[lldb-dev] Are overlapping ELF sections problematic?

[Thomas Goodfellow via lldb-dev]

I'm working with an embedded platform that segregates memory between
executable code, RAM, and constant values. The three kinds occupy
three separate address spaces, accessed by specific instructions (e.g.
"load from RAM address #0" vs "load from constant ROM address #0")
with fairly small ranges for literal address values. So necessarily
all three address spaces all start at zero.

We're using the LLVM toolchain with ELF32 files, mapping the three
spaces as.text, .data, and .crom sections, with a linker script
setting the address for all three sections to zero and so producing a
non-relocatable executable image (the .text section becomes a ROM for
an embedded device so final addresses are required). To support
debugging with LLDB (where the GDB server protocol presumes a single
flat memory space) the sections are mapped to address ranges in a
larger space (using the top two bits) and the debugger stub of the
platform then demuxes the memory accesses to the appropriate address
spaces).

Until recently this was done by loading the ELF file in LLDB, e.g:
"target modules load --file test.elf .data 0 .crom 0x40000000 .text
0x80000000". However the changes introduced through
https://reviews.llvm.org/D55998 removed support for overlapping
sections, with a remark "I don't anticipate running into this
situation in the real world. However, if we do run into it, and the
current behavior is not suitable for some reason, we can implement
this logic differently."

Our immediate coping strategy was implementing the remapping in the
file parsing of ObjectFileELF, but this LLDB change makes us
apprehensive that we may start encountering similar issues elsewhere
in the LLVM tooling. Are ELF sections with overlapping addresses so
rare (or even actually invalid) that ongoing support will be fragile?