SH: use register names instead of numbers

[NIIBE Yutaka]

Alexandre Oliva wrote:
 > There are a few other remarks I'd like to make about your patch, too.
 > First, I think it would be easier to have a function to gen the
 > unspec, probably enclosed in a const, instead of manipulating the
 > counter directly.  Also, I don't see a need for symbol_ref_operand.  I
 > think immediate_operand is enough, especially because you don't need
 > the symbol_ref at all.  Just using the unspec is enough.  Moreover,
 > then you won't have to modify the output patterns of calli_pcrel and
 > calli_value_pcrel, because the unspec will get output as the correct
 > symbol name (I suppose).
 > 
 > I like the idea of the insn_and_split, especially because it will
 > allow efficient PIC call sequences even in the presence of loop
 > unrolling.  Which means your patch may remove the `!
 > flag_unroll_loops' from the condition that chooses to emit the PIC
 > call sequences, in call and call_value.

Thanks much for your comments.  I'll update my patch for this issue,
later.

We're now building Debian GNU/Linux distribution for SuperH.  GNU C
library and GCC itself is very good testcase for the compiler.

While doing that, I'll send bug reports with test cases (and hopefully
the patch).
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