Inspect Manual

Using Inspect With Accelerated Programs on TNS/R
Systems
Inspect Manual—429164-006
16-16
TNS Register Access Limitations
At Memory-Exact Points
When the current program location is a memory-exact point that is not a register-exact
point, you can display memory with reliable results.
The accelerator defines memory-exact points such that all preceding memory store
operations have completed. Unless the point is a register-exact point, values used by
subsequent statements might already be loaded in TNS/R registers. In this case,
modifying the value of the variable in memory has no effect. Inspect has no way of
determining when this is the case; therefore, the commands that modify memory,
MODIFY and low-level M, report the following warning when the current location is a
memory-exact point:
As a guideline, values that have been accessed recently, are just about to be
accessed, or are accessed frequently are likely to be stored in registers.
At Non-Exact Points
When the current program location is a non-exact point, the TNS program state cannot
be mapped directly from TNS/R to TNS machine locations. Displayed memory may be
out of date. Attempting to modify memory at a non-exact point has the same
limitations as at memory-exact points.
In addition, it may result in the data being overwritten on a pending store operation.
TNS Register Access Limitations
The following paragraphs describe TNS register access limitations that exist at various
points in your program.
At Register-Exact Points
Register-exact points are locations in an accelerated program at which the values in
both memory and the register stack are up to date. You can both display and modify
TNS registers at register-exact points.
Even at register-exact points, the value of a given register will match what you would
see at the same point if running on a TNS system only if the register value is used by
subsequent TNS instructions. For example, TNS load instructions cause the condition
code to be set (N and Z bits in environment register), but the accelerated code will only
set the condition code if the program actually references it.
** Inspect warning 358 ** Modify may have no effect; data that is about to
be used may be stored in registers
Note. The usefulness of modifying TNS system register values is extremely limited
because of the limited number of register-exact points
.