When using C++23, use [[assume]] attribute.

dealii · Jan 24, 2024 · 7d715d2 · 7d715d2
1 parent 8315924
commit 7d715d2
Showing 1 changed file with 36 additions and 0 deletions.
diff --git a/include/deal.II/base/exceptions.h b/include/deal.II/base/exceptions.h
@@ -1519,6 +1519,42 @@ namespace deal_II_exceptions
 } /*namespace deal_II_exceptions*/
 
 
+#ifdef DEAL_II_HAVE_CXX23
+#  define define DEAL_II_ASSUME(expr) [[assume(expr)]]
+#else
+#  if defined(__clang__)
+#    define DEAL_II_ASSUME(expr) __builtin_assume(static_cast<bool>(expr))
+#  elif defined(__GNUC__) && !defined(__ICC)
+#    if __GNUC__ >= 13
+#      define DEAL_II_ASSUME(expr)                                         \
+        do                                                                 \
+          {                                                                \
+            _Pragma("GCC diagnostic push")                                 \
+              _Pragma("GCC diagnostic ignored \"-Wimplicit-fallthrough\"") \
+                [[assume(expr)]];                                          \
+            _Pragma("GCC diagnostic pop")                                  \
+          }                                                                \
+        while (false)
+#    else
+/* no way with GCC to express this without evaluating 'expr' */
+#      define DEAL_II_ASSUME(expr) \
+        do                         \
+          {                        \
+          }                        \
+        while (false)
+#    endif
+#  elif defined(_MSC_VER) || defined(__ICC)
+#    define DEAL_II_ASSUME(expr) __assume(expr);
+#  else
+#    define DEAL_II_ASSUME(expr) \
+      do                         \
+        {                        \
+        }                        \
+      while (false)
+#  endif
+#endif
+
+
 /**
  * A macro that serves as the main routine in the exception mechanism for debug
  * mode error checking. It asserts that a certain condition is fulfilled,