accel/tcg: Assert that tb->size != 0 after translation

If arch-specific code generates a translation block of size 0,
tb_gen_code() may generate a spurious exception. Add an assertion in
order to catch such situations early.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210416154939.32404-5-iii@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

accel/tcg/translate-all.c

@@ -1912,6 +1912,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
 
     tcg_ctx->cpu = env_cpu(env);
     gen_intermediate_code(cpu, tb, max_insns);
+    assert(tb->size != 0);
     tcg_ctx->cpu = NULL;
     max_insns = tb->icount;