Fix CPU features detection and stack alignment assert on iOS

Fix CPU features detection and stack alignment assert on iOS

R=zra@google.com

Committed: https://github.com/dart-lang/sdk/commit/dfd7c0b2213e5f7f289e86811210ceffcdd69bf0

[Chinmay, 2015-10-27 20:18:29]

chinmaygarde@google.com changed reviewers:
+ cutchccutchan@google.com, rmacnak@google.com

[Chinmay, 2015-10-27 20:18:29]

Depends on https://codereview.chromium.org/1421253004

[rmacnak, 2015-10-27 20:43:53]

rmacnak@google.com changed reviewers:
+ zra@google.com
- cutchccutchan@google.com

[rmacnak, 2015-10-27 20:44:22]

+Zach

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/cpu_arm.cc
File runtime/vm/cpu_arm.cc (right):

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/cpu_arm.cc#newco...
runtime/vm/cpu_arm.cc:132: void HostCPUFeatures::InitOnce() {
TODO(24743): Actually check the CPU features and fail if we're missing something
assumed in a precompiled snapshot.

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/os_macos.cc
File runtime/vm/os_macos.cc (right):

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/os_macos.cc#newc...
runtime/vm/os_macos.cc:146: return 8;
// Even if we generate code that maintains a strong alignment, we cannot assert
the stronger stack alignment because C++ code will not maintain it.

[Chinmay, 2015-10-27 20:49:47]

Done

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/cpu_arm.cc
File runtime/vm/cpu_arm.cc (right):

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/cpu_arm.cc#newco...
runtime/vm/cpu_arm.cc:132: void HostCPUFeatures::InitOnce() {
On 2015/10/27 at 20:44:22, rmacnak wrote:
> TODO(24743): Actually check the CPU features and fail if we're missing
something assumed in a precompiled snapshot.

ack

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/os_macos.cc
File runtime/vm/os_macos.cc (right):

https://codereview.chromium.org/1413643004/diff/1/runtime/vm/os_macos.cc#newc...
runtime/vm/os_macos.cc:146: return 8;
On 2015/10/27 at 20:44:22, rmacnak wrote:
> // Even if we generate code that maintains a strong alignment, we cannot
assert the stronger stack alignment because C++ code will not maintain it.

ack

[zra, 2015-10-27 20:58:42]

lgtm with question

https://codereview.chromium.org/1413643004/diff/20001/runtime/vm/cpu_arm.cc
File runtime/vm/cpu_arm.cc (right):

https://codereview.chromium.org/1413643004/diff/20001/runtime/vm/cpu_arm.cc#n...
runtime/vm/cpu_arm.cc:134: // something assumed in a precompiled snapshot.
How do you know what is assumed by a precompiled snapshot?

[Chinmay, 2015-10-27 21:23:50]

Committed patchset #2 (id:20001) manually as
dfd7c0b2213e5f7f289e86811210ceffcdd69bf0.