A couple of small OSR fixes (#38165)

* fix helper multithreading issue -- don't re-read flags that can change
* fix helper logging and abort on error
* change strategy for protecting original method entry block
  when doing an OSR compile. Instead of marking it don't remove, use
  artificial ref count boost.

Author: AndyAyersMS

src/coreclr/src/jit/flowgraph.cpp

@@ -3070,6 +3070,14 @@ void Compiler::fgComputePreds()
     // Treat the initial block as a jump target
     fgFirstBB->bbFlags |= BBF_JMP_TARGET | BBF_HAS_LABEL;
 
+    // Under OSR, we may need to specially protect the original method entry.
+    //
+    if (opts.IsOSR() && (fgEntryBB != nullptr) && (fgEntryBB->bbFlags & BBF_IMPORTED))
+    {
+        JITDUMP("OSR: protecting original method entry " FMT_BB "\n", fgEntryBB->bbNum);
+        fgEntryBB->bbRefs = 1;
+    }
+
     for (block = fgFirstBB; block; block = block->bbNext)
     {
         switch (block->bbJumpKind)
@@ -21272,6 +21280,13 @@ void Compiler::fgDebugCheckBBlist(bool checkBBNum /* = false */, bool checkBBRef
             blockRefs += 1;
         }
 
+        // Under OSR, if we also are keeping the original method entry around,
+        // mark that as implicitly referenced as well.
+        if (opts.IsOSR() && (block == fgEntryBB))
+        {
+            blockRefs += 1;
+        }
+
         /* Check the bbRefs */
         if (checkBBRefs)
         {

src/coreclr/src/jit/importer.cpp

@@ -8670,12 +8670,6 @@ var_types Compiler::impImportCall(OPCODE                  opcode,
             JITDUMP("\nOSR: found tail recursive call in the method, scheduling " FMT_BB " for importation\n",
                     fgEntryBB->bbNum);
             impImportBlockPending(fgEntryBB);
-
-            // Note there is no explicit flow to this block yet,
-            // make sure it stays around until we actually try
-            // the optimization.
-            fgEntryBB->bbFlags |= BBF_DONT_REMOVE;
-
             loopHead = fgEntryBB;
         }
         else

src/coreclr/src/jit/morph.cpp

@@ -16311,6 +16311,17 @@ void Compiler::fgMorphBlocks()
     fgGlobalMorph = false;
     compCurBB     = nullptr;
 
+    // Under OSR, we no longer need to specially protect the original method entry
+    //
+    if (opts.IsOSR() && (fgEntryBB != nullptr) && (fgEntryBB->bbFlags & BBF_IMPORTED))
+    {
+        JITDUMP("OSR: un-protecting original method entry " FMT_BB "\n", fgEntryBB->bbNum);
+        assert(fgEntryBB->bbRefs > 0);
+        fgEntryBB->bbRefs--;
+        // We don't need to remember this block anymore.
+        fgEntryBB = nullptr;
+    }
+
 #ifdef DEBUG
     if (verboseTrees)
     {

src/coreclr/src/vm/jithelpers.cpp

@@ -5206,7 +5206,7 @@ void JIT_Patchpoint(int* counter, int ilOffset)
             return;
         }
 
-        LONG newFlags = ppInfo->m_flags | PerPatchpointInfo::patchpoint_triggered;
+        LONG newFlags = oldFlags | PerPatchpointInfo::patchpoint_triggered;
         BOOL triggerTransition = InterlockedCompareExchange(&ppInfo->m_flags, newFlags, oldFlags) == oldFlags;
 
         if (!triggerTransition)
@@ -5238,8 +5238,8 @@ void JIT_Patchpoint(int* counter, int ilOffset)
         if (osrMethodCode == NULL)
         {
             // Unexpected, but not fatal
-            STRESS_LOG4(LF_TIEREDCOMPILATION, LL_WARNING, "Jit_Patchpoint: patchpoint (0x%p) OSR method creation failed,"
-                " marking patchpoint invalid for Method=0x%pM il offset %d\n", ip, hitCount, pMD, ilOffset);
+            STRESS_LOG3(LF_TIEREDCOMPILATION, LL_WARNING, "Jit_Patchpoint: patchpoint (0x%p) OSR method creation failed,"
+                " marking patchpoint invalid for Method=0x%pM il offset %d\n", ip, pMD, ilOffset);
 
             InterlockedOr(&ppInfo->m_flags, (LONG)PerPatchpointInfo::patchpoint_invalid);
             return;
@@ -5279,8 +5279,9 @@ void JIT_Patchpoint(int* counter, int ilOffset)
     if ((UINT_PTR)ip != GetIP(&frameContext))
     {
         // Should be fatal
-        STRESS_LOG2(LF_TIEREDCOMPILATION, LL_INFO10, "Jit_Patchpoint: patchpoint (0x%p) TRANSITION"
+        STRESS_LOG2(LF_TIEREDCOMPILATION, LL_FATALERROR, "Jit_Patchpoint: patchpoint (0x%p) TRANSITION"
             " unexpected context IP 0x%p\n", ip, GetIP(&frameContext));
+        EEPOLICY_HANDLE_FATAL_ERROR(COR_E_EXECUTIONENGINE);
     }
 
     // Now unwind back to the original method caller frame.