From f70af52a8fc735a84aa8d63b84dd56abd0b9e77c Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Wed, 21 Mar 2012 04:12:16 +0000
Subject: [PATCH] misched: fix LiveInterval update for bottom-up scheduling

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153162 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LiveIntervalAnalysis.cpp | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 1019ad2594c..3ade66097cb 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1049,9 +1049,19 @@ public:
     bool hasRegMaskOp = false;
     collectRanges(MI, Entering, Internal, Exiting, hasRegMaskOp, OldIdx);
 
-    moveAllEnteringFrom(OldIdx, Entering);
-    moveAllInternalFrom(OldIdx, Internal);
-    moveAllExitingFrom(OldIdx, Exiting);
+    // To keep the LiveRanges valid within an interval, move the ranges closest
+    // to the destination first. This prevents ranges from overlapping, to that
+    // APIs like removeRange still work.
+    if (NewIdx < OldIdx) {
+      moveAllEnteringFrom(OldIdx, Entering);
+      moveAllInternalFrom(OldIdx, Internal);
+      moveAllExitingFrom(OldIdx, Exiting);
+    }
+    else {
+      moveAllExitingFrom(OldIdx, Exiting);
+      moveAllInternalFrom(OldIdx, Internal);
+      moveAllEnteringFrom(OldIdx, Entering);
+    }
 
     if (hasRegMaskOp)
       updateRegMaskSlots(OldIdx);