This reverts commit 7f2e937469a8cec3fe977bf41ad2dfb9b4ce648a as it causes regressions in the tests it modifies, and undoes what was added in #100653 (which itself was a fix for a previous regression).
samesign
memcpy
(x < y) ? -1 : zext(x != y)
u/scmp(x,y)
passingValueIsAlwaysUndefined