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Add some more detail about spill bundles to design doc.

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Chris Fallin
2021-08-12 11:26:45 -07:00
parent a591535fe9
commit 0c795842fd
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doc/DESIGN.md
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@@ -449,6 +449,11 @@ it is where liveranges go when we give up on processing them via the
normal backtracking loop, and will only process them once more in the normal backtracking loop, and will only process them once more in the
"second-chance" stage. "second-chance" stage.
This fallback behavior implies that the spill bundle must always be
able to accept a spillslot allocation, i.e., it cannot require a
register. This invariant is what allows spill bundles to be processed
in a different way, after backtracking has completed.
The spill bundle acquires liveranges in two ways. First, as we split The spill bundle acquires liveranges in two ways. First, as we split
bundles, we will trim the split pieces in certain ways so that some bundles, we will trim the split pieces in certain ways so that some
liveranges are immediately placed in the spill bundle. Intuitively, liveranges are immediately placed in the spill bundle. Intuitively,