Instead of bailing out when we see an icmp, we can instead at least
say that if the upper bits of both operands are known zero, they are
not demanded. This doesn't help with signed comparisons, but it's at
least better than bailing out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249687 91177308-0d34-0410-b5e6-96231b3b80d8
Like adds and subtracts, muls ripple only to the left so we can use
the same logic.
While we're here, add a print method to DemandedBits so it can be used
with -analyze, which we'll use in the testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249686 91177308-0d34-0410-b5e6-96231b3b80d8
The algorithm itself is still eager, but it doesn't get run until a
query function is called. This greatly reduces the compile-time impact
of requiring DemandedBits when at runtime it is not often used.
NFCI.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249685 91177308-0d34-0410-b5e6-96231b3b80d8
