Fix two issues that Eli Friedman pointed out, where would misoptimized code like:

Fix two issues that Eli Friedman pointed out, where would misoptimized code like:

char a[200];
init(a, a+200);

OR

int a[200];
char* b = (char*)a;
char* c = (char*)a;
foo(b, c);

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51850 91177308-0d34-0410-b5e6-96231b3b80d8