alloca() can be useful in some (limited) circumstances.

src/include/alloca.h

@@ -0,0 +1,25 @@
+#ifndef _ALLOCA_H
+#define _ALLOCA_H
+
+/**
+ * @file
+ *
+ * Temporary memory allocation
+ *
+ */
+
+#include <stdint.h>
+
+/**
+ * Allocate temporary memory from the stack
+ *
+ * @v size		Size to allocate
+ * @ret ptr		Allocated memory
+ *
+ * This memory will be freed automatically when the containing
+ * function returns.  There are several caveats regarding use of
+ * alloca(); use it only if you already know what they are.
+ */
+#define alloca(size) __builtin_alloca ( size )
+
+#endif /* _ALLOCA_H */