Docs and NEWS for breakpoint changes

[Vladimir Prus <vladimir at codesourcery dot com>]

Now that the code patches for my breakpoint changes are in,
here's the doc patch and NEWS addition.

The doc patch document that a breakpoint can have several
locations, and that individual locations can be enabled
and disabled.  It also rewords pending breakpoint docs
to better reflect current code -- where every breakpoint is
reevaluated when new shared libraries are loaded, and pending
breakpoint is merely a breakpoint that don't have a valid
address as yet, not a temporary kind of breakpoint that
tends to morph into ordinary breakpoint on any occasion.

Comments?

- Volodya

Index: NEWS
===================================================================
RCS file: /cvs/src/src/gdb/NEWS,v
retrieving revision 1.239
diff -u -p -r1.239 NEWS
--- NEWS	17 Sep 2007 19:30:05 -0000	1.239
+++ NEWS	26 Sep 2007 18:00:47 -0000
@@ -3,6 +3,13 @@
 
 *** Changes since GDB 6.7
 
+* Pending breakpoints where changed to not change its number when
+  resolved.
+
+* Support for breakpoints with multiple locations was implemented,
+  including breakpoints on C++ constructors, inside C++ templates,
+  and in inlined functions.
+
 *** Changes in GDB 6.6
 
 * Resolved 101 resource leaks, null pointer dereferences, etc. in gdb, 
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.432
diff -u -p -r1.432 gdb.texinfo
--- doc/gdb.texinfo	16 Sep 2007 14:59:30 -0000	1.432
+++ doc/gdb.texinfo	26 Sep 2007 18:00:57 -0000
@@ -2991,11 +2991,17 @@ Breakpoint, watchpoint, or catchpoint.
 Whether the breakpoint is marked to be disabled or deleted when hit.
 @item Enabled or Disabled
 Enabled breakpoints are marked with @samp{y}.  @samp{n} marks breakpoints
-that are not enabled.
+that are not enabled.  An optional @samp{(p)} suffix marks pending
+breakpoints --- breakpoints for which address is either not yet
+resolved, pending load of a shared library, or for which address was
+in a shared library that was since resolved.  Such breakpoint won't
+fire until a shared library that has the symbol or line referred by
+breakpoint is loaded.  See below for details.
 @item Address
-Where the breakpoint is in your program, as a memory address.  If the
-breakpoint is pending (see below for details) on a future load of a shared library, the address
-will be listed as @samp{<PENDING>}.
+Where the breakpoint is in your program, as a memory address.  For a
+pending breakpoint that never had its address known,  this field will
+contain @samp{<PENDING>}.  A breakpoint with several locations will
+have @samp{<MULTIPLE>} in this field -- see below for details.
 @item What
 Where the breakpoint is in the source for your program, as a file and
 line number.  For a pending breakpoint, the original string passed to
@@ -3032,23 +3038,72 @@ your program.  There is nothing silly or
 the breakpoints are conditional, this is even useful
 (@pxref{Conditions, ,Break Conditions}).
 
-@cindex pending breakpoints
-If a specified breakpoint location cannot be found, it may be due to the fact
-that the location is in a shared library that is yet to be loaded.  In such
-a case, you may want @value{GDBN} to create a special breakpoint (known as
-a @dfn{pending breakpoint}) that
-attempts to resolve itself in the future when an appropriate shared library
-gets loaded.
-
-Pending breakpoints are useful to set at the start of your
-@value{GDBN} session for locations that you know will be dynamically loaded
-later by the program being debugged.  When shared libraries are loaded,
-a check is made to see if the load resolves any pending breakpoint locations.
-If a pending breakpoint location gets resolved,
-a regular breakpoint is created and the original pending breakpoint is removed.
+It is possible that a breakpoints correspond to several locations 
+in your program.  Examples of this situation are:
+
+@itemize @bullet
+
+@item
+For a C++ constructor, the gcc compiler generates several function
+bodies used in different cases.
+
+@item
+For a C++ template function, a given line in the function can
+correspond to unbounded set of instantiations.
 
-@value{GDBN} provides some additional commands for controlling pending
-breakpoint support:
+@item
+For an inlined function, a given line can correspond to
+several places where that function is inlined.
+
+@end itemize
+
+In all those cases, @value{GDBN} will associate the breakpoint
+with all relevant locations.
+
+A breakpoint with multiple locations is displayed in the
+breakpoint table using several rows --- one header row, followed
+by one row for each breakpoint location. The header row
+has @samp{<MULTIPLE>} in the address column.  The rows for
+individual locations contain the actual addresses for locations,
+and say what functions those locations are in.  The number
+column for a location has number in the format 
+@var{breakpoint-number}.@var{location-number}.
+
+Each location can be individually enabled or disabled by passing
+the @var{breakpoint-number}.@var{location-number} to the @code{enable}
+or @code{disable} commands.
+
+@cindex pending breakpoints
+It's quite common to have a breakpoint inside a shared library.
+Further, the shared library may be loaded and unloaded explicitly,
+and possible repeatedly, as the program is executed.  To support
+this use case, @value{GDBN} updates breakpoint locations whenever
+any shared library is loaded or unloaded. Typically, you would
+set a breakpoint in a shared library at the beginning of your 
+debugging session, when the library is not loaded, and when the
+symbols from the library are not available.  When you try to set
+breakpoint, @value{GDBN} will ask you if you want to set
+a so called @dfn{pending breakpoint} --- breakpoint that is not yet
+resolved to address.
+
+After the program is run, whenever a new shared library is loaded,
+@value{GDBN} reevaluates all breakpoints.  In case a newly loaded
+shared library contains the symbol or line referred to by breakpoint,
+breakpoint is resolved and becomes an ordinary breakpoint.  If a
+library is unloaded, all breakpoints it in become pending again.
+
+This logic works for breakpoints with multiple locations, too.  For
+example, if you have a breakpoint in a C++ template function, and
+a newly loaded shared library has an instantiation of that template,
+a new location will be added to the existing breakpoint.
+
+Except for having unresolved address, pending breakpoints do not
+differ from regular breakpoints.  You can set conditions or commands,
+enable and disable them and perform other breakpoint operations.
+
+@value{GDBN} provides some additional commands for controlling what
+happens when the @samp{break} command cannot resolve breakpoint
+address specification to an address:
 
 @kindex set breakpoint pending
 @kindex show breakpoint pending
@@ -3070,19 +3125,9 @@ not affect any pending breakpoints previ
 Show the current behavior setting for creating pending breakpoints.
 @end table
 
-@cindex operations allowed on pending breakpoints
-Normal breakpoint operations apply to pending breakpoints as well.  You may
-specify a condition for a pending breakpoint and/or commands to run when the
-breakpoint is reached.  You can also enable or disable
-the pending breakpoint.  When you specify a condition for a pending breakpoint,
-the parsing of the condition will be deferred until the point where the
-pending breakpoint location is resolved.  Disabling a pending breakpoint
-tells @value{GDBN} to not attempt to resolve the breakpoint on any subsequent
-shared library load.  When a pending breakpoint is re-enabled,
-@value{GDBN} checks to see if the location is already resolved.
-This is done because any number of shared library loads could have
-occurred since the time the breakpoint was disabled and one or more
-of these loads could resolve the location.
+The settings above only affect the @code{break} command and its
+variants.  Once breakpoint is set, it will be automatically updated
+as shared libraries are loaded and unloaded.
 
 @cindex automatic hardware breakpoints
 For some targets, @value{GDBN} can automatically decide if hardware or