From b9fb8d1e69aa910eb6bb03d3d66e5a2e25a20cd8 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Wed, 30 Jul 2008 00:21:16 +0000
Subject: [PATCH 1/1] When merging live intervals, we also need to merge in any
 live ranges that are inputs to two-address instructions that themselves
 define a range we already care about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54185 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/StrongPHIElimination.cpp | 55 +++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 13 deletions(-)

diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index 3d23efec7b0..0f1acc2d728 100644
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -792,20 +792,49 @@ void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
   VNInfo* NewVN = LHS.getNextValue(RangeMergingIn->valno->def,
                                    RangeMergingIn->valno->copy,
                                    LI.getVNInfoAllocator());
-                                   
-  for (LiveInterval::iterator RI = RHS.begin(), RE = RHS.end();
-       RI != RE; )
-    if (RI->valno == RHSVN) {
-      NewVN->hasPHIKill = true;
-      LiveRange NewRange(RI->start, RI->end, NewVN);
-      LHS.addRange(NewRange);
+
+  // If we discover that a live range was defined by a two-addr
+  // instruction, we need to merge over the input as well, even if
+  // it has a different VNInfo.
+  SmallPtrSet<VNInfo*, 4> MergedVNs;
+  MergedVNs.insert(RHSVN);
+  
+  DenseMap<VNInfo*, VNInfo*> VNMap;
+  VNMap.insert(std::make_pair(RangeMergingIn->valno, NewVN));
+  
+  bool changed = true;
+  while (changed) {
+    changed = false;
+    for (LiveInterval::iterator RI = RHS.begin(), RE = RHS.end();
+        RI != RE; )
+      if (MergedVNs.count(RI->valno)) {
+        NewVN->hasPHIKill = true;
+        LiveRange NewRange(RI->start, RI->end, VNMap[RI->valno]);
+        LHS.addRange(NewRange);
+      
+        MachineInstr* instr = LI.getInstructionFromIndex(RI->start);
+        for (unsigned i = 0; i < instr->getNumOperands(); ++i) {
+          if (instr->getOperand(i).isReg() &&
+              instr->getOperand(i).getReg() == secondary)
+            if (instr->isRegReDefinedByTwoAddr(secondary, i)) {
+              VNInfo* twoaddr = RHS.getLiveRangeContaining(RI->start-1)->valno;
+              MergedVNs.insert(twoaddr);
+              
+              VNInfo* NextVN = LHS.getNextValue(twoaddr->def,
+                                                twoaddr->copy,
+                                                LI.getVNInfoAllocator());
+              VNMap.insert(std::make_pair(twoaddr, NextVN));
+            }
+        }
       
-      unsigned start = RI->start;
-      unsigned end = RI->end;
-      ++RI;
-      RHS.removeRange(start, end, true);
-    } else
-      ++RI;
+        unsigned start = RI->start;
+        unsigned end = RI->end;
+        ++RI;
+        RHS.removeRange(start, end, true);
+        changed = true;
+      } else
+        ++RI;
+  }
   
   if (RHS.begin() == RHS.end())
     LI.removeInterval(RHS.reg);
-- 
2.34.1