gccint: Host Common

1 
1 19.1 Host Common
1 ================
1 
1 Some things are just not portable, even between similar operating
1 systems, and are too difficult for autoconf to detect.  They get
1 implemented using hook functions in the file specified by the
1 HOST_HOOK_OBJ variable in 'config.gcc'.
1 
1  -- Host Hook: void HOST_HOOKS_EXTRA_SIGNALS (void)
1      This host hook is used to set up handling for extra signals.  The
1      most common thing to do in this hook is to detect stack overflow.
1 
1  -- Host Hook: void * HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t SIZE, int
1           FD)
1      This host hook returns the address of some space that is likely to
1      be free in some subsequent invocation of the compiler.  We intend
1      to load the PCH data at this address such that the data need not be
1      relocated.  The area should be able to hold SIZE bytes.  If the
1      host uses 'mmap', FD is an open file descriptor that can be used
1      for probing.
1 
1  -- Host Hook: int HOST_HOOKS_GT_PCH_USE_ADDRESS (void * ADDRESS, size_t
1           SIZE, int FD, size_t OFFSET)
1      This host hook is called when a PCH file is about to be loaded.  We
1      want to load SIZE bytes from FD at OFFSET into memory at ADDRESS.
1      The given address will be the result of a previous invocation of
1      'HOST_HOOKS_GT_PCH_GET_ADDRESS'.  Return -1 if we couldn't allocate
1      SIZE bytes at ADDRESS.  Return 0 if the memory is allocated but the
1      data is not loaded.  Return 1 if the hook has performed everything.
1 
1      If the implementation uses reserved address space, free any
1      reserved space beyond SIZE, regardless of the return value.  If no
1      PCH will be loaded, this hook may be called with SIZE zero, in
1      which case all reserved address space should be freed.
1 
1      Do not try to handle values of ADDRESS that could not have been
1      returned by this executable; just return -1.  Such values usually
1      indicate an out-of-date PCH file (built by some other GCC
1      executable), and such a PCH file won't work.
1 
1  -- Host Hook: size_t HOST_HOOKS_GT_PCH_ALLOC_GRANULARITY (void);
1      This host hook returns the alignment required for allocating
1      virtual memory.  Usually this is the same as getpagesize, but on
1      some hosts the alignment for reserving memory differs from the
1      pagesize for committing memory.
1