Alias root or non-alias variable needs to be handled normally.

Only alias variable needs to be handled specially

Change-Id: I0034ab892184b1e40b9fbea9ae8191701d34bcf9

Author: jgu222

IGC/Compiler/CISACodeGen/CShader.cpp

@@ -2281,22 +2281,23 @@ CVariable* CShader::GetSymbol(llvm::Value *value, bool fromConstantPool)
         return it->second;
     }
 
-    if (IGC_IS_FLAG_ENABLED(EnableDeSSAAlias) && m_deSSA->isAlias(value))
+    if (IGC_IS_FLAG_ENABLED(EnableDeSSAAlias))
     {
         // Generate CVariable alias.
         // Value and its aliasee must be of the same size.
         Value* Aliasee = m_deSSA->getAliasee(value);
-        CVariable *Base = GetSymbol(Aliasee);
-        if (Aliasee == value) {
-            return Base;
-        }
-        Type *Ty = value->getType();
-        VectorType* VTy = dyn_cast<VectorType>(Ty);
-        Type *BTy = VTy ? VTy->getElementType() : Ty;
-        VISA_Type visaTy = GetType(BTy);
-        CVariable* AliasVar = GetNewAlias(Base, visaTy, 0, Base->GetNumberElement());
-        symbolMapping.insert(std::pair<llvm::Value*, CVariable*>(value, AliasVar));
-        return AliasVar;
+        if (Aliasee != value)
+        {
+            // An aliaser
+            CVariable *Base = GetSymbol(Aliasee);
+            Type *Ty = value->getType();
+            VectorType* VTy = dyn_cast<VectorType>(Ty);
+            Type *BTy = VTy ? VTy->getElementType() : Ty;
+            VISA_Type visaTy = GetType(BTy);
+            CVariable* AliasVar = GetNewAlias(Base, visaTy, 0, Base->GetNumberElement());
+            symbolMapping.insert(std::pair<llvm::Value*, CVariable*>(value, AliasVar));
+            return AliasVar;
+        }
     }
 
     if (IGC_IS_FLAG_ENABLED(EnableVariableAlias))

IGC/Compiler/CISACodeGen/DeSSA.cpp

@@ -968,11 +968,22 @@ DeSSA::CoalesceInsertElementsForBasicBlock(BasicBlock *Blk)
 
 Value* DeSSA::getRootValue(Value* Val, e_alignment *pAlign) const
 {
-    auto RI = InsEltMap.find(Val);
-    if (RI != InsEltMap.end()) {
-        Value *InsEltRoot = RI->second;
-        Value *PhiRootVal = getRegRoot(InsEltRoot, pAlign);
-        return (PhiRootVal ? PhiRootVal : InsEltRoot);
+    if (IGC_IS_FLAG_ENABLED(EnableDeSSAAlias))
+    {
+        auto AI = AliasMap.find(Val);
+        if (AI != AliasMap.end()) {
+            Value *Aliasee = AI->second;
+            Value *PhiRootVal = getRegRoot(Aliasee, pAlign);
+            return (PhiRootVal ? PhiRootVal : Aliasee);
+        }
+    }
+    else {
+        auto RI = InsEltMap.find(Val);
+        if (RI != InsEltMap.end()) {
+            Value *InsEltRoot = RI->second;
+            Value *PhiRootVal = getRegRoot(InsEltRoot, pAlign);
+            return (PhiRootVal ? PhiRootVal : InsEltRoot);
+        }
     }
     return getRegRoot(Val, pAlign);
 }