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[DebugInfo] Allow spill slots in call site parameter descriptions

Authored by vsk on Nov 14 2019, 10:08 AM.



Allow call site paramter descriptions to reference spill slots. Spill
slots are not visible to high-level LLVM IR, so they can safely be
referenced during entry value evaluation (as they cannot be clobbered by
some other function).

This gives a 5% increase in the number of call site parameter DIEs in an
LTO x86_64 build of the xnu kernel.

This reverts commit eb4c98ca3d2590bad9f6542afbf3a7824d2b53fa (
[DebugInfo] Exclude memory location values as parameter entry values),
effectively reintroducing the portion of D60716 which dealt with memory
locations (authored by Djordje, Nikola, Ananth, and Ivan).

This partially addresses However, not all memory
operands forwarded to callees live in spill slots. In the xnu build, it
may be possible to use an escape analysis to increase the number of call
site parameter by another 15% (more details in PR43343).

Diff Detail

Event Timeline

vsk created this revision.Nov 14 2019, 10:08 AM
aprantl accepted this revision.Nov 14 2019, 11:23 AM
This revision is now accepted and ready to land.Nov 14 2019, 11:23 AM
This revision was automatically updated to reflect the committed changes.