Could this be exposed to the shell, and used in tests to assert that a particular optimization is applied in a particular situation?
-j On Thu, Feb 5, 2015 at 6:20 PM, Shu-yu Guo <[email protected]> wrote: > Greetings, fellow subtrahend incrementers! > > I recently landed bug 1030389 to track the high-level optimizations > decisions > (i.e., deciding what MIR is emitted) made by IonBuilder. This information > will feed into the profiler and is attached to sampled JIT frames. > > Currently, getprop, setprop, getelem, setelem, and calls are tracked. I > should > like to introduce the API here so that upcoming patches of new > optimizations > like the SIMD.js optimizations are tracked from the beginning. > > High-level description > ---------------------- > > Optimizations are tracked by bytecode location. The API allows each > bytecode > location to track two things: optimization attempts, and type information. > > Each optimization attempt is is a pair of (strategy, outcome). These are > implemented by the enums TrackedStrategy and TrackedOutcome in > js/public/TrackedOptimizationInfo.h. The strategy describes the > optimization > Ion is attempting to emit (e.g., a definite slot load), and the outcome > describes a specific reason for its success or failure (e.g., failed due to > no type info). > > Each bytecode location can accumulate a list of attempts. This list is > terminated by the first successful attempt. The slow path is not encoded as > its own attempt pair and is inferred from a list of attempts whose outcomes > are all failures. That is, if only the slow path succeeded, the attempts > list > will all failed attempts. > > Each tracked type is a triple of (site, MIR type, type set). The site is > described by the enum TrackedTypeSite. > > API > --- > > Add the specific attempts, outcomes, and type sites you need, if not > already > present, to the enums in js/public/TrackedOptimizationInfo.h. > > To start tracking optimizations for a bytecode location, > call |startTrackingOptimizations()|. > > Usually, types are tracked in the beginning by > calling |trackTypeInfo(TrackedTypeSite, MIRType, TypeSet *)|. > > Before attempting to apply a strategy (e.g., before the call to > getPropTryConstant), call |trackOptimizationAttempt(TrackedStrategy)|. By > default, the outcome of the attempt is "generic failure". To refine the > outcome, call |trackOptimizationOutcome(TrackedOutcome)|. > > There is the convenience function |trackOptimizationSuccess()| to track > successes. Be sure to call this on successfully applying an optimization! > In > methods like IonBuilder::jsop_getprop where a series of strategies are > tried > one after another, each |*emitted = true| assignment should be accompanied > by > a call to |trackOptimizationSuccess()|. > > All tracking methods are infallible. OOM during tracking disables > optimization > tracking instead. > > That's it! Instrumentation bugs also make great first bugs, and I would be > happy to mentor. > > -- > shu > _______________________________________________ > dev-tech-js-engine-internals mailing list > [email protected] > https://lists.mozilla.org/listinfo/dev-tech-js-engine-internals > _______________________________________________ dev-tech-js-engine-internals mailing list [email protected] https://lists.mozilla.org/listinfo/dev-tech-js-engine-internals
