Add SplitKit::isOriginalEndpoint and use it to force live range splitting to terminate.
An original endpoint is an instruction that killed or defined the original live
range before any live ranges were split.
When splitting global live ranges, avoid creating local live ranges without any
original endpoints. We may still create global live ranges without original
endpoints, but such a range won't be split again, and live range splitting still
terminates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126151 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index c1372cd..378219b 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/lib/CodeGen/RegAllocGreedy.cpp
@@ -426,8 +426,13 @@
if (!IntI.valid())
break;
// Not live in, but before the first use.
- if (IntI.start() < BI.FirstUse)
+ if (IntI.start() < BI.FirstUse) {
BC.Entry = SpillPlacement::PrefSpill;
+ // If the block contains a kill from an earlier split, never split
+ // again in the same block.
+ if (!BI.LiveThrough && !SA->isOriginalEndpoint(BI.Kill))
+ BC.Entry = SpillPlacement::MustSpill;
+ }
}
// Does interference overlap the uses in the entry segment
@@ -458,8 +463,12 @@
IntI.advanceTo(BI.LastUse);
if (!IntI.valid())
break;
- if (IntI.start() < Stop)
+ if (IntI.start() < Stop) {
BC.Exit = SpillPlacement::PrefSpill;
+ // Avoid splitting twice in the same block.
+ if (!BI.LiveThrough && !SA->isOriginalEndpoint(BI.Def))
+ BC.Exit = SpillPlacement::MustSpill;
+ }
}
}
}