JIT: fix issue in cloning loops with trys in handlers

src/coreclr/jit/fgehopt.cpp

@@ -2680,8 +2680,8 @@ BasicBlock* Compiler::fgCloneTryRegion(BasicBlock* tryEntry, CloneTryInfo& info,
                 if (bbIsTryBeg(block))
                 {
                     assert(added);
-                    JITDUMP("==> found try entry for EH#%02u nested in handler at " FMT_BB "\n", block->bbNum,
-                            block->getTryIndex());
+                    JITDUMP("==> found try entry for EH#%02u nested in handler at " FMT_BB "\n", block->getTryIndex(),
+                            block->bbNum);
                     regionsToProcess.Push(block->getTryIndex());
                 }
             }
@@ -2761,6 +2761,12 @@ BasicBlock* Compiler::fgCloneTryRegion(BasicBlock* tryEntry, CloneTryInfo& info,
         assert(insertBeforeIndex == enclosingTryIndex);
     }
 
+    if (insertBeforeIndex != compHndBBtabCount)
+    {
+        JITDUMP("Existing EH region(s) EH#%02u...EH#%02u will become EH#%02u...EH#%02u\n", insertBeforeIndex,
+                compHndBBtabCount - 1, insertBeforeIndex + regionCount, compHndBBtabCount + regionCount - 1);
+    }
+
     // Once we call fgTryAddEHTableEntries with deferCloning = false,
     // all the EH indicies at or above insertBeforeIndex will shift,
     // and the EH table may reallocate.
@@ -2860,7 +2866,7 @@ BasicBlock* Compiler::fgCloneTryRegion(BasicBlock* tryEntry, CloneTryInfo& info,
         //
         if (ebd->ebdEnclosingTryIndex != EHblkDsc::NO_ENCLOSING_INDEX)
         {
-            if (XTnum < clonedOutermostRegionIndex)
+            if (ebd->ebdEnclosingTryIndex < clonedOutermostRegionIndex)
             {
                 ebd->ebdEnclosingTryIndex += (unsigned short)indexShift;
             }
@@ -2873,7 +2879,7 @@ BasicBlock* Compiler::fgCloneTryRegion(BasicBlock* tryEntry, CloneTryInfo& info,
 
         if (ebd->ebdEnclosingHndIndex != EHblkDsc::NO_ENCLOSING_INDEX)
         {
-            if (XTnum < clonedOutermostRegionIndex)
+            if (ebd->ebdEnclosingHndIndex < clonedOutermostRegionIndex)
             {
                 ebd->ebdEnclosingHndIndex += (unsigned short)indexShift;
             }

src/coreclr/jit/flowgraph.cpp

@@ -6140,14 +6140,30 @@ bool FlowGraphNaturalLoop::CanDuplicateWithEH(INDEBUG(const char** reason))
             // Check if this is an "outermost" try within the loop.
             // If so, we have more checking to do later on.
             //
-            const bool headerInTry         = header->hasTryIndex();
-            unsigned   blockIndex          = block->getTryIndex();
-            unsigned   outermostBlockIndex = comp->ehTrueEnclosingTryIndex(blockIndex);
+            bool const     headerIsInTry     = header->hasTryIndex();
+            unsigned const blockTryIndex     = block->getTryIndex();
+            unsigned const enclosingTryIndex = comp->ehTrueEnclosingTryIndex(blockTryIndex);
 
-            if ((headerInTry && (outermostBlockIndex == header->getTryIndex())) ||
-                (!headerInTry && (outermostBlockIndex == EHblkDsc::NO_ENCLOSING_INDEX)))
+            if ((headerIsInTry && (enclosingTryIndex == header->getTryIndex())) ||
+                (!headerIsInTry && (enclosingTryIndex == EHblkDsc::NO_ENCLOSING_INDEX)))
             {
-                tryRegionsToClone.Push(block);
+                // When we clone a try we also clone its handler.
+                //
+                // This try may be enclosed in a handler whose try begin is in the loop.
+                // If so we'll clone this try when we clone (the handler of) that try.
+                //
+                bool isInHandlerOfInLoopTry = false;
+                if (block->hasHndIndex())
+                {
+                    unsigned const    enclosingHndIndex = block->getHndIndex();
+                    BasicBlock* const associatedTryBeg  = comp->ehGetDsc(enclosingHndIndex)->ebdTryBeg;
+                    isInHandlerOfInLoopTry              = this->ContainsBlock(associatedTryBeg);
+                }
+
+                if (!isInHandlerOfInLoopTry)
+                {
+                    tryRegionsToClone.Push(block);
+                }
             }
         }
 

src/tests/JIT/opt/Cloning/loops_with_eh.cs

@@ -17,6 +17,7 @@
 // g   - giant finally (TF will remain try finally)
 // p   - regions are serial, not nested
 // TFi - try finally with what follows in the finally
+// I   - inlining
 // 
 // x: we currently cannot clone loops where the try is the first thing
 // as the header and preheader are different regions
@@ -1127,5 +1128,142 @@ public static int Sum_TFiTFxL(int[] data, int n)
 
         return sum;
     }
+
+    [Fact]
+    public static int Test_LTFiTF() => Sum_LTFiTF(data, n) - 130;
+
+    public static int Sum_LTFiTF(int[] data, int n)
+    {
+        int sum = 0;
+
+        for (int i = 0; i < n; i++)
+        {
+            sum += data[i];
+            try
+            {
+                SideEffect();
+            }
+            finally
+            {
+                try
+                {
+                    SideEffect();
+                }
+                finally
+                {
+                    sum += 1;
+                }
+
+                sum += 1;
+            }
+        }
+
+        return sum;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int SomeEH()
+    {
+        int sum = 0;
+
+        try
+        {
+            SideEffect();
+        }
+        finally
+        {
+            try
+            {
+                SideEffect();
+            }
+            finally
+            {
+                sum += 1;
+            }
+
+            sum += 1;
+        }
+
+        return sum;
+    }
+
+    [Fact]
+    public static int Test_LITFiTF() => Sum_LITFiTF(data, n) - 130;
+
+    public static int Sum_LITFiTF(int[] data, int n)
+    {
+        int sum = 0;
+
+        for (int i = 0; i < n; i++)
+        {
+            sum += data[i];
+            sum += SomeEH();
+        }
+
+        return sum;
+    }
+
+    [Fact]
+    public static int Test_TFLTFiTF() => Sum_TFLTFiTF(data, n) - 131;
+
+    public static int Sum_TFLTFiTF(int[] data, int n)
+    {
+        int sum = 0;
+
+        try
+        {
+            for (int i = 0; i < n; i++)
+            {
+                sum += data[i];
+                try
+                {
+                    SideEffect();
+                }
+                finally
+                {
+                    try
+                    {
+                        SideEffect();
+                    }
+                    finally
+                    {
+                        sum += 1;
+                    }
+
+                    sum += 1;
+                }
+            }
+        }
+        finally
+        {
+            SideEffect();
+            sum += 1;
+        }
+        return sum;
+    }
+
+    // [Fact]
+    public static int Test_TFLITFiTF() => Sum_TFLITFiTF(data, n) - 131;
+
+    public static int Sum_TFLITFiTF(int[] data, int n)
+    {
+        int sum = 0;
+
+        try
+        {
+            for (int i = 0; i < n; i++)
+            {
+                sum += data[i];
+                sum += SomeEH();
+            }
+        }
+        finally
+        {
+            SideEffect();
+            sum += 1;
+        }
+
+        return sum;
+    }
 }