Disable hoisting invariants when there is a yield in loop bodies

Author: nhat-nguyen

lib/Backend/FlowGraph.cpp

@@ -196,6 +196,7 @@ FlowGraph::Build(void)
     BasicBlock * currBlock = nullptr;
     BasicBlock * nextBlock = nullptr;
     bool hasCall = false;
+    bool hasYield = false;
 
     FOREACH_INSTR_IN_FUNC_BACKWARD_EDITING(instr, instrPrev, func)
     {
@@ -208,7 +209,9 @@ FlowGraph::Build(void)
                 nextBlock = currBlock;
                 currBlock = this->AddBlock(instr->m_next, currLastInstr, nextBlock);
                 currBlock->hasCall = hasCall;
+                currBlock->hasYield = hasYield;
                 hasCall = false;
+                hasYield = false;
             }
 
             currLastInstr = instr;
@@ -243,7 +246,9 @@ FlowGraph::Build(void)
             nextBlock = currBlock;
             currBlock = this->AddBlock(instr, currLastInstr, nextBlock);
             currBlock->hasCall = hasCall;
+            currBlock->hasYield = hasYield;
             hasCall = false;
+            hasYield = false;
             currLastInstr = nullptr;
         }
 
@@ -350,6 +355,11 @@ FlowGraph::Build(void)
             break;
         }
 
+        if (instr->m_opcode == Js::OpCode::Yield)
+        {
+            hasYield = true;
+        }
+
         if (OpCodeAttr::UseAllFields(instr->m_opcode))
         {
             // UseAllFields opcode are call instruction or opcode that would call.
@@ -1400,6 +1410,10 @@ FlowGraph::WalkLoopBlocks(BasicBlock *block, Loop *loop, JitArenaAllocator *temp
                     {
                         loop->SetHasCall();
                     }
+                    if (pred->loop->hasYield)
+                    {
+                        loop->SetHasYield();
+                    }
                     loop->SetImplicitCallFlags(pred->loop->GetImplicitCallFlags());
                 }
                 // Add pred to loop bit vector
@@ -1430,6 +1444,10 @@ FlowGraph::AddBlockToLoop(BasicBlock *block, Loop *loop)
     {
         loop->SetHasCall();
     }
+    if (block->hasYield)
+    {
+        loop->SetHasYield();
+    }
 }
 
 ///----------------------------------------------------------------------------
@@ -3500,6 +3518,29 @@ Loop::SetHasCall()
     while (current != nullptr);
 }
 
+void
+Loop::SetHasYield()
+{
+    Loop* current = this;
+    do
+    {
+        if (current->hasYield)
+        {
+#if DBG
+            current = current->parent;
+            while (current)
+            {
+                Assert(current->hasYield);
+                current = current->parent;
+            }
+#endif
+            break;
+        }
+        current->hasYield = true;
+        current = current->parent;
+    } while (current != nullptr);
+}
+
 void
 Loop::SetImplicitCallFlags(Js::ImplicitCallFlags newFlags)
 {
@@ -3570,7 +3611,7 @@ Loop::CanHoistInvariants() const
         return false;
     }
 
-    return true;
+    return !this->hasYield;
 }
 
 IR::LabelInstr *

lib/Backend/FlowGraph.h

@@ -371,6 +371,7 @@ class BasicBlock
     uint8                isDead:1;
     uint8                isLoopHeader:1;
     uint8                hasCall:1;
+    uint8                hasYield:1;
     uint8                isVisited:1;
     uint8                isAirLockCompensationBlock:1;
     uint8                beginsBailOnNoProfile:1;
@@ -429,6 +430,7 @@ class BasicBlock
         isDead(false),
         isLoopHeader(false),
         hasCall(false),
+        hasYield(false),
         liveFixedFields(nullptr),
         upwardExposedUses(nullptr),
         upwardExposedFields(nullptr),
@@ -614,6 +616,7 @@ class Loop
     bool                hasDeadStoreCollectionPass : 1;
     bool                hasDeadStorePrepass : 1;
     bool                hasCall : 1;
+    bool                hasYield : 1;
     bool                hasHoistedFields : 1;
     bool                needImplicitCallBailoutChecksForJsArrayCheckHoist : 1;
     bool                allFieldsKilled : 1;
@@ -763,6 +766,7 @@ class Loop
     bool                CanHoistInvariants() const;
     bool                CanDoFieldCopyProp();
     void                SetHasCall();
+    void                SetHasYield();
     IR::LabelInstr *    GetLoopTopInstr() const;
     void                SetLoopTopInstr(IR::LabelInstr * loopTop);
     Func *              GetFunc() const { return GetLoopTopInstr()->m_func; }