From c5b6135fb55362f5c052625043ebf3286f799f86 Mon Sep 17 00:00:00 2001
From: Cameron Zwarich <zwarich@apple.com>
Date: Wed, 20 Feb 2013 22:10:00 +0000
Subject: [PATCH] Find anchoring end points for repairIntervalsInRange and
 repairIndexesInRange automatically.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175673 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LiveIntervalAnalysis.cpp      |  7 +++++++
 lib/CodeGen/SlotIndexes.cpp               |  9 +++++++++
 lib/CodeGen/TwoAddressInstructionPass.cpp | 17 +++++------------
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index e07922b54c9..a716e8bbab0 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1038,6 +1038,13 @@ LiveIntervals::repairIntervalsInRange(MachineBasicBlock *MBB,
                                       MachineBasicBlock::iterator Begin,
                                       MachineBasicBlock::iterator End,
                                       ArrayRef<unsigned> OrigRegs) {
+  // Find anchor points, which are at the beginning/end of blocks or at
+  // instructions that already have indexes.
+  while (Begin != MBB->begin() && !Indexes->hasIndex(Begin))
+    --Begin;
+  while (End != MBB->end() && !Indexes->hasIndex(End))
+    ++End;
+
   SlotIndex endIdx;
   if (End == MBB->end())
     endIdx = getMBBEndIdx(MBB).getPrevSlot();
diff --git a/lib/CodeGen/SlotIndexes.cpp b/lib/CodeGen/SlotIndexes.cpp
index b4e562e45b2..f2937941ee9 100644
--- a/lib/CodeGen/SlotIndexes.cpp
+++ b/lib/CodeGen/SlotIndexes.cpp
@@ -146,6 +146,15 @@ void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
 void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
                                        MachineBasicBlock::iterator Begin,
                                        MachineBasicBlock::iterator End) {
+  // FIXME: Is this really necessary? The only caller repairIntervalsForRange()
+  // does the same thing.
+  // Find anchor points, which are at the beginning/end of blocks or at
+  // instructions that already have indexes.
+  while (Begin != MBB->begin() && !hasIndex(Begin))
+    --Begin;
+  while (End != MBB->end() && !hasIndex(End))
+    ++End;
+
   bool includeStart = (Begin == MBB->begin());
   SlotIndex startIdx;
   if (includeStart)
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 99d36071cfa..43d06557084 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1150,15 +1150,8 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi,
             LV->addVirtualRegisterKilled(Reg, NewMIs[1]);
           }
 
-          MachineBasicBlock::iterator Begin;
-          MachineBasicBlock::iterator End;
           SmallVector<unsigned, 4> OrigRegs;
           if (LIS) {
-            Begin = MachineBasicBlock::iterator(NewMIs[0]);
-            if (Begin != MBB->begin())
-              --Begin;
-            End = llvm::next(MachineBasicBlock::iterator(MI));
-
             for (MachineInstr::const_mop_iterator MOI = MI.operands_begin(),
                  MOE = MI.operands_end(); MOI != MOE; ++MOI) {
               if (MOI->isReg())
@@ -1169,8 +1162,11 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi,
           MI.eraseFromParent();
 
           // Update LiveIntervals.
-          if (LIS)
+          if (LIS) {
+            MachineBasicBlock::iterator Begin(NewMIs[0]);
+            MachineBasicBlock::iterator End(NewMIs[1]);
             LIS->repairIntervalsInRange(MBB, Begin, End, OrigRegs);
+          }
 
           mi = NewMIs[1];
           if (TransformSuccess)
@@ -1576,9 +1572,6 @@ eliminateRegSequence(MachineBasicBlock::iterator &MBBI) {
   }
 
   // Udpate LiveIntervals.
-  if (LIS) {
-    if (MBBI != MBB->begin())
-      --MBBI;
+  if (LIS)
     LIS->repairIntervalsInRange(MBB, MBBI, EndMBBI, OrigRegs);
-  }
 }