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Re: dangerous cleverness? ppc int<->float conversions, subreg
- To: Zack Weinberg <zack at codesourcery dot com>
- Subject: Re: dangerous cleverness? ppc int<->float conversions, subreg
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Fri, 26 Oct 2001 12:55:14 -0400
- cc: gcc at gcc dot gnu dot org
Zack,
Have you looked into my comment about move_by_pieces?
The problem is how to discourage GCC from using FPRs for DImode.
GCC only uses FPRs for DImode to move blocks of memory and float->int
conversions. In trying to avoid the block memory moves, you hit problems
with the fixunsdfsi pattern. Now the conversation has veered off trying
to solve the symptom instead of the problem, IMHO.
If wecan change the block move register preferences, we will have
solved the original problem and avoiding a lot of unnecessary complexity.
David