首先向R大表示感谢，同时也为我一直以来在R大提供回答后未能有进一步思考表示遗憾与抱歉（因为确实对整个代码还不熟悉，很多基础还要补充)

下面是我的问题：

(DVM中)Jit划分状态是根据什么而来的？&&SelfVerification在jit中的角色是什么呢？其状态划分依据是？
在vm/interp/InterpState.h中：
/* States of the interpreter when serving a JIT-related request */
enum JitState {
    /* Entering states in the debug interpreter */
    kJitNot = 0,               // Non-JIT related reasons */
    kJitTSelectRequest = 1,    // Request a trace (subject to filtering)
    kJitTSelectRequestHot = 2, // Request a hot trace (bypass the filter)
    kJitSelfVerification = 3,  // Self Verification Mode

    /* Operational states in the debug interpreter */
    kJitTSelect = 4,           // Actively selecting a trace
    kJitTSelectEnd = 5,        // Done with the trace - wrap it up
    kJitDone = 6,              // No further JIT actions for interpBreak
};

#if defined(WITH_SELF_VERIFICATION)
enum SelfVerificationState {
    kSVSIdle = 0,           // Idle
    kSVSStart = 1,          // Shadow space set up, running compiled code
    kSVSPunt = 2,           // Exiting compiled code by punting
    kSVSSingleStep = 3,     // Exiting compiled code by single stepping
    kSVSNoProfile = 4,      // Exiting compiled code and don't collect profiles
    kSVSTraceSelect = 5,    // Exiting compiled code and compile the next pc
    kSVSNormal = 6,         // Exiting compiled code normally
    kSVSNoChain = 7,        // Exiting compiled code by no chain
    kSVSBackwardBranch = 8, // Exiting compiled code with backward branch trace
    kSVSDebugInterp = 9,    // Normal state restored, running debug interpreter
};
#endif

/* Number of entries in the 2nd level JIT profiler filter cache */
#define JIT_TRACE_THRESH_FILTER_SIZE 32
/* Number of low dalvik pc address bits to include in 2nd level filter key */
#define JIT_TRACE_THRESH_FILTER_PC_BITS 16
#define MAX_JIT_RUN_LEN 64

enum JitHint {
   kJitHintNone = 0,
   kJitHintTaken = 1,         // Last inst in run was taken branch
   kJitHintNotTaken = 2,      // Last inst in run was not taken branch
   kJitHintNoBias = 3,        // Last inst in run was unbiased branch
};

/*
* Element of a Jit trace description. If the isCode bit is set, it describes
* a contiguous sequence of Dalvik byte codes.
*/
struct JitCodeDesc {
    unsigned numInsts:8;     // Number of Byte codes in run
    unsigned runEnd:1;       // Run ends with last byte code
    JitHint hint:7;          // Hint to apply to final code of run
    u2 startOffset;          // Starting offset for trace run
};

/*
* A complete list of trace runs passed to the compiler looks like the
* following:
*   frag1
*   frag2
*   frag3
*   meta1
*     :
*   metan
*   frag4
*
* frags 1-4 have the "isCode" field set and describe the location/length of
* real code traces, while metas 1-n are misc information.
* The meaning of the meta content is loosely defined. It is usually the code
* fragment right before the first meta field (frag3 in this case) to
* understand and parse them. Frag4 could be a dummy one with 0 "numInsts" but
* the "runEnd" field set.
*
* For example, if a trace run contains a method inlining target, the class
* descriptor/loader of "this" and the currently resolved method pointer are
* three instances of meta information stored there.
*/
struct JitTraceRun {
    union {
        JitCodeDesc frag;
        void*       meta;
    } info;
    u4 isCode:1;
    u4 unused:31;
};
还有关于jit chaining是什么东西呢？

/*
* A complete list of trace runs passed to the compiler looks like the
* following:
*   frag1
*   frag2
*   frag3
*   meta1
*     :
*   metan
*   frag4
*
* frags 1-4 have the "isCode" field set and describe the location/length of
* real code traces, while metas 1-n are misc information.
* The meaning of the meta content is loosely defined. It is usually the code
* fragment right before the first meta field (frag3 in this case) to
* understand and parse them. Frag4 could be a dummy one with 0 "numInsts" but
* the "runEnd" field set.
*
* For example, if a trace run contains a method inlining target, the class
* descriptor/loader of "this" and the currently resolved method pointer are
* three instances of meta information stored there.*/
这段注释没看懂，不知道：
* A complete list of trace runs passed to the compiler looks like the
* following:
*   frag1
*   frag2
*   frag3
*   meta1
*     :
*   metan
*   frag4
想表达什么意思！！