Check that we don't create null checks on an address that is not null. (#44059)

* Check that we don't create null checks on an address that is not null.

* Egor's request

diff --git a/src/coreclr/src/jit/compiler.hpp b/src/coreclr/src/jit/compiler.hpp
index ebb55a7..c9bd491 100644 (file)
--- a/src/coreclr/src/jit/compiler.hpp
+++ b/src/coreclr/src/jit/compiler.hpp
@@ -1301,6 +1301,7 @@ inline GenTree* Compiler::gtNewIndir(var_types typ, GenTree* addr)
 
 inline GenTree* Compiler::gtNewNullCheck(GenTree* addr, BasicBlock* basicBlock)
 {
+    assert(fgAddrCouldBeNull(addr));
     GenTree* nullCheck = gtNewOperNode(GT_NULLCHECK, TYP_BYTE, addr);
     nullCheck->gtFlags |= GTF_EXCEPT;
     basicBlock->bbFlags |= BBF_HAS_NULLCHECK;

diff --git a/src/coreclr/src/jit/flowgraph.cpp b/src/coreclr/src/jit/flowgraph.cpp
index ee8bee3..f2ca85c 100644 (file)
--- a/src/coreclr/src/jit/flowgraph.cpp
+++ b/src/coreclr/src/jit/flowgraph.cpp
@@ -23773,7 +23773,7 @@ Statement* Compiler::fgInlinePrependStatements(InlineInfo* inlineInfo)
         GenTree* thisOp = impInlineFetchArg(0, inlArgInfo, lclVarInfo);
         if (fgAddrCouldBeNull(thisOp))
         {
-            nullcheck = gtNewNullCheck(impInlineFetchArg(0, inlArgInfo, lclVarInfo), block);
+            nullcheck = gtNewNullCheck(thisOp, block);
             // The NULL-check statement will be inserted to the statement list after those statements
             // that assign arguments to temps and before the actual body of the inlinee method.
         }

diff --git a/src/coreclr/src/jit/importer.cpp b/src/coreclr/src/jit/importer.cpp
index c408667..0bc54d5 100644 (file)
--- a/src/coreclr/src/jit/importer.cpp
+++ b/src/coreclr/src/jit/importer.cpp
@@ -6175,8 +6175,12 @@ int Compiler::impBoxPatternMatch(CORINFO_RESOLVED_TOKEN* pResolvedToken, const B
                     if (((treeToBox->gtFlags & GTF_SIDE_EFFECT) == GTF_EXCEPT) &&
                         treeToBox->OperIs(GT_OBJ, GT_BLK, GT_IND))
                     {
-                        // Yes, we just need to perform a null check.
-                        treeToNullcheck = treeToBox->AsOp()->gtOp1;
+                        // Yes, we just need to perform a null check if needed.
+                        GenTree* const addr = treeToBox->AsOp()->gtGetOp1();
+                        if (fgAddrCouldBeNull(addr))
+                        {
+                            treeToNullcheck = addr;
+                        }
                     }
                     else
                     {