The RandomNumberGenerator is a pseudorandom number generator
with 48-bit state. It is properly seeded using either
(1) the --random-seed if specified, or
(2) the entropy_source function if configured, or
(3) /dev/urandom if available, or
(4) falls back to Time and TimeTicks based seeding.
Each Isolate now contains a RandomNumberGenerator, which replaces
the previous private_random_seed.
Every native context still has its own random_seed. But this random
seed is now properly initialized during bootstrapping,
instead of on-demand initialization. This will allow us to cleanup
and speedup the HRandom implementation quite a lot (this is delayed
for a followup CL)!
Also stop messing with the system rand()/random(), which should
not be done from a library anyway! We probably re-seeded the
libc rand()/random() after the application (i.e. Chrome) already
seeded it (with better entropy than what we used).
Another followup CL will replace the use of the per-isolate
random number generator for the address randomization and
thereby get rid of the Isolate::UncheckedCurrent() usage in
the platform code.
TEST=cctest/test-random-number-generator,cctest/test-random
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23548024
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16612 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Condition variables are synchronization primitives that can be used
to block one or more threads while waiting for condition to become
true.
Right now we have only semaphores, mutexes and atomic operations for
synchronization, which results in quite complex solutions where an
implementation using condition variables and mutexes would be straight
forward.
There's also a performance benefit to condition variables and mutexes
vs semaphores, especially on Windows, where semaphores are kernel
objects, while mutexes are implemented as fast critical sections,
it CAN be beneficial performance-wise to use condition variables
instead of semaphores.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23548007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Drop the previous Mutex and ScopedLock classes from platform files.
Add new Mutex, RecursiveMutex and LockGuard classes, which are
designed after their C++11 counterparts, so that at some point
we can simply drop our custom code and switch to the C++11
classes. We distinguish regular and recursive mutexes, as the
latter don't work well with condition variables, which will be
introduced by a followup CL.
R=mstarzinger@chromium.org
Review URL: https://codereview.chromium.org/23625003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16416 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
These classes are meant to replace OS::Ticks() and OS::TimeCurrentMillis(),
which are broken in several ways. The ElapsedTimer class implements a
stopwatch using TimeTicks::HighResNow() for high resolution, monotonic
timing.
Also fix the CpuProfile::GetStartTime() and CpuProfile::GetEndTime()
methods to actually return the time relative to the unix epoch as stated
in the documentation (previously that was relative to some arbitrary
point in time, i.e. boot time).
The previous Windows issues have been resolved, and we now use GetTickCount64()
on Windows Vista and later, falling back to timeGetTime() with rollover
protection for earlier Windows versions.
BUG=v8:2853
R=machenbach@chromium.org, yurys@chromium.org
Review URL: https://codereview.chromium.org/23490015
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16413 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
These classes are meant to replace OS::Ticks() and OS::TimeCurrentMillis(),
which are broken in several ways. The ElapsedTimer class implements a
stopwatch using TimeTicks::HighResNow() for high resolution, monotonic
timing.
Also fix the CpuProfile::GetStartTime() and CpuProfile::GetEndTime()
methods to actually return the time relative to the unix epoch as stated
in the documentation (previously that was relative to some arbitrary
point in time, i.e. boot time).
BUG=v8:2853
R=machenbach@chromium.org
Review URL: https://codereview.chromium.org/23469013
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16398 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
These classes are meant to replace OS::Ticks() and OS::TimeCurrentMillis(),
which are broken in several ways. The ElapsedTimer class implements a
stopwatch using TimeTicks::HighResNow() for high resolution, monotonic
timing.
Also fix the CpuProfile::GetStartTime() and CpuProfile::GetEndTime()
methods to actually return the time relative to the unix epoch as stated
in the documentation (previously that was relative to some arbitrary
point in time, i.e. boot time).
BUG=v8:2853
R=machenbach@chromium.org, yurys@chromium.org
Review URL: https://codereview.chromium.org/23295034
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16388 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Move all of the CPU detection logic to the CPU class, and make
all other code use the CPU class for feature detection.
This also fixes the ARM CPU feature detection logic, which was
based on fragile string search in /proc/cpuinfo. Now we use
ELF hwcaps if available, falling back to sane(!!) parsing of
/proc/cpuinfo for CPU features.
The ia32 and x64 code was also cleaned up to make it usable
outside the assembler.
R=svenpanne@chromium.org
Review URL: https://codereview.chromium.org/23401002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16315 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
For that, we maintain an abstract store typing of all variables with LOCAL location (i.e., those that do not escape the function's own scope). We treat assignments as sequential effects that modify this store.
When control flow branches, we have to compute the disjunction of possible effects. To that end, we represent the store as a stack of effect sets, such that we can cheaply push and pop "local" effects when control flow has to branch.
In cases of non-local control transfer from an unknown source, we currently erase all knowledge about the store.
The 'switch' statement is still to come.
For a formulation of the typing rules, see:
https://docs.google.com/a/google.com/file/d/0B3wuXSv9YKuKeUNkVXZDemZ0Z1E
;)
R=jkummerow@chromium.org
BUG=
Review URL: https://codereview.chromium.org/19054006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15776 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
