[NFC] Add DIExpression::calculateFragmentIntersect (#97738)

Patch [3/x] to fix structured bindings debug info in SROA.

This function computes a fragment, bit-extract operation if needed, and new
constant offset to describe a part of a variable covered by some memory.

This generalises, simplifies, and replaces at::calculateFragmentIntersect. That
version is still used as a wrapper for now though to keep this change NFC.

The new version takes doesn't have a DbgRecord parameter, instead using an
explicit address and address offset. The old version only operates on
dbg_assigns and this change means it can also operate on dbg_declare records
easily, which it will do in a subsequent patch.

The new version has a new out-param OffsetFromLocationInBits which is set to
the difference between the first bit of the variable location and the first
bit of the memory slice. This will be used in a subsequent patch in SROA to
determine the new offset to use in the address expression after splitting an
alloca.

0 files changed, 0 insertions, 0 deletions