base: Add warn_if_once macro

Change-Id: Ie68f3b07a35ed2e6b0eee20b3b34050542fcdc6c
Signed-off-by: Tiago Muck <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18420
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/logging.hh

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2017 ARM Limited
+ * Copyright (c) 2014, 2017, 2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -231,6 +231,12 @@ class Logger
             warn(__VA_ARGS__); \
     } while (0)
 
+#define warn_if_once(cond, ...) \
+    do { \
+        if ((cond)) \
+            warn_once(__VA_ARGS__); \
+    } while (0)
+
 /**
  * The chatty assert macro will function like a normal assert, but will allow
  * the specification of additional, helpful material to aid debugging why the