[RFC, ARM][PATCH 5/5] Swap passes peephole2 and if_after_reload

[Dmitry Melnik]

After Thumb-2's peephole2 adds flag clobbering on suitable insns in 
order to generate 16-bit encoding for them, if-conversion can't 
transform these insns into cond_execs.  In theory, if the instruction 
were converted to conditional form, it would also use 16-bit encoding, 
so the flag clobbering doesn't have to be added to force 16-bit encoding.
Swapping order of these passes has actually increased the number of 
if-conversions (it results in 2% more it-blocks on SPEC2K INT and
4% more "long" it-blocks that contain two or more instructions). 
However, this actually caused 2038 code size regression on SPEC2K INT. 
At first, we blamed this growth on the effects described in patches 1-4, 
but with these fixes the regression has only reduced by 474 bytes.  I.e. 
the more there are conditional insns, the better is the code size 
reduction from patches 1-4, but altered pass order still loses 1564 
bytes to the original one.
What do you think about the order of these passes on Thumb-2?
(The patch is obvious, and is not attached).