It doesn't really exist. The instruction always writes 16-bits of memory. Putting a REX.w on it won't change anything.
While I was touching the encoding tests to remove it, I added some other missing register form test cases.
llvm-svn: 331135
NFC.
Adding MC regressions tests to cover the I86, I186, I286, I386, I486, PPRO and MMX isa sets.
This patch is part of a larger task to cover MC encoding of all X86 ISA Sets.
Started in revision: https://reviews.llvm.org/D39952
Reviewers: zvi, RKSimon, AndreiGrischenko, craig.topper
Differential Revision: https://reviews.llvm.org/D40879
Change-Id: I231a35861611bfd3d23c74cc59507373f021a629
llvm-svn: 322544