Re: Experimental post-reload life analysis

[Bernd Schmidt <crux at Pool dot Informatik dot RWTH-Aachen dot DE>]

> I'm wondering if instead of writing a whole new pass to gather this info if
> instead we should simply re-use the existing life analysis code in flow.c.

>From a code duplication standpoint you are probably right.  However, flow.c
does a lot more stuff than we need, and I don't want to go cluttering it up
with "if (! reload_completed)".  Also, the patch I sent is a quite a bit more
efficient: instead of calling a function like propagate_block which has to
walk a whole list of insns, it implements the propagation of life info through
the function with some simple operations on HARD_REG_SETs.  Each insn is
processed exactly once, during an initial scan.
I'm not sure which is the best approach.  If you want me to look at using
flow.c instead, I'll do that.  Meanwhile, I'm going to post a new version
of the flow analysis in a separate message.

Bernd