swift234

When using simplifyInstruction, RAUW SimplifedInst[0] with the returned SILValue instead of attempting to replace all operands.

The specific case of interest I ran into was:

  sil-extract(struct(string_literal[2]))

which using the old logic would fail since we would be trying to replace all
sil-extract arguments with string_literal arguments. The different result arity
would then hit an assertion.

Swift SVN r11607