Inspect Manual

Using Inspect With Accelerated Programs on TNS/R
Systems
Inspect Manual—429164-006
16-13
Data Breakpoints

Read/write data breakpoints are available on both TNS and TNS/R processors.
When data breakpoints are set on read/write access on a TNS/R system, the
operating system or Inspect cannot filter unrelated accesses. You will have to use
context information associated with the program's current location to determine
breakpoints of interest.
Inspect issues the following warning message if you set a data breakpoint on a
variable that is larger than the 16-bit word size of the TNS system:
Inspect issues the following warning message when you set a write data breakpoint on
a variable that is smaller than the word size of the system (which is 32 bits on a TNS/R
system):
Usage Considerations for Accelerated Programs
The following additional considerations should be noted when using data breakpoints
with accelerated programs:

If an instruction accesses a memory location on which a data breakpoint is set, any
memory accesses made by subsequent instructions before the original breakpoint
is reported are not detected.

Data breakpoints most likely suspend the program at non-exact points; that is,
locations that are not memory-exact points.

Some read data breakpoints may not be reported because no memory operation
has taken place. The accelerated program may keep values of frequently used
variables in registers, avoiding the need to go to memory to fetch them, which then
results in those read data breakpoints not being reported.
COBOL85 Example
When a COBOL object file is accelerated, the accelerator often has a wide range of
instructions over which to apply optimizations since many COBOL constructs, such as
INITIALIZE, SEARCH, or UNSTRING, require a large number of instructions to
implement. This optimization may affect debugging in the following ways:

It may reduce the correspondence between the generated instructions and source
constructs.

It also increases the likelihood that a data breakpoint will leave the program at a
non-exact point.
** Inspect warning 363 ** Breakpoint is set on the first 16-bit word
containing the variable
** Inspect warning 127 ** Breakpoint will occur upon access to containing
word