This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: combine/dce patch for PR36003, PR42575

On 06/24/2010 03:00 PM, Bernd Schmidt wrote:
On 06/24/2010 02:53 PM, Eric Botcazou wrote: 
Would you be opposed to adding a simpler, basic-block-local pass that
only tries to eliminate unnecessary operations on DImode subregs?


The 3 words "adding a pass" always make me cringe. :-)  Couldn't this be
integrated into one of the existing RTL passes?


I can tack it onto something else, but I don't see how this would reduce
the amount of work we need to do?

It may be possible to piggy-back it onto an existing DCE pass, or onto lower-subreg, but I'm not sure without understanding exactly what transform you need to do (especially if you want to run this before register allocation).

But you're talking about replacing a buggy and expensive pass (byte-level DCE) with a smaller one, which isn't a bad idea.

Paolo

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]