Convert Constant->emit() definitions to allow multiple targets to define them.

Convert Constant->emit() definitions to allow multiple targets to define them.

Wasn't sure how to allow TargetX8632 and TargetARM32
to both define "ConstantInteger32::emit(GlobalContext *)",
and define them differently if both targets happen to be
ifdef'ed into the code. Rearranged things so that it's now
"TargetFoo::emit(ConstantInteger32 *)", so that each
TargetFoo can have a separate definition.

Some targets may allow emitting some types of constants
while other targets do not (64-bit int for x86-64?).
Also they emit constants with a different style.
E.g., the prefix for x86 is "$" while the prefix for ARM
is "#" and there isn't a prefix for mips(?).
Renamed emitWithoutDollar to emitWithoutPrefix.

Did this sort of multi-method dispatch via a visitor
pattern, which is a bit verbose though.

We may be able to remove the emitWithoutDollar/Prefix for
ConstantPrimitive by just inlining that into the few places
that need it (only needed for ConstantInteger32). This
undoes the unreachable methods added by: https://codereview.chromium.org/1017373002/diff/60001/src/IceTargetLoweringX8632.cpp
The only place extra was for emitting calls to constants.
There was already an inlined instance for OperandX8632Mem.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=76bb0bec94b99765be86525fa1ae2c607e66d9b6

[jvoung (off chromium), 2015-05-13 23:35:15]

jvoung@chromium.org changed reviewers:
+ kschimpf@google.com, stichnot@chromium.org

[Jim Stichnoth, 2015-05-14 00:36:06]

LGTM, thanks!

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
src/IceTargetLoweringX8632.cpp:4661: llvm_unreachable("Not expecting to emit
64-bit integers");
report_fatal_error?

[jvoung (off chromium), 2015-05-14 16:14:48]

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
src/IceTargetLoweringX8632.cpp:4661: llvm_unreachable("Not expecting to emit
64-bit integers");
On 2015/05/14 00:36:06, stichnot wrote:
> report_fatal_error?

Done.

Should this be conditioned on "if (!ALLOW_DUMP)" ?

[Jim Stichnoth, 2015-05-14 16:22:05]

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
File src/IceTargetLoweringX8632.cpp (right):

https://codereview.chromium.org/1129263005/diff/60001/src/IceTargetLoweringX8...
src/IceTargetLoweringX8632.cpp:4661: llvm_unreachable("Not expecting to emit
64-bit integers");
On 2015/05/14 16:14:48, jvoung wrote:
> On 2015/05/14 00:36:06, stichnot wrote:
> > report_fatal_error?
> 
> Done.
> 
> Should this be conditioned on "if (!ALLOW_DUMP)" ?

I don't think so.  The main purpose of ALLOW_DUMP is to reduce translator code
size (and to a small extent data size) in a minimal/production build.

In this case, I think it's really a fatal error.  I'm pretty sure there are
other uses of report_fatal_error that are not guarded by ALLOW_DUMP, so this
instance should have minimal code size impact.

[jvoung (off chromium), 2015-05-14 16:26:27]

Committed patchset #6 (id:100001) manually as
76bb0bec94b99765be86525fa1ae2c607e66d9b6 (presubmit successful).