Mark ExtendArg parameters as live on back edge in JIT loops

For HomeObj opcodes the helper call is done using ExtendArgs. When the ExtendArgs are hoisted outside the loop marking them as live on back edge to avoid being reused.

Author: aneeshdk

lib/Backend/LowerMDShared.cpp

@@ -231,6 +231,13 @@ LowererMD::LowerCallHelper(IR::Instr *instrCall)
             regArg->Free(this->m_func);
             instrArg->Remove();
         }
+        else if (instrArg->m_opcode == Js::OpCode::ExtendArg_A)
+        {
+            if (instrArg->GetSrc1()->IsRegOpnd())
+            {
+                m_lowerer->addToLiveOnBackEdgeSyms->Set(instrArg->GetSrc1()->AsRegOpnd()->GetStackSym()->m_id);
+            }
+        }
     }
 
     switch (helperMethod)

lib/Backend/arm/LowerMD.cpp

@@ -227,6 +227,13 @@ LowererMD::LowerCallHelper(IR::Instr *instrCall)
             regArg->Free(this->m_func);
             instrArg->Remove();
         }
+        else if (instrArg->m_opcode == Js::OpCode::ExtendArg_A)
+        {
+            if (instrArg->GetSrc1()->IsRegOpnd())
+            {
+                m_lowerer->addToLiveOnBackEdgeSyms->Set(instrArg->GetSrc1()->AsRegOpnd()->GetStackSym()->m_id);
+            }
+        }
     }
 
     switch (helperMethod)

lib/Backend/arm64/LowerMD.cpp

@@ -241,6 +241,13 @@ LowererMD::LowerCallHelper(IR::Instr *instrCall)
             regArg->Free(this->m_func);
             instrArg->Remove();
         }
+        else if (instrArg->m_opcode == Js::OpCode::ExtendArg_A)
+        {
+            if (instrArg->GetSrc1()->IsRegOpnd())
+            {
+                m_lowerer->addToLiveOnBackEdgeSyms->Set(instrArg->GetSrc1()->AsRegOpnd()->GetStackSym()->m_id);
+            }
+        }
     }
 
     switch (helperMethod)

test/Bugs/HomeObjInLoop.js

@@ -0,0 +1,30 @@
+//-------------------------------------------------------------------------------------------------------
+// Copyright (C) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
+//-------------------------------------------------------------------------------------------------------
+
+function test0(){
+  var arrObj0 = {};
+  arrObj0[0] = 1;
+
+  function v0(o)
+  {
+    for (var v1 = 0 ; v1 < 8 ; v1++)
+    {
+      class class7 {
+        func56 (){
+        }
+      }
+      o[v1] = v1;
+    }
+  }
+  
+  v0(arrObj0);
+
+  
+};
+
+test0();
+test0();
+test0();
+print("pass");

test/Bugs/rlexe.xml

@@ -477,5 +477,11 @@
       <files>bug_OS17417473.js</files> 
       <compile-flags>-pageheap:2 -CollectGarbage -lic:4 -Sja:4 -Fja:6 -maxInterpretCount:2 -MinBailOutsBeforeRejit:2 -args summary -endargs</compile-flags> 
     </default> 
+  </test>
+  <test> 
+    <default> 
+      <files>HomeObjInLoop.js</files> 
+      <compile-flags>-forceNative -forcejitloopbody -off:aggressiveinttypespec -off:ArrayCheckHoist</compile-flags> 
+    </default> 
   </test> 
 </regress-exe>