Dwarf Error: Cannot find DIE

[robin-nitrokey]

Only occurs with FEATURES=alpha on the lpc55, probably caused by a compiler bug related to LTO. rust-lang/rust#66118 suggests that replacing fat LTO with thin LTO should fix this, but that causes a hardfault for me. Should be investigated and reported upstream.

Dwarf Error: Cannot find DIE at 0x53752 referenced from DIE at 0xae6b4

Related tickets:

• Dwarf Error: Cannot find DIE at 0x2a09d803 referenced from DIE at 0x2a131f6e from GDB rust-lang/rust#41775
• rustc generates invalid DWARF when LTO is enabled rust-lang/rust#66118

[robin-nitrokey]

It turns out that using thin LTO actually fixes this. The hardfault was caused by the stack overflow that we were debugging at the time. Still, it’s probably better to use fat LTO for firmware releases. As a short-term solution, we can just set lto = "thin" in Cargo.toml when debugging. In the long term, we probably should introduce different build profiles for development and releases. Maybe we can go back to using the debug profile per default and the release profile in the CI?

https://doc.rust-lang.org/cargo/reference/profiles.html#lto

[daringer]

Oh there is a ticket for that. @sosthene-nitrokey and I recently also stumbled across this, disabling lto fixes it.

Long-term I would also suggest that we disable this only for the develop build.
....and in the meantime lto should be switched of by-hand for debugging ?

[robin-nitrokey]

We no longer have to use nightly, so we can close this for the time being.

[szszszsz]

Just for the completeness: shows up as well for the NRF52, when lto = true is used during build, on a gdb debugging attempt.

[robin-nitrokey]

Possible actions:

• submit bug report to rust-lang/rust
• setup a develop profile with thin lto and a release profile with fat lto

[szszszsz]

Moved to:

• rustc generates invalid DWARF when LTO is enabled rust-lang/rust#66118