[glib: 1/2] gslice: Allow inlining of memset() in g_slice_new0() macro

[Philip Withnall <pwithnall src gnome org>]

commit 4c5ccd3e8fd1126722e6b3dc3d87a77d90079902
Author: Hans Petter Jansson <hpj cl no>
Date:   Mon Jul 27 17:03:58 2020 +0200

    gslice: Allow inlining of memset() in g_slice_new0() macro
    
    Inlining the memset() is beneficial since the size here is constant
    and usually small.
    
    Closes #5

 glib/gslice.h | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)
---
diff --git a/glib/gslice.h b/glib/gslice.h
index ff8b02a65..002410635 100644
--- a/glib/gslice.h
+++ b/glib/gslice.h
@@ -23,6 +23,7 @@
 #endif
 
 #include <glib/gtypes.h>
+#include <string.h>
 
 G_BEGIN_DECLS
 
@@ -43,7 +44,22 @@ void     g_slice_free_chain_with_offset (gsize         block_size,
                                         gpointer      mem_chain,
                                         gsize         next_offset);
 #define  g_slice_new(type)      ((type*) g_slice_alloc (sizeof (type)))
-#define  g_slice_new0(type)     ((type*) g_slice_alloc0 (sizeof (type)))
+
+/* Allow the compiler to inline memset(). Since the size is a constant, this
+ * can significantly improve performance. */
+#if defined (__GNUC__) && (__GNUC__ >= 2) && defined (__OPTIMIZE__)
+#  define g_slice_new0(type)                                    \
+  (type *) (G_GNUC_EXTENSION ({                                 \
+    gsize __s = sizeof (type);                                  \
+    gpointer __p;                                               \
+    __p = g_slice_alloc (__s);                                  \
+    memset (__p, 0, __s);                                       \
+    __p;                                                        \
+  }))
+#else
+#  define g_slice_new0(type)    ((type*) g_slice_alloc0 (sizeof (type)))
+#endif
+
 /* MemoryBlockType *
  *       g_slice_dup                    (MemoryBlockType,
  *                                      MemoryBlockType *mem_block);