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* Mozilla TraceMonkey Team
* Asko Tontti <atontti@cc.hut.fi>
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#ifndef __nanojit_Fragmento__
#define __nanojit_Fragmento__
namespace nanojit
{
struct GuardRecord;
/**
* Fragments are linear sequences of native code that have a single entry
* point at the start of the fragment and may have one or more exit points
*
* It may turn out that that this arrangement causes too much traffic
* between d and i-caches and that we need to carve up the structure differently.
*/
class Fragment
{
public:
Fragment(const void*
verbose_only(, uint32_t profFragID));
NIns* code() { return _code; }
void setCode(NIns* codee) { _code = codee; }
int32_t& hits() { return _hits; }
LirBuffer* lirbuf;
LIns* lastIns;
const void* ip;
uint32_t recordAttempts;
NIns* fragEntry;
// for fragment entry and exit profiling. See detailed
// how-to-use comment below.
verbose_only( LIns* loopLabel; ) // where's the loop top?
verbose_only( uint32_t profFragID; )
verbose_only( uint32_t profCount; )
verbose_only( uint32_t nStaticExits; )
verbose_only( size_t nCodeBytes; )
verbose_only( size_t nExitBytes; )
verbose_only( uint32_t guardNumberer; )
verbose_only( GuardRecord* guardsForFrag; )
private:
NIns* _code; // ptr to start of code
int32_t _hits;
};
}
/*
* How to use fragment profiling
*
* Fragprofiling adds code to count how many times each fragment is
* entered, and how many times each guard (exit) is taken. Using this
* it's possible to easily find which fragments are hot, which ones
* typically exit early, etc. The fragprofiler also gathers some
* simple static info: for each fragment, the number of code bytes,
* number of exit-block bytes, and number of guards (exits).
*
* Fragments and guards are given unique IDs (FragID, GuardID) which
* are shown in debug printouts, so as to facilitate navigating from
* the accumulated statistics to the associated bits of code.
* GuardIDs are issued automatically, but FragIDs you must supply when
* calling Fragment::Fragment. Supply values >= 1, and supply a
* different value for each new fragment (doesn't matter what, they
* just have to be unique and >= 1); else
* js_FragProfiling_FragFinalizer will assert.
*
* How to use/embed:
*
* - use a debug build (one with NJ_VERBOSE). Without it, none of
* this code is compiled in.
*
* - set LC_FragProfile in the lcbits of the LogControl* object handed
* to Nanojit
*
* When enabled, Fragment::profCount is incremented every time the
* fragment is entered, and GuardRecord::profCount is incremented
* every time that guard exits. However, NJ has no way to know where
* the fragment entry/loopback point is. So you must set
* Fragment::loopLabel before running the assembler, so as to indicate
* where the fragment-entry counter increment should be placed. If
* the fragment does not naturally have a loop label then you will
* need to artificially add one.
*
* It is the embedder's problem to fish out, collate and present the
* accumulated stats at the end of the Fragment's lifetime. A
* Fragment contains stats indicating its entry count and static code
* sizes. It also has a ::guardsForFrag field, which is a linked list
* of GuardRecords, and by traversing them you can get hold of the
* exit counts.
*/
#endif // __nanojit_Fragmento__