dotnet · jeffschwMSFT · Mar 6, 2025 · Feb 12, 2025 · Feb 28, 2025 · Mar 4, 2025
diff --git a/src/coreclr/jit/emitarm64.cpp b/src/coreclr/jit/emitarm64.cpp
@@ -217,7 +217,6 @@ void emitter::emitInsSanityCheck(instrDesc* id)
        case IF_BR_1B: // BR_1B   ................ ......nnnnn.....         Rn
            if (emitComp->IsTargetAbi(CORINFO_NATIVEAOT_ABI) && id->idIsTlsGD())
            {
-                assert(isGeneralRegister(id->idReg1()));
                assert(id->idAddr()->iiaAddr != nullptr);
            }
            else
@@ -9184,11 +9183,14 @@ void emitter::emitIns_Call(EmitCallType          callType,
        if (emitComp->IsTargetAbi(CORINFO_NATIVEAOT_ABI) && EA_IS_CNS_TLSGD_RELOC(retSize))
        {
            // For NativeAOT linux/arm64, we need to also record the relocation of methHnd.
-            // Since we do not have space to embed it in instrDesc, we store the register in
-            // reg1 and instead use the `iiaAdd` to store the method handle. Likewise, during
-            // emitOutputInstr, we retrieve the register from reg1 for this specific case.
+            // Since we do not have space to embed it in instrDesc, we use the `iiaAddr` to
+            // store the method handle.
+            // The target handle need to be always in R2 and hence the assert check.
+            // We cannot use reg1 and reg2 fields of instrDesc because they contain the gc
+            // registers (emitEncodeCallGCregs()) that are live across the call.
+
+            assert(ireg == REG_R2);
            id->idSetTlsGD();
-            id->idReg1(ireg);
            id->idAddr()->iiaAddr = (BYTE*)methHnd;
        }
        else
@@ -10990,12 +10992,13 @@ size_t emitter::emitOutputInstr(insGroup* ig, instrDesc* id, BYTE** dp)
            {
                emitRecordRelocation(odst, (CORINFO_METHOD_HANDLE)id->idAddr()->iiaAddr,
                                     IMAGE_REL_AARCH64_TLSDESC_CALL);
-                code |= insEncodeReg_Rn(id->idReg1()); // nnnnn
+                code |= insEncodeReg_Rn(REG_R2); // nnnnn
            }
            else
            {
                code |= insEncodeReg_Rn(id->idReg3()); // nnnnn
            }
+
            dst += emitOutputCall(ig, dst, id, code);
            sz = id->idIsLargeCall() ? sizeof(instrDescCGCA) : sizeof(instrDesc);
            break;
@@ -13315,7 +13318,15 @@ void emitter::emitDispInsHelp(
        case IF_BR_1B: // BR_1B   ................ ......nnnnn.....         Rn
            // The size of a branch target is always EA_PTRSIZE
            assert(insOptsNone(id->idInsOpt()));
-            emitDispReg(id->idReg3(), EA_PTRSIZE, false);
+
+            if (emitComp->IsTargetAbi(CORINFO_NATIVEAOT_ABI) && id->idIsTlsGD())
+            {
+                emitDispReg(REG_R2, EA_PTRSIZE, false);
+            }
+            else
+            {
+                emitDispReg(id->idReg3(), EA_PTRSIZE, false);
+            }
            break;

        case IF_LS_1A: // LS_1A   XX...V..iiiiiiii iiiiiiiiiiittttt      Rt    PC imm(1MB)