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Re: [PATCH] combine fix and allow rs6000 insvsi_internal4
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Eric Christopher <echristo at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 14 Mar 2003 00:12:37 -0500
- Subject: Re: [PATCH] combine fix and allow rs6000 insvsi_internal4
- References: <1047604735.2632.21.camel@ghostwheel.ges.redhat.com>
I have been looking for the right way to fix GCC combiner to
generate this nice optimization on PowerPC. I have avoided removing the
expand_field_assignment() because I have been worried that other ports
have patterns matching a zero_extract combined with a a subset of the
shifts and masks from the other zero_extract. GCC really should try the
zero_extract/zero_extract and then try breaking it into shifts and masks
if the more complicated pair cannot be combined.
Once this pattern works, there are some additional 64-bit patterns
I have ready to add.
Thanks, David