Clang Tools Documentation

http://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/clang.1.html

 

NAME
       clang - the Clang C, C++, and Objective-C compiler

SYNOPSIS
       clang [-c|-S|-E] -std=standard -g
         [-O0|-O1|-O2|-Os|-O3|-O4]
         -Wwarnings... -pedantic
         -Idir... -Ldir...
         -Dmacro[=defn]
         -ffeature-option...
         -mmachine-option...
         -o output-file
         -stdlib=library
         input-filenames

DESCRIPTION
       clang is a C, C++, and Objective-C compiler which encompasses preprocessing, parsing, optimization,
       code generation, assembly, and linking.  Depending on which high-level mode setting is passed, Clang
       will stop before doing a full link.  While Clang is highly integrated, it is important to understand
       the stages of compilation, to understand how to invoke it.  These stages are:

       Driver
           The clang executable is actually a small driver which controls the overall execution of other
           tools such as the compiler, assembler and linker.  Typically you do not need to interact with the
           driver, but you transparently use it to run the other tools.

       Preprocessing
           This stage handles tokenization of the input source file, macro expansion, #include expansion and
           handling of other preprocessor directives.  The output of this stage is typically called a ".i"
           (for C), ".ii" (for C++), ".mi" (for Objective-C) , or ".mii" (for Objective-C++) file.

       Parsing and Semantic Analysis
           This stage parses the input file, translating preprocessor tokens into a parse tree.  Once in the
           form of a parser tree, it applies semantic analysis to compute types for expressions as well and
           determine whether the code is well formed. This stage is responsible for generating most of the
           compiler warnings as well as parse errors.  The output of this stage is an "Abstract Syntax Tree"
           (AST).

       Code Generation and Optimization
           This stage translates an AST into low-level intermediate code (known as "LLVM IR") and ultimately
           to machine code.  This phase is responsible for optimizing the generated code and handling
           target-specfic code generation.  The output of this stage is typically called a ".s" file or
           "assembly" file.

           Clang also supports the use of an integrated assembler, in which the code generator produces
           object files directly. This avoids the overhead of generating the ".s" file and of calling the
           target assembler.

       Assembler
           This stage runs the target assembler to translate the output of the compiler into a target object
           file.  The output of this stage is typically called a ".o" file or "object" file.

       Linker
           This stage runs the target linker to merge multiple object files into an executable or dynamic
           library.  The output of this stage is typically called an "a.out", ".dylib" or ".so" file.

       The Clang compiler supports a large number of options to control each of these stages.  In addition
       to compilation of code, Clang also supports other tools:

       Clang Static Analyzer

       The Clang Static Analyzer is a tool that scans source code to try to find bugs through code analysis.
       This tool uses many parts of Clang and is built into the same driver.

OPTIONS
       Stage Selection Options


       -E  Run the preprocessor stage.

       -fsyntax-only
           Run the preprocessor, parser and type checking stages.

       -S  Run the previous stages as well as LLVM generation and optimization stages and target-specific
           code generation, producing an assembly file.

       -c  Run all of the above, plus the assembler, generating a target ".o" object file.

       no stage selection option
           If no stage selection option is specified, all stages above are run, and the linker is run to
           combine the results into an executable or shared library.

       --analyze
           Run the Clang Static Analyzer.

       Language Selection and Mode Options


       -x language
           Treat subsequent input files as having type language.

       -std=language
           Specify the language standard to compile for.

       -stdlib=language
           Specify the C++ standard library to use; supported options are libstdc++ and libc++.

       -ansi
           Same as -std=c89.

       -ObjC++
           Treat source input files as Objective-C++ inputs.

       -ObjC
           Treat source input files as Objective-C inputs.

       -trigraphs
           Enable trigraphs.

       -ffreestanding
           Indicate that the file should be compiled for a freestanding, not a hosted, environment.

       -fno-builtin
           Disable special handling and optimizations of builtin functions like strlen and malloc.

       -fmath-errno
           Indicate that math functions should be treated as updating errno.

       -fpascal-strings
           Enable support for Pascal-style strings with "/pfoo".

       -fms-extensions
           Enable support for Microsoft extensions.

       -fmsc-version=
           Set _MSC_VER. Defaults to 1300 on Windows. Not set otherwise.

       -fborland-extensions
           Enable support for Borland extensions.

       -fwritable-strings
           Make all string literals default to writable.  This disables uniquing of strings and other
           optimizations.

       -flax-vector-conversions
           Allow loose type checking rules for implicit vector conversions.

       -fblocks
           Enable the "Blocks" language feature.

       -fobjc-gc-only
           Indicate that Objective-C code should be compiled in GC-only mode, which only works when
           Objective-C Garbage Collection is enabled.

       -fobjc-gc
           Indicate that Objective-C code should be compiled in hybrid-GC mode, which works with both GC and
           non-GC mode.

       -fobjc-abi-version=version
           Select the Objective-C ABI version to use. Available versions are 1 (legacy "fragile" ABI), 2
           (non-fragile ABI 1), and 3 (non-fragile ABI 2).

       -fobjc-nonfragile-abi-version=version
           Select the Objective-C non-fragile ABI version to use by default. This will only be used as the
           Objective-C ABI when the non-fragile ABI is enabled (either via -fobjc-nonfragile-abi, or because
           it is the platform default).

       -fobjc-nonfragile-abi
           Enable use of the Objective-C non-fragile ABI. On platforms for which this is the default ABI, it
           can be disabled with -fno-objc-nonfragile-abi.

       Target Selection Options

       Clang fully supports cross compilation as an inherent part of its design.  Depending on how your
       version of Clang is configured, it may have support for a number of cross compilers, or may only
       support a native target.

       -arch architecture
           Specify the architecture to build for.

       -mmacosx-version-min=version
           When building for Mac OS/X, specify the minimum version supported by your application.

       -miphoneos-version-min
           When building for iPhone OS, specify the minimum version supported by your application.

       -march=cpu
           Specify that Clang should generate code for a specific processor family member and later.  For
           example, if you specify -march=i486, the compiler is allowed to generate instructions that are
           valid on i486 and later processors, but which may not exist on earlier ones.

       Code Generation Options


       -O0 -O1 -O2 -Os -O3 -O4
           Specify which optimization level to use.  -O0 means "no optimization": this level compiles the
           fastest and generates the most debuggable code.  -O2 is a moderate level of optimization which
           enables most optimizations.  -Os is like -O2 with extra optimizations to reduce code size.  -O3
           is like -O2, except that it enables optimizations that take longer to perform or that may
           generate larger code (in an attempt to make the program run faster).  On supported platforms, -O4
           enables link-time optimization; object files are stored in the LLVM bitcode file format and whole
           program optimization is done at link time. -O1 is somewhere between -O0 and -O2.

       -g  Generate debug information.  Note that Clang debug information works best at -O0.  At higher
           optimization levels, only line number information is currently available.

       -fexceptions
           Enable generation of unwind information, this allows exceptions to be thrown through Clang
           compiled stack frames.  This is on by default in x86-64.

       -ftrapv
           Generate code to catch integer overflow errors.  Signed integer overflow is undefined in C, with
           this flag, extra code is generated to detect this and abort when it happens.

       -fvisibility
           This flag sets the default visibility level.

       -fcommon
           This flag specifies that variables without initializers get common linkage.  It can be disabled
           with -fno-common.

       -flto -emit-llvm
           Generate output files in LLVM formats, suitable for link time optimization. When used with -S
           this generates LLVM intermediate language assembly files, otherwise this generates LLVM bitcode
           format object files (which may be passed to the linker depending on the stage selection options).

       Driver Options


       -###
           Print the commands to run for this compilation.

       --help
           Display available options.

       -Qunused-arguments
           Don't emit warning for unused driver arguments.

       -Wa,args
           Pass the comma separated arguments in args to the assembler.

       -Wl,args
           Pass the comma separated arguments in args to the linker.

       -Wp,args
           Pass the comma separated arguments in args to the preprocessor.

       -Xanalyzer arg
           Pass arg to the static analyzer.

       -Xassembler arg
           Pass arg to the assembler.

       -Xclang arg
           Pass arg to the clang compiler frontend.

       -Xlinker arg
           Pass arg to the linker.

       -mllvm arg
           Pass arg to the LLVM backend.

       -Xpreprocessor arg
           Pass arg to the preprocessor.

       -o file
           Write output to file.

       -print-file-name=file
           Print the full library path of file.

       -print-libgcc-file-name
           Print the library path for "libgcc.a".

       -print-prog-name=name
           Print the full program path of name.

       -print-search-dirs
           Print the paths used for finding libraries and programs.

       -save-temps
           Save intermediate compilation results.

       -integrated-as -no-integrated-as
           Used to enable and disable, respectively, the use of the integrated assembler. Whether the
           integrated assembler is on by default is target dependent.

       -time
           Time individual commands.

       -ftime-report
           Print timing summary of each stage of compilation.

       -v  Show commands to run and use verbose output.

       Diagnostics Options


       -fshow-column -fshow-source-location -fcaret-diagnostics -fdiagnostics-fixit-info
       -fdiagnostics-parseable-fixits -fdiagnostics-print-source-range-info -fprint-source-range-info
       -fdiagnostics-show-option -fmessage-length
           These options control how Clang prints out information about diagnostics (errors and warnings).
           Please see the Clang User's Manual for more information.

       Preprocessor Options


       -Dmacroname=value
           Adds an implicit #define into the predefines buffer which is read before the source file is
           preprocessed.

       -Umacroname
           Adds an implicit #undef into the predefines buffer which is read before the source file is
           preprocessed.

       -include filename
           Adds an implicit #include into the predefines buffer which is read before the source file is
           preprocessed.

       -Idirectory
           Add the specified directory to the search path for include files.

       -Fdirectory
           Add the specified directory to the search path for framework include files.

       -nostdinc
           Do not search the standard system directories for include files.

       -nobuiltininc
           Do not search clang's builtin directory for include files.

ENVIRONMENT
       TMPDIR, TEMP, TMP
           These environment variables are checked, in order, for the location to write temporary files used
           during the compilation process.

       CPATH
           If this environment variable is present, it is treated as a delimited list of paths to be added
           to the default system include path list. The delimiter is the platform dependent delimitor, as
           used in the PATH environment variable.

           Empty components in the environment variable are ignored.

       C_INCLUDE_PATH, OBJC_INCLUDE_PATH, CPLUS_INCLUDE_PATH, OBJCPLUS_INCLUDE_PATH
           These environment variables specify additional paths, as for CPATH, which are only used when
           processing the appropriate language.

       MACOSX_DEPLOYMENT_TARGET
           If -mmacosx-version-min is unspecified, the default deployment target is read from this
           environment variable.  This option only affects darwin targets.

BUGS
       To report bugs, please visit <http://llvm.org/bugs/>.  Most bug reports should include preprocessed
       source files (use the -E option) and the full output of the compiler, along with information to
       reproduce.

SEE ALSO
        as(1), ld(1)

AUTHOR
       Maintained by the Clang / LLVM Team (<http://clang.llvm.org>).