1 files changed, 10 insertions, 95 deletions

diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index e9c038d..3b8a3e8 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -1187,65 +1187,6 @@ static unsigned ComputeUltimateVN(VNInfo *VNI,
   return ThisValNoAssignments[VN] = UltimateVN;
 }
 
-
-// Find out if we have something like
-// A = X
-// B = X
-// if so, we can pretend this is actually
-// A = X
-// B = A
-// which allows us to coalesce A and B.
-// MI is the definition of B. LR is the life range of A that includes
-// the slot just before B. If we return true, we add "B = X" to DupCopies.
-static bool RegistersDefinedFromSameValue(const TargetRegisterInfo &tri,
-                                          CoalescerPair &CP, MachineInstr *MI,
-                                          LiveRange *LR,
-                                     SmallVector<MachineInstr*, 8> &DupCopies) {
-  // FIXME: This is very conservative. For example, we don't handle
-  // physical registers.
-
-  if (!MI->isFullCopy() || CP.isPartial() || CP.isPhys())
-    return false;
-
-  unsigned Dst = MI->getOperand(0).getReg();
-  unsigned Src = MI->getOperand(1).getReg();
-
-  if (!TargetRegisterInfo::isVirtualRegister(Src) ||
-      !TargetRegisterInfo::isVirtualRegister(Dst))
-    return false;
-
-  unsigned A = CP.getDstReg();
-  unsigned B = CP.getSrcReg();
-
-  if (B == Dst)
-    std::swap(A, B);
-  assert(Dst == A);
-
-  VNInfo *Other = LR->valno;
-  if (!Other->isDefByCopy())
-    return false;
-  const MachineInstr *OtherMI = Other->getCopy();
-
-  if (!OtherMI->isFullCopy())
-    return false;
-
-  unsigned OtherDst = OtherMI->getOperand(0).getReg();
-  unsigned OtherSrc = OtherMI->getOperand(1).getReg();
-
-  if (!TargetRegisterInfo::isVirtualRegister(OtherSrc) ||
-      !TargetRegisterInfo::isVirtualRegister(OtherDst))
-    return false;
-
-  assert(OtherDst == B);
-
-  if (Src != OtherSrc)
-    return false;
-
-  DupCopies.push_back(MI);
-
-  return true;
-}
-
 /// JoinIntervals - Attempt to join these two intervals.  On failure, this
 /// returns false.
 bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) {
@@ -1301,8 +1242,6 @@ bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) {
   DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
   SmallVector<VNInfo*, 16> NewVNInfo;
 
-  SmallVector<MachineInstr*, 8> DupCopies;
-
   LiveInterval &LHS = li_->getOrCreateInterval(CP.getDstReg());
   DEBUG({ dbgs() << "\t\tLHS = "; LHS.print(dbgs(), tri_); dbgs() << "\n"; });
 
@@ -1318,18 +1257,15 @@ bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) {
     if (VNI->hasRedefByEC())
       return false;
 
-    // Figure out the value # from the RHS.
-    LiveRange *lr = RHS.getLiveRangeContaining(VNI->def.getPrevSlot());
-    // The copy could be to an aliased physreg.
-    if (!lr) continue;
-
     // DstReg is known to be a register in the LHS interval.  If the src is
     // from the RHS interval, we can use its value #.
-    MachineInstr *MI = VNI->getCopy();
-    if (!CP.isCoalescable(MI) &&
-        !RegistersDefinedFromSameValue(*tri_, CP, MI, lr, DupCopies))
+    if (!CP.isCoalescable(VNI->getCopy()))
       continue;
 
+    // Figure out the value # from the RHS.
+    LiveRange *lr = RHS.getLiveRangeContaining(VNI->def.getPrevSlot());
+    // The copy could be to an aliased physreg.
+    if (!lr) continue;
     LHSValsDefinedFromRHS[VNI] = lr->valno;
   }
 
@@ -1345,18 +1281,15 @@ bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) {
     if (VNI->hasRedefByEC())
       return false;
 
+    // DstReg is known to be a register in the RHS interval.  If the src is
+    // from the LHS interval, we can use its value #.
+    if (!CP.isCoalescable(VNI->getCopy()))
+      continue;
+
     // Figure out the value # from the LHS.
     LiveRange *lr = LHS.getLiveRangeContaining(VNI->def.getPrevSlot());
     // The copy could be to an aliased physreg.
     if (!lr) continue;
-
-    // DstReg is known to be a register in the RHS interval.  If the src is
-    // from the LHS interval, we can use its value #.
-    MachineInstr *MI = VNI->getCopy();
-    if (!CP.isCoalescable(MI) &&
-        !RegistersDefinedFromSameValue(*tri_, CP, MI, lr, DupCopies))
-        continue;
-
     RHSValsDefinedFromLHS[VNI] = lr->valno;
   }
 
@@ -1461,24 +1394,6 @@ bool RegisterCoalescer::JoinIntervals(CoalescerPair &CP) {
   if (RHSValNoAssignments.empty())
     RHSValNoAssignments.push_back(-1);
 
-  for (SmallVector<MachineInstr*, 8>::iterator I = DupCopies.begin(),
-         E = DupCopies.end(); I != E; ++I) {
-    MachineInstr *MI = *I;
-
-    // We have pretended that the assignment to B in
-    // A = X
-    // B = X
-    // was actually a copy from A. Now that we decided to coalesce A and B,
-    // transform the code into
-    // A = X
-    // X = X
-    // and mark the X as coalesced to keep the illusion.
-    unsigned Src = MI->getOperand(1).getReg();
-    MI->getOperand(0).substVirtReg(Src, 0, *tri_);
-
-    markAsJoined(MI);
-  }
-
   // If we get here, we know that we can coalesce the live ranges.  Ask the
   // intervals to coalesce themselves now.
   LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo,