[llvm] [hwasan] Update dbg.assign intrinsics in HWAsan pass (PR #78606)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

I managed to reproduce it locally and have pushed a fixed patch 13c6f1ea2e7eb15fe492d8fca4fa1857c6f86370.

The issue was caused by using `getExpression()` rather than `getAddressExpression()` to get the expression to prepend (which is then used to set the address expression). I've updated the test `llvm/test/Instrumentation/HWAddressSanitizer/dbg-assign-tag-offset.ll` to check this doesn't happen.

https://github.com/llvm/llvm-project/pull/78606