9 Document Revision History

Revision A (March 2018)

Initial release of this document, adapted from the MPLAB XC8 C Compiler User’s Guide, DS50002053.

Added information relating to const-specified objects being located in program memory
Added information on the new code coverage feature
Added information relating to chipinfo HTML files
Added descriptions and screen captures of the MPLAB X IDE project property dialogs corresponding to the compiler command-line options
Updated configuration bit information
Clarified information relating to absolute objects
Updated predefined macros table
Miscellaneous corrections and improvements

This guide has been migrated to a new authoring and publication system; you may see differences in the formatting compared to previous revisions
The documentation for the standard libraries has been updated
Updated information relating to the structure of the DFPs
Clarified and expanded information relating to optimizations

Updated and added new screen captures of MPLAB X IDE project properties dialogs
Added screen captures of Microchip Studio project properties dialogs
Added new -Wl,--no-data-init option to control new data initialisation feature
Documented additional options, including: -Werror, -fdata-sections, -ffunction-sections, -glevel

Removed standard C library functions; these are now described in a separate Microchip Universal Standard Library Reference Guide document
Added information on Smart IO features
Added new -m[no-]gas-isr-prologues option and no_gccisr attribute
Added new -mcall-isr-prologues option
Added information on the code coverage feature
Added information on stack guidance feature
Expanded and updated information linking sections
Updated and added new screen captures of MPLAB X IDE project properties dialogs

Corrected code examples and expanded information relating to writing interrupt routines
Added sections describing the -msmart-io and -msmart-io-format options, which control the feature set of library code that performs formatted IO
Added section describing the new -mreserve option, which allows you to prevent regions of memory being populated by the linker
Added sections describing the -mno-pa-on-file and -mno-pa-on-function options, as well as the new -mno-pa-outline-calls option, which all control procedural abstraction optimizations
Added sections describing the -f[no-]fat-lto-objects, -flto-partition, -fomit-frame-pointer, and -funroll-[all-]loops optimzation options
Added the mapped linker option, -Wl,--section-start
Added in missing sections for the -MF, -P and -U driver options.
Clarified information relating to the const-in-program-memory feature
Added sections describing the supported built-in functions
Adjusted description of how quoted strings can be passed using the -D option, which has changed in the compiler
Made mention of the Analysis Tools Suite license (which replaces the Code Coverage license) required for the code coverage feature
Added the __CODECOV preprocessor macro and indicated when it is defined
Clarified that the __nopa specifier is only available when the CCI is enabled
Added a section discussing linker script symbols

Updated the operation of the -mrelax option, which now performs additional optimizations
Ensured that the no- forms of options are indicated in the option summary tables
Added description for the -fcommon option
Adjusted the placement of some option descriptions to be consistent with the placement used by GCC docs
Updated the screen captures of MPLAB X IDE project properties dialogs and described new options
Added a C99 language divergence relating to the floating-point type specification
Expanded description of -d option
Provided a summary of the optimizations performed by the compiler
Added descriptions of the ei() and di() macros provided by <xc.h>
Added description of the new NOP() macro provided by <xc.h>
Corrected the operation summary for the builtin_avr_cli and builtin_avr_insert_bits built-in functions

Added section for the new -mfuse-action option, which can adjust linker options based on some configuration fuse settings
Added the Common C Interface (CCI) chapter, present in some other compiler user's guides
Clarified the operation of the -mconst-data-in-config-mapped-progmem option and its setting of the FLMAPLOCK bit
Expanded information relating to the -fcommon option
Expanded information relating to the -fdata-sections and -ffunction-sections options
Added new checksum field to the MPLAB X IDE project properties dialogs
General improvements to the descriptions of compiler features and options

Added section for the -W[no-]msg option, which can enable and disable warning and advisory messages
Expanded the description of the -Werror option
Added description for the -finline-functions option
Added description for the -mno-data-init option, which had previously been shown as a mapped linker option
Added description for the -T option, which had previously been shown as a mapped linker option
Added section on dual-core device support
Added section on how to program the User Row memory
Added section on how to program the Boot Row memory
Added sections on the keep object and function attribute
Added section on the DIVA module routines and associated options, attribute and macro
Rewrote the sections on writing interrupt code to describe the different strategies available, and added a section on writing interrupt functions using the compiler's new compact vector table feature

Modified command-line examples to now use the -mdfp option
Added description of the -mpa option and clarified that all procedural abstraction options are for licensed compilers only
Expanded the description of the avr-objdump utility
Added description of the -mreorder-stack-vars option, which controls a new optimization
Added description of __nodiva specifier
Clarified that the __nopa specifier is provided by <xc.h>, not CCI