1 files changed, 17 insertions, 16 deletions

diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp
index ce62594..7aa0a91 100644
--- a/lib/CodeGen/VirtRegRewriter.cpp
+++ b/lib/CodeGen/VirtRegRewriter.cpp
@@ -46,7 +46,7 @@ namespace {
 
 static cl::opt<RewriterName>
 RewriterOpt("rewriter",
-            cl::desc("Rewriter to use: (default: local)"),
+            cl::desc("Rewriter to use (default=local)"),
             cl::Prefix,
             cl::values(clEnumVal(local,   "local rewriter"),
                        clEnumVal(trivial, "trivial rewriter"),
@@ -62,6 +62,7 @@ VirtRegRewriter::~VirtRegRewriter() {}
 
 /// substitutePhysReg - Replace virtual register in MachineOperand with a
 /// physical register. Do the right thing with the sub-register index.
+/// Note that operands may be added, so the MO reference is no longer valid.
 static void substitutePhysReg(MachineOperand &MO, unsigned Reg,
                               const TargetRegisterInfo &TRI) {
   if (unsigned SubIdx = MO.getSubReg()) {
@@ -123,14 +124,15 @@ struct TrivialRewriter : public VirtRegRewriter {
           continue;
         unsigned pReg = VRM.getPhys(reg);
         mri->setPhysRegUsed(pReg);
-        for (MachineRegisterInfo::reg_iterator regItr = mri->reg_begin(reg),
-             regEnd = mri->reg_end(); regItr != regEnd;) {
-          MachineOperand &mop = regItr.getOperand();
-          assert(mop.isReg() && mop.getReg() == reg && "reg_iterator broken?");
-          ++regItr;
-          substitutePhysReg(mop, pReg, *tri);
-          changed = true;
-        }
+        // Copy the register use-list before traversing it.
+        SmallVector<std::pair<MachineInstr*, unsigned>, 32> reglist;
+        for (MachineRegisterInfo::reg_iterator I = mri->reg_begin(reg),
+               E = mri->reg_end(); I != E; ++I)
+          reglist.push_back(std::make_pair(&*I, I.getOperandNo()));
+        for (unsigned N=0; N != reglist.size(); ++N)
+          substitutePhysReg(reglist[N].first->getOperand(reglist[N].second),
+                            pReg, *tri);
+        changed |= !reglist.empty();
       }
     }
     
@@ -1850,19 +1852,18 @@ private:
       KilledMIRegs.clear();
       for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
         unsigned i = VirtUseOps[j];
-        MachineOperand &MO = MI.getOperand(i);
-        unsigned VirtReg = MO.getReg();
+        unsigned VirtReg = MI.getOperand(i).getReg();
         assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
                "Not a virtual register?");
 
-        unsigned SubIdx = MO.getSubReg();
+        unsigned SubIdx = MI.getOperand(i).getSubReg();
         if (VRM.isAssignedReg(VirtReg)) {
           // This virtual register was assigned a physreg!
           unsigned Phys = VRM.getPhys(VirtReg);
           RegInfo->setPhysRegUsed(Phys);
-          if (MO.isDef())
+          if (MI.getOperand(i).isDef())
             ReusedOperands.markClobbered(Phys);
-          substitutePhysReg(MO, Phys, *TRI);
+          substitutePhysReg(MI.getOperand(i), Phys, *TRI);
           if (VRM.isImplicitlyDefined(VirtReg))
             // FIXME: Is this needed?
             BuildMI(MBB, &MI, MI.getDebugLoc(),
@@ -1871,10 +1872,10 @@ private:
         }
 
         // This virtual register is now known to be a spilled value.
-        if (!MO.isUse())
+        if (!MI.getOperand(i).isUse())
           continue;  // Handle defs in the loop below (handle use&def here though)
 
-        bool AvoidReload = MO.isUndef();
+        bool AvoidReload = MI.getOperand(i).isUndef();
         // Check if it is defined by an implicit def. It should not be spilled.
         // Note, this is for correctness reason. e.g.
         // 8   %reg1024<def> = IMPLICIT_DEF