x64: Remove handling of cmpps and cmppd in produces_const#4714
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elliottt merged 1 commit intoAug 15, 2022
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cfallin
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Aug 15, 2022
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On
main, thecmppsandcmppdinstructions will be treated as producing constants if their arguments are the same and their immediate operand is0, which corresponds to ordered equality. The runtime behavior of this instruction is not constant however, as it will output a lane of0s if either of the corresponding components areNaN.This PR removes the special handling of
cmppsandcmppdfromproduces_const, as it's not correctly identifying constants. An alternative approach here would be to say that unordered equality will produce constants, looking instead for the immediate value8. We don't currently have any way of emitting unordered equality tests, so that would be an optimization that would be worth making if we add that capability in the future.