Currently, if an instruction with a memory operand has no debug information, X86DiscriminateMemOps will generate one based on the first line of the enclosing function, or the last seen debug info.
This may cause confusion in certain debugging scenarios. The long term approach would be to use the line number '0' in such cases, however, that brings in challenges: the base discriminator value range is limited (4096 values).
For the short term, adding an opt-in flag for this feature.
See bug 40319 (https://bugs.llvm.org/show_bug.cgi?id=40319)