Zilog Z8F0130 - Manual (Page 101)

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Zilog Developer Studio II – Z8 Encore!
User Manual
77
Limit Optimizations for Easier Debugging
Selecting this checkbox causes the compiler to generate code in which certain optimiza-
tions are turned off. These optimizations can cause confusion when debugging. For exam-
ple, they might rearrange the order of instructions so that they are no longer exactly
correlated with the order of source code statements or remove code or variables that are
not used. You can still use the debugger to debug your code without selecting this check-
box, but it might difficult because of the changes that these optimizations make in the
assembly code generated by the compiler.
Selecting the Limit Optimizations for Easier Debugging checkbox makes it more
straightforward to debug your code and interpret what you see in the various Debug win-
dows. However, selecting this checkbox also causes a moderate increase in code size.
Many users select this checkbox until they are ready to go to production code and then
deselect it.
Selecting this checkbox can also increase the data size required by your application. This
happens because this option turns off the use of register variables (see the
Use Register
Variables section on page 83). The variables that are no longer stored in registers must
instead be stored in memory (and on the stack if dynamic frames are in use), thereby
increasing the overall data storage requirements of your application. Usually this increase
is fairly small.
You can debug your application when this checkbox is deselected. The debugger contin-
ues to function normally, but debugging might be more confusing due to the factors
described earlier.
This checkbox interacts with the Generate Debug Information checkbox (see the Gener-
ate Debug Information section on page 70).
Memory Model
The Memory Model drop-down list box allows you to choose between the two memory
models, Small or Large . Select Small for a small memory model or select Large for a
large memory model. Using the small model results in more compact code and might
reduce the RAM requirements as well. However, the small model places constraints on the
data space size (not on the code space size) of your application. Some applications might
not be able to fit into the small model’s data space size; the large model is provided to sup-
port such applications. See the
Memory Models section on page 199 for full details of the
memory models.
Frames
Select Static for static frames or select Dynamic for dynamic frames. The use of static
frames generally helps reduce code size, but this option can only be used if your code
obeys certain restrictions. Specifically, recursive function calls (either direct or indirect)
Note: