functions within a module.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_TOOLS_LLVM_DIFF_DIFFERENCEENGINE_H
16 #define LLVM_TOOLS_LLVM_DIFF_DIFFERENCEENGINE_H
17 
18 #include "DiffConsumer.h"
19 #include "DiffLog.h"
20 #include "llvm/ADT/StringRef.h"
21 #include <utility>
22 
23 namespace llvm {
24   class Function;
25   class GlobalValue;
26   class Instruction;
27   class LLVMContext;
28   class Module;
29   class Twine;
30   class Value;
31 
32   /// A class for performing structural comparisons of LLVM assembly.
33   class DifferenceEngine {
34   public:
35     /// A RAII object for recording the current context.
36     struct Context {
ContextContext37       Context(DifferenceEngine &Engine, Value *L, Value *R) : Engine(Engine) {
38         Engine.consumer.enterContext(L, R);
39       }
40 
~ContextContext41       ~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()(Value *L, Value *R) = 0;
55 
56     protected:
~Oracle()57       virtual ~Oracle() {}
58     };
59 
DifferenceEngine(Consumer & consumer)60     DifferenceEngine(Consumer &consumer)
61       : consumer(consumer), globalValueOracle(nullptr) {}
62 
63     void diff(Module *L, Module *R);
64     void diff(Function *L, Function *R);
log(StringRef text)65     void log(StringRef text) {
66       consumer.log(text);
67     }
logf(StringRef text)68     LogBuilder logf(StringRef text) {
69       return LogBuilder(consumer, text);
70     }
getConsumer()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.
setGlobalValueOracle(Oracle * oracle)77     void setGlobalValueOracle(Oracle *oracle) {
78       globalValueOracle = oracle;
79     }
80 
81     /// Determines whether two global values are equivalent.
82     bool equivalentAsOperands(GlobalValue *L, GlobalValue *R);
83 
84   private:
85     Consumer &consumer;
86     Oracle *globalValueOracle;
87   };
88 }
89 
90 #endif
91