From 06c0f25499fd502668ca720b0fea4a4dfe6eb44a Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Mon, 21 Feb 2011 23:09:46 +0000 Subject: 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 --- lib/CodeGen/RegAllocGreedy.cpp | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'lib/CodeGen/RegAllocGreedy.cpp') diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp index c1372cd038..378219b97b 100644 --- a/lib/CodeGen/RegAllocGreedy.cpp +++ b/lib/CodeGen/RegAllocGreedy.cpp @@ -426,8 +426,13 @@ float RAGreedy::calcInterferenceInfo(LiveInterval &VirtReg, unsigned PhysReg) { 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 @@ float RAGreedy::calcInterferenceInfo(LiveInterval &VirtReg, unsigned PhysReg) { 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; + } } } } -- cgit v1.2.3