[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide which FP register t…

[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide which FP register to load.

Android and Linux use R11 as the FP register in ARM code and R7 in Thumb code. We've been assuming all code in our process is ARM and reading R11 as FP. This made our stack walks fail if they started in Thumb code.

This issue does not arise on iOS, because its ABI uses R7 as the FP register for both ARM and Thumb code.

R=zra@google.com

Committed: https://github.com/dart-lang/sdk/commit/daa38a2ea21d290e45adb509dc60418b22ec7eba

[rmacnak, 2017-06-30 21:27:59]

Description was changed from

==========
[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide
which FP register to load.

Android and Linux use R11 as the FP register in ARM code and R7 in Thumb code.
We've been assuming all code in our process is ARM and reading R11 as FP. This
made our stack walks fail if they started in Thumb code.

This issue does not arise on iOS, because it's ABI use R7 as the FP register for
both ARM and Thumb code.
==========

to

==========
[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide
which FP register to load.

Android and Linux use R11 as the FP register in ARM code and R7 in Thumb code.
We've been assuming all code in our process is ARM and reading R11 as FP. This
made our stack walks fail if they started in Thumb code.

This issue does not arise on iOS, because its ABI uses R7 as the FP register for
both ARM and Thumb code.
==========

[rmacnak, 2017-06-30 21:28:13]

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

[zra, 2017-06-30 21:35:31]

lgtm w/ nit

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_a...
File runtime/vm/signal_handler_android.cc (right):

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_a...
runtime/vm/signal_handler_android.cc:40: if (mcontext.arm_cpsr & (1 << 5)) {
if ((mcontext.arm_cpsr & (1 << 5)) != 0) {

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_l...
File runtime/vm/signal_handler_linux.cc (right):

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_l...
runtime/vm/signal_handler_linux.cc:40: if (mcontext.arm_cpsr & (1 << 5)) {
ditto

[rmacnak, 2017-06-30 21:44:21]

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_a...
File runtime/vm/signal_handler_android.cc (right):

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_a...
runtime/vm/signal_handler_android.cc:40: if (mcontext.arm_cpsr & (1 << 5)) {
On 2017/06/30 21:35:30, zra wrote:
> if ((mcontext.arm_cpsr & (1 << 5)) != 0) {

Done.

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_l...
File runtime/vm/signal_handler_linux.cc (right):

https://codereview.chromium.org/2965823002/diff/1/runtime/vm/signal_handler_l...
runtime/vm/signal_handler_linux.cc:40: if (mcontext.arm_cpsr & (1 << 5)) {
On 2017/06/30 21:35:30, zra wrote:
> ditto

Done.

[rmacnak, 2017-07-05 16:43:17]

Description was changed from

==========
[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide
which FP register to load.

Android and Linux use R11 as the FP register in ARM code and R7 in Thumb code.
We've been assuming all code in our process is ARM and reading R11 as FP. This
made our stack walks fail if they started in Thumb code.

This issue does not arise on iOS, because its ABI uses R7 as the FP register for
both ARM and Thumb code.
==========

to

==========
[profiler, linux/android] Check whether a sample is ARM or Thumb code to decide
which FP register to load.

Android and Linux use R11 as the FP register in ARM code and R7 in Thumb code.
We've been assuming all code in our process is ARM and reading R11 as FP. This
made our stack walks fail if they started in Thumb code.

This issue does not arise on iOS, because its ABI uses R7 as the FP register for
both ARM and Thumb code.

R=zra@google.com

Committed:
https://github.com/dart-lang/sdk/commit/daa38a2ea21d290e45adb509dc60418b22ec7eba
==========

[rmacnak, 2017-07-05 16:43:18]

Committed patchset #2 (id:20001) manually as
daa38a2ea21d290e45adb509dc60418b22ec7eba (presubmit successful).