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Re: Register Allocation Algorithm..
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: Jim Wilson <wilson at redhat dot com>
- Cc: Ritu Sabharwal <ritu at csa dot iisc dot ernet dot in>, gcc at gcc dot gnu dot org
- Date: Thu, 3 Oct 2002 15:26:34 -0400
- Subject: Re: Register Allocation Algorithm..
On Thursday, October 3, 2002, at 03:19 PM, Jim Wilson wrote:
what is the register allocation algorithm used in gcc-3.0, can
you get us some reference paper/material on this.
It uses an ad hoc algorithm based on register lifetime and number of
register
uses. See the code for more details.
It actually might be easier to just look up the major register
allocator patents, and then think of what it would take to get around
them, if you can't understand the code.
There is a new optional register allocator in the current development
sources
that uses graph-coloring algorithms. See the ra-*.c files and the
-fnew-ra
option.
Why does the register allocator does not handle predicated
instructions?
Because no one has contributed a patch to do it yet.
And if someone was to work on this, i would suggest they do it in the
new RA, not the old one.
Jim