[FunctionAttrs] Volatile loads should disable readonly

A volatile load has side effects beyond what callers expect readonly to
signify.  For example, it is not safe to reorder two function calls
which each perform a volatile load to the same memory location.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@270671 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed