tcg/mips: implement goto_ptr

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <20170430145254.25616-2-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>

tcg/mips/tcg-target.h

@@ -130,7 +130,7 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_muluh_i32        1
 #define TCG_TARGET_HAS_mulsh_i32        1
 #define TCG_TARGET_HAS_bswap32_i32      1
-#define TCG_TARGET_HAS_goto_ptr         0
+#define TCG_TARGET_HAS_goto_ptr         1
 
 #if TCG_TARGET_REG_BITS == 64
 #define TCG_TARGET_HAS_add2_i32         0

tcg/mips/tcg-target.inc.c

@@ -1747,6 +1747,11 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
         tcg_out_nop(s);
         s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
         break;
+    case INDEX_op_goto_ptr:
+        /* jmp to the given host address (could be epilogue) */
+        tcg_out_opc_reg(s, OPC_JR, 0, a0, 0);
+        tcg_out_nop(s);
+        break;
     case INDEX_op_br:
         tcg_out_brcond(s, TCG_COND_EQ, TCG_REG_ZERO, TCG_REG_ZERO,
                        arg_label(a0));
@@ -2160,6 +2165,7 @@ static const TCGTargetOpDef mips_op_defs[] = {
     { INDEX_op_exit_tb, { } },
     { INDEX_op_goto_tb, { } },
     { INDEX_op_br, { } },
+    { INDEX_op_goto_ptr, { "r" } },
 
     { INDEX_op_ld8u_i32, { "r", "r" } },
     { INDEX_op_ld8s_i32, { "r", "r" } },
@@ -2451,6 +2457,13 @@ static void tcg_target_qemu_prologue(TCGContext *s)
     /* delay slot */
     tcg_out_mov(s, TCG_TYPE_PTR, TCG_AREG0, tcg_target_call_iarg_regs[0]);
 
+    /*
+     * Return path for goto_ptr. Set return value to 0, a-la exit_tb,
+     * and fall through to the rest of the epilogue.
+     */
+    s->code_gen_epilogue = s->code_ptr;
+    tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_V0, TCG_REG_ZERO);
+
     /* TB epilogue */
     tb_ret_addr = s->code_ptr;
     for (i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {