cgen/gas: some support for funny-endian instruction sets

[Doug Evans]

Frank Ch. Eigler writes:
 > The patch below gives an interpretation to the hitherto-unused
 > cgen "word-bitsize" CPU parameter.  It is interpreted to mean
 > the chunking size for endianness conversions when processing
 > long instructions.

This isn't the definition of "word-bitsize" that a gcc hacker
would expect.  I think a lot of other people would also find this confusing.

What's "word-bitsize" on sparc64?  If it's not 64, you've got problems.

Setting aside the naming problem,

 > When this parameter is set smaller than
 > "base-insn-size" or happens to be smaller than the length of an
 > instruction, then the instruction bytes are chunked into
 > "word-bitsize" units, and individually endianness-converted.

As I'm sure you know, you can't uniformly chunk up an insn
in the general case.

What problem are you trying to solve?