Accelerator Manual (G06.27+, H06.04+, J06.03+)

Debugging Accelerated Programs

Accelerator Manual—527303-003

7-2

When executing TNS instructions on a TNS/R system, the TNS/R system maintains

the TNS machine state (the register stack, S, P, E, and L registers) as if you were

running your program on a TNS system. Because the TNS machine state is

maintained, no change is required to run existing TNS programs on TNS/R systems

and, with very few exceptions, debugging is the same.

both memory and the TNS register stack are the same as if the program were

executing on a TNS system. No optimizations cross register-exact points. Complex

statements might contain several such points: at each function call, privileged

instruction, and embedded assignment. Register-exact points are a subset of

memoryexact points.

By default, the Accelerator defines register-exact points only where necessary for

correct execution; for example, following procedure calls. Register-exact points are the

only points at which an accelerated program makes transitions to and from executing

TNS instructions.

At register-exact points, you can safely use all Inspect debugging commands (including

modifying memory variables) as if the program were on a TNS system.

Memory-Exact Points

Memory-exact points are locations in an accelerated program at which the values in

memory (but not necessarily in the register stack) are the same as if the program were

running on a TNS processor. Displaying memory variables gives accurate results at

memory-exact points. However, modifying memory variables at these points might not

reliably affect the program’s subsequent actions because the changed variable might

have already been loaded in registers. Most source statement boundaries are memory-

exact points. Register-exact points are a subset of memory-exact points.

Nonexact Points

Nonexact points are locations in an accelerated program that are not memory-exact

points. Most code locations in an accelerated program are nonexact points. At

nonexact points, the TNS program state is not consistent, displayed memory might not

be current, and the reported current program counter location is only approximate.

Attempting to modify memory at a nonexact point might result in the data being

overwritten by a subsequent store operation.

Accelerator Debugging Options

The Accelerator offers you two debugging options—ProcDebug and StmtDebug. The

Accelerator debugging option you use slightly affects source-level debugging and

significantly affects machine-level debugging. Most source-level debugging capabilities

are preserved. Source-level debugging restrictions include the possibility of deleted