target/arm: optimize cross-page direct jumps in softmmu

Instead of unconditionally exiting to the exec loop, use the
lookup_and_goto_ptr helper to jump to the target if it is valid.

Perf impact: see next commit's log.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NEmilio G. Cota <cota@braap.org>
Message-Id: <1493263764-18657-7-git-send-email-cota@braap.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

target/arm/translate.c

@@ -4157,8 +4157,12 @@ static inline void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
         gen_set_pc_im(s, dest);
         tcg_gen_exit_tb((uintptr_t)s->tb + n);
     } else {
+        TCGv addr = tcg_temp_new();
+
         gen_set_pc_im(s, dest);
-        tcg_gen_exit_tb(0);
+        tcg_gen_extu_i32_tl(addr, cpu_R[15]);
+        tcg_gen_lookup_and_goto_ptr(addr);
+        tcg_temp_free(addr);
     }
 }