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[Bug target/14552] compiled trivial vector intrinsic code is inefficient
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Mar 2008 10:45:24 -0000
- Subject: [Bug target/14552] compiled trivial vector intrinsic code is inefficient
- References: <bug-14552-4523@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #23 from ubizjak at gmail dot com 2008-03-19 10:45 -------
As said in PR 19161:
The LCM infrastructure doesn't support mode switching in the way that would be
usable for emms. Additionally, there are MANY problems expected when sharing
x87 and MMX registers (i.e. handling of uninitialized x87 registers at the
beginning of the function - this is the reason we don't implement x87 register
passing ABI).
Automatic MMX vectorization is not exactly a much usable feature nowadays (we
have SSE that works quite well here). Due to recent changes in MMX register
allocation area, excellent code is produced using MMX intrinsics, I'm closing
this bug as WONTFIX.
Also, auto-vectorization would produce either MMX or SSE code, but not both of
them:
#define UNITS_PER_SIMD_WORD (TARGET_SSE ? 16 : UNITS_PER_WORD)
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |WONTFIX
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14552