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diff --git a/gnulib b/gnulib deleted file mode 160000 -Subproject 443bc5ffcf7429e557f4a371b0661abe98ddbc1 diff --git a/gnulib/doc/alloca-opt.texi b/gnulib/doc/alloca-opt.texi new file mode 100644 index 0000000..d224b97 --- /dev/null +++ b/gnulib/doc/alloca-opt.texi @@ -0,0 +1,41 @@ +@c Documentation of gnulib module 'alloca-opt'. + +@c Copyright (C) 2004, 2007, 2009-2011 Free Software Foundation, Inc. + +@c Permission is granted to copy, distribute and/or modify this document +@c under the terms of the GNU Free Documentation License, Version 1.3 or +@c any later version published by the Free Software Foundation; with no +@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover +@c Texts. A copy of the license is included in the ``GNU Free +@c Documentation License'' file as part of this distribution. + +The alloca-opt module provides for a function @code{alloca} which allocates +memory on the stack, where the system allows it. A memory block allocated with +@code{alloca} exists only until the function that calls @code{alloca} returns +or exits abruptly. + +There are a few systems where this is not possible: HP-UX systems, and some +other platforms when the C++ compiler is used. On these platforms the +alloca-opt module provides no replacement, just a preprocessor macro +HAVE_ALLOCA. + +The user can @code{#include <alloca.h>} on all platforms, and use +@code{alloca} on those platforms where the preprocessor macro HAVE_ALLOCA +evaluates to true. If HAVE_ALLOCA is false, the code should use a heap-based +memory allocation based on @code{malloc} or - in C++ - @code{new}. Note that +the @code{#include <alloca.h>} must be the first one after the +autoconf-generated @file{config.h}, for AIX 3 compatibility. Thanks to IBM for +this nice restriction! + +Note that GCC 3.1 and 3.2 can @emph{inline} functions that call @code{alloca}. +When this happens, the memory blocks allocated with @code{alloca} will not be +freed until @emph{the end of the calling function}. If this calling function +runs a loop calling the function that uses @code{alloca}, the program easily +gets a stack overflow and crashes. To protect against this compiler behaviour, +you can mark the function that uses @code{alloca} with the following attribute: + +@smallexample +#ifdef __GNUC__ +__attribute__ ((__noinline__)) +#endif +@end smallexample |