Handle getting the address of an RVA static correctly in a composite image

src/coreclr/jit/emitxarch.cpp

@@ -12226,10 +12226,12 @@ BYTE* emitter::emitOutputRR(BYTE* dst, instrDesc* id)
                         regMaskTP regMask;
                         regMask = genRegMask(reg1) | genRegMask(reg2);
 
-                        // r1/r2 could have been a GCREF as GCREF + int=BYREF
-                        //                            or BYREF+/-int=BYREF
-                        assert(((regMask & emitThisGCrefRegs) && (ins == INS_add)) ||
-                               ((regMask & emitThisByrefRegs) && (ins == INS_add || ins == INS_sub)));
+// Assert disabled as requested in PR 55301. A use of the Unsafe api
+// which produces correct code, but isn't handled correctly here.
+// r1/r2 could have been a GCREF as GCREF + int=BYREF
+//                            or BYREF+/-int=BYREF
+// assert(((regMask & emitThisGCrefRegs) && (ins == INS_add)) ||
+//       ((regMask & emitThisByrefRegs) && (ins == INS_add || ins == INS_sub)));
 #endif
                         // Mark r1 as holding a byref
                         emitGCregLiveUpd(GCT_BYREF, reg1, dst);

src/coreclr/jit/importer.cpp

@@ -7704,14 +7704,24 @@ GenTree* Compiler::impImportStaticFieldAccess(CORINFO_RESOLVED_TOKEN* pResolvedT
                 void** pFldAddr = nullptr;
                 void*  fldAddr  = info.compCompHnd->getFieldAddress(pResolvedToken->hField, (void**)&pFldAddr);
 
-                // We should always be able to access this static's address directly
-                //
+// We should always be able to access this static's address directly unless this is a field RVA
+// used within a composite image during R2R composite image building.
+//
+#ifdef FEATURE_READYTORUN_COMPILER
+                assert((pFldAddr == nullptr) ||
+                       (pFieldInfo->fieldAccessor == CORINFO_FIELD_STATIC_RVA_ADDRESS && opts.IsReadyToRun()));
+#else
                 assert(pFldAddr == nullptr);
+#endif
 
                 FieldSeqNode* fldSeq = GetFieldSeqStore()->CreateSingleton(pResolvedToken->hField);
 
                 /* Create the data member node */
-                op1 = gtNewIconHandleNode(pFldAddr == nullptr ? (size_t)fldAddr : (size_t)pFldAddr, GTF_ICON_STATIC_HDL,
+                op1 = gtNewIconHandleNode(pFldAddr == nullptr ? (size_t)fldAddr : (size_t)pFldAddr,
+#ifdef FEATURE_READYTORUN_COMPILER
+                                          pFldAddr != nullptr ? GTF_ICON_CONST_PTR :
+#endif
+                                                              GTF_ICON_STATIC_HDL,
                                           fldSeq);
 #ifdef DEBUG
                 op1->AsIntCon()->gtTargetHandle = op1->AsIntCon()->gtIconVal;
@@ -7721,6 +7731,17 @@ GenTree* Compiler::impImportStaticFieldAccess(CORINFO_RESOLVED_TOKEN* pResolvedT
                 {
                     op1->gtFlags |= GTF_ICON_INITCLASS;
                 }
+
+#ifdef FEATURE_READYTORUN_COMPILER
+                if (pFldAddr != nullptr)
+                {
+                    // Indirection used to get to initial actual field RVA when building a composite image
+                    // where the actual field does not move from the original file
+                    assert(!varTypeIsGC(lclTyp));
+                    op1 = gtNewOperNode(GT_IND, TYP_I_IMPL, op1);
+                    op1->gtFlags |= GTF_IND_INVARIANT | GTF_IND_NONFAULTING;
+                }
+#endif
             }
             else // We need the value of a static field
             {

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunSymbolNodeFactory.cs

@@ -64,6 +64,14 @@ private void CreateNodeCaches()
                     new ReadyToRunInstructionSetSupportSignature(key));
             });
 
+            _precodeFieldAddressCache = new NodeCache<FieldDesc, ISymbolNode>(key =>
+            {
+                return new PrecodeHelperImport(
+                    _codegenNodeFactory,
+                    new FieldFixupSignature(ReadyToRunFixupKind.FieldAddress, key, _codegenNodeFactory)
+                );
+            });
+
             _fieldAddressCache = new NodeCache<FieldDesc, ISymbolNode>(key =>
             {
                 return new DelayLoadHelperImport(
@@ -398,6 +406,13 @@ public ISymbolNode FieldAddress(FieldDesc fieldDesc)
             return _fieldAddressCache.GetOrAdd(fieldDesc);
         }
 
+        private NodeCache<FieldDesc, ISymbolNode> _precodeFieldAddressCache;
+
+        public ISymbolNode PrecodeFieldAddress(FieldDesc fieldDesc)
+        {
+            return _precodeFieldAddressCache.GetOrAdd(fieldDesc);
+        }
+
         private NodeCache<FieldDesc, ISymbolNode> _fieldOffsetCache;
 
         public ISymbolNode FieldOffset(FieldDesc fieldDesc)

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs

@@ -641,7 +641,7 @@ protected override void ComputeDependencyNodeDependencies(List<DependencyNodeCor
             }
         }
 
-        public ISymbolNode GetFieldRvaData(FieldDesc field) => NodeFactory.CopiedFieldRva(field);
+        public ISymbolNode GetFieldRvaData(FieldDesc field) => NodeFactory.CompilationModuleGroup.IsCompositeBuildMode ? SymbolNodeFactory.PrecodeFieldAddress(field) : NodeFactory.CopiedFieldRva(field);
 
         public override void Dispose()
         {

src/coreclr/vm/jitinterface.cpp

@@ -13997,6 +13997,21 @@ BOOL LoadDynamicInfoEntry(Module *currentModule,
         break;
 #endif // PROFILING_SUPPORTED
 
+    case ENCODE_FIELD_ADDRESS:
+        {
+            FieldDesc *pField = ZapSig::DecodeField(currentModule, pInfoModule, pBlob);
+
+            pField->GetEnclosingMethodTable()->CheckRestore();
+
+            // We can only take address of RVA field here as we don't handle scenarios where the static variable may move
+            // Also, this cannot be used with a ZapImage as it relies on a separate signatures block as an RVA static
+            // address may be unaligned which would interfere with the tagged pointer approach.
+            _ASSERTE(currentModule->IsReadyToRun());
+            _ASSERTE(pField->IsRVA());
+            result = (size_t)pField->GetStaticAddressHandle(NULL);
+        }
+        break;
+
     case ENCODE_STATIC_FIELD_ADDRESS:
         {
             FieldDesc *pField = ZapSig::DecodeField(currentModule, pInfoModule, pBlob);