tree fd2f221e9598fc7fa5066b2a9c746b228ef53faf
parent 2be6fc74bce10ac68d3d1b39a5019f520ad170ea
author Sebastien Hertz <shertz@google.com> 1395947207 +0100
committer Sebastien Hertz <shertz@google.com> 1397060608 +0200

Speed up single-stepping

During single-stepping sequence, we need to deoptimize everything when we
register a single-step event and undeoptimize everything when it is done. This
causes a slow pattern where we continuously deoptimize-undeoptimize everything
for each single-step.

This CL introduces a special handling of single-step undeoptimization. We now
delay the undeoptimization to the next resume (one thread or all threads) or
the end of the debugging session. Indeed, a single-step event registration is
always followed by a resume command.
At the "resume" point, we know if a single-step event is registered and if we
really need to undeoptimize. At the "registration" point, we know we did not
undeoptimized everything so we don't need to deoptimize everything again.
Therefore, in a sequence of single-steps, we only do a full deoptimization for
the first single-step and a full undeoptimization for the last single-step.

We update logs at deoptimization points so we can track more precisely. Note
they are verbose logs that still must be enabled with -verbose:jdwp option.

We also make some improvement inside instrumentation:
* updates Instrumentation::ShouldNotifyMethodEnterExitEvents to comply with its
name.
* compute frame id only once when looking for the corresponding instrumentation
frame.
* compute the OatMethod once in ClassLinker::GetPortableOatCodeFor to avoid
looking for it again.

Bug: 13577964
Change-Id: If6fa198a676b515cd474b8c4d7bf7ef3626f2dc7