Revert of Make base::WeakPtr::Get() fast

Revert of Make base::WeakPtr::Get() fast (patchset #10 id:180001 of https://codereview.chromium.org/2963623002/ )

Reason for revert:
This seems to have broken Cronet tests and Linux TSan. See bugs.

Original issue's description:
> Make base::WeakPtr::Get() fast
> 
> It was previously calling WeakReference::is_valid() which was an out-of-line
> method. That means code like
> 
>   if (my_weak_ptr)
>     my_weak_ptr->foo();
> 
> would do two calls to is_valid(), plus tests and branching.
> 
> The is_valid() method showed up as one of the most frequently called non-inline
> functions during browser start-up on Windows (about 1M calls).
> 
> is_valid() was also inefficient because it had to do a null-pointer check on
> flag_, as well as checking if the flag was marked valid.
> 
> This patch removes the null-pointer check by using a sentinel object instead of
> a nullptr. And instead of storing a bool in the flag, it stores a pointer-sized
> bitmask 0 or ~0, so it can be AND'ed with the pointer value and conveniently
> setting EFLAGS so that the code above just becomes a few loads, AND, branch,
> and call. (The size of Flag is unchanged; it grows into the padding only.)
> 
> This is expected to reduce the binary size by ~48KB on Android, and increase it
> by 79KB on x64 Linux -- something that's paid for by the split-out refactorings
> to WeakPtr and WeakPtrFactory.
> 
> Exposing the SequenceChecker calls in inline functions caused the
> MessageLoopTestType*.Nesting test to overflow on Win64 dcheck release builds,
> which is why this patch also lowers the recursion depth there.
> 
> BUG=728324
> 
> Review-Url: https://codereview.chromium.org/2963623002
> Cr-Commit-Position: refs/heads/master@{#483427}
> Committed: https://chromium.googlesource.com/chromium/src/+/526f714c9ae172c3b16581b7e11eb035fd14274e

TBR=thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=728324, 738167, 738183, 738193
Review-Url: https://codereview.chromium.org/2966633002
Cr-Commit-Position: refs/heads/master@{#483509}
Committed: https://chromium.googlesource.com/chromium/src/+/24046fd36c1a132243a7ffd279f59734f947d223

[hans, 2017-06-29 22:02:48]

Created Revert of Make base::WeakPtr::Get() fast

[hans, 2017-06-29 22:06:46]

Description was changed from

==========
Revert of Make base::WeakPtr::Get() fast (patchset #10 id:180001 of
https://codereview.chromium.org/2963623002/ )

Reason for revert:
This seems to have broken Cronet tests and Linux TSan. See bugs.

Original issue's description:
> Make base::WeakPtr::Get() fast
> 
> It was previously calling WeakReference::is_valid() which was an out-of-line
> method. That means code like
> 
>   if (my_weak_ptr)
>     my_weak_ptr->foo();
> 
> would do two calls to is_valid(), plus tests and branching.
> 
> The is_valid() method showed up as one of the most frequently called
non-inline
> functions during browser start-up on Windows (about 1M calls).
> 
> is_valid() was also inefficient because it had to do a null-pointer check on
> flag_, as well as checking if the flag was marked valid.
> 
> This patch removes the null-pointer check by using a sentinel object instead
of
> a nullptr. And instead of storing a bool in the flag, it stores a
pointer-sized
> bitmask 0 or ~0, so it can be AND'ed with the pointer value and conveniently
> setting EFLAGS so that the code above just becomes a few loads, AND, branch,
> and call. (The size of Flag is unchanged; it grows into the padding only.)
> 
> This is expected to reduce the binary size by ~48KB on Android, and increase
it
> by 79KB on x64 Linux -- something that's paid for by the split-out
refactorings
> to WeakPtr and WeakPtrFactory.
> 
> Exposing the SequenceChecker calls in inline functions caused the
> MessageLoopTestType*.Nesting test to overflow on Win64 dcheck release builds,
> which is why this patch also lowers the recursion depth there.
> 
> BUG=728324
> 
> Review-Url: https://codereview.chromium.org/2963623002
> Cr-Commit-Position: refs/heads/master@{#483427}
> Committed:
https://chromium.googlesource.com/chromium/src/+/526f714c9ae172c3b16581b7e11e...

TBR=thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=728324
==========

to

==========
Revert of Make base::WeakPtr::Get() fast (patchset #10 id:180001 of
https://codereview.chromium.org/2963623002/ )

Reason for revert:
This seems to have broken Cronet tests and Linux TSan. See bugs.

Original issue's description:
> Make base::WeakPtr::Get() fast
> 
> It was previously calling WeakReference::is_valid() which was an out-of-line
> method. That means code like
> 
>   if (my_weak_ptr)
>     my_weak_ptr->foo();
> 
> would do two calls to is_valid(), plus tests and branching.
> 
> The is_valid() method showed up as one of the most frequently called
non-inline
> functions during browser start-up on Windows (about 1M calls).
> 
> is_valid() was also inefficient because it had to do a null-pointer check on
> flag_, as well as checking if the flag was marked valid.
> 
> This patch removes the null-pointer check by using a sentinel object instead
of
> a nullptr. And instead of storing a bool in the flag, it stores a
pointer-sized
> bitmask 0 or ~0, so it can be AND'ed with the pointer value and conveniently
> setting EFLAGS so that the code above just becomes a few loads, AND, branch,
> and call. (The size of Flag is unchanged; it grows into the padding only.)
> 
> This is expected to reduce the binary size by ~48KB on Android, and increase
it
> by 79KB on x64 Linux -- something that's paid for by the split-out
refactorings
> to WeakPtr and WeakPtrFactory.
> 
> Exposing the SequenceChecker calls in inline functions caused the
> MessageLoopTestType*.Nesting test to overflow on Win64 dcheck release builds,
> which is why this patch also lowers the recursion depth there.
> 
> BUG=728324
> 
> Review-Url: https://codereview.chromium.org/2963623002
> Cr-Commit-Position: refs/heads/master@{#483427}
> Committed:
https://chromium.googlesource.com/chromium/src/+/526f714c9ae172c3b16581b7e11e...

TBR=thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=728324,738167,738183,738193
==========

[hans, 2017-06-29 22:06:57]

The CQ bit was checked by hans@chromium.org

[commit-bot: I haz the power, 2017-06-29 22:07:28]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-06-29 22:07:47]

CQ is committing da patch.

Bot data: {"patchset_id": 100001, "attempt_start_ts": 1498774017325160,
"parent_rev": "df39d072bdadb328ed3c1a3ae7bf245512e09fe8", "commit_rev":
"24046fd36c1a132243a7ffd279f59734f947d223"}

[commit-bot: I haz the power, 2017-06-29 22:08:03]

Description was changed from

==========
Revert of Make base::WeakPtr::Get() fast (patchset #10 id:180001 of
https://codereview.chromium.org/2963623002/ )

Reason for revert:
This seems to have broken Cronet tests and Linux TSan. See bugs.

Original issue's description:
> Make base::WeakPtr::Get() fast
> 
> It was previously calling WeakReference::is_valid() which was an out-of-line
> method. That means code like
> 
>   if (my_weak_ptr)
>     my_weak_ptr->foo();
> 
> would do two calls to is_valid(), plus tests and branching.
> 
> The is_valid() method showed up as one of the most frequently called
non-inline
> functions during browser start-up on Windows (about 1M calls).
> 
> is_valid() was also inefficient because it had to do a null-pointer check on
> flag_, as well as checking if the flag was marked valid.
> 
> This patch removes the null-pointer check by using a sentinel object instead
of
> a nullptr. And instead of storing a bool in the flag, it stores a
pointer-sized
> bitmask 0 or ~0, so it can be AND'ed with the pointer value and conveniently
> setting EFLAGS so that the code above just becomes a few loads, AND, branch,
> and call. (The size of Flag is unchanged; it grows into the padding only.)
> 
> This is expected to reduce the binary size by ~48KB on Android, and increase
it
> by 79KB on x64 Linux -- something that's paid for by the split-out
refactorings
> to WeakPtr and WeakPtrFactory.
> 
> Exposing the SequenceChecker calls in inline functions caused the
> MessageLoopTestType*.Nesting test to overflow on Win64 dcheck release builds,
> which is why this patch also lowers the recursion depth there.
> 
> BUG=728324
> 
> Review-Url: https://codereview.chromium.org/2963623002
> Cr-Commit-Position: refs/heads/master@{#483427}
> Committed:
https://chromium.googlesource.com/chromium/src/+/526f714c9ae172c3b16581b7e11e...

TBR=thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=728324,738167,738183,738193
==========

to

==========
Revert of Make base::WeakPtr::Get() fast (patchset #10 id:180001 of
https://codereview.chromium.org/2963623002/ )

Reason for revert:
This seems to have broken Cronet tests and Linux TSan. See bugs.

Original issue's description:
> Make base::WeakPtr::Get() fast
> 
> It was previously calling WeakReference::is_valid() which was an out-of-line
> method. That means code like
> 
>   if (my_weak_ptr)
>     my_weak_ptr->foo();
> 
> would do two calls to is_valid(), plus tests and branching.
> 
> The is_valid() method showed up as one of the most frequently called
non-inline
> functions during browser start-up on Windows (about 1M calls).
> 
> is_valid() was also inefficient because it had to do a null-pointer check on
> flag_, as well as checking if the flag was marked valid.
> 
> This patch removes the null-pointer check by using a sentinel object instead
of
> a nullptr. And instead of storing a bool in the flag, it stores a
pointer-sized
> bitmask 0 or ~0, so it can be AND'ed with the pointer value and conveniently
> setting EFLAGS so that the code above just becomes a few loads, AND, branch,
> and call. (The size of Flag is unchanged; it grows into the padding only.)
> 
> This is expected to reduce the binary size by ~48KB on Android, and increase
it
> by 79KB on x64 Linux -- something that's paid for by the split-out
refactorings
> to WeakPtr and WeakPtrFactory.
> 
> Exposing the SequenceChecker calls in inline functions caused the
> MessageLoopTestType*.Nesting test to overflow on Win64 dcheck release builds,
> which is why this patch also lowers the recursion depth there.
> 
> BUG=728324
> 
> Review-Url: https://codereview.chromium.org/2963623002
> Cr-Commit-Position: refs/heads/master@{#483427}
> Committed:
https://chromium.googlesource.com/chromium/src/+/526f714c9ae172c3b16581b7e11e...

TBR=thakis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=728324,738167,738183,738193

Review-Url: https://codereview.chromium.org/2966633002
Cr-Commit-Position: refs/heads/master@{#483509}
Committed:
https://chromium.googlesource.com/chromium/src/+/24046fd36c1a132243a7ffd279f5...
==========

[commit-bot: I haz the power, 2017-06-29 22:08:04]

Committed patchset #2 (id:100001) as
https://chromium.googlesource.com/chromium/src/+/24046fd36c1a132243a7ffd279f5...