kc3-lang/gnulib/doc/alloca-opt.texi

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  Date : 2007-12-26T16:31:08
  

  Avoid using the syntax symbol() in formatted documentation.
  

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• doc/alloca-opt.texi

• @c Documentation of gnulib module 'alloca-opt'.
  
  @c Copyright (C) 2004, 2007 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 1.2 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
  

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