Don't scan for SSA register operands to update when not in SSA form.

TailDuplicate can run on either on SSA code or non-SSA code, as indicated to
it by MRI->isSSA() ("PreRegAlloc" here). TailDuplicate does extra work to
preserve SSA invariants when it duplicates code. This patch makes it skip
some of this extra work in the case where the code is not in SSA form.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261450 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 22 deletions

diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index d2fbf533a78..c2c7a1a3d92 100644
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -429,28 +429,30 @@ void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI,
                                      DenseMap<unsigned, unsigned> &LocalVRMap,
                                      const DenseSet<unsigned> &UsedByPhi) {
   MachineInstr *NewMI = TII->duplicate(MI, MF);
-  for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = NewMI->getOperand(i);
-    if (!MO.isReg())
-      continue;
-    unsigned Reg = MO.getReg();
-    if (!TargetRegisterInfo::isVirtualRegister(Reg))
-      continue;
-    if (MO.isDef()) {
-      const TargetRegisterClass *RC = MRI->getRegClass(Reg);
-      unsigned NewReg = MRI->createVirtualRegister(RC);
-      MO.setReg(NewReg);
-      LocalVRMap.insert(std::make_pair(Reg, NewReg));
-      if (isDefLiveOut(Reg, TailBB, MRI) || UsedByPhi.count(Reg))
-        AddSSAUpdateEntry(Reg, NewReg, PredBB);
-    } else {
-      DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
-      if (VI != LocalVRMap.end()) {
-        MO.setReg(VI->second);
-        // Clear any kill flags from this operand.  The new register could have
-        // uses after this one, so kills are not valid here.
-        MO.setIsKill(false);
-        MRI->constrainRegClass(VI->second, MRI->getRegClass(Reg));
+  if (PreRegAlloc) {
+    for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
+      MachineOperand &MO = NewMI->getOperand(i);
+      if (!MO.isReg())
+        continue;
+      unsigned Reg = MO.getReg();
+      if (!TargetRegisterInfo::isVirtualRegister(Reg))
+        continue;
+      if (MO.isDef()) {
+        const TargetRegisterClass *RC = MRI->getRegClass(Reg);
+        unsigned NewReg = MRI->createVirtualRegister(RC);
+        MO.setReg(NewReg);
+        LocalVRMap.insert(std::make_pair(Reg, NewReg));
+        if (isDefLiveOut(Reg, TailBB, MRI) || UsedByPhi.count(Reg))
+          AddSSAUpdateEntry(Reg, NewReg, PredBB);
+      } else {
+        DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
+        if (VI != LocalVRMap.end()) {
+          MO.setReg(VI->second);
+          // Clear any kill flags from this operand.  The new register could have
+          // uses after this one, so kills are not valid here.
+          MO.setIsKill(false);
+          MRI->constrainRegClass(VI->second, MRI->getRegClass(Reg));
+        }
       }
     }
   }