Treat R19 is a C preserved register, fixing crashing on Linux ARM64.

Note that R19 is a C preserved register, fixing crash returning from the first Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.

R=regis@google.com

Committed: https://github.com/dart-lang/sdk/commit/642f75421976e0f19ce21ca17cc6226f75871eab

[rmacnak, 2016-01-05 22:11:43]

Description was changed from

==========
Treat R19 is a C preserved register, fixing crashing on Linux ARM64.

 - Move the Dart stack pointer from R19 to R15 so it isn't among the registers
saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Don't try to use the IA32 binary to build Observatory on ARM64 hosts.

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

to

==========
Treat R19 as a C preserved register, fixing crash returning from first Dart
entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Don't try to use the IA32 binary to build Observatory on ARM64 hosts.
==========

[rmacnak, 2016-01-05 22:29:00]

Description was changed from

==========
Treat R19 as a C preserved register, fixing crash returning from first Dart
entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Don't try to use the IA32 binary to build Observatory on ARM64 hosts.
==========

to

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Don't try to use the IA32 binary to build Observatory on ARM64 hosts.

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

[rmacnak, 2016-01-06 00:21:03]

rmacnak@google.com changed reviewers:
+ regis@google.com

[rmacnak, 2016-01-06 00:36:07]

Description was changed from

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Don't try to use the IA32 binary to build Observatory on ARM64 hosts.

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

to

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.
 - Use ARM32 instead of missing ARM64 binary to run ./tools/test.py.
==========

[rmacnak, 2016-01-06 19:13:33]

Description was changed from

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.
 - Use ARM32 instead of missing ARM64 binary to run ./tools/test.py.
==========

to

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.
==========

[regis, 2016-01-07 09:16:21]

LGTM

I wonder how we missed th

https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
File runtime/vm/constants_arm64.h (right):

https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
runtime/vm/constants_arm64.h:33: R20 = 20,  // THR
R20 now looks lonely in the middle of the R19-R28 callee-saved range. You could
consider using R19 as the THR register and mark it here as
// THR and first callee-saved register.
Even better, using consecutive callee-saved registers for our Dart needs would
make R26 our THR register.
But that is not important.

[rmacnak, 2016-01-07 17:05:49]

https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
File runtime/vm/constants_arm64.h (right):

https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
runtime/vm/constants_arm64.h:33: R20 = 20,  // THR
On 2016/01/07 09:16:21, regis wrote:
> R20 now looks lonely in the middle of the R19-R28 callee-saved range. You
could
> consider using R19 as the THR register and mark it here as
> // THR and first callee-saved register.
> Even better, using consecutive callee-saved registers for our Dart needs would
> make R26 our THR register.
> But that is not important.

Yes, I like that better. I'll do it in a separate CL.

[regis, 2016-01-07 17:19:39]

On 2016/01/07 17:05:49, rmacnak wrote:
>
https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
> File runtime/vm/constants_arm64.h (right):
> 
>
https://codereview.chromium.org/1559223003/diff/40001/runtime/vm/constants_ar...
> runtime/vm/constants_arm64.h:33: R20 = 20,  // THR
> On 2016/01/07 09:16:21, regis wrote:
> > R20 now looks lonely in the middle of the R19-R28 callee-saved range. You
> could
> > consider using R19 as the THR register and mark it here as
> > // THR and first callee-saved register.
> > Even better, using consecutive callee-saved registers for our Dart needs
would
> > make R26 our THR register.
> > But that is not important.
> 
> Yes, I like that better. I'll do it in a separate CL.

Sounds good.

[rmacnak, 2016-01-07 17:30:20]

Description was changed from

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.
==========

to

==========
Note that R19 is a C preserved register, fixing crash returning from the first
Dart entry on Linux ARM64.

Bug was introduced by 91bc8005fe28a4d613c3c9d26f03fd6ae08b83aa.

 - Move the Dart stack pointer from R19 (C preserved) to R15 (C volatile) so it
isn't among the registers saved by the InvokeDartCode stub.
 - Set a default cross compiler for ARM64.
 - Use ARM32 instead of IA32 binary to build Observatory on ARM64 hosts.

R=regis@google.com

Committed:
https://github.com/dart-lang/sdk/commit/642f75421976e0f19ce21ca17cc6226f75871eab
==========

[rmacnak, 2016-01-07 17:30:22]

Committed patchset #3 (id:40001) manually as
642f75421976e0f19ce21ca17cc6226f75871eab (presubmit successful).