[MemorySSA] Use fewer magic numbers. NFC
authorGeorge Burgess IV <george.burgess.iv@gmail.com>
Fri, 23 Feb 2018 18:56:42 +0000 (18:56 +0000)
committerGeorge Burgess IV <george.burgess.iv@gmail.com>
Fri, 23 Feb 2018 18:56:42 +0000 (18:56 +0000)
commit0e61efc58f3f2a29c3018f008bc57e52535e8e13
tree9d191014c6bda686322b5aada73cd0dbf66a5e46
parenta2fb097c804838cefc77f1187c2c918c50aa602d
[MemorySSA] Use fewer magic numbers. NFC

INVALID_MEMORYACCESS_ID == 0.

This patch also makes this initialization consistent with the rest of
the "invalid" ones in this file.

llvm-svn: 325935
llvm/include/llvm/Analysis/MemorySSA.h