Question on GCC register optimization.

Henri Cloetens
Fri Jan 17 10:40:00 GMT 2020

Hello All,

I am still working on a GCC backend for a custom processor.

When running the compiler with following flags:

gcc -O3 -S -c -fcprop-registers -frename-registers,

I find out it does not optimize the allocation of the registers.
The routine used is simple function, and what I see is that
it allocates excess registers, in short, it does not optimize
register usage. I would expect it:
  - performs register lifetime analysis
  - performs register renames as to minimize cost.

Question is: I think I invoked the 2 optimizers. Could
   anybody point me to documentation on them ?. I think
   I am missing some target 'hooks', but I have no idea what it is.

Best Regards,


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