Duncan Sands c0362d5c6e Boost the power of phi node constant folding slightly: if all ...

operands are the phi node itself or undef, then return undef.
This logic already existed at a higher level so in practice it
shouldn't make the slightest difference.  Note that this code
could be replaced by a call to PN->hasConstantValue().  However
since we bail out the moment we see a non-constant operand, it
is more efficient to have a specialized version of that logic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119041 91177308-0d34-0410-b5e6-96231b3b80d8

2010-11-14 12:53:18 +00:00

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