[Qemu-devel] [PATCH v5 2/2] trace: Avoid implicit bool->integer conversions

[Lluís Vilanova]

An explicit if/else is clearer than arithmetic assuming #true is 1,
while the compiler should be able to generate just as optimal code.

Signed-off-by: Lluís Vilanova <address@hidden>
---
 stubs/trace-control.c  |   17 +++++++++++++++--
 trace/control-target.c |   31 ++++++++++++++++++++++++++-----
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/stubs/trace-control.c b/stubs/trace-control.c
index 3740c38..2dfcd9f 100644
--- a/stubs/trace-control.c
+++ b/stubs/trace-control.c
@@ -19,10 +19,23 @@ void trace_event_set_state_dynamic_init(TraceEvent *ev, 
bool state)
 void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
 {
     TraceEventID id;
+    bool state_pre;
     assert(trace_event_get_state_static(ev));
     id = trace_event_get_id(ev);
-    trace_events_enabled_count += state - trace_events_dstate[id];
-    trace_events_dstate[id] = state;
+    /*
+     * We ignore the "vcpu" property here, since there's no target code. Then
+     * dstate can only be 1 or 0.
+     */
+    state_pre = trace_events_dstate[id];
+    if (state_pre != state) {
+        if (state) {
+            trace_events_enabled_count++;
+            trace_events_dstate[id] = 1;
+        } else {
+            trace_events_enabled_count--;
+            trace_events_dstate[id] = 0;
+        }
+    }
 }
 
 void trace_event_set_vcpu_state_dynamic(CPUState *vcpu,
diff --git a/trace/control-target.c b/trace/control-target.c
index 4ee3733..72081e2 100644
--- a/trace/control-target.c
+++ b/trace/control-target.c
@@ -16,10 +16,22 @@
 void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state)
 {
     TraceEventID id = trace_event_get_id(ev);
+    bool state_pre;
     assert(trace_event_get_state_static(ev));
-    /* Ignore "vcpu" property, since no vCPUs have been created yet */
-    trace_events_enabled_count += state - trace_events_dstate[id];
-    trace_events_dstate[id] = state;
+    /*
+     * We ignore the "vcpu" property here, since no vCPUs have been created
+     * yet. Then dstate can only be 1 or 0.
+     */
+    state_pre = trace_events_dstate[id];
+    if (state_pre != state) {
+        if (state) {
+            trace_events_enabled_count++;
+            trace_events_dstate[id] = 1;
+        } else {
+            trace_events_enabled_count--;
+            trace_events_dstate[id] = 0;
+        }
+    }
 }
 
 void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
@@ -31,9 +43,18 @@ void trace_event_set_state_dynamic(TraceEvent *ev, bool 
state)
             trace_event_set_vcpu_state_dynamic(vcpu, ev, state);
         }
     } else {
+        /* Without the "vcpu" property, dstate can only be 1 or 0 */
         TraceEventID id = trace_event_get_id(ev);
-        trace_events_enabled_count += state - trace_events_dstate[id];
-        trace_events_dstate[id] = state;
+        bool state_pre = trace_events_dstate[id];
+        if (state_pre != state) {
+            if (state) {
+                trace_events_enabled_count++;
+                trace_events_dstate[id] = 1;
+            } else {
+                trace_events_enabled_count--;
+                trace_events_dstate[id] = 0;
+            }
+        }
     }
 }