Propagate flags properly in indirectCallTransformer (#107790)

Author: EgorBo

src/coreclr/jit/indirectcalltransformer.cpp

@@ -223,15 +223,20 @@ class IndirectCallTransformer
         // and insert in into the basic block list.
         //
         // Arguments:
-        //    jumpKind - jump kind for the new basic block
+        //    jumpKind    - jump kind for the new basic block
         //    insertAfter - basic block, after which compiler has to insert the new one.
+        //    flagsSource - basic block to copy BBF_SPLIT_GAINED flags from
         //
         // Return Value:
         //    new basic block.
-        BasicBlock* CreateAndInsertBasicBlock(BBKinds jumpKind, BasicBlock* insertAfter)
+        BasicBlock* CreateAndInsertBasicBlock(BBKinds jumpKind, BasicBlock* insertAfter, BasicBlock* flagsSource)
         {
             BasicBlock* block = compiler->fgNewBBafter(jumpKind, insertAfter, true);
             block->SetFlags(BBF_IMPORTED);
+            if (flagsSource != nullptr)
+            {
+                block->CopyFlags(flagsSource, BBF_SPLIT_GAINED);
+            }
             return block;
         }
 
@@ -380,7 +385,7 @@ class IndirectCallTransformer
         {
             assert(checkIdx == 0);
 
-            checkBlock                 = CreateAndInsertBasicBlock(BBJ_ALWAYS, currBlock);
+            checkBlock                 = CreateAndInsertBasicBlock(BBJ_ALWAYS, currBlock, currBlock);
             GenTree*   fatPointerMask  = new (compiler, GT_CNS_INT) GenTreeIntCon(TYP_I_IMPL, FAT_POINTER_MASK);
             GenTree*   fptrAddressCopy = compiler->gtCloneExpr(fptrAddress);
             GenTree*   fatPointerAnd   = compiler->gtNewOperNode(GT_AND, TYP_I_IMPL, fptrAddressCopy, fatPointerMask);
@@ -398,7 +403,7 @@ class IndirectCallTransformer
         virtual void CreateThen(uint8_t checkIdx)
         {
             assert(remainderBlock != nullptr);
-            thenBlock                     = CreateAndInsertBasicBlock(BBJ_ALWAYS, checkBlock);
+            thenBlock                     = CreateAndInsertBasicBlock(BBJ_ALWAYS, checkBlock, currBlock);
             Statement* copyOfOriginalStmt = compiler->gtCloneStmt(stmt);
             compiler->fgInsertStmtAtEnd(thenBlock, copyOfOriginalStmt);
         }
@@ -408,7 +413,7 @@ class IndirectCallTransformer
         //
         virtual void CreateElse()
         {
-            elseBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock);
+            elseBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock, currBlock);
 
             GenTree* fixedFptrAddress  = GetFixedFptrAddress();
             GenTree* actualCallAddress = compiler->gtNewIndir(pointerType, fixedFptrAddress);
@@ -605,7 +610,7 @@ class IndirectCallTransformer
                 // In case of multiple checks, append to the previous thenBlock block
                 // (Set jump target of new checkBlock in CreateThen())
                 BasicBlock* prevCheckBlock = checkBlock;
-                checkBlock                 = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock);
+                checkBlock                 = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock, currBlock);
                 checkFallsThrough          = false;
 
                 // We computed the "then" likelihood in CreateThen, so we
@@ -1059,8 +1064,7 @@ class IndirectCallTransformer
 
             // thenBlock always jumps to remainderBlock
             //
-            thenBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, checkBlock);
-            thenBlock->CopyFlags(currBlock, BBF_SPLIT_GAINED);
+            thenBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, checkBlock, currBlock);
             thenBlock->inheritWeight(checkBlock);
             thenBlock->scaleBBWeight(adjustedThenLikelihood);
             FlowEdge* const thenRemainderEdge = compiler->fgAddRefPred(remainderBlock, thenBlock);
@@ -1091,8 +1095,7 @@ class IndirectCallTransformer
         //
         virtual void CreateElse()
         {
-            elseBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock);
-            elseBlock->CopyFlags(currBlock, BBF_SPLIT_GAINED);
+            elseBlock = CreateAndInsertBasicBlock(BBJ_ALWAYS, thenBlock, currBlock);
 
             // We computed the "then" likelihood in CreateThen, so we
             // just use that to figure out the "else" likelihood.