[LoongArch64] add the coreclr/unwinder/loongarch64 from the #62979. (#63489)

* [LoongArch64] add the `coreclr/unwinder/loongarch64` from the #62979.

* [LoongArch64] replace the `__in` with `_In_`.

* [LoongArch64] update the version of the `LICENSE description`.

* [LoongArch64] update the macro-define for crossgen2.

* [LoongArch64] amend the comment notes.

Co-authored-by: qiaopengcheng <[email protected]>

Author: shushanhf

src/coreclr/inc/clrnt.h

@@ -1030,4 +1030,69 @@ RtlVirtualUnwind(
 
 #endif
 
+#ifdef TARGET_LOONGARCH64
+#include "daccess.h"
+
+#define UNW_FLAG_NHANDLER               0x0             /* any handler */
+#define UNW_FLAG_EHANDLER               0x1             /* filter handler */
+#define UNW_FLAG_UHANDLER               0x2             /* unwind handler */
+
+// This function returns the RVA of the end of the function (exclusive, so one byte after the actual end)
+// using the unwind info on LOONGARCH64. (see ExternalAPIs\Win9CoreSystem\inc\winnt.h)
+FORCEINLINE
+ULONG64
+RtlpGetFunctionEndAddress (
+    _In_ PT_RUNTIME_FUNCTION FunctionEntry,
+    _In_ ULONG64 ImageBase
+    )
+{
+    ULONG64 FunctionLength;
+
+    FunctionLength = FunctionEntry->UnwindData;
+    if ((FunctionLength & 3) != 0) {
+        FunctionLength = (FunctionLength >> 2) & 0x7ff;
+    } else {
+        memcpy(&FunctionLength, (void*)(ImageBase + FunctionLength), sizeof(UINT32));
+        FunctionLength &= 0x3ffff;
+    }
+
+    return FunctionEntry->BeginAddress + 4 * FunctionLength;
+}
+
+#define RUNTIME_FUNCTION__BeginAddress(FunctionEntry)               ((FunctionEntry)->BeginAddress)
+#define RUNTIME_FUNCTION__SetBeginAddress(FunctionEntry,address)    ((FunctionEntry)->BeginAddress = (address))
+
+#define RUNTIME_FUNCTION__EndAddress(FunctionEntry, ImageBase)      (RtlpGetFunctionEndAddress(FunctionEntry, (ULONG64)(ImageBase)))
+
+#define RUNTIME_FUNCTION__SetUnwindInfoAddress(prf,address)         do { (prf)->UnwindData = (address); } while (0)
+
+typedef struct _UNWIND_INFO {
+    // dummy
+} UNWIND_INFO, *PUNWIND_INFO;
+
+EXTERN_C
+NTSYSAPI
+PEXCEPTION_ROUTINE
+NTAPI
+RtlVirtualUnwind(
+    IN ULONG HandlerType,
+    IN ULONG64 ImageBase,
+    IN ULONG64 ControlPc,
+    IN PRUNTIME_FUNCTION FunctionEntry,
+    IN OUT PCONTEXT ContextRecord,
+    OUT PVOID *HandlerData,
+    OUT PULONG64 EstablisherFrame,
+    IN OUT PKNONVOLATILE_CONTEXT_POINTERS ContextPointers OPTIONAL
+    );
+
+#ifndef IMAGE_REL_LOONGARCH64_PC
+#define IMAGE_REL_LOONGARCH64_PC  0x0003
+#endif
+
+#ifndef IMAGE_REL_LOONGARCH64_JIR
+#define IMAGE_REL_LOONGARCH64_JIR  0x0004
+#endif
+
+#endif // TARGET_LOONGARCH64
+
 #endif  // CLRNT_H_

src/coreclr/pal/inc/rt/ntimage.h

@@ -1025,6 +1025,12 @@ typedef IMAGE_RELOCATION UNALIGNED *PIMAGE_RELOCATION;
 #define IMAGE_REL_IA64_GPREL32          0x001C
 #define IMAGE_REL_IA64_ADDEND           0x001F
 
+//
+// LOONGARCH64 relocation types
+//
+#define IMAGE_REL_LOONGARCH64_PC        0x0003
+#define IMAGE_REL_LOONGARCH64_JIR       0x0004
+
 //
 // CEF relocation types.
 //