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CLANG(1)		   Clang Tools Documentation		      CLANG(1)

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

       clang [-c|-S|-E]	-std=standard -g
	 -Wwarnings... -pedantic
	 -Idir... -Ldir...
	 -o output-file

       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:

	   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.

	   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-
	   specific 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

	   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.

	   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.

   Stage Selection Options
       -E  Run the preprocessor	stage.

	   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

       -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.

	   Run the Clang Static	Analyzer.

   Language Selection and Mode Options
       -x language
	   Treat subsequent input files	as having type language.

	   Specify the language	standard to compile for.

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

	   Same	as -std=c89.

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

	   Treat source	input files as Objective-C inputs.

	   Enable trigraphs.

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

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

	   Indicate that math functions	should be treated as updating errno.

	   Enable support for Pascal-style strings with	"\pfoo".

	   Enable support for Microsoft	extensions.

	   Set _MSC_VER. Defaults to 1300 on Windows. Not set otherwise.

	   Enable support for Borland extensions.

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

	   Allow loose type checking rules for implicit	vector conversions.

	   Enable the "Blocks" language	feature.

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

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

	   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).

	   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).

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

   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.

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

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

	   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 -Oz -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.  -Oz is like -Os (and thus -O2),
	   but reduces code size further.  -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.

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

	   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.

	   This	flag sets the default visibility level.

	   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.

	   Display available options.

	   Don't emit warning for unused driver	arguments.

	   Pass	the comma separated arguments in args to the assembler.

	   Pass	the comma separated arguments in args to the linker.

	   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.

       -Xlinker	arg
	   Pass	arg to the linker.

       -Xpreprocessor arg
	   Pass	arg to the preprocessor.

       -o file
	   Write output	to file.

	   Print the full library path of file.

	   Print the library path for "libgcc.a".

	   Print the full program path of name.

	   Print the paths used	for finding libraries and programs.

	   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	individual commands.

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

	   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.

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

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

	   Do not search the standard system directories or compiler builtin
	   directories for include files.

	   Do not search the standard system directories for include files,
	   but do search compiler builting include directories.

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

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

	   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.

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

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

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

	as(1), ld(1)

       Maintained by the Clang / LLVM Team (<>).

clang 3.0			  2011-10-17			      CLANG(1)


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