[x86/Linux] Implement SinglecastDelegateInvokeStub (#8799)

Implement SinglecastDelegateInvokeStub for x86/Linux
- Code copied from that of AMD64 and some translation
- Fixes LargeObjectAlloc.exe unit test case and maybe others

3 files changed, 39 insertions, 5 deletions

diff --git a/src/vm/i386/asmconstants.h b/src/vm/i386/asmconstants.h
index c42b167f32..ee34300387 100644
--- a/src/vm/i386/asmconstants.h
+++ b/src/vm/i386/asmconstants.h
@@ -467,6 +467,24 @@ ASMCONSTANTS_C_ASSERT(Thread__m_pDomain == offsetof(Thread, m_pDomain));
 
 #endif
 
+#ifdef FEATURE_STUBS_AS_IL
+// DelegateObject from src/vm/object.h
+#define DelegateObject___target             0x04    // offset 0 is m_pMethTab of base class Object
+#define DelegateObject___methodBase         0x08
+#define DelegateObject___methodPtr          0x0c
+#define DelegateObject___methodPtrAux       0x10
+#define DelegateObject___invocationList     0x14
+#define DelegateObject___invocationCount    0x18
+
+ASMCONSTANTS_C_ASSERT(DelegateObject___target           == offsetof(DelegateObject, _target));
+ASMCONSTANTS_C_ASSERT(DelegateObject___methodBase       == offsetof(DelegateObject, _methodBase));
+ASMCONSTANTS_C_ASSERT(DelegateObject___methodPtr        == offsetof(DelegateObject, _methodPtr));
+ASMCONSTANTS_C_ASSERT(DelegateObject___methodPtrAux     == offsetof(DelegateObject, _methodPtrAux));
+ASMCONSTANTS_C_ASSERT(DelegateObject___invocationList   == offsetof(DelegateObject, _invocationList));
+ASMCONSTANTS_C_ASSERT(DelegateObject___invocationCount  == offsetof(DelegateObject, _invocationCount));
+
+#endif
+
 #undef ASMCONSTANTS_C_ASSERT
 #undef ASMCONSTANTS_RUNTIME_ASSERT
 
diff --git a/src/vm/i386/asmhelpers.S b/src/vm/i386/asmhelpers.S
index 1c6f0a36f6..6f3dc31045 100644
--- a/src/vm/i386/asmhelpers.S
+++ b/src/vm/i386/asmhelpers.S
@@ -1138,3 +1138,24 @@ NESTED_ENTRY ResolveWorkerAsmStub, _TEXT, NoHandler
     // Now jump to the target
     jmp     eax             // continue on into the method
 NESTED_END ResolveWorkerAsmStub, _TEXT
+
+#ifdef FEATURE_STUBS_AS_IL
+// ==========================================================================
+// void SinglecastDelegateInvokeStub();
+//
+LEAF_ENTRY SinglecastDelegateInvokeStub, _TEXT
+
+    test        ecx, ecx
+    jz          LOCAL_LABEL(NullObject)
+
+    mov         eax, [ecx + DelegateObject___methodPtr]
+    mov         ecx, [ecx + DelegateObject___target]    // replace "this" pointer
+    jmp         eax
+
+LOCAL_LABEL(NullObject):
+
+    mov         ecx, CORINFO_NullReferenceException_ASM
+    jmp         C_FUNC(JIT_InternalThrow)
+
+LEAF_END SinglecastDelegateInvokeStub, _TEXT
+#endif // FEATURE_STUBS_AS_IL
diff --git a/src/vm/i386/unixstubs.cpp b/src/vm/i386/unixstubs.cpp
index 9fe7127946..8ad84192a8 100644
--- a/src/vm/i386/unixstubs.cpp
+++ b/src/vm/i386/unixstubs.cpp
@@ -70,11 +70,6 @@ VOID __cdecl PopSEHRecords(LPVOID pTargetSP)
     PORTABILITY_ASSERT("Implement for PAL");
 }
 
-EXTERN_C VOID SinglecastDelegateInvokeStub()
-{
-    PORTABILITY_ASSERT("SinglecastDelegateInvokeStub");
-}
-
 EXTERN_C VOID ResolveWorkerChainLookupAsmStub()
 {
     PORTABILITY_ASSERT("ResolveWorkerChainLookupAsmStub");