Remove padding in v8::internal::compiler::Constant class

Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=chromium:710933
Review-Url: https://codereview.chromium.org/2841343002
Cr-Commit-Position: refs/heads/master@{#45001}
Committed: https://chromium.googlesource.com/v8/v8/+/9ede481a8c873058f76a315a89c8803868403913

[stanisc, 2017-04-27 00:46:08]

The CQ bit was checked by stanisc@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-04-27 00:46:15]

Dry run: 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, 2017-04-27 01:15:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-27 01:15:11]

Dry run: This issue passed the CQ dry run.

[brucedawson, 2017-04-27 17:15:34]

Description was changed from

==========
Remove padding in Constant class

BUG=
==========

to

==========
Remove padding in Constant class

BUG=710933
==========

[brucedawson, 2017-04-27 17:18:38]

Trivia:

On Linux (and presumably OSX and Android) this class would already have no
padding on 32-bit builds, because int64_t only has four-byte alignment
requirements on those 32-bit platforms.

On Windows (32-bit and 64-bit) and 64-bit Linux, OSX, and Android this class had
eight bytes of padding.

The point being that this change helps all 64-bit processes, and 32-bit Windows
processes. FYI.

[stanisc, 2017-04-27 17:51:21]

Description was changed from

==========
Remove padding in Constant class

BUG=710933
==========

to

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes. I looked at the usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=710933
==========

[stanisc, 2017-04-27 17:52:15]

Description was changed from

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes. I looked at the usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=710933
==========

to

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the
usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=710933
==========

[stanisc, 2017-04-27 17:52:32]

stanisc@chromium.org changed reviewers:
+ titzer@chromium.org

[stanisc, 2017-04-27 17:52:32]

PTAL!

[stanisc, 2017-04-28 20:58:16]

Description was changed from

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the
usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=710933
==========

to

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the
usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=chromium:710933
==========

[titzer, 2017-04-30 23:51:09]

lgtm

[stanisc, 2017-05-01 03:35:46]

The CQ bit was checked by stanisc@chromium.org

[commit-bot: I haz the power, 2017-05-01 03:35:53]

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, 2017-05-01 04:05:01]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493609746714790, "parent_rev":
"e3207836388b1254dbb3e4b67a5822658b7a2dc4", "commit_rev":
"9ede481a8c873058f76a315a89c8803868403913"}

[commit-bot: I haz the power, 2017-05-01 04:05:09]

Description was changed from

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the
usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=chromium:710933
==========

to

==========
Remove padding in v8::internal::compiler::Constant class.

This makes the size of the class smaller by 8 bytes on 64-bit. I looked at the
usage
pattern. Even though it seems the number of instances doesn't get higher
than a few thousand, this class is still very hot because it is constructed and
passed by value a lot. So perhaps reducing the size would make passing this
class by value or growing arrays more optimal and might save some cycles.

Before:
    class v8::internal::compiler::Constant [sizeof = 24] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      <padding> (4 bytes)
      [sizeof=8] __int64 value_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      <padding> (4 bytes)
    }

After:
    class v8::internal::compiler::Constant [sizeof = 16] {
      [sizeof=4] v8::internal::compiler::Constant::Type type_
      [sizeof=4] v8::internal::RelocInfo::Mode rmode_
      [sizeof=8] __int64 value_
    }

BUG=chromium:710933

Review-Url: https://codereview.chromium.org/2841343002
Cr-Commit-Position: refs/heads/master@{#45001}
Committed:
https://chromium.googlesource.com/v8/v8/+/9ede481a8c873058f76a315a89c88038684...
==========

[commit-bot: I haz the power, 2017-05-01 04:05:10]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/9ede481a8c873058f76a315a89c88038684...