Propagate BBF flags during hoisting (#57825)

Author: EgorBo

src/coreclr/jit/compiler.h

@@ -6357,7 +6357,7 @@ class Compiler
     bool optIsProfitableToHoistableTree(GenTree* tree, unsigned lnum);
 
     // Performs the hoisting 'tree' into the PreHeader for loop 'lnum'
-    void optHoistCandidate(GenTree* tree, unsigned lnum, LoopHoistContext* hoistCtxt);
+    void optHoistCandidate(GenTree* tree, BasicBlock* treeBb, unsigned lnum, LoopHoistContext* hoistCtxt);
 
     // Returns true iff the ValueNum "vn" represents a value that is loop-invariant in "lnum".
     //   Constants and init values are always loop invariant.
@@ -6387,7 +6387,7 @@ class Compiler
     bool optComputeLoopSideEffectsOfBlock(BasicBlock* blk);
 
     // Hoist the expression "expr" out of loop "lnum".
-    void optPerformHoistExpr(GenTree* expr, unsigned lnum);
+    void optPerformHoistExpr(GenTree* expr, BasicBlock* exprBb, unsigned lnum);
 
 public:
     void optOptimizeBools();

src/coreclr/jit/optimizer.cpp

@@ -5462,7 +5462,7 @@ int Compiler::optIsSetAssgLoop(unsigned lnum, ALLVARSET_VALARG_TP vars, varRefKi
     return 0;
 }
 
-void Compiler::optPerformHoistExpr(GenTree* origExpr, unsigned lnum)
+void Compiler::optPerformHoistExpr(GenTree* origExpr, BasicBlock* exprBb, unsigned lnum)
 {
 #ifdef DEBUG
     if (verbose)
@@ -5476,6 +5476,8 @@ void Compiler::optPerformHoistExpr(GenTree* origExpr, unsigned lnum)
     }
 #endif
 
+    assert(exprBb != nullptr);
+
     // This loop has to be in a form that is approved for hoisting.
     assert(optLoopTable[lnum].lpFlags & LPFLG_HOISTABLE);
 
@@ -5512,6 +5514,8 @@ void Compiler::optPerformHoistExpr(GenTree* origExpr, unsigned lnum)
     compCurBB = preHead;
     hoist     = fgMorphTree(hoist);
 
+    preHead->bbFlags |= (exprBb->bbFlags & (BBF_HAS_IDX_LEN | BBF_HAS_NULLCHECK));
+
     Statement* hoistStmt = gtNewStmt(hoist);
     hoistStmt->SetCompilerAdded();
 
@@ -6205,6 +6209,7 @@ void Compiler::optHoistLoopBlocks(unsigned loopNum, ArrayStack<BasicBlock*>* blo
         bool              m_beforeSideEffect;
         unsigned          m_loopNum;
         LoopHoistContext* m_hoistContext;
+        BasicBlock*       m_currentBlock;
 
         bool IsNodeHoistable(GenTree* node)
         {
@@ -6297,19 +6302,21 @@ void Compiler::optHoistLoopBlocks(unsigned loopNum, ArrayStack<BasicBlock*>* blo
             , m_beforeSideEffect(true)
             , m_loopNum(loopNum)
             , m_hoistContext(hoistContext)
+            , m_currentBlock(nullptr)
         {
         }
 
         void HoistBlock(BasicBlock* block)
         {
+            m_currentBlock = block;
             for (Statement* const stmt : block->NonPhiStatements())
             {
                 WalkTree(stmt->GetRootNodePointer(), nullptr);
                 assert(m_valueStack.TopRef().Node() == stmt->GetRootNode());
 
                 if (m_valueStack.TopRef().m_hoistable)
                 {
-                    m_compiler->optHoistCandidate(stmt->GetRootNode(), m_loopNum, m_hoistContext);
+                    m_compiler->optHoistCandidate(stmt->GetRootNode(), block, m_loopNum, m_hoistContext);
                 }
 
                 m_valueStack.Reset();
@@ -6612,7 +6619,7 @@ void Compiler::optHoistLoopBlocks(unsigned loopNum, ArrayStack<BasicBlock*>* blo
                         value.m_hoistable = false;
                         value.m_invariant = false;
 
-                        m_compiler->optHoistCandidate(value.Node(), m_loopNum, m_hoistContext);
+                        m_compiler->optHoistCandidate(value.Node(), m_currentBlock, m_loopNum, m_hoistContext);
                     }
                 }
             }
@@ -6654,7 +6661,7 @@ void Compiler::optHoistLoopBlocks(unsigned loopNum, ArrayStack<BasicBlock*>* blo
     }
 }
 
-void Compiler::optHoistCandidate(GenTree* tree, unsigned lnum, LoopHoistContext* hoistCtxt)
+void Compiler::optHoistCandidate(GenTree* tree, BasicBlock* treeBb, unsigned lnum, LoopHoistContext* hoistCtxt)
 {
     assert(lnum != BasicBlock::NOT_IN_LOOP);
     assert((optLoopTable[lnum].lpFlags & LPFLG_HOISTABLE) != 0);
@@ -6679,7 +6686,7 @@ void Compiler::optHoistCandidate(GenTree* tree, unsigned lnum, LoopHoistContext*
     }
 
     // Expression can be hoisted
-    optPerformHoistExpr(tree, lnum);
+    optPerformHoistExpr(tree, treeBb, lnum);
 
     // Increment lpHoistedExprCount or lpHoistedFPExprCount
     if (!varTypeIsFloating(tree->TypeGet()))

src/tests/issues.targets

@@ -661,9 +661,6 @@
         <ExcludeList Include="$(XunitTestBinBase)/JIT/Regression/JitBlue/GitHub_19601/Github_19601/*">
             <Issue>Needs Triage</Issue>
         </ExcludeList>
-        <ExcludeList Include="$(XunitTestBinBase)/JIT/Regression/JitBlue/Runtime_56953/Runtime_56953/*">
-            <Issue>https://github.com/dotnet/runtime/issues/57774</Issue>
-        </ExcludeList>
     </ItemGroup>
 
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