tcg/mips: reserve a register for the guest_base.

Reserve a register for the guest_base using ppc code for reference.
By doing so, we do not have to recompute it for every memory load.

Signed-off-by: Jiang Biao <jiang.biao2@zte.com.cn>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <1499677934-2249-1-git-send-email-jiang.biao2@zte.com.cn>

tcg/mips/tcg-target.inc.c

@@ -85,6 +85,10 @@ static const char * const tcg_target_reg_names[TCG_TARGET_NB_REGS] = {
 #define TCG_TMP2  TCG_REG_T8
 #define TCG_TMP3  TCG_REG_T7
 
+#ifndef CONFIG_SOFTMMU
+#define TCG_GUEST_BASE_REG TCG_REG_S1
+#endif
+
 /* check if we really need so many registers :P */
 static const int tcg_target_reg_alloc_order[] = {
     /* Call saved registers.  */
@@ -1547,8 +1551,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, bool is_64)
     } else if (guest_base == (int16_t)guest_base) {
         tcg_out_opc_imm(s, ALIAS_PADDI, base, addr_regl, guest_base);
     } else {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, guest_base);
-        tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_TMP0, addr_regl);
+        tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_GUEST_BASE_REG, addr_regl);
     }
     tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
 #endif
@@ -1652,8 +1655,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, bool is_64)
     } else if (guest_base == (int16_t)guest_base) {
         tcg_out_opc_imm(s, ALIAS_PADDI, base, addr_regl, guest_base);
     } else {
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, guest_base);
-        tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_TMP0, addr_regl);
+        tcg_out_opc_reg(s, ALIAS_PADD, base, TCG_GUEST_BASE_REG, addr_regl);
     }
     tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
 #endif
@@ -2452,6 +2454,13 @@ static void tcg_target_qemu_prologue(TCGContext *s)
                    TCG_REG_SP, SAVE_OFS + i * REG_SIZE);
     }
 
+#ifndef CONFIG_SOFTMMU
+    if (guest_base) {
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_GUEST_BASE_REG, guest_base);
+        tcg_regset_set_reg(s->reserved_regs, TCG_GUEST_BASE_REG);
+    }
+#endif
+
     /* Call generated code */
     tcg_out_opc_reg(s, OPC_JR, 0, tcg_target_call_iarg_regs[1], 0);
     /* delay slot */