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_DIFFERENCE_ENGINE_H_
16 #define _LLVM_DIFFERENCE_ENGINE_H_
17 
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "DiffLog.h"
21 #include "DiffConsumer.h"
22 
23 #include <utility>
24 
25 namespace llvm {
26   class Function;
27   class GlobalValue;
28   class Instruction;
29   class LLVMContext;
30   class Module;
31   class Twine;
32   class Value;
33 
34   /// A class for performing structural comparisons of LLVM assembly.
35   class DifferenceEngine {
36   public:
37     /// A RAII object for recording the current context.
38     struct Context {
ContextContext39       Context(DifferenceEngine &Engine, Value *L, Value *R) : Engine(Engine) {
40         Engine.consumer.enterContext(L, R);
41       }
42 
~ContextContext43       ~Context() {
44         Engine.consumer.exitContext();
45       }
46 
47     private:
48       DifferenceEngine &Engine;
49     };
50 
51     /// An oracle for answering whether two values are equivalent as
52     /// operands.
53     struct Oracle {
54       virtual bool operator()(Value *L, Value *R) = 0;
55 
56     protected:
~OracleOracle57       virtual ~Oracle() {}
58     };
59 
DifferenceEngine(LLVMContext & context,Consumer & consumer)60     DifferenceEngine(LLVMContext &context, Consumer &consumer)
61       : context(context), consumer(consumer), globalValueOracle(0) {}
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     LLVMContext &context;
86     Consumer &consumer;
87     Oracle *globalValueOracle;
88   };
89 }
90 
91 #endif
92