- Add TargetInstrInfo::isIdentical(). It's similar to MachineInstr::isIdentical

  except it doesn't care if the definitions' virtual registers differ. This is
  used by machine LICM and other MI passes to perform CSE.
- Teach Thumb2InstrInfo::isIdentical() to check two t2LDRpci_pic are identical.
  Since pc relative constantpool entries are always different, this requires it
  it check if the values can actually the same.

llvm-svn: 86328

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
index c646869e8a7..50587f1af80 100644
--- a/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -143,6 +143,37 @@ void TargetInstrInfoImpl::reMaterialize(MachineBasicBlock &MBB,
   MBB.insert(I, MI);
 }
 
+bool
+TargetInstrInfoImpl::isIdentical(const MachineInstr *MI,
+                                 const MachineInstr *Other,
+                                 const MachineRegisterInfo *MRI) const {
+  if (MI->getOpcode() != Other->getOpcode() ||
+      MI->getNumOperands() != Other->getNumOperands())
+    return false;
+
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    const MachineOperand &MO = MI->getOperand(i);
+    const MachineOperand &OMO = Other->getOperand(i);
+    if (MO.isReg() && MO.isDef()) {
+      assert(OMO.isReg() && OMO.isDef());
+      unsigned Reg = MO.getReg();
+      if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+        if (Reg != OMO.getReg())
+          return false;
+      } else if (MRI->getRegClass(MO.getReg()) !=
+                 MRI->getRegClass(OMO.getReg()))
+        return false;
+
+      continue;
+    }
+
+    if (!MO.isIdenticalTo(OMO))
+      return false;
+  }
+
+  return true;
+}
+
 unsigned
 TargetInstrInfoImpl::GetFunctionSizeInBytes(const MachineFunction &MF) const {
   unsigned FnSize = 0;