Implement code patcher for x64

Implement code patcher for x64.

Use the code patcher for the patching of the JS return sequence used by the debugger.

Added explicit instruction cache flushing in a code patching section which did not have it for completeness, even though it is not required on Intel processors.

Committed: http://code.google.com/p/v8/source/detail?r=2870

[Lasse Reichstein, 2009-09-10 12:33:12]

LGTM

http://codereview.chromium.org/203016/diff/1/3
File src/x64/assembler-x64.cc (right):

http://codereview.chromium.org/203016/diff/1/3#newcode184
Line 184: patcher.masm()->call(r10);
Could you add a (debug only) assertion that the patcher's
masm's pc_offset is pc_+13 at this point?

[Søren Thygesen Gjesse, 2009-09-10 12:57:54]

http://codereview.chromium.org/203016/diff/1/3
File src/x64/assembler-x64.cc (right):

http://codereview.chromium.org/203016/diff/1/3#newcode184
Line 184: patcher.masm()->call(r10);
On 2009/09/10 12:33:12, Lasse Reichstein wrote:
> Could you add a (debug only) assertion that the patcher's
> masm's pc_offset is pc_+13 at this point?

Done. Added that to the IA32 version as well.