JIT: relax another check in conditional escape analysis

src/coreclr/jit/importercalls.cpp

@@ -10420,6 +10420,13 @@ NamedIntrinsic Compiler::lookupNamedIntrinsic(CORINFO_METHOD_HANDLE method)
                             result = NI_System_Collections_Generic_EqualityComparer_get_Default;
                         }
                     }
+                    else if (strcmp(className, "IEnumerable`1") == 0)
+                    {
+                        if (strcmp(methodName, "GetEnumerator") == 0)
+                        {
+                            result = NI_System_Collections_Generic_IEnumerable_GetEnumerator;
+                        }
+                    }
                 }
                 else if (strcmp(namespaceName, "Numerics") == 0)
                 {

src/coreclr/jit/namedintrinsiclist.h

@@ -255,10 +255,11 @@ enum NamedIntrinsic : unsigned short
     NI_PRIMITIVE_END,
 
     //
-    // Array Intrinsics
+    // Enumeration Intrinsics
     //
     NI_System_SZArrayHelper_GetEnumerator,
     NI_System_Array_T_GetEnumerator,
+    NI_System_Collections_Generic_IEnumerable_GetEnumerator,
 };
 
 #endif // _NAMEDINTRINSICLIST_H_

src/coreclr/jit/objectalloc.cpp

@@ -3845,13 +3845,21 @@ bool ObjectAllocator::CheckCanClone(CloneInfo* info)
     // (if it does, optimization does not require cloning, as
     // there should be only one reaching def...)
     //
+    // For now we're going to just go ahead and clone, despite the
+    // fact that this is wasteful.
+    //
+    // In the transformation that follows the cloned path is the
+    // "fast" path and gets properly specialized; the original "slow
+    // path" will become unreachable and get cleaned up later on.
+    //
+    // See dotnet/runtime issue #117204.
+    //
     if (comp->m_domTree->Dominates(allocBlock, defBlock))
     {
-        JITDUMP("Unexpected, alloc site " FMT_BB " dominates def block " FMT_BB "\n", allocBlock->bbNum,
-                defBlock->bbNum);
-
-        return false;
+        JITDUMP("Unexpected, alloc site " FMT_BB " dominates def block " FMT_BB ". We will clone anyways.\n",
+                allocBlock->bbNum, defBlock->bbNum);
     }
+
     // Classify the other local appearances
     // as Ts (allocTemps) or Us (useTemps), and look for guard appearances.
     //