[Qemu-devel] [PATCH v2 4/5] trace: [tcg] Do not generate TCG code to trace dinamically-disabled events

[Lluís Vilanova]

If an event is dynamically disabled, the TCG code that calls the
execution-time tracer is not generated.

Removes the overheads of execution-time tracers for dynamically disabled
events. As a bonus, also avoids checking the event state when the
execution-time tracer is called from TCG-generated code (since otherwise
TCG would simply not call it).

Signed-off-by: Lluís Vilanova <address@hidden>
---
 scripts/tracetool/format/h.py            |   23 +++++++++++++++++------
 scripts/tracetool/format/tcg_h.py        |   20 +++++++++++++++++---
 scripts/tracetool/format/tcg_helper_c.py |    3 ++-
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/scripts/tracetool/format/h.py b/scripts/tracetool/format/h.py
index 3763e9a..99fcbc0 100644
--- a/scripts/tracetool/format/h.py
+++ b/scripts/tracetool/format/h.py
@@ -29,6 +29,19 @@ def generate(events, backend):
     backend.generate_begin(events)
 
     for e in events:
+        # tracer without checks
+        out('',
+            'static inline void __nocheck__%(api)s(%(args)s)',
+            '{',
+            api=e.api(),
+            args=e.args)
+
+        if "disable" not in e.properties:
+            backend.generate(e)
+
+        out('}')
+
+        # tracer wrapper with checks (per-vCPU tracing)
         if "vcpu" in e.properties:
             trace_cpu = next(iter(e.args))[1]
             cond = "trace_event_get_vcpu_state(%(cpu)s,"\
@@ -44,16 +57,14 @@ def generate(events, backend):
             'static inline void %(api)s(%(args)s)',
             '{',
             '    if (%(cond)s) {',
+            '        __nocheck__%(api)s(%(names)s);',
+            '    }',
+            '}',
             api=e.api(),
             args=e.args,
+            names=", ".join(e.args.names()),
             cond=cond)
 
-        if "disable" not in e.properties:
-            backend.generate(e)
-
-        out('    }',
-            '}')
-
     backend.generate_end(events)
 
     out('#endif /* TRACE__GENERATED_TRACERS_H */')
diff --git a/scripts/tracetool/format/tcg_h.py 
b/scripts/tracetool/format/tcg_h.py
index e2331f2..fb2503a 100644
--- a/scripts/tracetool/format/tcg_h.py
+++ b/scripts/tracetool/format/tcg_h.py
@@ -41,7 +41,7 @@ def generate(events, backend):
 
     for e in events:
         # just keep one of them
-        if "tcg-trans" not in e.properties:
+        if "tcg-exec" not in e.properties:
             continue
 
         out('static inline void %(name_tcg)s(%(args)s)',
@@ -53,12 +53,26 @@ def generate(events, backend):
             args_trans = e.original.event_trans.args
             args_exec = tracetool.vcpu.transform_args(
                 "tcg_helper_c", e.original.event_exec, "wrapper")
+            if "vcpu" in e.properties:
+                trace_cpu = e.args.names()[0]
+                cond = "trace_event_get_vcpu_state(%(cpu)s,"\
+                       " TRACE_%(id)s,"\
+                       " TRACE_VCPU_%(id)s)"\
+                       % dict(
+                           cpu=trace_cpu,
+                           id=e.original.event_exec.name.upper())
+            else:
+                cond = "true"
+
             out('    %(name_trans)s(%(argnames_trans)s);',
-                '    gen_helper_%(name_exec)s(%(argnames_exec)s);',
+                '    if (%(cond)s) {',
+                '        gen_helper_%(name_exec)s(%(argnames_exec)s);',
+                '    }',
                 name_trans=e.original.event_trans.api(e.QEMU_TRACE),
                 name_exec=e.original.event_exec.api(e.QEMU_TRACE),
                 argnames_trans=", ".join(args_trans.names()),
-                argnames_exec=", ".join(args_exec.names()))
+                argnames_exec=", ".join(args_exec.names()),
+                cond=cond)
 
         out('}')
 
diff --git a/scripts/tracetool/format/tcg_helper_c.py 
b/scripts/tracetool/format/tcg_helper_c.py
index e3485b7..f9adb3c 100644
--- a/scripts/tracetool/format/tcg_helper_c.py
+++ b/scripts/tracetool/format/tcg_helper_c.py
@@ -66,7 +66,8 @@ def generate(events, backend):
 
         out('void %(name_tcg)s(%(args_api)s)',
             '{',
-            '    %(name)s(%(args_call)s);',
+            # NOTE: the check was already performed at TCG-generation time
+            '    __nocheck__%(name)s(%(args_call)s);',
             '}',
             name_tcg="helper_%s_proxy" % e.api(),
             name=e.api(),