cpu-exec: Do not invalidate original TB in cpu_exec_nocache()

Instead of invalidating an original TB in cpu_exec_nocache()
prematurely, just save a link to it in the temporary generated TB. If
cpu_io_recompile() is raised subsequently from the temporary TB,
invalidate the original one as well. That allows reusing the original TB
each time cpu_exec_nocache() is called to handle expired instruction
counter in icount mode.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Message-Id: <1435656909-29116-1-git-send-email-serge.fdrv@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 6 deletions

diff --git a/cpu-exec.c b/cpu-exec.c
index 75694f3bb3..407fa4715a 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -231,19 +231,15 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
                              TranslationBlock *orig_tb)
 {
     TranslationBlock *tb;
-    target_ulong pc = orig_tb->pc;
-    target_ulong cs_base = orig_tb->cs_base;
-    uint64_t flags = orig_tb->flags;
 
     /* Should never happen.
        We only end up here when an existing TB is too long.  */
     if (max_cycles > CF_COUNT_MASK)
         max_cycles = CF_COUNT_MASK;
 
-    /* tb_gen_code can flush our orig_tb, invalidate it now */
-    tb_phys_invalidate(orig_tb, -1);
-    tb = tb_gen_code(cpu, pc, cs_base, flags,
+    tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
                      max_cycles | CF_NOCACHE);
+    tb->orig_tb = tcg_ctx.tb_ctx.tb_invalidated_flag ? NULL : orig_tb;
     cpu->current_tb = tb;
     /* execute the generated code */
     trace_exec_tb_nocache(tb, tb->pc);