Fast TLS support.

Fast TLS support.

This patch adds common infrastructure for fast TLS support and
implementation on win32. More implementations will be added soon.

Fast TLS is controlled by V8_FAST_TLS define which is enabled by
default in our gyp and scons builds. The scons build has
fasttls={on,off} option so that we can see the effects of slow TLS
when needed.

[antonm, 2011-03-25 16:44:44]

LGTM

I hope that this fast way to read TLS is covered by the current tests as it's
quite a common path, correct?

http://codereview.chromium.org/6696112/diff/1/SConstruct
File SConstruct (right):

http://codereview.chromium.org/6696112/diff/1/SConstruct#newcode794
SConstruct:794: 'help': 'enable fast thread local storage support'
maybe add something like 'if supported for the given platform'

http://codereview.chromium.org/6696112/diff/1/src/platform-tls-win32.h
File src/platform-tls-win32.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform-tls-win32.h#newcode43
src/platform-tls-win32.h:43: const intptr_t kTibInlineTlsOffset = 0xE10;
nit: do not we use lower case in hex constants?

http://codereview.chromium.org/6696112/diff/1/src/platform-tls.h
File src/platform-tls.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform-tls.h#newcode39
src/platform-tls.h:39: // provided fast TLS support for the current platform and
architecture
nit: provided -> provides?

http://codereview.chromium.org/6696112/diff/1/src/platform.h
File src/platform.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform.h#newcode433
src/platform.h:433: static inline void* GetExistingThreadLocal(LocalStorageKey
key) {
maybe make this method a template by a return type?

[Vitaly Repeshko, 2011-03-27 15:54:48]

Anton, thanks for reviewing this! I addressed most of your comments and added a
unit test for TLS stores/reads.


-- Vitaly

http://codereview.chromium.org/6696112/diff/1/SConstruct
File SConstruct (right):

http://codereview.chromium.org/6696112/diff/1/SConstruct#newcode794
SConstruct:794: 'help': 'enable fast thread local storage support'
On 2011/03/25 16:44:44, antonm wrote:
> maybe add something like 'if supported for the given platform'

Done.

http://codereview.chromium.org/6696112/diff/1/src/platform-tls-win32.h
File src/platform-tls-win32.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform-tls-win32.h#newcode43
src/platform-tls-win32.h:43: const intptr_t kTibInlineTlsOffset = 0xE10;
On 2011/03/25 16:44:44, antonm wrote:
> nit: do not we use lower case in hex constants?

Upper case seems to be more common.

http://codereview.chromium.org/6696112/diff/1/src/platform-tls.h
File src/platform-tls.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform-tls.h#newcode39
src/platform-tls.h:39: // provided fast TLS support for the current platform and
architecture
On 2011/03/25 16:44:44, antonm wrote:
> nit: provided -> provides?

Done.

http://codereview.chromium.org/6696112/diff/1/src/platform.h
File src/platform.h (right):

http://codereview.chromium.org/6696112/diff/1/src/platform.h#newcode433
src/platform.h:433: static inline void* GetExistingThreadLocal(LocalStorageKey
key) {
On 2011/03/25 16:44:44, antonm wrote:
> maybe make this method a template by a return type?

I'd like to avoid significant interface changes in this patch.