[Runtime] Remove RuntimeFunctionCounters in no-assert builds.

A build option to include or exclude RuntimeFunctionCounters. By default, it's enabled when assertions are enabled.

rdar://problem/35864525

CMakeLists.txt

@@ -300,6 +300,10 @@ option(SWIFT_ENABLE_GUARANTEED_NORMAL_ARGUMENTS
   "Build the standard libraries, overlays, and runtime with normal arguments at +0"
   FALSE)
 
+option(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS
+  "Enable runtime function counters and expose the API. Defaults to on if assertions are on."
+  ${SWIFT_STDLIB_ASSERTIONS})
+
 #
 # End of user-configurable options.
 #

cmake/modules/AddSwift.cmake

@@ -255,6 +255,10 @@ function(_add_variant_c_compile_flags)
   else()
     list(APPEND result "-DNDEBUG")
   endif()
+
+  if(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS)
+    list(APPEND result "-DSWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS")
+  endif()
 
   if(CFLAGS_ANALYZE_CODE_COVERAGE)
     list(APPEND result "-fprofile-instr-generate"
@@ -316,6 +320,10 @@ function(_add_variant_swift_compile_flags
   if (SWIFT_ENABLE_GUARANTEED_NORMAL_ARGUMENTS)
     list(APPEND result "-Xfrontend" "-enable-guaranteed-normal-arguments")
   endif()
+
+  if(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS)
+    list(APPEND result "-D" "SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS")
+  endif()
 
   set("${result_var_name}" "${result}" PARENT_SCOPE)
 endfunction()

stdlib/public/core/RuntimeFunctionCounters.swift

@@ -18,6 +18,13 @@
 //  number of invocations, or per-object counters, which represent the
 //  number of runtime functions calls for a specific object.
 
+// By default, this feature is enabled only when assertions are enabled. To enable when
+// assertions are off, use this option with build-script:
+// --extra-cmake-options='-DSWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS=TRUE'
+// Or to disable in debug builds:
+// --extra-cmake-options='-DSWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS=FALSE'
+#if SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS
+
 /// Collect all references inside the object using Mirrors.
 /// - Parameter value: the value to be inspected
 /// - Parameter references: the array which should contain the collected
@@ -541,3 +548,5 @@ func _measureRuntimeFunctionCountersDiffs(
       mode: savedMode)
     return (globalCountersBefore.diff(globalCountersAfter), objectsCountersDiff)
 }
+
+#endif

stdlib/public/runtime/RuntimeInvocationsTracking.cpp

@@ -21,10 +21,7 @@
 #include "swift/Runtime/HeapObject.h"
 #include "swift/Runtime/Mutex.h"
 
-// This file is compiled always, even if assertions are disabled and no runtime
-// functions are being tracked. This is done to avoid recompiling Swift clients
-// using these APIs. They should be able to link against the standard library
-// independent of the fact whether assertions are enabled or not.
+#if defined(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS)
 
 #define SWIFT_RT_FUNCTION_INVOCATION_COUNTER_NAME(RT_FUNCTION)                 \
   invocationCounter_##RT_FUNCTION
@@ -238,3 +235,5 @@ _swift_setGlobalRuntimeFunctionCountersUpdateHandler(
 /// TODO: Provide an API to remove any counters releated to a specific object
 /// or all objects.
 /// This is useful if you want to reset the stats for some/all objects.
+
+#endif

stdlib/public/runtime/RuntimeInvocationsTracking.h

@@ -20,6 +20,9 @@
 
 #include "swift/Runtime/Config.h"
 
+/// This API is only enabled if this define is set.
+#if defined(SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS)
+
 #if defined(__cplusplus)
 
 namespace swift {
@@ -39,10 +42,6 @@ struct RuntimeFunctionCountersState;
 #define SWIFT_RT_TRACK_INVOCATION_NAME(RT_FUNCTION)                            \
   swift_trackRuntimeInvocation_##RT_FUNCTION
 
-/// Instrument the runtime functions only if we are building with
-/// assertions enabled.
-#if !defined(NDEBUG)
-
 /// Invoke a helper function for tracking the calls of a runtime function.
 #define SWIFT_RT_TRACK_INVOCATION(OBJ, RT_FUNCTION)                            \
   SWIFT_RT_TRACK_INVOCATION_NAME(RT_FUNCTION)(OBJ)
@@ -52,13 +51,6 @@ struct RuntimeFunctionCountersState;
 /// Declarations of external functions for invocations tracking.
 #include "RuntimeInvocationsTracking.def"
 
-#else
-
-/// It is just a NOP if assertions are not enabled.
-#define SWIFT_RT_TRACK_INVOCATION(OBJ, RT_FUNCTION)
-
-#endif // NDEBUG
-
 /// This type defines a callback to be called on any intercepted runtime
 /// function.
 using RuntimeFunctionCountersUpdateHandler =
@@ -118,4 +110,12 @@ SWIFT_RUNTIME_EXPORT RuntimeFunctionCountersUpdateHandler
 _swift_setGlobalRuntimeFunctionCountersUpdateHandler(
     RuntimeFunctionCountersUpdateHandler handler);
 
+#else
+
+/// Let runtime functions uncoditionally use this define by making it a NOP if
+/// counters are not enabled.
+#define SWIFT_RT_TRACK_INVOCATION(OBJ, RT_FUNCTION)
+
+#endif // SWIFT_ENABLE_RUNTIME_FUNCTION_COUNTERS
+
 #endif