# wg-incr-comp meeting 2020-10-06
## Items
- @spastorino has opened a PR to reduce the amount of inlined function duplication in debug builds [rust#76896](https://github.com/rust-lang/rust/pull/76896)
- @wesleywiser is looking into regressions
- losses (on microbenchmarks) are on order of 4-5%
- but wins are on level of 3-4% on *real* programs (like regex and a servo crate)
- @davidtwco has opened a draft PR for an initial implementation of split debuginfo [rust#77117](https://github.com/rust-lang/rust/pull/77117)
- Currently pending a solution for linking together dwarf objects.
- `dwp` tool exists which can link pre-standard GNU-flavoured dwarf objects, but not DWARF 5-flavoured dwarf objects.
- Could add support to `dwp` (part of `binutils`) for this, but would need to wait for it to be in distros.
- LLVM selects whether or not to use DWARF 5 based on the target, so that isn't something we can easily control (or want to?).
- Also need a solution for modifying the DWARF attribute in the binary/object file to point at new linked dwarf package file.
- Not aware of any tools that currently do this - assuming that existing usage of split dwarf in other languages/projects doesn't add the split dwarf attributes and only uses `add-symbol-file` in gdb; or just keeps the per `.o` dwarf objects around (rustc produces more of these with our codegen units).
- @AmanArora has opened a PR implementing anonymous query nodes [rust#77070](https://github.com/rust-lang/rust/pull/77070)
- @wesleywiser is working on adding more detailed tracing data for the self-profiling feature.
- https://github.com/rust-lang/measureme/pull/138
- The goal is to add estimated cost and potentially information about why the cgu is being codegen'd (especially for incremental cases).
## Issue triage
- [9 open `WG-incr-comp` issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AWG-incr-comp)
- https://github.com/rust-lang/rust/issues/65023
"error: unused attribute const_fn_union with incr-comp"
- https://github.com/rust-lang/rust/issues/64291
"Hard-linking incremental files can be expensive."
- https://github.com/rust-lang/rust/issues/55500
"Incremental compiliation is ineffective when building compiler"
- https://github.com/rust-lang/rust/issues/54960
"unexpected panic whilst using base64!() macro from binary_macros crate"
- https://github.com/rust-lang/rust/issues/53929
"Incremental compilation fails when a generic function uses a private symbol"
- [108 open `A-incr-comp` issues](https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-incr-comp)