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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: 19 Dec 2007 12:32:19 -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 #20 from bonzini at gnu dot org 2007-12-19 12:32 -------
There is a big catch-22. When GCC ties one of regs 64/66 with reg 61, it
enlarges reg 61's live range to cover the live range of the tied range. When
it does this, it basically locks up %edx for the whole live range of reg 61.
:-(
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17236