Clean up use of ifdefs for ARM variants....

Clean up use of ifdefs for ARM variants.
If you are cross-compiling snapshots for an ARM CPU that supports
VFP or ARMv7 instructions you need to define the
CAN_USE_VFP_INSTRUCTIONS and CAN_USE_ARMV7_INSTRUCTIONS in the
mksnapshot stage.  Otherwise the snapshot will not make use
of the instructions, resulting in slower floating point
performance.
Should also fix http://code.google.com/p/v8/issues/detail?id=590

Committed: http://code.google.com/p/v8/source/detail?r=3951

[Søren Thygesen Gjesse, 2010-02-25 11:25:57]

LGTM with comments addressed.

http://codereview.chromium.org/661075/diff/1/6
File src/arm/assembler-arm.cc (right):

http://codereview.chromium.org/661075/diff/1/6#newcode51
src/arm/assembler-arm.cc:51: #ifdef __arm__
Please add comment

  // NAME_OF_DEFINE

to all #else's and #endif's

http://codereview.chromium.org/661075/diff/1/6#newcode72
src/arm/assembler-arm.cc:72: #if !defined(__arm__)
#ifndef for consistency? Maybe turn it around to be an #ifdef.

http://codereview.chromium.org/661075/diff/1/3
File src/platform-freebsd.cc (right):

http://codereview.chromium.org/661075/diff/1/3#newcode194
src/platform-freebsd.cc:194: void OS::DebugBreak() {
Wont this not lead to emitting int $3 with __arm__ defined and 
CAN_USE_ARMV5_INSTRUCTIONS not defined?

In platform-linux.cc and platform-openbsd.cc as well.

[david1, 2010-08-16 09:16:05]

On 2010/02/25 11:25:57, Søren Gjesse wrote:

[...]

> 
> http://codereview.chromium.org/661075/diff/1/3#newcode194
> src/platform-freebsd.cc:194: void OS::DebugBreak() {
> Wont this not lead to emitting int $3 with __arm__ defined and 
> CAN_USE_ARMV5_INSTRUCTIONS not defined?
> 
> In platform-linux.cc and platform-openbsd.cc as well.

Yes, it does. Which is why v8 does not build on ARMv4.

See:
http://code.google.com/p/v8/issues/detail?id=590