Fix for an ARM register allocation bug.

Fix for an ARM register allocation bug.

An off-by-one in the register allocator could lead to allocating (and
clobbering) the reserved 0.0 double register.  This required a function with
14 or more live double values.

BUG=
TEST=

Committed: http://code.google.com/p/v8/source/detail?r=10374

[Kevin Millikin (Chromium), 2012-01-10 15:24:38]

Slava, would you please take a look at this?

[Vyacheslav Egorov (Chromium), 2012-01-10 15:28:27]

lgtm 

please add a test in a separate revision

also please when transitioning from js -> c and exiting topmost js frame check
that d14 is 0.0.

http://codereview.chromium.org/9114038/diff/1/src/arm/assembler-arm.h
File src/arm/assembler-arm.h (right):

http://codereview.chromium.org/9114038/diff/1/src/arm/assembler-arm.h#newcode180
src/arm/assembler-arm.h:180: ASSERT(reg.code() != 14 && reg.code() != 15);
I don't like this magic constants a bit.

[Kevin Millikin (Chromium), 2012-01-10 16:15:03]

The ARM gap resolver had a hard coded r0 as an available scratch register.  This
obviously might not work if we allow r0 to be allocated.

I'm a-gonna need you to take another look.

[Kevin Millikin (Chromium), 2012-01-10 16:52:57]

Redirecting to fschneider.

[fschneider, 2012-01-10 16:59:05]

LGTM.