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Re: REG_N_REFS vs regmove
- To: wilson at cygnus dot com (Jim Wilson)
- Subject: Re: REG_N_REFS vs regmove
- From: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Date: Sat, 27 Jun 1998 01:38:31 +0100 (BST)
- Cc: law at cygnus dot com, egcs-patches at cygnus dot com, amylaar at cygnus dot com
> If a register is eliminated, but REG_N_REFS is still non-zero, then we end
> up allocating a stack slot for it which will never be used. This causes
> us to use more stack space than we should, but is otherwise harmless.
It's not just stack space. There are sometimes a lot more eliminated
registers than remaining ones - and the extra stack space means also
that the ofsets of the remaining stack slots are farther apart - i.e.
it is harder to reload them, and we see less reload inheritance due
to large offsets.