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Alias analysis is a technique in compiler theory, used to determine if a storage location may be accessed in more than one way. Two pointers are said to be aliased if they point to the same location. Alias analysis techniques are usually classified by flow-sensitivity and context-sensitivity. They may determine may-alias or must-alias information. The term alias analysis is often used interchangeably with term points-to analysis, a specific case. Alias analysers intend to make and compute useful information for understanding aliasing in programs. ==Overview== In general, alias analysis determines whether or not separate memory references point to the same area of memory. This allows the compiler to determine what variables in the program will be affected by a statement. For example, consider the following section of code that accesses members of structures: p.foo = 1; q.foo = 2; i = p.foo + 3; There are three possible alias cases here: #The variables p and q cannot alias. #The variables p and q must alias. #It cannot be conclusively determined at compile time if p and q alias or not. If p and q cannot alias, then i = p.foo + 3; can be changed to i = 4. If p and q must alias, then i = p.foo + 3; can be changed to i = 5. In both cases, we are able to perform optimizations from the alias knowledge. On the other hand, if it is not known if p and q alias or not, then no optimizations can be performed and the whole of the code must be executed to get the result. Two memory references are said to have a ''may-alias'' relation if their aliasing is unknown.抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Alias analysis」の詳細全文を読む スポンサード リンク
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