1 files changed, 21 insertions, 15 deletions

diff --git a/lib/CodeGen/GlobalISel/RegBankSelect.cpp b/lib/CodeGen/GlobalISel/RegBankSelect.cpp
index 9e2d48d1dc42..dcc8b7cc23c5 100644
--- a/lib/CodeGen/GlobalISel/RegBankSelect.cpp
+++ b/lib/CodeGen/GlobalISel/RegBankSelect.cpp
@@ -115,8 +115,8 @@ bool RegBankSelect::assignmentMatch(
   // By default we assume we will have to repair something.
   OnlyAssign = false;
   // Each part of a break down needs to end up in a different register.
-  // In other word, Reg assignement does not match.
-  if (ValMapping.NumBreakDowns > 1)
+  // In other word, Reg assignment does not match.
+  if (ValMapping.NumBreakDowns != 1)
     return false;
 
   const RegisterBank *CurRegBank = RBI->getRegBank(Reg, *MRI, *TRI);
@@ -140,7 +140,7 @@ bool RegBankSelect::repairReg(
     return false;
   assert(ValMapping.NumBreakDowns == 1 && "Not yet implemented");
   // An empty range of new register means no repairing.
-  assert(NewVRegs.begin() != NewVRegs.end() && "We should not have to repair");
+  assert(!empty(NewVRegs) && "We should not have to repair");
 
   // Assume we are repairing a use and thus, the original reg will be
   // the source of the repairing.
@@ -528,7 +528,7 @@ RegBankSelect::MappingCost RegBankSelect::computeMapping(
 bool RegBankSelect::applyMapping(
     MachineInstr &MI, const RegisterBankInfo::InstructionMapping &InstrMapping,
     SmallVectorImpl<RegBankSelect::RepairingPlacement> &RepairPts) {
-  // OpdMapper will hold all the information needed for the rewritting.
+  // OpdMapper will hold all the information needed for the rewriting.
   RegisterBankInfo::OperandsMapper OpdMapper(MI, InstrMapping, *MRI);
 
   // First, place the repairing code.
@@ -714,18 +714,23 @@ RegBankSelect::RepairingPlacement::RepairingPlacement(
     // - Terminators must be the last instructions:
     //   * Before, move the insert point before the first terminator.
     //   * After, we have to split the outcoming edges.
-    unsigned Reg = MO.getReg();
     if (Before) {
       // Check whether Reg is defined by any terminator.
-      MachineBasicBlock::iterator It = MI;
-      for (auto Begin = MI.getParent()->begin();
-           --It != Begin && It->isTerminator();)
-        if (It->modifiesRegister(Reg, &TRI)) {
-          // Insert the repairing code right after the definition.
-          addInsertPoint(*It, /*Before*/ false);
-          return;
-        }
-      addInsertPoint(*It, /*Before*/ true);
+      MachineBasicBlock::reverse_iterator It = MI;
+      auto REnd = MI.getParent()->rend();
+
+      for (; It != REnd && It->isTerminator(); ++It) {
+        assert(!It->modifiesRegister(MO.getReg(), &TRI) &&
+               "copy insertion in middle of terminators not handled");
+      }
+
+      if (It == REnd) {
+        addInsertPoint(*MI.getParent()->begin(), true);
+        return;
+      }
+
+      // We are sure to be right before the first terminator.
+      addInsertPoint(*It, /*Before*/ false);
       return;
     }
     // Make sure Reg is not redefined by other terminators, otherwise
@@ -733,7 +738,8 @@ RegBankSelect::RepairingPlacement::RepairingPlacement(
     for (MachineBasicBlock::iterator It = MI, End = MI.getParent()->end();
          ++It != End;)
       // The machine verifier should reject this kind of code.
-      assert(It->modifiesRegister(Reg, &TRI) && "Do not know where to split");
+      assert(It->modifiesRegister(MO.getReg(), &TRI) &&
+             "Do not know where to split");
     // Split each outcoming edges.
     MachineBasicBlock &Src = *MI.getParent();
     for (auto &Succ : Src.successors())