Handle getting the address of an RVA static correctly in a composite image (dotnet#55301)

* Handle getting the address of an RVA static correctly in a composite image
- Since composite images have the original RVA statics in the original files, use the value from there
- This required re-enabling the ability of getFieldAddress to return an indirection
- And adding some new processing for the fixup as needed
* Silence pointless assert
- There is an assert around incorrect handling of byref pointers, that isn't right. It fails for various issues with the Unsafe.* apis under jit stress, and this change makes it occur during one of our regular builds. As this is just an assert firing when it isn't appropriate, I'm disabling the warning as suggested by the JIT team.

Author: davidwrighton

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

@@ -14034,6 +14034,21 @@ 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);