public abstract class InlinedProfile extends Object
Truffle compiler
directives to guard for and/or forward runtime information to the compiler. Whenever Truffle DSL
can be used inlined profiles subclasses should be used instead of regular
profile subclasses.
Usage: Inlined profiles are used using the Cached annotation in specialization
methods. See the individual profile subclasses for further usage examples. Profiles are intended
for local speculation only. For global speculations use assumptions instead.
Compilation: Some profiles like branch profiles do not induce
additional overhead in compiled code. Others like value profiles
might require a runtime check to verify their local speculation. Even if profiles do not induce
direct overhead in compiled code it still might get invalidated as a result of using profiles.
Invalidating profiles will result in the invalidation of compiled code. It is therefore essential
to place these profiles in way that is neither too aggressive nor too conservative, ideally based
on measurements in real world applications.
Footprint: Inlined versions of profiles have a significantly reduced memory footprint
compared to their allocated counterparts, however they do rely on their usage
being inlined to have the same performance characteristics. Whether profiling information can be
forwarded to the compiler depends on the capabilities of the runtime
system. If the runtime returns true in TruffleRuntime.isProfilingEnabled()
then runtime information will get collected. This comes at at the cost of additional overhead and
footprint in interpreted mode. Thats why the factory methods of profiles can return
implementations where profiling is disabled. Using disabled profiles makes sense for runtimes
that are unable to use the collected profiling information. Even runtime implementations that are
able to use this information might decide to turn off profiling for benchmarking purposes.
Inlined profile subclasses:
InlinedBranchProfile to profile on unlikely branches like errors.InlinedConditionProfile to profile on conditionals or boolean values.InlinedCountingConditionProfile to profile on conditionals or boolean values using
counters.InlinedLoopConditionProfile to profile on conditionals of loops with special support
for counted loops.InlinedByteValueProfile to profile on byte values.InlinedIntValueProfile to profile on int values.InlinedLongValueProfile to profile on long values.InlinedFloatValueProfile to profile on float values.InlinedDoubleValueProfile to profile on double values.InlinedProfile,
Assumption| Modifier and Type | Method and Description |
|---|---|
abstract void |
disable(Node node)
Disables this profile by setting it to its generic state.
|
abstract void |
reset(Node node)
Resets this profile to its uninitialized state.
|
String |
toString() |
abstract String |
toString(Node node)
Prints a string representation of this inlined profile given a target node.
|
public abstract void disable(Node node)
deoptimize on any
invocation of a profile method.
This method must not be called on compiled code paths. Note that disabling the profile will not invalidate existing compiled code that uses this profile.
public abstract void reset(Node node)
This method must not be called on compiled code paths. Note that disabling the profile will not invalidate existing compiled code that uses this profile.
public abstract String toString(Node node)