Changes for basic block flags.

src/coreclr/src/jit/flowgraph.cpp

@@ -5275,7 +5275,7 @@ void Compiler::fgMarkBackwardJump(BasicBlock* targetBlock, BasicBlock* sourceBlo
 
     for (BasicBlock* block = targetBlock; block != sourceBlock->bbNext; block = block->bbNext)
     {
-        if ((block->bbFlags & BBF_BACKWARD_JUMP) == 0)
+        if (((block->bbFlags & BBF_BACKWARD_JUMP) == 0) && (block->bbJumpKind != BBJ_RETURN))
         {
             block->bbFlags |= BBF_BACKWARD_JUMP;
             compHasBackwardJump = true;
@@ -22625,9 +22625,10 @@ Compiler::fgWalkResult Compiler::fgUpdateInlineReturnExpressionPlaceHolder(GenTr
         // This folding may uncover more GT_RET_EXPRs, so we loop around
         // until we've got something distinct.
         //
-        GenTree* inlineCandidate = tree->gtRetExprVal();
-        inlineCandidate          = comp->gtFoldExpr(inlineCandidate);
-        var_types retType        = tree->TypeGet();
+        unsigned __int64 bbFlags         = 0;
+        GenTree*         inlineCandidate = tree->gtRetExprVal(&bbFlags);
+        inlineCandidate                  = comp->gtFoldExpr(inlineCandidate);
+        var_types retType                = tree->TypeGet();
 
 #ifdef DEBUG
         if (comp->verbose)
@@ -22643,6 +22644,7 @@ Compiler::fgWalkResult Compiler::fgUpdateInlineReturnExpressionPlaceHolder(GenTr
 #endif // DEBUG
 
         tree->ReplaceWith(inlineCandidate, comp);
+        comp->compCurBB->bbFlags |= (bbFlags & BBF_SPLIT_GAINED);
 
 #ifdef DEBUG
         if (comp->verbose)
@@ -22992,6 +22994,7 @@ void Compiler::fgInvokeInlineeCompiler(GenTreeCall* call, InlineResult* inlineRe
     inlineInfo.iciBlock               = compCurBB;
     inlineInfo.thisDereferencedFirst  = false;
     inlineInfo.retExpr                = nullptr;
+    inlineInfo.retBB                  = nullptr;
     inlineInfo.retExprClassHnd        = nullptr;
     inlineInfo.retExprClassHndIsExact = false;
     inlineInfo.inlineResult           = inlineResult;
@@ -23355,7 +23358,7 @@ void Compiler::fgInsertInlineeBlocks(InlineInfo* pInlineInfo)
 
         // topBlock contains at least one statement before the split.
         // And the split is before the first statement.
-        // In this case, topBlock should be empty, and everything else should be moved to the bottonBlock.
+        // In this case, topBlock should be empty, and everything else should be moved to the bottomBlock.
         bottomBlock->bbStmtList = topBlock->bbStmtList;
         topBlock->bbStmtList    = nullptr;
     }
@@ -23535,13 +23538,17 @@ void Compiler::fgInsertInlineeBlocks(InlineInfo* pInlineInfo)
             gtDispTree(pInlineInfo->retExpr);
         }
 #endif // DEBUG
-        // Replace the call with the return expression
-        iciCall->ReplaceWith(pInlineInfo->retExpr, this);
 
-        if (bottomBlock != nullptr)
+        // Replace the call with the return expression. Note that iciCall won't be part of the IR
+        // but may still be referenced from a GT_RET_EXPR node. We will replace GT_RET_EXPR node
+        // in fgUpdateInlineReturnExpressionPlaceHolder. At that time we will also update the flags
+        // on the basic block of GT_RET_EXPR node.
+        if (iciCall->gtInlineCandidateInfo->retExpr->OperGet() == GT_RET_EXPR)
         {
-            bottomBlock->bbFlags |= InlineeCompiler->fgLastBB->bbFlags & BBF_SPLIT_GAINED;
+            // Save the basic block flags from the retExpr basic block.
+            iciCall->gtInlineCandidateInfo->retExpr->AsRetExpr()->bbFlags = pInlineInfo->retBB->bbFlags;
         }
+        iciCall->ReplaceWith(pInlineInfo->retExpr, this);
     }
 
     //

src/coreclr/src/jit/gentree.cpp

@@ -6263,9 +6263,11 @@ GenTree* Compiler::gtNewInlineCandidateReturnExpr(GenTree* inlineCandidate, var_
 {
     assert(GenTree::s_gtNodeSizes[GT_RET_EXPR] == TREE_NODE_SZ_LARGE);
 
-    GenTree* node = new (this, GT_RET_EXPR) GenTreeRetExpr(type);
+    GenTreeRetExpr* node = new (this, GT_RET_EXPR) GenTreeRetExpr(type);
 
-    node->AsRetExpr()->gtInlineCandidate = inlineCandidate;
+    node->gtInlineCandidate = inlineCandidate;
+
+    node->bbFlags = 0;
 
     if (varTypeIsStruct(inlineCandidate) && !inlineCandidate->OperIsBlkOp())
     {

src/coreclr/src/jit/gentree.h

@@ -1708,7 +1708,7 @@ struct GenTree
     inline GenTree* gtEffectiveVal(bool commaOnly = false);
 
     // Tunnel through any GT_RET_EXPRs
-    inline GenTree* gtRetExprVal();
+    inline GenTree* gtRetExprVal(unsigned __int64* pbbFlags = nullptr);
 
     // Return the child of this node if it is a GT_RELOAD or GT_COPY; otherwise simply return the node itself
     inline GenTree* gtSkipReloadOrCopy();
@@ -5628,6 +5628,8 @@ struct GenTreeRetExpr : public GenTree
 {
     GenTree* gtInlineCandidate;
 
+    unsigned __int64 bbFlags;
+
     CORINFO_CLASS_HANDLE gtRetClsHnd;
 
     GenTreeRetExpr(var_types type) : GenTree(GT_RET_EXPR, type)
@@ -7040,6 +7042,11 @@ inline GenTree* GenTree::gtEffectiveVal(bool commaOnly)
 //-------------------------------------------------------------------------
 // gtRetExprVal - walk back through GT_RET_EXPRs
 //
+// Arguments:
+//    pbbFlags - out-parameter that is set to the flags of the basic block
+//               containing the inlinee return value. The value is 0
+//               for unsuccessful inlines.
+//
 // Returns:
 //    tree representing return value from a successful inline,
 //    or original call for failed or yet to be determined inline.
@@ -7048,17 +7055,25 @@ inline GenTree* GenTree::gtEffectiveVal(bool commaOnly)
 //    Multi-level inlines can form chains of GT_RET_EXPRs.
 //    This method walks back to the root of the chain.
 
-inline GenTree* GenTree::gtRetExprVal()
+inline GenTree* GenTree::gtRetExprVal(unsigned __int64* pbbFlags)
 {
-    GenTree* retExprVal = this;
+    GenTree*         retExprVal = this;
+    unsigned __int64 bbFlags    = 0;
+
     for (;;)
     {
         if (retExprVal->gtOper == GT_RET_EXPR)
         {
-            retExprVal = retExprVal->AsRetExpr()->gtInlineCandidate;
+            GenTreeRetExpr* retExp = retExprVal->AsRetExpr();
+            retExprVal             = retExp->gtInlineCandidate;
+            bbFlags                = retExp->bbFlags;
         }
         else
         {
+            if (pbbFlags != nullptr)
+            {
+                *pbbFlags = bbFlags;
+            }
             return retExprVal;
         }
     }

src/coreclr/src/jit/importer.cpp

@@ -16836,6 +16836,11 @@ bool Compiler::impReturnInstruction(int prefixFlags, OPCODE& opcode)
                     }
                 }
             }
+
+            if (impInlineInfo->retExpr != nullptr)
+            {
+                impInlineInfo->retBB = compCurBB;
+            }
         }
     }
 

src/coreclr/src/jit/inline.h

@@ -584,6 +584,7 @@ struct InlineInfo
     InlineResult* inlineResult;
 
     GenTree*             retExpr; // The return expression of the inlined candidate.
+    BasicBlock*          retBB;   // The basic block of the return expression of the inlined candidate.
     CORINFO_CLASS_HANDLE retExprClassHnd;
     bool                 retExprClassHndIsExact;