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Using the Global Optimizer and the Object Module Disassembler |
Each of these topics is treated in detail in the SAS/C Compiler and Library User's Guide.
Global Optimization Compiler Options |
The
-O
compiler option is used to enable global optimization.
The following options alter the behavior of the global optimizer.
Each of these options is described in Compiling C and C++ Programs.
Global Optimization and the Debugger |
The cross-platform compiler does not
optimize programs when the
-g
option is used. To use all the
capabilities of the SAS/C Debugger,
there must be an accurate correspondence between object code and source line
numbers, and optimizations can alter this correspondence. Also, the
-g
option causes the compiler to suppress allocation of variables to
registers, so the resulting code is not completely optimal.
You can, however, use the
-Kdbhook
option along with the
-O
option to generate optimized
object code that can be used with the debugger. The
-Kdbhook
option generates hooks in the object code that enable the debugger
to gain control of an executing program.
When using the debugger with optimized object code that
has been compiled with the
-Kdbhook
option, the source code is
not displayed in the debugger's Source window and you cannot access variables.
Therefore, the debugger's
print
command, and other commands,
which are normally used with variables, are not used when debugging optimized
code. However, source code line numbers are displayed in the Source window,
providing an indication of your location in the code. You also have the capability
of viewing register values in the debugger's Register window, and you can
use commands such as
step
,
goto
, and
runto
to control the execution of your program. However, due to optimizations that
affect register contents, the
goto
command may fail when
debugging optimized code.
See Cross-Debugging for more information about using the SAS/C Debugger with the SAS/C Cross-Platform Compiler.
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