[Bug c/46076] [4.6/4.7 regression] constant propagation and compile-time math no longer happening versus 4.4 and 4.5

[matt at use dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46076

--- Comment #25 from Matt Hargett <matt at use dot net> 2011-04-12 16:24:33 UTC 
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backport to 4.6 for 4.6.1? I'll apply locally and report any issues in the
meantime.