Portable EntryPoint feature (#119178)

* Create FEATURE_PORTABLE_ENTRYPOINTS build flag.

* WASM uses PortableEntryPoint

* Add note to clr-abi about Portable Entry Points.

* Create TargetsWasm MSBuild property.

* Disable FEATURE_REJIT and FEATURE_TIERED_COMPILATION for wasm.

Author: AaronRobinsonMSFT

docs/design/coreclr/botr/clr-abi.md

@@ -537,6 +537,22 @@ The extra state created by the JIT for synchronized methods (lock taken flag) mu
 
 EnC is supported for adding and editing generic methods and methods on generic types and generic methods on non-generic types.
 
+# Portable entrypoints
+
+On platforms that allow dynamic code generation, the runtime abstracts away execution strategies for dynamically loaded methods by allocating [`Precode`](method-descriptor.md#precode)s. The `Precode` is a small code fragment that is used as a temporary method entrypoint until the actual method code is acquired. `Precode`s are also used as part of the execution for methods that do not have regular JITed or AOT-compiled code, for example stubs or interpreted methods. `Precode`s allow native code to use the same native code calling convention irrespective of the execution strategy used by the target method.
+
+On platforms that do not allow dynamic code generation (Wasm), the runtime abstracts away execution strategies by allocating portable entrypoints for dynamically loaded methods. The `PortableEntryPoint` is a data structure that allows efficient transition to the desired execution strategy for the target method. When the runtime is configured to use portable entrypoints, the managed calling convention is modified as follows:
+
+- The native code to call is obtained by dereferencing the entrypoint
+
+- The entrypoint address is passed in as an extra last hidden argument. The extra hidden argument must be present in signatures of all methods. It is unused by the code of JITed or AOT-compiled methods.
+
+Pseudo code for a call with portable entrypoints:
+
+> `(*(void**)pfn)(arg0, arg1, ..., argN, pfn)`
+
+Portable entrypoints are used for Wasm with interpreter only currently. Note that portable entrypoints are unnecessary for Wasm with native AOT since native AOT does not support dynamic loading.
+
 # System V x86_64 support
 
 This section relates mostly to calling conventions on System V systems (such as Ubuntu Linux and Mac OS X).

eng/OSArch.props

@@ -33,6 +33,10 @@
     <Platform Condition="'$(Platform)' == '' and '$(InferPlatformFromTargetArchitecture)' == 'true'">$(TargetArchitecture)</Platform>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <TargetsWasm Condition="'$(TargetArchitecture)' == 'wasm'">true</TargetsWasm>
+  </PropertyGroup>
+
   <PropertyGroup>
     <_ImportedOSArchProps>true</_ImportedOSArchProps>
   </PropertyGroup>

src/coreclr/clr.featuredefines.props

@@ -3,13 +3,18 @@
         <FeatureCoreCLR>true</FeatureCoreCLR>
         <FeaturePerfTracing>true</FeaturePerfTracing>
         <FeatureEHFunclets>true</FeatureEHFunclets>
+        <FeaturePortableEntryPoints>false</FeaturePortableEntryPoints>
         <ProfilingSupportedBuild>true</ProfilingSupportedBuild>
     </PropertyGroup>
 
     <PropertyGroup Condition="'$(TargetsAndroid)' == 'true' OR '$(Configuration)' == 'debug' OR '$(Configuration)' == 'checked'">
         <FeatureJavaMarshal>true</FeatureJavaMarshal>
     </PropertyGroup>
 
+    <PropertyGroup Condition="'$(TargetsWasm)' == 'true'">
+        <FeaturePortableEntryPoints>true</FeaturePortableEntryPoints>
+    </PropertyGroup>
+
     <PropertyGroup Condition="'$(TargetsUnix)' == 'true'">
         <FeatureXplatEventSource Condition="'$(FeatureXplatEventSource)' == '' AND '$(TargetOS)' == 'linux'">true</FeatureXplatEventSource>
         <FeatureComWrappers>true</FeatureComWrappers>
@@ -43,6 +48,7 @@
         <DefineConstants Condition="'$(FeatureTypeEquivalence)' == 'true'">$(DefineConstants);FEATURE_TYPEEQUIVALENCE</DefineConstants>
         <DefineConstants Condition="'$(FeatureEHFunclets)' == 'true'">$(DefineConstants);FEATURE_EH_FUNCLETS</DefineConstants>
         <DefineConstants Condition="'$(FeatureInterpreter)' == 'true'">$(DefineConstants);FEATURE_INTERPRETER</DefineConstants>
+        <DefineConstants Condition="'$(FeaturePortableEntryPoints)' == 'true'">$(DefineConstants);FEATURE_PORTABLE_ENTRYPOINTS</DefineConstants>
 
         <DefineConstants Condition="'$(ProfilingSupportedBuild)' == 'true'">$(DefineConstants);PROFILING_SUPPORTED</DefineConstants>
     </PropertyGroup>

src/coreclr/clrdefinitions.cmake

@@ -118,6 +118,9 @@ if (CLR_CMAKE_TARGET_WIN32 AND (CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_
 endif (CLR_CMAKE_TARGET_WIN32 AND (CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_ARCH_I386 OR CLR_CMAKE_TARGET_ARCH_ARM64))
 
 add_compile_definitions($<${FEATURE_INTERPRETER}:FEATURE_INTERPRETER>)
+if (FEATURE_PORTABLE_ENTRYPOINTS)
+  add_compile_definitions(FEATURE_PORTABLE_ENTRYPOINTS)
+endif()
 
 if (CLR_CMAKE_TARGET_WIN32)
     add_definitions(-DFEATURE_ISYM_READER)
@@ -160,7 +163,9 @@ add_definitions(-DFEATURE_READYTORUN)
 
 set(FEATURE_READYTORUN 1)
 
-add_compile_definitions(FEATURE_REJIT)
+if(FEATURE_REJIT)
+  add_compile_definitions(FEATURE_REJIT)
+endif()
 
 if (CLR_CMAKE_HOST_UNIX AND CLR_CMAKE_TARGET_UNIX)
   add_definitions(-DFEATURE_REMOTE_PROC_MEM)
@@ -174,7 +179,11 @@ if (NOT CLR_CMAKE_HOST_ANDROID)
   add_definitions(-DFEATURE_SVR_GC)
 endif(NOT CLR_CMAKE_HOST_ANDROID)
 add_definitions(-DFEATURE_SYMDIFF)
-add_compile_definitions(FEATURE_TIERED_COMPILATION)
+
+if (FEATURE_TIERED_COMPILATION)
+  add_compile_definitions(FEATURE_TIERED_COMPILATION)
+endif(FEATURE_TIERED_COMPILATION)
+
 add_compile_definitions(FEATURE_PGO)
 if (CLR_CMAKE_TARGET_ARCH_AMD64)
   # Enable the AMD64 Unix struct passing JIT-EE interface for all AMD64 platforms, to enable altjit.

src/coreclr/clrfeatures.cmake

@@ -1,5 +1,7 @@
 if (NOT CLR_CMAKE_TARGET_ARCH_WASM AND NOT CLR_CMAKE_TARGET_IOS AND NOT CLR_CMAKE_TARGET_TVOS AND NOT CLR_CMAKE_TARGET_MACCATALYST)
   set(FEATURE_JIT 1)
+  set(FEATURE_TIERED_COMPILATION 1)
+  set(FEATURE_REJIT 1)
 endif()
 
 if (CLR_CMAKE_TARGET_ARCH_WASM OR CLR_CMAKE_TARGET_IOS OR CLR_CMAKE_TARGET_TVOS OR CLR_CMAKE_TARGET_MACCATALYST)
@@ -39,6 +41,7 @@ if(NOT DEFINED FEATURE_INTERPRETER)
     set(FEATURE_INTERPRETER 0)
   elseif(CLR_CMAKE_TARGET_ARCH_WASM)
     set(FEATURE_INTERPRETER 1)
+    set(FEATURE_PORTABLE_ENTRYPOINTS 1)
   else()
     if(CLR_CMAKE_TARGET_ARCH_AMD64 OR CLR_CMAKE_TARGET_ARCH_ARM64)
       set(FEATURE_INTERPRETER $<IF:$<CONFIG:Debug,Checked>,1,0>)

src/coreclr/interpreter/compiler.cpp

@@ -2233,7 +2233,7 @@ int32_t InterpCompiler::GetDataForHelperFtn(CorInfoHelpFunc ftn)
 
     static_assert(sizeof(InterpHelperData) == sizeof(int32_t), "InterpHelperData must be the same size as an int32_t");
 
-    InterpHelperData result;
+    InterpHelperData result{};
     result.accessType = ftnLookup.accessType;
     int32_t dataItemIndex = GetDataItemIndex(ftnLookup.addr);
     result.addressDataItemIndex = dataItemIndex;
@@ -6577,8 +6577,8 @@ void InterpCompiler::PrintPointer(void* pointer)
 
 void InterpCompiler::PrintHelperFtn(int32_t _data)
 {
-    InterpHelperData data;
-    memcpy(&data, &_data, sizeof(int32_t));
+    InterpHelperData data{};
+    memcpy(&data, &_data, sizeof(_data));
 
     void *helperAddr = GetDataItemAtIndex(data.addressDataItemIndex);
     PrintPointer(helperAddr);

src/coreclr/interpreter/interpretershared.h

@@ -30,7 +30,8 @@ struct InterpMethod
     InterpMethod *self;
 #endif
     CORINFO_METHOD_HANDLE methodHnd;
-    int32_t argsSize, allocaSize;
+    int32_t argsSize;
+    int32_t allocaSize;
     void** pDataItems;
     // This stub is used for calling the interpreted method from JITted/AOTed code
     CallStubHeader *pCallStub;

src/coreclr/vm/CMakeLists.txt

@@ -112,6 +112,7 @@ set(VM_SOURCES_DAC_AND_WKS_COMMON
     peimage.cpp
     perfmap.cpp
     pgo.cpp
+    precode_portable.cpp
     precode.cpp
     prestub.cpp
     readytorunstandalonemethodmetadata.cpp
@@ -215,6 +216,7 @@ set(VM_HEADERS_DAC_AND_WKS_COMMON
     peimagelayout.inl
     perfmap.h
     pgo.h
+    precode_portable.hpp
     precode.h
     rejit.h
     rejit.inl

src/coreclr/vm/appdomain.hpp

@@ -1549,8 +1549,6 @@ class AppDomain final
 
 #endif
 
-#if defined(FEATURE_TIERED_COMPILATION)
-
 public:
     TieredCompilationManager * GetTieredCompilationManager()
     {
@@ -1561,8 +1559,6 @@ class AppDomain final
 private:
     TieredCompilationManager m_tieredCompilationManager;
 
-#endif
-
     friend struct cdac_data<AppDomain>;
 };  // class AppDomain
 

src/coreclr/vm/callhelpers.cpp

@@ -180,11 +180,11 @@ void CopyReturnedFpStructFromRegisters(void* dest, UINT64 returnRegs[2], FpStruc
 #endif // TARGET_RISCV64 || TARGET_LOONGARCH64
 
 // Helper for VM->managed calls with simple signatures.
-void * DispatchCallSimple(
-                    SIZE_T *pSrc,
-                    DWORD numStackSlotsToCopy,
-                    PCODE pTargetAddress,
-                    DWORD dwDispatchCallSimpleFlags)
+void* DispatchCallSimple(
+    SIZE_T *pSrc,
+    DWORD numStackSlotsToCopy,
+    PCODE pTargetAddress,
+    DWORD dwDispatchCallSimpleFlags)
 {
     CONTRACTL
     {