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[Bug middle-end/44382] Slow integer multiply
- From: "hjl dot tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 4 Jun 2010 14:40:08 -0000
- Subject: [Bug middle-end/44382] Slow integer multiply
- References: <bug-44382-682@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #5 from hjl dot tools at gmail dot com 2010-06-04 14:40 -------
tree-ssa-reassoc.c has
2. Left linearization of the expression trees, so that (A+B)+(C+D)
becomes (((A+B)+C)+D), which is easier for us to rewrite later.
During linearization, we place the operands of the binary
expressions into a vector of operand_entry_t
I think this may always generate slower codes. We may not want to
use much more registers. We can limit us to 2 temporaries.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44382