Remove more write-barriers around byreflike structs (#111576)

src/coreclr/jit/assertionprop.cpp

@@ -5207,9 +5207,10 @@ bool Compiler::optNonNullAssertionProp_Ind(ASSERT_VALARG_TP assertions, GenTree*
 // Return Value:
 //    Exact type of write barrier required for the given address.
 //
-static GCInfo::WriteBarrierForm GetWriteBarrierForm(ValueNumStore* vnStore, ValueNum vn)
+static GCInfo::WriteBarrierForm GetWriteBarrierForm(Compiler* comp, ValueNum vn)
 {
-    const var_types type = vnStore->TypeOfVN(vn);
+    ValueNumStore*  vnStore = comp->vnStore;
+    const var_types type    = vnStore->TypeOfVN(vn);
     if (type == TYP_REF)
     {
         return GCInfo::WriteBarrierForm::WBF_BarrierUnchecked;
@@ -5250,18 +5251,38 @@ static GCInfo::WriteBarrierForm GetWriteBarrierForm(ValueNumStore* vnStore, Valu
             //
             if (vnStore->IsVNConstantNonHandle(funcApp.m_args[0]))
             {
-                return GetWriteBarrierForm(vnStore, funcApp.m_args[1]);
+                return GetWriteBarrierForm(comp, funcApp.m_args[1]);
             }
             if (vnStore->IsVNConstantNonHandle(funcApp.m_args[1]))
             {
-                return GetWriteBarrierForm(vnStore, funcApp.m_args[0]);
+                return GetWriteBarrierForm(comp, funcApp.m_args[0]);
             }
         }
-    }
+        if (funcApp.m_func == VNF_InitVal)
+        {
+            unsigned lclNum = vnStore->CoercedConstantValue<unsigned>(funcApp.m_args[0]);
+            assert(lclNum != BAD_VAR_NUM);
+            CORINFO_CLASS_HANDLE srcCls = NO_CLASS_HANDLE;
 
-    // TODO:
-    // * addr is ByRefLike - NoBarrier (https://github.com/dotnet/runtime/issues/9512)
-    //
+            if (comp->compMethodHasRetVal() && (lclNum == comp->info.compRetBuffArg))
+            {
+                // See if the address is in current method's return buffer
+                // while the return type is a byref-like type.
+                srcCls = comp->info.compMethodInfo->args.retTypeClass;
+            }
+            else if (lclNum == comp->info.compThisArg)
+            {
+                // Same for implicit "this" parameter
+                assert(!comp->info.compIsStatic);
+                srcCls = comp->info.compClassHnd;
+            }
+
+            if ((srcCls != NO_CLASS_HANDLE) && comp->eeIsByrefLike(srcCls))
+            {
+                return GCInfo::WriteBarrierForm::WBF_NoBarrier;
+            }
+        }
+    }
     return GCInfo::WriteBarrierForm::WBF_BarrierUnknown;
 }
 
@@ -5315,7 +5336,7 @@ bool Compiler::optWriteBarrierAssertionProp_StoreInd(ASSERT_VALARG_TP assertions
     {
         // NOTE: we might want to inspect indirs with GTF_IND_TGT_HEAP flag as well - what if we can prove
         // that they actually need no barrier? But that comes with a TP regression.
-        barrierType = GetWriteBarrierForm(vnStore, addr->gtVNPair.GetConservative());
+        barrierType = GetWriteBarrierForm(this, addr->gtVNPair.GetConservative());
     }
 
     JITDUMP("Trying to determine the exact type of write barrier for STOREIND [%d06]: ", dspTreeID(indir));

src/coreclr/jit/codegenarm.cpp

@@ -811,8 +811,7 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
         sourceIsLocal = true;
     }
 
-    bool dstOnStack =
-        dstAddr->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR) || cpObjNode->GetLayout()->IsStackOnly(compiler);
+    bool dstOnStack = cpObjNode->IsAddressNotOnHeap(compiler);
 
 #ifdef DEBUG
     assert(!dstAddr->isContained());

src/coreclr/jit/codegenarm64.cpp

@@ -3695,8 +3695,7 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
         sourceIsLocal = true;
     }
 
-    bool dstOnStack =
-        dstAddr->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR) || cpObjNode->GetLayout()->IsStackOnly(compiler);
+    bool dstOnStack = cpObjNode->IsAddressNotOnHeap(compiler);
 
 #ifdef DEBUG
     assert(!dstAddr->isContained());

src/coreclr/jit/codegenloongarch64.cpp

@@ -2233,8 +2233,7 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
         sourceIsLocal = true;
     }
 
-    bool dstOnStack =
-        dstAddr->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR) || cpObjNode->GetLayout()->IsStackOnly(compiler);
+    bool dstOnStack = cpObjNode->IsAddressNotOnHeap(compiler);
 
 #ifdef DEBUG
     assert(!dstAddr->isContained());

src/coreclr/jit/codegenriscv64.cpp

@@ -2153,8 +2153,7 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
         sourceIsLocal = true;
     }
 
-    bool dstOnStack =
-        dstAddr->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR) || cpObjNode->GetLayout()->IsStackOnly(compiler);
+    bool dstOnStack = cpObjNode->IsAddressNotOnHeap(compiler);
 
 #ifdef DEBUG
     assert(!dstAddr->isContained());

src/coreclr/jit/codegenxarch.cpp

@@ -4218,8 +4218,7 @@ void CodeGen::genCodeForCpObj(GenTreeBlk* cpObjNode)
     GenTree*  dstAddr     = cpObjNode->Addr();
     GenTree*  source      = cpObjNode->Data();
     var_types srcAddrType = TYP_BYREF;
-    bool      dstOnStack =
-        dstAddr->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR) || cpObjNode->GetLayout()->IsStackOnly(compiler);
+    bool      dstOnStack  = cpObjNode->IsAddressNotOnHeap(compiler);
 
     // If the GenTree node has data about GC pointers, this means we're dealing
     // with CpObj, so this requires special logic.

src/coreclr/jit/gentree.cpp

@@ -18246,6 +18246,26 @@ bool GenTree::isIndir() const
     return OperGet() == GT_IND || OperGet() == GT_STOREIND;
 }
 
+bool GenTreeIndir::IsAddressNotOnHeap(Compiler* comp)
+{
+    if (OperIs(GT_STOREIND, GT_STORE_BLK) && ((gtFlags & GTF_IND_TGT_NOT_HEAP) != 0))
+    {
+        return true;
+    }
+
+    if (HasBase() && Base()->gtSkipReloadOrCopy()->OperIs(GT_LCL_ADDR))
+    {
+        return true;
+    }
+
+    if (OperIs(GT_STORE_BLK) && AsBlk()->GetLayout()->IsStackOnly(comp))
+    {
+        return true;
+    }
+
+    return false;
+}
+
 bool GenTreeIndir::HasBase()
 {
     return Base() != nullptr;

src/coreclr/jit/gentree.h

@@ -7943,6 +7943,7 @@ struct GenTreeIndir : public GenTreeOp
         return gtOp2;
     }
 
+    bool     IsAddressNotOnHeap(Compiler* comp);
     bool     HasBase();
     bool     HasIndex();
     GenTree* Base();

src/coreclr/jit/importer.cpp

@@ -10607,7 +10607,14 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                 op1 = impPopStack().val; // Ptr
                 assertImp(varTypeIsStruct(op2));
 
-                op1 = gtNewStoreValueNode(layout, op1, op2, impPrefixFlagsToIndirFlags(prefixFlags));
+                GenTreeFlags indirFlags = impPrefixFlagsToIndirFlags(prefixFlags);
+                if (eeIsByrefLike(resolvedToken.hClass))
+                {
+                    indirFlags |= GTF_IND_TGT_NOT_HEAP;
+                }
+
+                op1 = gtNewStoreValueNode(layout, op1, op2, indirFlags);
+
                 op1 = impStoreStruct(op1, CHECK_SPILL_ALL);
                 goto SPILL_APPEND;
             }

src/coreclr/jit/lowerarmarch.cpp

@@ -762,7 +762,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
         {
             // No write barriers are needed on the stack.
             // If the layout contains a byref, then we know it must live on the stack.
-            if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
+            if (blkNode->IsAddressNotOnHeap(comp))
             {
                 // If the size is small enough to unroll then we need to mark the block as non-interruptible
                 // to actually allow unrolling. The generated code does not report GC references loaded in the

src/coreclr/jit/lowerloongarch64.cpp

@@ -362,7 +362,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
         {
             // No write barriers are needed on the stack.
             // If the layout contains a byref, then we know it must live on the stack.
-            if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
+            if (blkNode->IsAddressNotOnHeap(comp))
             {
                 // If the size is small enough to unroll then we need to mark the block as non-interruptible
                 // to actually allow unrolling. The generated code does not report GC references loaded in the

src/coreclr/jit/lowerriscv64.cpp

@@ -311,7 +311,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
         {
             // No write barriers are needed on the stack.
             // If the layout contains a byref, then we know it must live on the stack.
-            if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
+            if (blkNode->IsAddressNotOnHeap(comp))
             {
                 // If the size is small enough to unroll then we need to mark the block as non-interruptible
                 // to actually allow unrolling. The generated code does not report GC references loaded in the

src/coreclr/jit/lowerxarch.cpp

@@ -450,7 +450,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
         {
             // No write barriers are needed on the stack.
             // If the layout is byref-like, then we know it must live on the stack.
-            if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
+            if (blkNode->IsAddressNotOnHeap(comp))
             {
                 // If the size is small enough to unroll then we need to mark the block as non-interruptible
                 // to actually allow unrolling. The generated code does not report GC references loaded in the
@@ -477,7 +477,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
             // the entire operation takes 20 cycles and encodes in 5 bytes (loading RCX and REP MOVSD/Q).
             unsigned nonGCSlots = 0;
 
-            if (dstAddr->OperIs(GT_LCL_ADDR) || layout->IsStackOnly(comp))
+            if (blkNode->IsAddressNotOnHeap(comp))
             {
                 // If the destination is on the stack then no write barriers are needed.
                 nonGCSlots = layout->GetSlotCount();

src/coreclr/jit/morphblock.cpp

@@ -1358,8 +1358,13 @@ GenTree* MorphCopyBlockHelper::CopyFieldByField()
                 }
                 else
                 {
-                    GenTree* fldAddr = grabAddr(srcFieldOffset);
-                    dstFldStore      = m_comp->gtNewStoreIndNode(srcType, fldAddr, srcFld);
+                    GenTree*     fldAddr    = grabAddr(srcFieldOffset);
+                    GenTreeFlags indirFlags = GTF_EMPTY;
+                    if (m_store->OperIs(GT_STORE_BLK, GT_STOREIND))
+                    {
+                        indirFlags = m_store->gtFlags & (GTF_IND_TGT_NOT_HEAP | GTF_IND_TGT_HEAP);
+                    }
+                    dstFldStore = m_comp->gtNewStoreIndNode(srcType, fldAddr, srcFld, indirFlags);
                 }
             }
         }