[X86] Fix fcmp+select to min/max lowering (#185594) This does a few changes that are hard to separate from each other: * Consider forming minnum/maxnum from setcc+select non-profitable. X86 has instructions specifically for the setcc+select pattern. (Without this it's hard to get good coverage on this code path.) * Reduce duplication in the code for forming FMIN/FMAX, by using predicate inversion (to make setcc and select operand order match) and predicate invswap (to canonicalize to ordered predicates). This leaves us with just ordered and NaN-less predicates. * For non-strict non-less predicates, convert them to strict ones via invswap (i.e. swapping the operands of both the setcc and select). Previously this just treated them the same as strict predicates, but I believe that's incorrect in terms of signed zero handling.
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