[Loads] Properly populate the visited set in isDereferenceableAndAlignedPointer

There were paths where we wouldn't populate the visited set, causing us
to recurse forever if an SSA variable was defined in terms of itself.

This fixes PR30210.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280191 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed