This is a scrap page, so things might be duplicated and those kinds of things.
Tickets I'm interested in:
#9660 - After/During tag inference
IO Manager: !1224 (diffs)
This is currently my main focus. Things below are on my list but not neccesarily listed by priority.
#16354 - LLVM broken on windows - TODO
Also include it in CI: AndreasK, Ideally we would handle LLVM toolchain the same way we handle GHC and xcabal-install 3:59 PM see .gitlab/win32-init.sh
Pointer tagging in GHC (various tickets, see below).
- #16970 - Tag inference work
- #18285 - GHC should keep unfoldings for recursive functions which are suitable for specialization.
- #17238 - Generate lookup tables instead of jump tables where possible.
- !1990 - Use dataToTag - needs work
- #17092 - Implement stack check elision - TODO
- #7741 - NCG-SIMD - TODO
Things to do in the near future:
Branch likelyhood: #14672
Avoid certain stack checks: #17092
#17784 lookupIdSubst fails because bindings are not in dep order.
#13535 Simplifier choking on vector test suite
!2580 (closed) - Update RULES for elem
!2575 - MR to enable fdicts-strict by default. Seems to be correct, needs perf analysis.
!2574 (closed)- Refactor DataCon codegen - needs review
#17759 investigate base functions which currently fail to specialize
#9342 - Branchless Int operations
#17237 Cmm FloatOut - Put shared cmm statements into the common path
#17238 Generate lookup instead of jump tables
#17242 Use dataToTag# for Eq instances
#17240 Code duplication for code evaluating arguments.
#1257 (closed) - Support unboxed tuples in GHCi/bytecode.
#13763 - Runtime (register alloc?) regression
Maybe eventually list
- #15808 (closed) GHC Linker woes
- #16351 Constant folding for bit operations
- #13569 Large constructor updates.
Most things runtime performance related
Out of the above these have likely bounded time requirements
- #17242 Use dataToTag# for Eq instances
- #9342 - Branchless Int operations
- #17238 Generate lookup instead of jump tables
Regressions worth looking into
Pointer tagging in GHC
See also the "pointer tagging" tag: issues
#14373 (closed) Pointer tagging for large families
Instead of tagging large families with a flag indicating evaluation, tag them with the tag if possible and the flag only for constructors not fitting in the tag.
This is a project of Gabor Greif and he indicated he still want's to finish this recently (@ICFP 2019)
He stated this is blocked on #15155 in the past but I did not look into why/how.
#17004 (closed) Export LFInfo for bindings
This patch exposes the backends view of exported ids in interface files.
The benefits are that we can:
- Tag certain bindings which do not have an unfolding otherwise.
- Get accurate information about arity after all transformations have been applied
The benefits of this are:
- We can omit code to enter closures if we know statically they are evaluated constructors.
- We avoid entering closures since more closures will be appropriately tagged
- We can omit entry code for all constructors. If we can ensure all references to constructors are tagged there is never a reason to enter them.
- We can use a more efficient calling convention in some places, as LFInfo allows us to replace slow calls with more efficient variants.
Untagged pointers find their way into strict fields.
There are two tickets about this currently:
- #15155 How untagged pointers sneak into banged fields
- #14677 Code generator does not correctly tag a pointer
Other smaller issues:
See the issues tagged with
pointer tagging on the tracker.