From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Sat, 30 Apr 2011 05:07:46 +0000 (+0000)
Subject: Use hysteresis for local live range splitting as well.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=66446c803a11a26e4bb39b74091d146ac850ae4c;p=oota-llvm.git

Use hysteresis for local live range splitting as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130596 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index d57bc88a13a..7c461d8ea78 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/lib/CodeGen/RegAllocGreedy.cpp
@@ -1225,13 +1225,13 @@ unsigned RAGreedy::tryLocalSplit(LiveInterval &VirtReg, AllocationOrder &Order,
                               PrevSlot[SplitBefore].distance(Uses[SplitAfter]));
         // Would this split be possible to allocate?
         // Never allocate all gaps, we wouldn't be making progress.
-        float Diff = EstWeight - MaxGap;
-        DEBUG(dbgs() << " w=" << EstWeight << " d=" << Diff);
-        if (Diff > 0) {
+        DEBUG(dbgs() << " w=" << EstWeight);
+        if (EstWeight * Hysteresis >= MaxGap) {
           Shrink = false;
+          float Diff = EstWeight - MaxGap;
           if (Diff > BestDiff) {
             DEBUG(dbgs() << " (best)");
-            BestDiff = Diff;
+            BestDiff = Hysteresis * Diff;
             BestBefore = SplitBefore;
             BestAfter = SplitAfter;
           }