HP 3000 Manuals HP 3000 Manuals
Entering Commands (cont..)
Entering Procedure Calls (cont.)
Breakpoint Commands
A breakpoint, when encountered, suspends the execution of the program at
a particular location. HP Symbolic Debugger provides a number of
commands for setting, deleting, and managing breakpoints. The breakpoint
commands are:
* Overall
* lb (list breakpoints)
* tb (toggle breakpoints)
* Creation
* b (breakpoint)
* ba (breakpoint address)
* bb (breakpoint beginning)
* bt (breakpoint trace)
* bu (breakpoint uplevel)
* bx (breakpoint exit)
* Status
* ab (activate breakpoint)
* bc (breakpoint count)
* db (delete breakpoint)
* sb (suspend breakpoint)
* All-Procedures
* bp (breakpoint procedure)
* bpt
* bpx
* dp (delete procedure)
* Dpt
* Dpx
* Global
* abc
* dbc
* All-Paragraph (HP COBOL II only)
* bpg (breakpoint paragraph)
* dpg (delete paragraph)
* tpg (trace paragraph)
* Auxiliary
* "any string"
* i (if)
* Q (Quiet)
Once a breakpoint has been encountered during program execution, you can
examine the program state, unless the breakpoint command list includes a
command that causes the child process to continue or terminate. Examples
of these commands are the c (continue), r (run), k (kill) and q (quit)
commands. Individual breakpoints are identified by a unique number,
which is assigned by the debugger.
Breakpoints can be activated or deactivated (suspended) individually.
When a breakpoint is suspended, information for that breakpoint is
retained, but it will not affect program execution. There is also an
overall breakpoint mode for breakpoint activation and suspension, which
is independent of the state of any individual breakpoint. Any given
breakpoint will affect program execution only if it is individually
activated and the overall mode is activated. Any active breakpoint whose
location is visible in the source window will be marked with an asterisk
(*) in the leftmost screen column. Note that only those breakpoints that
are associated with a line number are marked in the source window in
source mode. In disassembly mode, all breakpoints are displayed whether
associated with a line or machine instruction.
Three parameters are associated with breakpoint commands, location, count
and
command list. These parameters are described below:
Location You can set a breakpoint at the current location
(where the prompt (>) appears in the source window)
or at any other executable statement or instruction.
You can specify the location of the breakpoint in a
variety of ways:
* line number
* procedure name
* label
* symbolic address (with or without offset)
* absolute (numeric) address
Each of these ways of specifying a location is simply
an alternate way to specify the breakpoint address.
The breakpoint is encountered whenever the location
is about to be executed, regardless of the path taken
to get there. Only one breakpoint at a time of a
particular type may be set at a given location.
Setting a new breakpoint at the same location
replaces the existing one.
Count The count is the number of times a breakpoint
statement or instruction is executed before the
program is stopped. If the count is positive, the
breakpoint is permanent. If the count is negative,
the breakpoint is temporary and is cleared when the
program stops there. When you enter a new breakpoint
without a count, the breakpoint is permanent and a
count of 1 is used. To change the count of an
existing breakpoint, use the bc (breakpoint count)
command.
An alternate way to enter a breakpoint is to enter t
for a temporary breakpoint and p for a permanent
breakpoint. Entering a t or p by itself sets the
count to -1 or 1, respectively. You can precede a t
or p with a positive integer for a count of more than
one.
Command List A command list is one or more commands that are
executed when its associated breakpoint occurs.
Separate commands in a command list by semicolons.
Use braces {} to separate the breakpoint
command list from other debugger commands on the same
line.
____________________________________________________
CAUTION Only one active command line can exist at
one time. A command line is either the
sequence of commands you enter at the
debugger prompt or the command list
associated with a breakpoint or assertion.
If a new command line is encountered before
all commands in the previous command line
are executed, those remaining commands are
discarded. For example, suppose you set a
breakpoint in a function called func1 which
has the following command list:
{Q;p "hello\n";c}
Then, from the command line you execute:
>p func1();p "goodbye\n"
This will print hello, but not goodbye.
____________________________________________________
Types of Breakpoints
Breakpoints can be separated into two general classes:
* Individual (single) breakpoints
These are explicitly set by the user at a given location.
* All-Procedure or All-Paragraph breakpoints
These are breakpoints attached to all debuggable procedures or
paragraphs by a single command. They do not have a count or
lifespan.
There are six basic types of single breakpoints. There can only be one
type of single breakpoint at a given location in the code.
Generic Set with the b (breakpoint) command
at a given source-line.
Address Set with the ba (breakpoint
address) command at a given address
(which might not correspond
directly to a source line).
Procedure or paragraph beginning Set with the bb (breakpoint
(entry) beginning) command at the first
executable statement of a
procedure.
Procedure or paragraph exit Set with the bx (breakpoint exit)
command at the common exit point of
a procedure, for example, the
procedure epilogue where all
returns go through (usually does
not correspond to a source line).
Procedure trace (entry/exit) Set with the bt (breakpoint trace)
command at the procedure entry and
exit.
Uplevel Set with the bu (breakpoint
uplevel) command at the return
address of a given procedure call,
for example, the first instruction
executed after a return (which
might not correspond directly to a
source line).
There are three basic types of all-procedure breakpoints. These may
co-exist with other all-procedure breakpoints and/or a single breakpoint
at a given location.
Procedure (beginning) Set with the bp (breakpoint procedure) command
at the first executable statement of all
procedures.
Procedure exit Set with the bpx command at the common exit
point of all procedures.
Procedure trace Set with the bpt command at the entry and exit
of all procedures.
At a given procedure entry, up to four command lists can be associated
with the location:
* Global breakpoint command list
Set with the abc command.
* Individual procedure beginning breakpoint command list
Set with the bb (breakpoint beginning) command.
* All-procedure beginning breakpoint command list
Set with the bp (breakpoint procedure) command.
* All-procedure trace breakpoint command list
Set with the bpt command.
Also, at a given procedure exit, up to four command lists can be
associated with the location:
* Global breakpoint command list
Set with the abc command.
* Individual procedure exit breakpoint command list
Set with the bx (breakpoint exit) command.
* All-procedure exit breakpoint command list
Set with the bpx command.
* All-procedure trace breakpoint command list
Set with the bpt command.
There are two basic types of all-paragraph breakpoints. These may
co-exist with other all-paragraph breakpoints and/or a single breakpoint
at a given location.
Paragraph (beginning) Set with the bpg (breakpoint paragraph) command
at the first executable statement of all
paragraphs.
Paragraph trace Set with the tpg (trace paragraph) command at
the entry of all paragraphs.
At a given paragraph entry, up to four command lists can be associated
with the location:
* Global breakpoint command list
Set with the abc command.
* Individual paragraph beginning breakpoint command list
Set with the bb (breakpoint beginning) command.
* All-paragraph beginning breakpoint command list
Set with the bpg (breakpoint paragraph) command.
* All-paragraph trace breakpoint command list
Set with the tpg command.
At a given paragraph exit, up to two command lists can be associated with
the location:
* Global breakpoint command list
Set with the abc command.
* Individual paragraph exit breakpoint command list
Set with the bx (breakpoint exit) command.
Overall Breakpoint Commands
lb (list breakpoints)
{lb }
{list breakpoints}
Displays all breakpoints in the program, both active and suspended, and
the overall breakpoint state.
The display shows the number, count, status and commands for each
breakpoint. Figure 4-2 gives an example of the information that is
displayed for a typical breakpoint. This information is also displayed
whenever a breakpoint is added or deleted.
![[]](../../pic3k/M012092/FFN163c50.gif)
Figure 4-2. Listing a Breakpoint
tb (toggle breakpoints)
{tb }
{toggle breakpoints}
Toggles the overall breakpoint state from active to suspended or vice
versa. The state of the individual breakpoints remains unchanged.