[MIPS] Add support for direct-to-nacl in Clang

[MIPS] Add support for direct-to-nacl in Clang

Cherry-picked r241678 from upstream, modified it to the current
PNaCl-Clang tree, and added an extra flag "-direct-to-nacl" that is not
present upstream.

Original commit message:

For Mips direct-to-nacl, the goal is to be close to le32 front-end and
use Mips32EL backend. This patch defines new NaClMips32ELTargetInfo and
modifies it slightly to be close to le32. It also adds necessary parts,
inline with ARM and X86.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4205
R=dschuff@chromium.org

Committed: 239048208dd9a33e670cad064b47b92a9f4335ec

[petarj, 2015-06-25 15:48:11]

petarj@mips.com changed reviewers:
+ dschuff@chromium.org

[petarj, 2015-06-25 15:48:31]

PTAL.

[Derek Schuff, 2015-06-25 17:05:07]

On 2015/06/25 15:48:31, petarj wrote:
> PTAL.

looks mostly ok. I'm not a big fan of the  llvm flag to enable the extra LLVM
passes, but there might not be a better option. Otherwise this looks like it can
go upstream, so we should do that first.

[petarj, 2015-06-25 17:57:36]

On 2015/06/25 17:05:07, Derek Schuff wrote:
> On 2015/06/25 15:48:31, petarj wrote:
> > PTAL.
> 
> looks mostly ok. I'm not a big fan of the  llvm flag to enable the extra LLVM
> passes, but there might not be a better option. Otherwise this looks like it
can
> go upstream, so we should do that first.

OK, I have just uploaded it at:

http://reviews.llvm.org/D10739

[Derek Schuff, 2015-06-25 18:18:16]

On 2015/06/25 17:57:36, petarj wrote:
> On 2015/06/25 17:05:07, Derek Schuff wrote:
> > On 2015/06/25 15:48:31, petarj wrote:
> > > PTAL.
> > 
> > looks mostly ok. I'm not a big fan of the  llvm flag to enable the extra
LLVM
> > passes, but there might not be a better option. Otherwise this looks like it
> can
> > go upstream, so we should do that first.
> 
> OK, I have just uploaded it at:
> 
> http://reviews.llvm.org/D10739

thanks, I have comments on phabricator.

[Derek Schuff, 2015-07-22 00:38:10]

LGTM if this can now be the same as the upstream change (with the extra LLVM
flag)

[petarj, 2015-07-24 18:19:11]

The change has been updated.

[petarj, 2015-07-24 18:44:18]

Committed patchset #2 (id:20001) manually as
239048208dd9a33e670cad064b47b92a9f4335ec (presubmit successful).