1 files changed, 20 insertions, 24 deletions
diff --git a/gcc/doc/hostconfig.texi b/gcc/doc/hostconfig.texi
index 5c38313efd2..8830c6b8ac1 100644
--- a/gcc/doc/hostconfig.texi
+++ b/gcc/doc/hostconfig.texi
@@ -42,35 +42,31 @@ This host hook is used to set up handling for extra signals.  The most
 common thing to do in this hook is to detect stack overflow.
 @end deftypefn
 
-@deftypefn {Host Hook} void * HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @var{size})
-This host hook returns the address of some space in which a PCH may be
-loaded with @samp{HOST_HOOKS_PCH_LOAD_PCH}.  The space will need to
-have @var{size} bytes.  If insufficient space is available,
-@samp{NULL} may be returned; the PCH machinery will try to find a
-suitable address using a heuristic.
-
-The memory does not have to be available now.  In fact, usually
-@samp{HOST_HOOKS_PCH_LOAD_PCH} will already have been called.  The memory
-need only be available in future invocations of GCC.
+@deftypefn {Host Hook} void * HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @var{size}, int @var{fd})
+This host hook returns the address of some space that is likely to be
+free in some subsequent invocation of the compiler.  We intend to load
+the PCH data at this address such that the data need not be relocated.
+The area should be able to hold @var{size} bytes.  If the host uses
+@code{mmap}, @var{fd} is an open file descriptor that can be used for
+probing.
 @end deftypefn
 
-@deftypefn {Host Hook} bool HOST_HOOKS_GT_PCH_USE_ADDRESS (size_t @var{size}, void * @var{address})
-This host hook is called when a PCH file is about to be loaded.  If
-@var{address} is the address that would have been returned by
-@samp{HOST_HOOKS_PCH_MEMORY_ADDRESS}, and @var{size} is smaller than
-the maximum than @samp{HOST_HOOKS_PCH_MEMORY_ADDRESS} would have
-accepted, return true, otherwise return false.
+@deftypefn {Host Hook} int HOST_HOOKS_GT_PCH_USE_ADDRESS (void * @var{address}, size_t @var{size}, int @var{fd}, size_t @var{offset})
+This host hook is called when a PCH file is about to be loaded.
+We want to load @var{size} bytes from @var{fd} at @var{offset}
+into memory at @var{address}.  The given address will be the result of
+a previous invocation of @code{HOST_HOOKS_GT_PCH_GET_ADDRESS}.
+Return @minus{}1 if we couldn't allocate @var{size} bytes at @var{address}.
+Return 0 if the memory is allocated but the data is not loaded.  Return 1
+if the hook has performed everything.
 
-In addition, free any address space reserved that isn't needed to hold
-@var{size} bytes (whether or not true is returned).  The PCH machinery will
-use @samp{mmap} with @samp{MAP_FIXED} to load the PCH if @samp{HAVE_MMAP_FILE},
-or will use @samp{fread} otherwise.
-
-If no PCH will be loaded, this hook may be called with @var{size}
-zero, in which case all reserved address space should be freed.
+If the implementation uses reserved address space, free any reserved
+space beyond @var{size}, regardless of the return value.  If no PCH will
+be loaded, this hook may be called with @var{size} zero, in which case
+all reserved address space should be freed.
 
 Do not try to handle values of @var{address} that could not have been
-returned by this executable; just return false.  Such values usually
+returned by this executable; just return @minus{}1.  Such values usually
 indicate an out-of-date PCH file (built by some other GCC executable),
 and such a PCH file won't work.
 @end deftypefn