Use sets instead of hashamps for the spillmaps.#302
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ltratt merged 1 commit intoykjit:mainfrom Jan 28, 2026
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The spillmap analysis has been a consistent source of bugs, mostly (in
my opinion) due to the choice of data structures.
This change moves from a hashmap-centric representation to a set-based
one. This is much less error prone and easier to understand than our
previous hashmap-based method. It's also more compact.
For example, before if we had:
{
rax -> {rbx, rcx},
rbx -> {rax, rcx},
rcx -> {rax, rbx},
r11 -> {rbp-16},
// no `rbp-16 -> {r11}` because hashmap keyed by register!
}
Now it is stored as:
[
{rax, rbx, rcx},
{r11, rbp-16}
]
This fixes 3 broken benchmarks in an upcoming optimisation branch I have
locally. The only reason I don't include the optimisation is that there
are some other bugs that need to be fixed first (maybe related to the
spill map, maybe not).
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The spillmap analysis has been a consistent source of bugs, mostly (in my opinion) due to the choice of data structures.
This change moves from a hashmap-centric representation to a set-based one. This is much less error prone and easier to understand than our previous hashmap-based method. It's also more compact.
For example, before if we had:
Now it is stored as:
This fixes 3 broken benchmarks in an upcoming optimisation branch I have locally. The only reason I don't include the optimisation is that there are some other bugs that need to be fixed first (maybe related to the spill map, maybe not).