/* Code blocks, which in proper compiler terminology are superblocks   (single entry, multiple exit code sequences) contain:
　　【与Intel Pin中的概念trace是相似的】   - A table giving a type for each temp (the "type environment")   - An expandable array of statements   - An expression of type 32 or 64 bits, depending on the     guest‘s word size, indicating the next destination if the block      executes all the way to the end, without a side exit   - An indication of any special actions (JumpKind) needed     for this final jump.      "IRSB" stands for "IR Super Block".*/typedef   struct {      IRTypeEnv* tyenv;      IRStmt**   stmts;      Int        stmts_size;      Int        stmts_used;      IRExpr*    next;      IRJumpKind jumpkind;   }   IRSB;

 Each IRSB contains three things:   - a type environment, which indicates the type of each temporary     value present in the IRSB   - a list of statements, which represent code   - a jump that exits from the end the IRSB

Statements (type ‘IRStmt‘) represent operations with side-effects,   eg.  guest register writes, stores, and assignments to temporaries.   Expressions (type ‘IRExpr‘) represent operations without   side-effects, eg. arithmetic operations, loads, constants.   Expressions can contain sub-expressions, forming expression trees,   eg. (3 + (4 * load(addr1)).

在代表guest state的缓存中的offset代表操作数长度的type