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[Bug rtl-optimization/17236] inefficient code for long long multiply on x86
- From: "bonzini at gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 Dec 2007 16:01:40 -0000
- Subject: [Bug rtl-optimization/17236] inefficient code for long long multiply on x86
- References: <bug-17236-1008@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #12 from bonzini at gnu dot org 2007-12-18 16:01 -------
The problem in comment #11 is that GCC generates a widening multiply, and
cannot remove the DImode operations until after register allocation (!). While
the root cause is a deficiency in RTL-level DCE, I suggest filing a separate
bug, because it could also be fixed on the tree-level.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17236