PowerPC -mcpu=future patches, V11

[Michael Meissner <meissner@linux.ibm.com>]

This set of patches reworks the vector extract issues in the V10 patches.

If you recall, in V10, you pointed out that for vector extract, the existing
code overwrote an input argument, and that is fixed in these patches.

In V10, I added two new constraints (ep and em) to categorize whether a memory
is prefixed or not prefixed, and we had some discussion about how to write the
predicates.

However, yesterday I realized that for the case adding new constraints (vector
extract with a variable element number, where the vector is in memory, and we
are optimizing the load to just load up the element being extract), what we
want is just the address of the vector in a base register.

This is because in order access the element where the element number is
variable, we eventually will need to do an X-FORM load, with the vector address
in one register, and the byte offset in another.

Instead of adding new alternatives and new scratch registers, I could just
simplify the code and use the 'Q' constraint that says use a single register as
the address.  The register allocator will do the necessary work to load up the
address during register allocation.

I did notice that the documentation for 'Q' was wrong, so one of the patches
updates the documentation.

In addition, after committing the first 3 patches from V10 that added PADDI and
PLI support for -mcpu=future, Segher asked me to do a patch to rename two of
the macros.  That patch is now checked in, and some of these patches include
changes due to the macro renaming.

After the vector extract patch rework, I included the remaining patch to the
compiler (make -mpcrel default on Linux 64-bit for -mcpu=future).  I included
the tests after doing the -mpcrel default changes.  In addition to the tests in
V10, I added some new tests for the vector extract code.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797