[Bug tree-optimization/19832] don't remove an if when we know the value is the same as with the if (subtraction)

[jimis at gmx dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19832

jimis <jimis at gmx dot net> changed:

           What    |Removed                     |Added
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                 CC|                            |jimis at gmx dot net

--- Comment #3 from jimis <jimis at gmx dot net> 2011-08-13 01:39:23 UTC ---
I think that the logic in this function is expressed in complicated manner. It
took me some time to figure out what happens in various corner cases. The
attached patch I think makes the code more readable/maintainable, hopefully it
doesn't affect the function's logic at all. Runtime measured unaffected, if not
a couple milliseconds faster. Bootstrapped and tested on x86_64.

Thanks to Cristophe for pointing me here.