[cDAC] Change pointer data to be compile-time constant

docs/design/datacontracts/StressLog.md

@@ -53,6 +53,7 @@ Data descriptors used:
 | StressLog | TickFrequency | Number of ticks per second for stresslog timestamps |
 | StressLog | StartTimestamp | Timestamp when the stress log was started |
 | StressLog | ModuleOffset | Offset of the module in the stress log |
+| StressLog | Modules | Offset of the stress log's module table (if StressLogHasModuleTable is `1`) |
 | StressLog | Logs | Pointer to the thread-specific logs |
 | StressLogModuleDesc | BaseAddress | Base address of the module |
 | StressLogModuleDesc | Size | Size of the module |
@@ -80,7 +81,6 @@ Global variables used:
 | StressLogChunkSize | uint | Size of a stress log chunk |
 | StressLogMaxMessageSize | ulong | Maximum size of a stress log message |
 | StressLogHasModuleTable | byte | Whether the stress log module table is present |
-| StressLogModuleTable | pointer | Pointer to the stress log's module table (if StressLogHasModuleTable is `1`) |
 
 ```csharp
 bool HasStressLog()
@@ -216,12 +216,21 @@ protected TargetPointer GetFormatPointer(ulong formatOffset)
         return new TargetPointer(stressLog.ModuleOffset + formatOffset);
     }
 
-    TargetPointer moduleTable = target.ReadGlobalPointer(Constants.Globals.StressLogModuleTable);
+    TargetPointer? moduleTable;
+    if (!target.TryReadGlobalPointer(Constants.Globals.StressLogModuleTable, out moduleTable))
+    {
+        if (!target.TryReadGlobalPointer(Constants.Globals.StressLog, out TargetPointer? pStressLog))
+        {
+            throw new InvalidOperationException("StressLogModuleTable is not set and StressLog is not available, but StressLogHasModuleTable is set to 1.");
+        }
+        Data.StressLog stressLog = target.ProcessedData.GetOrAdd<Data.StressLog>(pStressLog.Value);
+        moduleTable = stressLog.Modules ?? throw new InvalidOperationException("StressLogModuleTable is not set and StressLog does not contain a ModuleTable offset, but StressLogHasModuleTable is set to 1.");
+    }
     uint moduleEntrySize = target.GetTypeInfo(DataType.StressLogModuleDesc).Size!.Value;
     uint maxModules = target.ReadGlobal<uint>(Constants.Globals.StressLogMaxModules);
     for (uint i = 0; i < maxModules; ++i)
     {
-        StressLogModuleDesc module = new(Target, moduleTable + i * moduleEntrySize);
+        StressLogModuleDesc module = new(Target, moduleTable.Value + i * moduleEntrySize);
         ulong relativeOffset = formatOffset - cumulativeOffset;
         if (relativeOffset < module.Size.Value)
         {

src/coreclr/clrdatadescriptors.cmake

@@ -78,5 +78,13 @@ function(generate_data_descriptors)
 
     # inherit definitions, include directories, and dependencies from the INTERFACE target
     target_link_libraries(${LIBRARY} PRIVATE ${DATA_DESCRIPTORS_INTERFACE_TARGET})
+
+    if(MSVC)
+      # /Zc:externConstexpr is required to export constexpr variables
+      # from the object file, otherwise the linker will not export them.
+      # See https://learn.microsoft.com/en-us/cpp/build/reference/zc-externconstexpr
+      # for more details.
+      target_compile_options(${LIBRARY} PRIVATE /Zc:externConstexpr)
+    endif(MSVC)
   endif()
 endfunction(generate_data_descriptors)

src/coreclr/debug/datadescriptor-shared/contract-descriptor.c.in

@@ -18,12 +18,12 @@ struct ContractDescriptor
     const char *descriptor;
     const uint32_t pointer_data_count;
     uint32_t pad0;
-    const uintptr_t *pointer_data;
+    const void** pointer_data;
 };
 
 // POINTER_DATA_NAME and CONTRACT_NAME are macros provided by
 // contractconfiguration.h which is configured by CMake
-extern const uintptr_t POINTER_DATA_NAME[];
+extern const void* POINTER_DATA_NAME[];
 
 #if EXPORT_CONTRACT
 DLLEXPORT

src/coreclr/debug/datadescriptor-shared/contractdescriptorstub.c

@@ -18,15 +18,15 @@ struct ContractDescriptor
     const char *descriptor;
     const uint32_t pointer_data_count;
     uint32_t pad0;
-    const uintptr_t *pointer_data;
+    const void** pointer_data;
 };
 
 // POINTER_DATA_NAME and CONTRACT_NAME are macros provided by
 // contractconfiguration.h which is configured by CMake
-extern const uintptr_t POINTER_DATA_NAME[];
+extern const void* POINTER_DATA_NAME[];
 
 // just the placeholder pointer
-const uintptr_t POINTER_DATA_NAME[] = { (uintptr_t)0 };
+const void* POINTER_DATA_NAME[] = { (void*)0 };
 
 DLLEXPORT struct ContractDescriptor CONTRACT_NAME;
 

src/coreclr/debug/datadescriptor-shared/contractpointerdata.cpp

@@ -6,13 +6,12 @@
 
 extern "C"
 {
-// without an extern declaration, clang does not emit this global into the object file
-extern const uintptr_t POINTER_DATA_NAME[];
-
-const uintptr_t POINTER_DATA_NAME[] = {
-    (uintptr_t)0, // placeholder
-#define CDAC_GLOBAL_POINTER(name,value) (uintptr_t)(value),
-#define CDAC_GLOBAL_SUB_DESCRIPTOR(name,value) (uintptr_t)(value),
-#include "wrappeddatadescriptor.inc"
+    // without an extern declaration, clang does not emit this global into the object file
+    extern constexpr const void* POINTER_DATA_NAME[] = {
+        (void*)0, // placeholder
+    #define CDAC_GLOBAL_POINTER(name,value) (void*)(value),
+    #define CDAC_GLOBAL_SUB_DESCRIPTOR(name,value) (void*)(value),
+    #include "wrappeddatadescriptor.inc"
+    };
 };
-}
+

src/coreclr/inc/stresslog.h

@@ -396,23 +396,24 @@ inline BOOL StressLog::LogOn(unsigned facility, unsigned level)
 template<>
 struct cdac_offsets<StressLog>
 {
-    static const size_t facilitiesToLog = offsetof(StressLog, facilitiesToLog);
-    static const size_t levelToLog = offsetof(StressLog, levelToLog);
-    static const size_t MaxSizePerThread = offsetof(StressLog, MaxSizePerThread);
-    static const size_t MaxSizeTotal = offsetof(StressLog, MaxSizeTotal);
-    static const size_t totalChunk = offsetof(StressLog, totalChunk);
-    static const size_t logs = offsetof(StressLog, logs);
-    static const size_t tickFrequency = offsetof(StressLog, tickFrequency);
-    static const size_t startTimeStamp = offsetof(StressLog, startTimeStamp);
-    static const size_t startTime = offsetof(StressLog, startTime);
-    static const size_t moduleOffset = offsetof(StressLog, moduleOffset);
-    static constexpr uint64_t MAX_MODULES = StressLog::MAX_MODULES;
+    static constexpr size_t facilitiesToLog = offsetof(StressLog, facilitiesToLog);
+    static constexpr size_t levelToLog = offsetof(StressLog, levelToLog);
+    static constexpr size_t MaxSizePerThread = offsetof(StressLog, MaxSizePerThread);
+    static constexpr size_t MaxSizeTotal = offsetof(StressLog, MaxSizeTotal);
+    static constexpr size_t totalChunk = offsetof(StressLog, totalChunk);
+    static constexpr size_t logs = offsetof(StressLog, logs);
+    static constexpr size_t tickFrequency = offsetof(StressLog, tickFrequency);
+    static constexpr size_t startTimeStamp = offsetof(StressLog, startTimeStamp);
+    static constexpr size_t startTime = offsetof(StressLog, startTime);
+    static constexpr size_t moduleOffset = offsetof(StressLog, moduleOffset);
+    static constexpr size_t MAX_MODULES = StressLog::MAX_MODULES;
+    static constexpr size_t modules = offsetof(StressLog, modules);
 
     struct ModuleDesc
     {
         static constexpr size_t type_size = sizeof(StressLog::ModuleDesc);
-        static const size_t baseAddress = offsetof(StressLog::ModuleDesc, baseAddress);
-        static const size_t size = offsetof(StressLog::ModuleDesc, size);
+        static constexpr size_t baseAddress = offsetof(StressLog::ModuleDesc, baseAddress);
+        static constexpr size_t size = offsetof(StressLog::ModuleDesc, size);
     };
 };
 

src/coreclr/vm/datadescriptor/datadescriptor.inc

@@ -317,6 +317,7 @@ CDAC_TYPE_FIELD(StressLog, /* pointer */, Logs, cdac_offsets<StressLog>::logs)
 CDAC_TYPE_FIELD(StressLog, /* uint64 */, TickFrequency, cdac_offsets<StressLog>::tickFrequency)
 CDAC_TYPE_FIELD(StressLog, /* uint64 */, StartTimestamp, cdac_offsets<StressLog>::startTimeStamp)
 CDAC_TYPE_FIELD(StressLog, /* nuint */, ModuleOffset, cdac_offsets<StressLog>::moduleOffset)
+CDAC_TYPE_FIELD(StressLog, /* StressLogModuleDesc[] */, Modules, cdac_offsets<StressLog>::modules)
 CDAC_TYPE_END(StressLog)
 
 CDAC_TYPE_BEGIN(StressLogModuleDesc)
@@ -908,7 +909,6 @@ CDAC_GLOBAL_POINTER(TlsIndexBase, &::_tls_index)
 CDAC_GLOBAL(StressLogEnabled, uint8, 1)
 CDAC_GLOBAL_POINTER(StressLog, &g_pStressLog)
 CDAC_GLOBAL(StressLogHasModuleTable, uint8, 1)
-CDAC_GLOBAL_POINTER(StressLogModuleTable, &g_pStressLog->modules)
 CDAC_GLOBAL(StressLogMaxModules, uint64, cdac_offsets<StressLog>::MAX_MODULES)
 CDAC_GLOBAL(StressLogChunkSize, uint32, STRESSLOG_CHUNK_SIZE)
 CDAC_GLOBAL(StressLogValidChunkSig, uint32, StressLogChunk::ValidChunkSig)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StressLog.cs

@@ -112,13 +112,22 @@ private TargetPointer GetFormatPointer(ulong formatOffset)
             return new TargetPointer(stressLog.ModuleOffset.Value + formatOffset);
         }
 
-        TargetPointer moduleTable = target.ReadGlobalPointer(Constants.Globals.StressLogModuleTable);
+        TargetPointer? moduleTable;
+        if (!target.TryReadGlobalPointer(Constants.Globals.StressLogModuleTable, out moduleTable))
+        {
+            if (!target.TryReadGlobalPointer(Constants.Globals.StressLog, out TargetPointer? pStressLog))
+            {
+                throw new InvalidOperationException("StressLogModuleTable is not set and StressLog is not available, but StressLogHasModuleTable is set to 1.");
+            }
+            Data.StressLog stressLog = target.ProcessedData.GetOrAdd<Data.StressLog>(pStressLog.Value);
+            moduleTable = stressLog.Modules ?? throw new InvalidOperationException("StressLogModuleTable is not set and StressLog does not contain a ModuleTable offset, but StressLogHasModuleTable is set to 1.");
+        }
         uint moduleEntrySize = target.GetTypeInfo(DataType.StressLogModuleDesc).Size!.Value;
         uint maxModules = target.ReadGlobal<uint>(Constants.Globals.StressLogMaxModules);
         ulong cumulativeOffset = 0;
         for (uint i = 0; i < maxModules; ++i)
         {
-            Data.StressLogModuleDesc module = target.ProcessedData.GetOrAdd<Data.StressLogModuleDesc>(moduleTable + i * moduleEntrySize);
+            Data.StressLogModuleDesc module = target.ProcessedData.GetOrAdd<Data.StressLogModuleDesc>(moduleTable.Value + i * moduleEntrySize);
             ulong relativeOffset = formatOffset - cumulativeOffset;
             if (relativeOffset < module.Size.Value)
             {

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/StressLog.cs

@@ -23,6 +23,9 @@ public StressLog(Target target, TargetPointer address)
         StartTimestamp = target.Read<ulong>(address + (ulong)type.Fields[nameof(StartTimestamp)].Offset);
         ModuleOffset = target.ReadNUInt(address + (ulong)type.Fields[nameof(ModuleOffset)].Offset);
 
+        if (type.Fields.ContainsKey(nameof(Modules)))
+            Modules = target.ReadPointer(address + (ulong)type.Fields[nameof(Modules)].Offset);
+
         Logs = target.ReadPointer(address + (ulong)type.Fields[nameof(Logs)].Offset);
     }
 
@@ -42,5 +45,7 @@ public StressLog(Target target, TargetPointer address)
 
     public TargetNUInt ModuleOffset { get; init; }
 
+    public TargetPointer? Modules { get; init; }
+
     public TargetPointer Logs { get; init; }
 }

src/tools/StressLogAnalyzer/src/Program.cs

@@ -520,7 +520,7 @@ private static ContractDescriptorParser.ContractDescriptor GetDescriptor(int str
         {
             Baseline = BaseContractDescriptor.Baseline,
             Version = BaseContractDescriptor.Version,
-            Contracts = new(){ { "StressLog", stressLogVersion } },
+            Contracts = new() { { "StressLog", stressLogVersion } },
             Types = BaseContractDescriptor.Types,
             Globals = BaseContractDescriptor.Globals,
         };
@@ -542,7 +542,8 @@ private static ContractDescriptorParser.ContractDescriptor GetDescriptor(int str
                         "Logs": 24,
                         "TickFrequency": 48,
                         "StartTimestamp": 56,
-                        "ModuleOffset": 72
+                        "ModuleOffset": 72,
+                        "Modules": 80
                     },
                     "StressLogModuleDesc": {
                         "!": 16,