[InstSimplify] Avoid poison value for ctz/abs in simplifyWithOpsReplaced() (#176168) If we drop flags, we'll set the zero_is_poison/int_min_is_poison flag to false as part of the transform. However, the constant folding was still performed with the value true, which made constant folding return poison. This resulted in the pattern failing to match, as the poison value is not equal to the other select arm. To avoid this, add some special handling to set the argument to false during constant folding as well. Fixes https://github.com/llvm/llvm-project/issues/175282.
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