[LoongArch64] Implement Inline TLS field access for LoongArch64. (#88819)

Author: LuckyXu-HF

src/coreclr/jit/codegenloongarch64.cpp

@@ -1966,7 +1966,14 @@ void CodeGen::genCodeForStoreLclVar(GenTreeLclVar* lclNode)
         }
         else // store into register (i.e move into register)
         {
-            if (dataReg != targetReg)
+            if (data->IsIconHandle(GTF_ICON_TLS_HDL))
+            {
+                assert(data->AsIntCon()->IconValue() == 0);
+                emitAttr attr = emitActualTypeSize(targetType);
+                // need to load the address from $tp.
+                emit->emitIns_R_R_I(INS_ori, attr, targetReg, REG_TP, 0);
+            }
+            else if (dataReg != targetReg)
             {
                 // Assign into targetReg when dataReg (from op1) is not the same register
                 inst_Mov(targetType, targetReg, dataReg, true, emitActualTypeSize(targetType));

src/coreclr/jit/helperexpansion.cpp

@@ -658,6 +658,12 @@ bool Compiler::fgExpandThreadLocalAccessForCall(BasicBlock** pBlock, Statement*
         //      mrs xt, tpidr_elf0
         //      mov xd, [xt+cns]
         tlsValue = gtNewIconHandleNode(0, GTF_ICON_TLS_HDL);
+#elif defined(TARGET_LOONGARCH64)
+        // Code sequence to access thread local variable on linux/loongarch64:
+        //
+        //      ori, targetReg, $tp, 0
+        //      load rd, targetReg, cns
+        tlsValue = gtNewIconHandleNode(0, GTF_ICON_TLS_HDL);
 #else
         assert(!"Unsupported scenario of optimizing TLS access on Linux Arm32/x86");
 #endif

src/coreclr/vm/jitinterface.cpp

@@ -1414,11 +1414,11 @@ static void* GetTlsIndexObjectAddress()
     return GetThreadStaticDescriptor(p);
 }
 
-#elif TARGET_ARM64
+#elif defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64)
 
 extern "C" size_t GetThreadStaticsVariableOffset();
 
-#endif  // TARGET_ARM64
+#endif // TARGET_ARM64 || TARGET_LOONGARCH64
 #endif // TARGET_WINDOWS
 
 
@@ -1452,10 +1452,11 @@ void CEEInfo::getThreadLocalStaticBlocksInfo (CORINFO_THREAD_STATIC_BLOCKS_INFO*
     pInfo->tlsGetAddrFtnPtr = reinterpret_cast<void*>(&__tls_get_addr);
     pInfo->tlsIndexObject = GetTlsIndexObjectAddress();
 
-#elif defined(TARGET_ARM64)
+#elif defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64)
 
-    // For Linux/arm64, just get the offset of thread static variable, and during execution,
-    // this offset, taken from trpid_elp0 system register gives back the thread variable address.
+    // For Linux arm64/loongarch64, just get the offset of thread static variable, and during execution,
+    // this offset, arm64 taken from trpid_elp0 system register gives back the thread variable address.
+    // this offset, loongarch64 taken from $tp register gives back the thread variable address.
     threadStaticBaseOffset = GetThreadStaticsVariableOffset();
 
 #else
@@ -1600,7 +1601,7 @@ void CEEInfo::getFieldInfo (CORINFO_RESOLVED_TOKEN * pResolvedToken,
 
                 if (optimizeThreadStaticAccess)
                 {
-                    // For windows x64/x86/arm64, linux x64/arm64:
+                    // For windows x64/x86/arm64, linux x64/arm64/loongarch64:
                     // We convert the TLS access to the optimized helper where we will store
                     // the static blocks in TLS directly and access them via inline code.
                     if ((pResult->helper == CORINFO_HELP_GETSHARED_NONGCTHREADSTATIC_BASE_NOCTOR) ||

src/coreclr/vm/loongarch64/asmhelpers.S

@@ -1079,3 +1079,17 @@ NESTED_ENTRY OnCallCountThresholdReachedStub, _TEXT, NoHandler
 NESTED_END OnCallCountThresholdReachedStub, _TEXT
 
 #endif // FEATURE_TIERED_COMPILATION
+
+// ------------------------------------------------------------------
+// size_t GetThreadStaticsVariableOffset()
+
+// Helper to calculate the offset of native thread local variable `t_ThreadStatics` in TCB. The offset has to be found at runtime
+// once linker does its relocation and fixup of thread locals. The offset, after calculation is returned in `$a0` register.
+
+LEAF_ENTRY GetThreadStaticsVariableOffset, _TEXT
+        PROLOG_SAVE_REG_PAIR_INDEXED   22, 1, 16
+        la.tls.ie   $a0, t_ThreadStatics
+        EPILOG_RESTORE_REG_PAIR_INDEXED 22, 1, 16
+        EPILOG_RETURN
+LEAF_END GetThreadStaticsVariableOffset, _TEXT
+// ------------------------------------------------------------------