Merge pull request #6094 from mikedn/x86-uncontained-long

Allow uncontained GT_LONG nodes

Author: sivarv

src/jit/codegenxarch.cpp

@@ -2736,6 +2736,13 @@ CodeGen::genCodeForTreeNode(GenTreePtr treeNode)
         genProduceReg(treeNode);
         break;
 
+#if !defined(_TARGET_64BIT_)
+    case GT_LONG:
+        assert(!treeNode->isContained());
+        genConsumeRegs(treeNode);
+        break;
+#endif
+
     default:
         {
 #ifdef  DEBUG

src/jit/gentree.cpp

@@ -13248,6 +13248,14 @@ bool GenTree::isContained() const
 #endif
         return false;
 
+#if !defined(LEGACY_BACKEND) && !defined(_TARGET_64BIT_)
+    case GT_LONG:
+        // GT_LONG nodes are normally contained. The only exception is when the result
+        // of a TYP_LONG operation is not used and this can only happen if the GT_LONG
+        // is the last node in the statement (in linear order).
+        return gtNext != nullptr;
+#endif
+
     case GT_CALL:
         // Note: if you hit this assert you are probably calling isContained() 
         // before the LSRA phase has allocated physical register to the tree nodes

src/jit/lowerxarch.cpp

@@ -247,8 +247,16 @@ void Lowering::TreeNodeInfoInit(GenTree* stmt)
 #if !defined(_TARGET_64BIT_)
 
         case GT_LONG:
-            // Passthrough
-            info->srcCount = 0;
+            if (tree->gtNext == nullptr)
+            {
+                // An uncontained GT_LONG node needs to consume its source operands
+                info->srcCount = 2;
+            }
+            else
+            {
+                // Passthrough
+                info->srcCount = 0;
+            }
             info->dstCount = 0;
             break;