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[Bug middle-end/24644] [4.1 Regression] gcc-4.1 compiled ppc64 kernels do not boot
- From: "ian at airs dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 4 Nov 2005 16:09:07 -0000
- Subject: [Bug middle-end/24644] [4.1 Regression] gcc-4.1 compiled ppc64 kernels do not boot
- References: <bug-24644-1216@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #14 from ian at airs dot com 2005-11-04 16:09 -------
gcc is free to copy non-volatile variables. It does this in many places and
for many reasons, particularly in the new SSA optimizers in 4.0 and later. I
don't know the details of where it decided to copy the register in this test
case, but presumably it seemed profitable to some heuristic. I expect that it
could happen if the usage is in a loop, or used on both branches of an if
conditional, etc.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24644