[Qemu-devel] [PATCH v2 22/45] cpu-exec: lookup/generate TB outside exclusive region during step_atomic

[Emilio G. Cota]

Now that all code generation has been converted to check CF_PARALLEL, we can
generate !CF_PARALLEL code without having yet set !parallel_cpus --
and therefore without having to be in the exclusive region during
cpu_exec_step_atomic.

While at it, merge cpu_exec_step into cpu_exec_step_atomic.

Signed-off-by: Emilio G. Cota <address@hidden>
---
 accel/tcg/cpu-exec.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index efe5c85..23e6d2c 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -226,7 +226,7 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
 }
 #endif
 
-static void cpu_exec_step(CPUState *cpu)
+void cpu_exec_step_atomic(CPUState *cpu)
 {
     CPUClass *cc = CPU_GET_CLASS(cpu);
     TranslationBlock *tb;
@@ -239,16 +239,26 @@ static void cpu_exec_step(CPUState *cpu)
         if (tb == NULL) {
             mmap_lock();
             tb_lock();
-            tb = tb_gen_code(cpu, pc, cs_base, flags, cflags);
+            tb = tb_htable_lookup(cpu, pc, cs_base, flags, mask_cf(cflags));
+            if (likely(tb == NULL)) {
+                tb = tb_gen_code(cpu, pc, cs_base, flags, cflags);
+            }
             tb_unlock();
             mmap_unlock();
         }
 
+        start_exclusive();
+
+        /* Since we got here, we know that parallel_cpus must be true.  */
+        parallel_cpus = false;
         cc->cpu_exec_enter(cpu);
         /* execute the generated code */
         trace_exec_tb(tb, pc);
         cpu_tb_exec(cpu, tb);
         cc->cpu_exec_exit(cpu);
+        parallel_cpus = true;
+
+        end_exclusive();
     } else {
         /* We may have exited due to another problem here, so we need
          * to reset any tb_locks we may have taken but didn't release.
@@ -262,18 +272,6 @@ static void cpu_exec_step(CPUState *cpu)
     }
 }
 
-void cpu_exec_step_atomic(CPUState *cpu)
-{
-    start_exclusive();
-
-    /* Since we got here, we know that parallel_cpus must be true.  */
-    parallel_cpus = false;
-    cpu_exec_step(cpu);
-    parallel_cpus = true;
-
-    end_exclusive();
-}
-
 struct tb_desc {
     target_ulong pc;
     target_ulong cs_base;
-- 
2.7.4