Fix .gyp file and avoid adding -m32 on 32 bit systems.

Fix .gyp file and avoid adding -m32 on 32 bit systems.
Fix SConstruct to only add -m32 if the compiler needs it.

[Lasse Reichstein, 2009-04-29 15:20:09]

TBR.
It turns out that "wordsize" should not be used as the desired word size, but as
the compilers expected word size.
Only add -m32 or -m64 if desired word size doesn't match compiler's.

[iposva, 2009-04-29 21:30:30]

http://codereview.chromium.org/100160/diff/1/2
File SConstruct (right):

http://codereview.chromium.org/100160/diff/1/2#newcode158
Line 158: 'CPPDEFINES':   ['V8_ARCH_X64', 'LP64']
Shouldn't you rely on __LP64__ being defined by the compiler?

Also as a note of warning Windows 64-bit uses (LL)P64, so while we are bringing
this up we should take care to not use long to mean 64-bit values, but use a
sized type such as int64_t.

Actually thinking about this second point, I think it illustrates well that you
should not define LP64 here because it will be wrong on certain architectures.

Same for ILP32, I don't think it should be defined in the build files.

http://codereview.chromium.org/100160/diff/1/2#newcode213
Line 213: 'CPPDEFINES':   ['ARM']
This is now redundant and should be removed. As are the other defintions of ARM.

http://codereview.chromium.org/100160/diff/1/2#newcode612
Line 612: Abort("X64 compilation only allowed on Linux OS.")
Why? The Mac has a perfectly fine working x64 environment. And it would be nice
to be able to test on a secondary platform occasionally.

[Mads Ager (chromium), 2009-04-30 07:02:00]

LGTM.

Ivan's comments make sense to me.

[Lasse Reichstein, 2009-05-01 06:36:29]

http://codereview.chromium.org/100160/diff/1/2
File SConstruct (right):

http://codereview.chromium.org/100160/diff/1/2#newcode158
Line 158: 'CPPDEFINES':   ['V8_ARCH_X64', 'LP64']
Personally, I prefer setting everything myself to depending on the compiler.
It is exactly because of Windows using LLPC64 that we are going to need to
differentiate, and I much prefer being in control to relying on some property
that might differ between compilers.

If not all GCC compilers use LP64 as 64-bit data model, then these declarations
should be fixed. The ones I am aware of should do so. The setting for the MSVC
compiler should be in another sub-section (and hasn't been added yet).

I.e., it was deliberate, but I'm open to arguments for other approaches.

http://codereview.chromium.org/100160/diff/1/2#newcode213
Line 213: 'CPPDEFINES':   ['ARM']
Done.

http://codereview.chromium.org/100160/diff/1/2#newcode612
Line 612: Abort("X64 compilation only allowed on Linux OS.")
Yes, there is probably no reason for this restriction anyway. We don't guarantee
that it compiles anyway, yet. I didn't remove it before committing, but it
should be removed when there's an occasion.