[PATCH] D149330: [RegAllocFast] Use uint16_t SparseT for LiveRegMap

[Alexis Engelke via Phabricator via llvm-commits]

aengelke created this revision.
aengelke added reviewers: efriedma, LuoYuanke, arsenm.
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For functions with very large numbers of live variables, lookups into
LiveRegMap previously detoriated to linear searches.

This slightly increases memory usage, but that is barely measurable.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149330

Files:
  llvm/lib/CodeGen/RegAllocFast.cpp


Index: llvm/lib/CodeGen/RegAllocFast.cpp
===================================================================
--- llvm/lib/CodeGen/RegAllocFast.cpp
+++ llvm/lib/CodeGen/RegAllocFast.cpp
@@ -106,7 +106,7 @@
       }
     };
 
-    using LiveRegMap = SparseSet<LiveReg>;
+    using LiveRegMap = SparseSet<LiveReg, identity<unsigned>, uint16_t>;
     /// This map contains entries for each virtual register that is currently
     /// available in a physical register.
     LiveRegMap LiveVirtRegs;


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