ARM patch: New cbranchqi, cbranchhi patterns for Thumb-1

[Bernd Schmidt <bernds at codesourcery dot com>]

On Thumb-1, comparisons of integer values smaller than a word can be
done by shifting the value to the left.  This patch adds a new macroized
pattern, cbranch<mode>4_insn, which is used for QImode and HImode, and
does exactly that.  Effects:

-       lsl     r2, r1, #24
-       lsr     r2, r2, #24
-       cmp     r2, #0
+       lsl     r1, #24
        bne     .L195

This uses the neat trick of putting a matching constraint on a
match_scratch.

An earlier version (with slightly more stupid code) was regression
tested on qemu/arm-linux with my usual set of three flags.  This version
generates identical code as the tested one for all my testcases.  Ok if
retest passes?


Bernd

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