[llvm-commits] [llvm] r37851 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
clattner at apple.com
Wed Jul 4 11:53:43 CDT 2007
On Jul 4, 2007, at 1:13 AM, Duncan Sands wrote:
>> Looking at it a little more, I think the instcombine folds are
>> wrong here. For example, it does X + undef -> undef, but that's
>> wrong if
>> X is a NaN.
> Right, that's why I suggested X + undef -> X.
Generally it's better to fold to a constant (e.g. a NAN) instead of
retaining a use of X. Folding to a NAN makes the computation of X
dead, and theoretically the nan will be folded through lots of other
operations (which probably isn't true right now, but could be
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