XCC Command-Line Manual

The four possible stages of compilation are preprocessing, compilation proper, assembly and linking/mapping. The first three stages are applied to an individual source file, producing an object file. Linking and mapping combine the object files and an XN file into a single executable XE file, which contains the code and data segments for each tile.

• source-file

  The suffix of a source file determines how it is handled by default.

• -xlanguage

  Specifies the language for the following input files. This option applies to all following input files until the next -x option. Supported values for language are:

  • xc
  • c
  • c++
  • assembler
  • assembler-with-cpp
  • xn
  • xta
  • none (turn off language specification)

• -std=standard

  Specifies the language variant for the following input C or C++ file. Supported values for standard are:

  c89

  ISO C89

  gnu89

  ISO C89 with GNU extensions

  c99

  ISO C99

  gnu99

  ISO C99 with GNU extensions (default for C programs)

  c++98

  ISO C++ (1998)

  gnu++98

  ISO C++ (1998) with GNU extensions (default for C++ programs)

• -fsubword-select

  In XC, allows selecting on channel inputs where the size of the desstination variable is less than 32 bits.

  This is default for targets based on XS1-L devices. It is not default for targets based on XS1-G devices. For further details, see Channel Communication.

• -target=platform

  Specifies the target platform. The platform configuration must be specified in the file platform.xn, which is searched for in the paths specified by the XCC_DEVICE_PATH environment variable.

• -foverlay

  Enable support for memory overlays. Functions marked as overlay roots are placed in external memory and are loaded on demand at runtime. The option should be passed when compiling and linking. An overlay runtime should be supplied in the application.

• -foverlay=flash

  Enable support for memory overlays linking in the flash overlay runtime. Overlays are only enabled on tiles which boot from flash.

• -foverlay=syscall

  Enable support for memory overlays linking in the syscall overlay runtime. Overlay are enabled on all tiles. Overlays are loaded from a host machine using a system call.

• -fxscope

  Enable support for xSCOPE tracing. The XN file of the target must contain an xSCOPE link. The option should be passed when compiling and linking.

• -funroll-loops

  Unroll loops with small iteration counts. This is enabled at -O2 and above.

• -finline-functions

  Integrate simple functions into their callers. This is enabled at -O2 and above and also at -Os.

• -pass-exit-codes

  Returns the numerically highest error code produced by any phase of compilation. (By default XCC returns 1 if any phase of the compiler returns non-success, otherwise it returns 0.)

• -c

  Compiles or assembles the source files, producing an object file for each source file, but does not link/map. By default the object filename is formed by replacing the source file suffix with .o (for example, a.c produces a.o).

• -S

  Stops after compilation proper, producing an assembly code file for each nonassembly input file specified. By default the assembly filename is formed by replacing the source file suffix with .s.

  Input files not requiring compilation are ignored.

• -E

  Preprocesses the source files only, outputting the preprocessed source to stdout.

  Input files not requiring preprocessing are ignored.

• -ofile

  Places output in file.

  If -o is not specified, the executable file is placed in a.xe, the object file for source.suffix in source.o, its assembly code file in source.s, and all preprocessed C/C++/XC source on standard output.

• -v

  Prints (on standard error) the commands executed at each stage of compilation. Also prints the version number of XCC, the preprocessor and the compiler proper.

• -###

  The same as -v except that the commands are not executed and all command arguments are quoted.

• --help

  Prints a description of the supported command line options. If the -v option is also specified, --help is also passed to the subprocesses invoked by XCC.

• --version

  Displays the version number and copyrights.

Many specific warnings can be controlled with options beginning -W. Each of the following options has a negative form beginning -Wno- to turn off warnings.

• -fsyntax-only

  Checks the code for syntax errors only, then exits.

• -w

  Turns off all warning messages.

• -Wbidirectional-buffered-port

  Warns about the use of buffered ports not qualified with either in or out. This warning is enabled by default.

• -Wchar-subscripts

  Warns if an array subscript has type char.

• -Wcomment

  Warns if a comment-start sequence /* appears in a /* comment, or if a backslash-newline appears in a // comment. This is default.

• -Wimplicit-int

  Warns if a declaration does not specify a type. In C also warns about function declarations with no return type.

• -Wmain

  Warns if the type of main is not a function with external linkage returning int. In XC also warns if main does not take zero arguments. In C also warns if main does not take either zero or two arguments of appropriate type.

• -Wmissing-braces

  Warns if an aggregate or union initializer is not fully bracketed.

• -Wparentheses

  Warns if parentheses are omitted when there is an assignment in a context where a truth value is expected or if operators are nested whose precedence people often find confusing.

• -Wreturn-type

  Warns if a function is defined with a return type that defaults to int or if a return statement returns no value in a function whose return type is not void.

• -Wswitch-default

  Warns if a switch statement does not have a default case.

• -Wswitch-fallthrough

  (XC only) Warns if a case in a switch statement with at least one statement can have control fall through to the following case.

• -Wtiming

  Warns if timing constraints are not satisfied. This is default.

• -Wtiming-syntax

  Warns about invalid syntax in timing scripts. This is default.

• -Wunused-function

  Warns if a static function is declared but not defined or a non-inline static function is unused.

• -Wunused-parameter

  Warns if a function parameter is unused except for its declaration.

• -Wunused-variable

  Warns if a local variable or non-constant static variable is unused except for its declaration.

• -Wunused

  Same as -Wunused-function, -Wunused-variable and -Wno-unused-parameter.

• -Wall

  Turns on all of the above -W options.

The following -W... options are not implied by -Wall.

• -Wextra

  -W

  Prints extra warning messages for the following:

  • A function can return either with or without a value (C, C++ only).
  • An expression statement or left-hand side of a comma expression contains no side effects. This warning can be suppressed by casting the unused expression to void (C, C++ only).
  • An unsigned value is compared against zero with < or <=.
  • Storage-class specifiers like static are not the first things in a declaration (C, C++ only).
  • A comparison such as x<=y<=z appears (XC only).
  • The return type of a function has a redundant qualifier such as const.
  • Warns about unused arguments if -Wall or -Wunused is also specified.
  • A comparison between signed and unsigned values could produce an incorrect result when the signed value is converted to unsigned. (Not warned if -Wno-sign-compare is also specified.)
  • An aggregate has an initializer that does not initialize all members.
  • An initialized field without side effects is overridden when using designated initializers (C, C++ only).
  • A function parameter is declared without a type specifier in K&R-style functions (C, C++ only).
  • An empty body occurs in an if or else statement (C, C++ only).
  • A pointer is compared against integer zero with <, <=, >, or >=. (C, C++ only).
  • An enumerator and a non-enumerator both appear in a conditional expression. (C++ only).
  • A non-static reference or non-static const enumerator and a non-enumerator both appear in a conditional expression (C++ only).
  • Ambiguous virtual bases (C++ only).
  • Subscripting an array which has been declared register (C++ only).
  • Taking the address of a variable which has been declared register (C++ only).
  • A base class is not initialized in a derived class’ copy constructor (C++ only).

• -Wconversion

  Warns if a negative integer constant expression is implicitly converted to an unsigned type.

• -Wdiv-by-zero

  Warns about compile-time integer division by zero. This is default.

• -Wfloat-equal

  Warns if floating point values are used in equality comparisons.

• -Wlarger-than-len

  Warns if an object of larger than len bytes is defined.

• -Wpadded

  Warns if a structure contains padding. (It may be possible to rearrange the fields of the structure to reduce padding and thus make the structure smaller.)

• -Wreinterpret-alignment

  Warns when a reinterpret cast moves to a larger alignment.

• -Wshadow

  Warns if a local variable shadows another local variable, parameter or global variable or if a built-in function is shadowed.

• -Wsign-compare

  Warns if a comparison between signed and unsigned values could produce an incorrect result when the signed value is converted to unsigned.

• -Wsystem-headers

  Prints warning messages for constructs found in system header files. This is not default. See Directory Options.

• -Wundef

  Warns if an undefined macro is used in a #if directive.

• -Werror

  Treat all warnings as errors.

• -Werror=option

  Turns a warning message into an error. The option should be one of the warning options to the compiler that can be prefixed with -W.

  By default, the flag -Werror=timing-syntax is set. Turning this warning into an error implies that timing warnings (-Wtiming) are also errors and vice versa.

• -g

  Produces debugging information.

• -fxta-info

  Produces timing information for use with XTA. This is default.

• -fresource-checks

  Produces code in the executable that traps if a resource allocation fails. This causes resource errors to be detected as early as possible.

• -save-temps

  Saves the intermediate files. These files are placed in the current directory and named based on the source file.

• -fverbose-asm

  Produces extra compilation information as comments in intermediate assembly files.

• -dumpmachine

  Prints the target machine and exit.

• -dumpversion

  Prints the compiler version and exit.

• -print-multi-lib

  Prints the mapping from multilib directory names to compiler switches that enable them. The directory name is seperated from the switches by ‘;‘, and each switch starts with a ‘@‘ instead of the ‘-‘, without spaces between multiple switches.

• -print-targets

  Prints the target platforms supported by the compiler. The target names correspond to strings accepted by the -target option.

Turning on optimization makes the compiler attempt to improve performance and/or code size at the expense of compilation time and the ability to debug the program.

• -O0

  Do not optimize. This is the default.

• -O

  -O1

  Optimize. Attempts to reduce execution time and code size without performing any optimizations that take a large amount of compilation time.

• -O2

  Optimize more. None of these optimizations involve a space-speed tradeoff.

• -O3

  Optimize even more. These optimizations may involve a space-speed tradeoff; high performance is preferred to small code size.

• -Os

  Optimize for the smallest code size possible.

• -fschedule

  Attempt to reorder instructions to increase performance. This is not default at any optimization level.

The following options control the preprocessor.

• -E

  Preprocesses only, then exit.

• -Dname

  Predefines name as a macro with definition 1.

• -Dname=definition

  Tokenizes and preprocesses the contents of definition as if it appeared in a #define directive.

• -Uname

  Removes any previous definition of name.

  -D and -U options are processed in the order given on the command line.

• -MD

  Outputs to a file a rule suitable for make describing the dependencies of the source file. The default name of the dependency file is determined based on whether the -o option is specified. If -o is specified, the filename is the basename of the argument to -o with the suffix .d. If -o is not specified, the filename is the basename of the input file with the suffix .d. The name of the file may be overriden with -MF.

• -MMD

  The same as -MD expect that dependencies on system headers are ignored.

• -MF file

  Specifies the file to write dependency information to.

• -MP

  Emits phony targets for each dependency of the source file. Each phony target depends on nothing. These dummy rules work around errors make gives if header files are removed without updating the Makefile to match.

• -MT file

  Specifies the target of the rule emitted by dependency generation.

The following options control the linker/mapper.

• -llibrary

  Searches the library library when linking. The linker searches and processes libraries and object files in the order specified. The actual library name searched for is liblibrary.a.

  The directories searched include any specified with -L.

  Libraries are archive files whose members are object files. The linker scans the archive for its members which define symbols that have so far been referenced but not defined.

• -nostartfiles

  Do not link with the system startup files.

• -nodefaultlibs

  Do not link with the system libraries.

• -nostdlib

  Do not link with the system startup files or system libraries.

• -s

  Removes all symbol table and relocation information from the executable.

• -default-clkblk clk

  Use clk as the default clock block. The clock block may be specified by its name in <xs1.h> or by its resource number.

  The startup code turns on the default clock block, configures it to be clocked off the reference clock with no divide and puts it into a running state. Ports declared in XC are initially attached to the default clock block. If this option is unspecified, the default clock block is set to XS1_CLKBLK_REF.

• -Wm,option

  Passes option as an option to the linker/mapper. If option contains commas, it is split into multiple options at the commas.

  To view the full set of advanced mapper options, type xmap --help.

• -Xmapper option

  Passes option as an option to the linker/mapper. To pass an option that takes an argument use -Xmapper twice.

• -report

  Prints a summary of resource usage.

The following options specify directories to search for header files and libraries.

• -Idir

  Adds dir to the list of directories to be searched for header files.

• -isystemdir

  Searches dir for header files after all directories specified by -I. Marks it as a system directory.

  The compiler suppresses warnings for header files in system directories.

• -iquotedir

  Searches dir only for header files requested with #include "file" (not with #include <file>) before all directories specified by -I and before the system directories.

• -Ldir

  Adds dir to the list of directories to be searched for by -l.

The following environment variables affect the operation of XCC. Multiple paths are separated by an OS-specific path separator (‘;‘ for Windows, ‘:‘ for Mac and Linux).

• XCC_INCLUDE_PATH

  A list of directories to be searched as if specified with -I, but after any paths given with -I options on the command line.

• XCC_XC_INCLUDE_PATH

  XCC_C_INCLUDE_PATH

  XCC_CPLUS_INCLUDE_PATH

  XCC_ASSEMBLER_INCLUDE_PATH

  Each of these environment variables applies only when preprocessing files of the named language. The variables specify lists of directories to be searched as if specified with -isystem, but after any paths given with -isystem options on the command line.

• XCC_LIBRARY_PATH

  A list of directories to be searched as if specified with -L, but after any paths given with -L on the command line.

• XCC_DEVICE_PATH

  A list of directories to be searched for device configuration files.

• XCC_EXEC_PREFIX

  If set, subprograms executed by the compiler are prefixed with the value of this environment variable. No directory seperated is added when the prefix is combined with the name of a subprogram. The prefix is not applied when executing the assembler or the mapper.

• XCC_DEFAULT_TARGET

  The default target platform, to be located as if specified with -target=. The default target platform is used if no target is specified with -target= and no XN file is passed.

During compilation of a program, the compiler generates a temporary header file named platform.h that contains variable and macro definitions, as defined by the target XN file, which includes:

• Declarations of variables of type tileref (see Declaration).
• Macro definitions of port names (see Port).