From 1e743732e7879bed2f8cbc1a875569a3a5e147d8 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <engelke@in.tum.de>
Date: Wed, 26 Apr 2023 16:26:42 +0200
Subject: [PATCH] [RegAllocFast] Use uint16_t SparseT for LiveRegMap

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.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D149330
---
 llvm/lib/CodeGen/RegAllocFast.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/CodeGen/RegAllocFast.cpp b/llvm/lib/CodeGen/RegAllocFast.cpp
index f60e176..17df5d6 100644
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@@ -106,7 +106,7 @@ namespace {
       }
     };
 
-    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;
-- 
2.7.4