No instcountci changes yet, since nothing currently spills in instcountci. This
mitigates spilling later seen with #3703, and should help for certain
pathological blocks even without those changes (maybe we should try to get some
of those blocks in instcountci?).
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
find-and-replace across the tree, excluding IR.h itself.
also excluded IRValidation because its treatment of blocks blows up and will be
reformed in the new IR anyway.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Generally, there are three reasons to track progress:
* Conditional optimizations. E.g. only run DCE if ConstProp succeeds.
* Fixed point optimizations. E.g. keep running the opt loop until convergence.
* Metadata shenianigans.
None of these apply to FEX. We explicitly do not want a nonlinear pass ordering,
instead we want just a few passes that each converge in a single iteration. We
expect them all to make progress when run. As such, tracking progress is a waste
of CPU cycles. Stop doing it.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
I recommend viewing the new source file as the diff is quite messy.
---
The old RA commits every "how not to write an RA" sin in the book.
Chaitin spill-one loop? Check.
Potential spilling caused by alignment issues since there's no live range
splitting? Check.
Panic spilling? Check.
Generating an interference graph with linear live ranges, so you get the code
quality of linear scan with the cost of graph colouring? Check.
...
It is wholly unsuitable to any application, and specifically unsuitable for FEX.
---
The new RA exploits a key IR invariant unique to FEX: no values are live across
block boundaries. This is validated.
Because of this invariant, all RA is block local. This lets us use a dead simple
2 pass RA that generates ~optimal code in linear time.
The first pass walks the IR backwards, analyzing the IR. This is a souped up
analogue to liveness analysis.
The second pass walks the IR forward, blasting out registers. If necessary, it
will insert spill and/or shuffle code on the fly. Spilling uses the well-known
furthest-first heuristic, which has excellent results for straight line code.
That's it :-)
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
RA should not depend on whether we support AVX, that's a huge layering
violation! and fortunately, it does not.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
SRA is fundamentally about hardware registers, not stores into a
software-defined context. So, it should take a register instead of an offset.
This makes all the unaligned special cases unrepresentable (by design).
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Just like #3508, clang-18 complains about VLA usage.
This vector is relatively small, only around 18 elements but is
semi-dynamic depending on arch and if FEXCore is targeting Linux or
Win32.
It has been a long time coming that FEX no longer needed to leak IR
implementation details to the frontend, this was legacy due to IR CI and
various other problems.
Now that the last bits of IR leaking has been removed, move everything
that we can internally to the implementation.
We still have a couple of minor details in the exposed IR.h to the
frontend, but these are limited to a few enums and some thunking struct
information rather than all the implementation details.
No functional change with this, just moving headers around.
FEXCore includes was including an FHU header which would result in
compilation failure for external projects trying to link to libFEXCore.
Moves it over to fix this, it was the only FHU usage in FEXCore/include
NFC
Alyssa Rosenzweig