Inspect Manual

Using Inspect With Accelerated Programs on TNS/R
Systems
Inspect Manual—429164-006
16-12
Data Breakpoints

Data breakpoints of type change
There may be occasions when data breakpoints will not be reported. Consider the
following pseudocode:
If the current location of Inspect within the program is line #110 and a change data
breakpoint is set on X (note that change is the default for data breakpoints), when
the program is resumed the data breakpoint cycle will begin when the store to X
occurs at line #120. Before the four cycles have elapsed, X might be restored to a
value of 1 and the data breakpoint will not be reported because it appears that the
data did not change.
Accesses to 32-Bit Words
The TNS/R system reports data breakpoints on accesses to 32-bit words. For
variables that occupy fewer than 32 bits, this can result in unrelated breakpoints being
reported when an access is made to the other portion of the 32-bit word.
When data breakpoints of type change are used, Inspect can filter out such unrelated
breakpoints, reporting only when the value of the variable has changed. When
read/write data breakpoints are used, data breakpoints may be reported as a result of
memory accesses to the 32-bit word containing the variable. i
Data Breakpoints
The following considerations apply to data breakpoints:

The default type for high-level data breakpoints is change.
This applies to both TNS and TNS/R processors. Data breakpoints of type change
are only reported if the value of the variable has changed; writes that store the
same value already contained in the variable are not reported. Use of the change
breakpoint allows Inspect to filter all unrelated breakpoints.

Write breakpoints are available on TNS processors, but not on NSR-L processors.
You receive the following error message if you attempt to set a write data
breakpoint in a program executing on a NSR-L processor:
Because write breakpoints are not supported on NSR-L processors, use change
breakpoints instead.
#100 X :=1
#110 Y :=1
#120 X :=3
#130 Y :=X
#140 X :=1
** Inspect error 365 ** Machine does not support write memory access
breakpoints