[llvm-commits] [llvm] r130428 - /llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
Duncan Sands
baldrick at free.fr
Thu Apr 28 13:20:04 PDT 2011
Hi Benjamin,
> - // (trunc x) == C1& (and x, CA) == C2 -> (and CA|CMAX) == C1|C2
> + // (trunc x) == C1& (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
> // where CMAX is the all ones value for the truncated type,
> // iff the lower bits of CA are zero.
don't you need the lower bits of C2 to also be zero?
Ciao,
Duncan.
PS: Of course, if they are not zero then "(and x, CA) == C2" can be folded to
false, so probably you will never hit this in practice.
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