Ensure stack alignment in ARM port...

Ensure stack alignment in ARM port

In the CEntryStub keep track of the actual skew from the correct alignment to ensure proper alignment before calling the runtime. Add checks to test the expected skew when running on hardware.

Use the PrepareCallCFunction/CallCFunction in a few other places.

Add check to the ARM simulator for correct alignment.

Add option --sim-stack-alignment to set the stack alignment in the simulator. Currntly only values 4 and 8 makes sense. 8 is the default to make snapshots generated with the simulator work on hardware requiring 8 byte stack alignment.

Committed: http://code.google.com/p/v8/source/detail?r=4425

[Søren Thygesen Gjesse, 2010-04-15 08:08:26]

I am quite sure that the push of 0 in the CEntryStub::GenerateCore might as well
be a decrement of sp, as pushing 1 instead does not break any tests, so most
likely the GC does not look at this part of the stack. However I will like to
check this more throughly before making that change.

I am in the process of running the tests on ARM hardware.

[Erik Corry, 2010-04-15 08:42:14]

Don't we need something similar on Intel?  Mac has stack alignment requirements
in the ABI

LGTM

http://codereview.chromium.org/1530043/diff/26001/14007
File src/arm/codegen-arm.cc (right):

http://codereview.chromium.org/1530043/diff/26001/14007#newcode7157
src/arm/codegen-arm.cc:7157: // restore sp back to before aligning the stack.
restore -> Restore
to before -> to its value from before

[Søren Thygesen Gjesse, 2010-04-15 09:34:22]

http://codereview.chromium.org/1530043/diff/26001/14007
File src/arm/codegen-arm.cc (right):

http://codereview.chromium.org/1530043/diff/26001/14007#newcode7157
src/arm/codegen-arm.cc:7157: // restore sp back to before aligning the stack.
On 2010/04/15 08:42:14, Erik Corry wrote:
> restore -> Restore
> to before -> to its value from before

Done.