Using registers as a queue

[James E Wilson]

Pavel Boytchev wrote:
> IÂ’m porting GCC to a new processor. IÂ’m looking for ideas how to force
> registers act like a queue.

You can get consecutive registers by using larger modes, and then using 
subregs.  Assuming you have 32-bit registers, you can allocate a TImode 
(128-bit) pseudo-reg, which will give you 4 consecutive registers, and 
then use subregs to get the individual registers.  However, I seriously 
doubt that this helps you.

Otherwise, if you have a special register file with special accessing 
needs, then you just have to write a machine dependent pass that fixes 
what the register allocator gave you.  The reg-stack.c file for instance 
does this for the x86 FP register stack.  It rewrites the 
flat-register-file allocation that we get from the register allocator 
into a stack-register-file allocation.  You could try doing something 
similar for your target, though this is likely quite a bit of work.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com