XCC

Synopsis

xcc [-c|-S|-E] [-g] [-O<level>]
    [-W<warn>...]
    [-I<dir>...] [-L<dir>...]
    [-D<macro>[=<defn>]]
    [-f<option>...]
    [-target=<platform>]
    [-o <outfile>] infile

Only the most useful options are listed here; see below for the remainder.

Description

XCC is deliberately analogous to GCC and imitates many of its behaviours. XCC is a wrapper around a collection of tools to make the use of those tools simpler. Those tools perform the steps of preprocessing, compilation (both C/C++ and XC), assembly and ‘mapping’. Those tools may be used individually, but are more easily used via xcc.

XCC will normally run all of the steps. The first three steps are similar to GCC in that they are applied to an individual source file to produce an object file. The ‘mapping’ step, as the name suggests, is different. Rather than producing an executable for a single processor, the linker is invoked multiple times to produce an executable per processor. Furthermore, the process includes auto-generating source code, compiling it and invoking the linker further times. The resulting single output file is an XE file , which contains the multiple executables.

Options such as -c, -S and -E prevent all the steps running, and instead produce an intermediate output.

No matter which step is being performed, a platform conforming to the XN Specification must be specified. This is done via XCC_DEFAULT_TARGET, -target or, better, listed as one of the input files.

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 include:

• Declarations of variables of type tileref (see Declaration).

• Macro definitions of port names (see Port).

Many options are passed directly through to the tool performing the processing step. For instance, some options directly influence the behaviour of the compiler or the linker.

For the most part, the order you use for the options doesn’t matter. Order does matter when you use several options of the same kind; for example, if you specify -L more than once, the directories are searched in the order specified. In other cases, such as with -O repeated usage will result in the rightmost usage to take precedence.

Many options have negative forms (for example, -fno-<option>).

A space between an option and its argument is permitted.

Options

Overall Options

-x <language>

Overrides default handling 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

• xscope

• none (turn off language specification)

Default handling of the input files is determined by their suffix:

File extensions recognized by XCC and their meaning

Extension	Type of File	Preprocessed by XCC
.xc	XC source code	Y
.c	C source code	Y
.cpp	CPP source code (for compatability, the extensions cc, cp, c++, C and cxx are also recognized)	Y
.S	Assembly code	Y
.xscope	xSCOPE configuration file	N
.xn	xCORE Network Description	N
.xi	XC source code	N
.i	C source code	N
.ii	C++ source code	N
.s	Assembly code	N
other	Object file .o be given to the linker	N

-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>

Convenience mechanism for specifying a pre-canned target platform. The platform configuration must be specified in the file platform.xn, which is searched for in the paths specified by the XCC_TARGET_PATH environment variable.

The use of this option is not recommended for long-lived projects due to the likelihood of the target platform changing in an uncontrolled fashion. It is best practice to specify a platform explicitly by defining and supplying a target platform as one of the xcc input files. For example:

$ xcc my_target.xn main.c

-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[=link|uart]

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

-fcmdline-buffer-bytes=<n>

Add a buffer of size <n> bytes to be used to hold command line arguments.

-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.

-o <file>

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 -v is also specified, --help is also passed to the subprocesses invoked by XCC.

--version

Displays the version number and copyrights.

-save-temps

Save intermediate files to current directory. Where possible, files are named based on the source file. The generated file platform.h is always written with the same name, and therefore parallel builds with this option enabled should be avoided.

This option is not forwarded to xmap; see -Xmapper if this is the desired behaviour.

Warning Options

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.

Debugging Options

-g

Produces debugging information.

-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.

-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

Lists the target platforms (XN files) found via XCC_TARGET_PATH, excluding those in folders with name .deprecated.

-print-boards

Same as -print-targets, but only lists target platforms with the < Type> element set to “Board”.

Optimization Options

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.

-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.

Preprocessor Options

The following options control the preprocessor.

-E

Preprocesses only, then exit.

-D <name>

Predefines name as a macro with definition 1.

-D <name=definition>

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

-U <name>

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>

Write dependency information to file.

-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.

Mapper Options

The following options control the mapper and its linker.

-l <library>

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.

Directory Options

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

-I <dir>

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

-isystem <dir>

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.

-iquote <dir>

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.

-L <dir>

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

Environment

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_TARGET_PATH

A list of directories to be searched for target configuration files. See -target, -print-targets and -print-boards.

XCC_EXEC_PREFIX

If set, subprograms executed by the compiler are prefixed with the value of this environment variable. No directory seperater 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 provided as an input file.