i#3544: RV64: Mangle pc-relative addressing destining to tp (#7068)

Reuse mangle_stolen_reg_and_tp_reg() to simplify register spilling.

This handles code sequence like

```
_start:
        lla             tp,             slot
	lw              a0,             0(tp)
	li              a7,             93
	ecall
slot:   .long           0x5a
```

Issue: #3544

core/arch/riscv64/mangle.c

@@ -608,40 +608,6 @@ mangle_indirect_jump(dcontext_t *dcontext, instrlist_t *ilist, instr_t *instr,
     return next_instr;
 }
 
-instr_t *
-mangle_rel_addr(dcontext_t *dcontext, instrlist_t *ilist, instr_t *instr,
-                instr_t *next_instr)
-{
-    opnd_t dst = instr_get_dst(instr, 0);
-    app_pc tgt;
-    ASSERT(instr_get_opcode(instr) == OP_auipc);
-    ASSERT(instr_has_rel_addr_reference(instr));
-    instr_get_rel_data_or_instr_target(instr, &tgt);
-    ASSERT(opnd_is_reg(dst));
-    ASSERT(opnd_is_rel_addr(instr_get_src(instr, 0)));
-
-    ASSERT_NOT_IMPLEMENTED(!instr_uses_reg(instr, DR_REG_TP));
-
-    if (instr_uses_reg(instr, dr_reg_stolen)) {
-        dst = opnd_create_reg(DR_REG_A0);
-        PRE(ilist, next_instr,
-            instr_create_save_to_tls(dcontext, DR_REG_A0, TLS_REG0_SLOT));
-    }
-
-    insert_mov_immed_ptrsz(dcontext, (ptr_int_t)tgt, dst, ilist, next_instr, NULL, NULL);
-
-    if (instr_uses_reg(instr, dr_reg_stolen)) {
-        PRE(ilist, next_instr,
-            instr_create_save_to_tls(dcontext, DR_REG_A0, TLS_REG_STOLEN_SLOT));
-        PRE(ilist, next_instr,
-            instr_create_restore_from_tls(dcontext, DR_REG_A0, TLS_REG0_SLOT));
-    }
-
-    instrlist_remove(ilist, instr);
-    instr_destroy(dcontext, instr);
-    return NULL;
-}
-
 static reg_id_t
 pick_scratch_reg(dcontext_t *dcontext, instr_t *instr, reg_id_t do_not_pick,
                  reg_id_t do_not_pick_2, ushort *scratch_slot DR_PARAM_OUT)
@@ -866,6 +832,29 @@ mangle_special_registers(dcontext_t *dcontext, instrlist_t *ilist, instr_t *inst
     return next_instr;
 }
 
+instr_t *
+mangle_rel_addr(dcontext_t *dcontext, instrlist_t *ilist, instr_t *instr,
+                instr_t *next_instr)
+{
+    app_pc tgt;
+    ASSERT(instr_get_opcode(instr) == OP_auipc);
+    ASSERT(instr_has_rel_addr_reference(instr));
+    instr_get_rel_data_or_instr_target(instr, &tgt);
+
+    if (instr_uses_reg(instr, dr_reg_stolen) || instr_uses_reg(instr, DR_REG_TP))
+        mangle_stolen_reg_and_tp_reg(dcontext, ilist, instr, next_instr);
+
+    opnd_t dst = instr_get_dst(instr, 0);
+    ASSERT(opnd_is_reg(dst));
+    ASSERT(opnd_is_rel_addr(instr_get_src(instr, 0)));
+
+    insert_mov_immed_ptrsz(dcontext, (ptr_int_t)tgt, dst, ilist, instr, NULL, NULL);
+
+    instrlist_remove(ilist, instr);
+    instr_destroy(dcontext, instr);
+    return NULL;
+}
+
 /***************************************************************************
  * LR/SC sequence mangling.
  */