* Made preemption work in Irregexp-native-ia32

Preemption code for irregexp-native-ia32. Regexps can not only succeede or
fail, but also report a thrown exception.

[Lasse Reichstein, 2008-12-12 08:53:20]

Major review.
Suggestions for alternative location or name for
Execution::HandleStackGuardInterrup appreciated.

[Erik Corry, 2008-12-12 10:01:05]

LGTM.

We need to devise a test for GC-during-regexp-matching.

Does it lint?

Does it run on Mac?

http://codereview.chromium.org/13783/diff/1/4
File src/assembler-ia32.h (right):

http://codereview.chromium.org/13783/diff/1/4#newcode187
Line 187: inline explicit Immediate(Label* value);
I think this is rather confusing.  It's for emitting an offset to the start of
the code object, but it looks like it's for emitting the address of the label
itself.  Since constructors can't be renamed I'd prefer a static method that
returns the result of a private constructor.  That way you can call it
CodeObjectRelativeOffset(Label*).

http://codereview.chromium.org/13783/diff/1/4#newcode753
Line 753: inline void emit_label(Label* label);
The name of this is very generic.  It should have a longer name that reflects
what it does, eg. emit_code_relative_offset.

http://codereview.chromium.org/13783/diff/1/5
File src/assembler.h (right):

http://codereview.chromium.org/13783/diff/1/5#newcode178
Line 178: INTERNAL_REFERENCE,  // An address inside the same function.
I liked it better before.

http://codereview.chromium.org/13783/diff/1/7
File src/execution.h (right):

http://codereview.chromium.org/13783/diff/1/7#newcode124
Line 124: // stack overflow, the handle the interruption.
this sense make no

http://codereview.chromium.org/13783/diff/1/9
File src/regexp-macro-assembler-ia32.cc (right):

http://codereview.chromium.org/13783/diff/1/9#newcode198
Line 198: switch (mode_) {
I liked it better before with if instead of switch.  Since there are only two
possibilities you might as well tell the compiler and the reader that.  One of
them can optimize better and the other can understand better.

http://codereview.chromium.org/13783/diff/1/9#newcode215
Line 215: switch (mode_) {
Ditto and more places below.