gdb and binutils branch master updated. bb9d5f81c36ecc61e3d4a70ce7e41348c8b12fef

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=bb9d5f81c36ecc61e3d4a70ce7e41348c8b12fef

commit bb9d5f81c36ecc61e3d4a70ce7e41348c8b12fef
Author: Patrick Palka <patrick@parcs.ath.cx>
Date:   Tue Sep 16 17:40:06 2014 +0100

    Fix PR12526: -location watchpoints for bitfield arguments
    
    PR 12526 reports that -location watchpoints against bitfield arguments
    trigger false positives when bits around the bitfield, but not the
    bitfield itself, are modified.
    
    This happens because -location watchpoints naturally operate at the
    byte level, not at the bit level.  When the address of a bitfield
    lvalue is taken, information about the bitfield (i.e. its offset and
    size) is lost in the process.
    
    This information must first be retained throughout the lifetime of the
    -location watchpoint.  This patch achieves this by adding two new
    fields to the watchpoint struct: val_bitpos and val_bitsize.  These
    fields are set when a watchpoint is first defined in watch_command_1.
    They are both equal to zero if the watchpoint is not a -location
    watchpoint or if the argument is not a bitfield.
    
    Then these bitfield parameters are used inside update_watchpoint and
    watchpoint_check to extract the actual value of the bitfield from the
    watchpoint address, with the help of a local helper function
    extract_bitfield_from_watchpoint_value.
    
    Finally when creating a HW breakpoint pointing to a bitfield, we
    optimize the address and length of the breakpoint.  By skipping over
    the bytes that don't cover the bitfield, this step reduces the
    frequency at which a read watchpoint for the bitfield is triggered.
    It also reduces the number of times a false-positive call to
    check_watchpoint is triggered for a write watchpoint.
    
    gdb/
    	PR breakpoints/12526
    	* breakpoint.h (struct watchpoint): New fields val_bitpos and
    	val_bitsize.
    	* breakpoint.c (watch_command_1): Use these fields to retain
    	bitfield information.
    	(extract_bitfield_from_watchpoint_value): New function.
    	(watchpoint_check): Use it.
    	(update_watchpoint): Use it.  Optimize the address and length of a
    	HW watchpoint pointing to a bitfield.
    	* value.h (unpack_value_bitfield): New prototype.
    	* value.c (unpack_value_bitfield): Make extern.
    
    gdb/testsuite/
    	PR breakpoints/12526
    	* gdb.base/watch-bitfields.exp: New file.
    	* gdb.base/watch-bitfields.c: New file.

-----------------------------------------------------------------------

Summary of changes:
 gdb/ChangeLog                              |   14 +++++
 gdb/breakpoint.c                           |   74 +++++++++++++++++++++++++++-
 gdb/breakpoint.h                           |    5 ++
 gdb/testsuite/ChangeLog                    |    6 ++
 gdb/testsuite/gdb.base/watch-bitfields.c   |   54 ++++++++++++++++++++
 gdb/testsuite/gdb.base/watch-bitfields.exp |   56 +++++++++++++++++++++
 gdb/value.c                                |    2 +-
 gdb/value.h                                |    5 ++
 8 files changed, 214 insertions(+), 2 deletions(-)
 create mode 100644 gdb/testsuite/gdb.base/watch-bitfields.c
 create mode 100644 gdb/testsuite/gdb.base/watch-bitfields.exp


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