[SubZero] Implement address optimization for MIPS

src/IceOperand.cpp

 //===- subzero/src/IceOperand.cpp - High-level operand implementation -----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 281 matching lines @@
           Definitions.empty() ? FirstOrSingleDefinition : Definitions.back();
       (void)LastInstruction;
       assert(LastInstruction == nullptr ||
              Instr->getNumber() >= LastInstruction->getNumber());
     }
   }
   constexpr bool IsImplicit = false;
   markUse(TrackingKind, Instr, Node, IsImplicit);
   if (TrackingKind == VMK_Uses)
     return;
-  if (FirstOrSingleDefinition == nullptr)
+  if (FirstOrSingleDefinition == nullptr) {
     FirstOrSingleDefinition = Instr;
-  else if (TrackingKind == VMK_All)
+    FirstOrSingleDefinitionNode = Node;
+  } else if (TrackingKind == VMK_All)
     Definitions.push_back(Instr);
   switch (MultiDef) {
   case MDS_Unknown:
     assert(SingleDefNode == nullptr);
     MultiDef = MDS_SingleDef;
     SingleDefNode = Node;
     break;
   case MDS_SingleDef:
     assert(SingleDefNode);
     if (Node == SingleDefNode) {
@@ skipping 35 matching lines @@
   case MDS_MultiDefMultiBlock:
   case MDS_MultiDefSingleBlock:
     return nullptr;
   case MDS_SingleDef:
     assert(FirstOrSingleDefinition);
     return FirstOrSingleDefinition;
   }
   return nullptr;
 }
 
+const CfgNode *VariableTracking::getSingleDefinitionNode() const {
+  switch (MultiDef) {
+  case MDS_Unknown:
+  case MDS_MultiDefMultiBlock:
+  case MDS_MultiDefSingleBlock:
+    return nullptr;
+  case MDS_SingleDef:
+    assert(FirstOrSingleDefinitionNode);
+    return FirstOrSingleDefinitionNode;
+  }
+  return nullptr;
+}
+
 const Inst *VariableTracking::getFirstDefinition() const {
   switch (MultiDef) {
   case MDS_Unknown:
     return nullptr;
   case MDS_MultiDefMultiBlock:
   case MDS_SingleDef:
   case MDS_MultiDefSingleBlock:
     assert(FirstOrSingleDefinition);
     return FirstOrSingleDefinition;
   }
@@ skipping 121 matching lines @@
 }
 
 const Inst *VariablesMetadata::getSingleDefinition(const Variable *Var) const {
   assert(Kind != VMK_Uses);
   if (!isTracked(Var))
     return nullptr; // conservative answer
   SizeT VarNum = Var->getIndex();
   return Metadata[VarNum].getSingleDefinition();
 }
 
+const CfgNode *
+VariablesMetadata::getSingleDefinitionNode(const Variable *Var) const {
+  assert(Kind != VMK_Uses);
+  if (!isTracked(Var))
+    return nullptr; // conservative answer
+  SizeT VarNum = Var->getIndex();
+  return Metadata[VarNum].getSingleDefinitionNode();
+}
+
 const Inst *VariablesMetadata::getFirstDefinition(const Variable *Var) const {
   assert(Kind != VMK_Uses);
   if (!isTracked(Var))
     return nullptr; // conservative answer
   SizeT VarNum = Var->getIndex();
   return Metadata[VarNum].getFirstDefinition();
 }
 
 const InstDefList &
 VariablesMetadata::getLatterDefinitions(const Variable *Var) const {
@@ skipping 148 matching lines @@
   if (getType() != IceType_i32 && getType() != IceType_i16 &&
       getType() != IceType_i8)
     return false;
   // The Following checks if the signed representation of Value is between
   // -Threshold/2 and +Threshold/2
   bool largerThanThreshold = Threshold / 2 + Value >= Threshold;
   return largerThanThreshold;
 }
 
 } // end of namespace Ice