4.4.4 xc32-g++ (32-bit C++ Compiler)

A subset of command-line options may be specified in MPLAB X IDE. Select a category, and then set up linker options. For additional options, see MPLAB Object Linker for 32-bit Devices documentation. See also 4.4.8 Options Page Features.

Table 4-7. xc32-g++ c++ specific Category
Option	Description	Command Line
Generate run time type descriptor information	Enable generation of information about every class with virtual functions for use by the C++ runtime type identification features ('dynamic_cast' and 'typeid'). If you don't use those parts of the language, you can save some space by disabling this option. Note that exception handling uses the same information, but it will generate it as needed. The 'dynamic_cast' operator can still be used for casts that do not require runtime type information, i.e., casts to void * or to unambiguous base classes.	`-f[no-]rtti`
Enable C++ exception handling	Enable exception handling. Generates extra code needed to propagate exceptions.	`-f[no-]exceptions`
Check that the pointer returned by operator 'new' is non-null	Check that the pointer returned by operator new is non-null before attempting to modify the storage allocated.	`-fcheck-new`
Generate code to check for violation of exception specification	Generate code to check for violation of exception specifications at runtime. Using this option may increase code size in production builds.	`-fenforce-eh-specs`

Table 4-8. xc32-g++ General Category
Option	Description	Command Line
Enable unaligned access	Enables (or disables) reading and writing of 16- and 32-bit values from addresses that are not 16- or 32-bit aligned. By default, unaligned access is disabled for all pre-ARMv6 and all ARMv6-M architectures and enabled for all other architectures. If unaligned access is not enabled then words in packed data structures are accessed one byte at a time.	`-m[no-]unaligned-access`
Have symbols in production build	Build for debugging in a production build image.	`-g`
Isolate each function in a section	Place each function into its own section in the output file if the target supports arbitrary sections. The name of the function or the name of the data item determines the section's name in the output file. This option is useful when combined with the linker’s `--gc-sections` option to remove unreferenced functions.	`-ffunction-sections`
Place data into its own section	Place each data item into its own section in the output file if the target supports arbitrary sections. The name of the function or the name of the data item determines the section's name in the output file. This option is useful when combined with the linker’s `--gc-sections` option to remove unreferenced variables.	`-fdata-sections`
Enable toplevel reordering	Allow reordering of top-level functions, variables, and `asm` statements, such that they might not be output in the same order in which they appear in source files. When this feature is disabled, using the `-fno-toplevel-reorder` option, unreferenced static variables will not be removed. Use this options with optimization level 1 or greater.	`-f[no-]toplevel-reorder`
Use indirect calls	Enable full-range calls, which are typically required when calling a function in another memory region.	`-mlong-calls`

Table 4-9. xc32-g++ Optimization Category
Option	Description	Command Line
Optimization Level	Select an optimization level. Your compiler edition may support only some optimizations. Equivalent to `-On` option, where `n` is an option below: 0 - Do not optimize.The compiler’s goal is to reduce the cost of compilation and to make debugging produce the expected results. 1 - Optimize. Optimizing compilation takes somewhat longer, and a lot more host memory for a large function. The compiler tries to reduce code size and execution time. 2 - Optimize even more. The compiler performs nearly all supported optimizations that do not involve a space-speed trade-off. 3 - Optimize yet more favoring speed (superset of O2). s - Optimize yet more favoring size (superset of O2).	`-O0 -O1 -O2 -O3 -Os`
Unroll loops	Check to perform the optimization of loop unrolling. This is only done for loops whose number of iterations can be determined at compile time or run time. Uncheck to not unroll loops.	`-funroll-loops`
Omit frame pointer	Check to not keep the Frame Pointer in a register for functions that don’t need one. Uncheck to keep the Frame Pointer.	`-fomit-frame-pointer`
Pre-optimization instruction scheduling	Attempts to reorder instructions to eliminate instruction stalls. Select "Default for optimization level"for this feature to be controlled purely by the `-O` level selection.	`-f[no-]schedule-insns`
Post-optimization instruction scheduling	Attempts to reorder instructions to eliminate instruction stalls. Select "Default for optimization level"for this feature to be controlled purely by the `-O` level selection.	`-f[no-]schedule-insns2`

Table 4-10. xc32-g++ Preprocessing and Messages Category
Option	Description	Command Line
Preprocessor macros	Project-specific preprocessor macro defines passed via the compiler’s `–D` option.	`-Dmacro[=defn]`
Include directories	Search these directories for project-specific include files.	`-I dir`
Make warnings into errors	Check to halt compilation based on warnings as well as errors. Uncheck to halt compilation based on errors only.	`-Werror`
Additional warnings	Check to enable all warnings. Uncheck to disable warnings.	`-Wall`
Enable Address-attribute warning	Emit a warning for all uses of the `address()` attribute. This option is for engineering-support use only.	`-Waddress-attribute-use`
strict-ansi	Issue all the warnings demanded by strict ISO C and ISO C++; reject all programs that use forbidden extensions, and some other programs that do not follow ISO C and ISO C++.	`-pedantic`

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