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[Bug target/48077] [Code Improvement] Poor expansion of multiply on powerpc64-linux
- From: "wschmidt at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 11 Mar 2011 21:27:55 +0000
- Subject: [Bug target/48077] [Code Improvement] Poor expansion of multiply on powerpc64-linux
- Auto-submitted: auto-generated
- References: <bug-48077-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48077
--- Comment #5 from William J. Schmidt <wschmidt at gcc dot gnu.org> 2011-03-11 21:27:25 UTC ---
BTW, I mis-entered the optimization level before. The code generation was at
-O2 when the mulhw was expanded into shifts/adds with the default P6 tuning.
At -O3 and up, the mulhw is intact.
This is all explained by the default tuning model in place during testing,
since Power6 had a poorer performing integer multiply than the other machine
models.