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CLANG(1)			     Clang			      CLANG(1)

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

SYNOPSIS
       clang [options] filename	...

DESCRIPTION
       clang  is  a C, C++, and	Objective-C compiler which encompasses prepro-
       cessing,	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	parse 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 tar-
	      get 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.

       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.    Please   see   <-
       http://clang-analyzer.llvm.org> for more	details	 on  how  to  use  the
       static analyzer.

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 optimiza-
	      tion 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 exe-
	      cutable or shared	library.

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

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

	      Supported	values for the C language are:
		 c89
		 c90
		 iso9899:1990

		     ISO C 1990
		 iso9899:199409

		     ISO C 1990	with amendment 1
		 gnu89
		 gnu90

		     ISO C 1990	with GNU extensions
		 c99
		 iso9899:1999

		     ISO C 1999
		 gnu99

		     ISO C 1999	with GNU extensions
		 c11
		 iso9899:2011

		     ISO C 2011
		 gnu11

		     ISO C 2011	with GNU extensions
		 c17
		 iso9899:2017

		     ISO C 2017
		 gnu17

		     ISO C 2017	with GNU extensions

	      The default C language standard is gnu11,	except on  PS4,	 where
	      it is gnu99.

	      Supported	values for the C++ language are:
		 c++98
		 c++03

		     ISO C++ 1998 with amendments
		 gnu++98
		 gnu++03

		     ISO C++ 1998 with amendments and GNU extensions
		 c++11

		     ISO C++ 2011 with amendments
		 gnu++11

		     ISO C++ 2011 with amendments and GNU extensions
		 c++14

		     ISO C++ 2014 with amendments
		 gnu++14

		     ISO C++ 2014 with amendments and GNU extensions
		 c++17

		     ISO C++ 2017 with amendments
		 gnu++17

		     ISO C++ 2017 with amendments and GNU extensions
		 c++2a

		     Working draft for ISO C++ 2020
		 gnu++2a

		     Working draft for ISO C++ 2020 with GNU extensions

	      The default C++ language standard	is gnu++14.

	      Supported	values for the OpenCL language are:
		 cl1.0

		     OpenCL 1.0
		 cl1.1

		     OpenCL 1.1
		 cl1.2

		     OpenCL 1.2
		 cl2.0

		     OpenCL 2.0

	      The default OpenCL language standard is cl1.0.

	      Supported	values for the CUDA language are:
		 cuda

		     NVIDIA CUDA(tm)

       -stdlib=<library>
	      Specify  the  C++	standard library to use; supported options are
	      libstdc++	and libc++. If not specified, platform default will be
	      used.

       -rtlib=<library>
	      Specify  the  compiler runtime library to	use; supported options
	      are libgcc and compiler-rt. If not specified,  platform  default
	      will be used.

       -ansi  Same as -std=c89.

       -ObjC, -ObjC++
	      Treat  source  input  files as Objective-C and Object-C++	inputs
	      respectively.

       -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-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, -fno-objc-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  sup-
	      ported by	your application.

       -miphoneos-version-min
	      When  building  for  iPhone OS, specify the minimum version sup-
	      ported 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, -O3, -Ofast, -Os,	-Oz, -Og, -O, -O4
	      Specify which optimization level to use:
		 -O0 Means "no optimization": this level compiles the  fastest
		 and generates the most	debuggable code.

		 -O1 Somewhere between -O0 and -O2.

		 -O2  Moderate	level of optimization which enables most opti-
		 mizations.

		 -O3 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).

		 -Ofast	Enables	all the	 optimizations	from  -O3  along  with
		 other	aggressive  optimizations that may violate strict com-
		 pliance with language standards.

		 -Os Like -O2 with extra optimizations to reduce code size.

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

		 -Og Like -O1. In future versions, this	option	might  disable
		 different optimizations in order to improve debuggability.

		 -O Equivalent to -O2.

		 -O4 and higher
		     Currently equivalent to -O3

       -g, -gline-tables-only, -gmodules
	      Control  debug information output.  Note that Clang debug	infor-
	      mation works best	at -O0.	 When more than	 one  option  starting
	      with -g is specified, the	last one wins:
		 -g Generate debug information.

		 -gline-tables-only  Generate  only  line table	debug informa-
		 tion. This allows for symbolicated backtraces	with  inlining
		 information, but does not include any information about vari-
		 ables,	their locations	or types.

		 -gmodules Generate debug information that  contains  external
		 references  to	 types defined in Clang	modules	or precompiled
		 headers instead of emitting redundant debug type  information
		 into  every  object file.  This option	transparently switches
		 the Clang module format to object file	containers  that  hold
		 the  Clang  module together with the debug information.  When
		 compiling a program that uses Clang  modules  or  precompiled
		 headers, this option produces complete	debug information with
		 faster	compile	times and much smaller object files.

		 This option should not	be used	when building static libraries
		 for  distribution  to	other  machines	because	the debug info
		 will contain references to the	module cache  on  the  machine
		 the object files in the library were built on.

       -fstandalone-debug -fno-standalone-debug
	      Clang  supports  a number	of optimizations to reduce the size of
	      debug information	in the binary. They work based on the  assump-
	      tion that	the debug type information can be spread out over mul-
	      tiple compilation	units.	For instance, Clang will not emit type
	      definitions  for types that are not needed by a module and could
	      be replaced with a forward  declaration.	 Further,  Clang  will
	      only  emit  type info for	a dynamic C++ class in the module that
	      contains the vtable for the class.

	      The -fstandalone-debug option  turns  off	 these	optimizations.
	      This  is useful when working with	3rd-party libraries that don't
	      come with	debug information.  This is  the  default  on  Darwin.
	      Note  that Clang will never emit type information	for types that
	      are not referenced at all	by the program.

       -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	gener-
	      ated to detect this and abort when it happens.

       -fvisibility
	      This flag	sets the default visibility level.

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

       -ftls-model=<model>
	      Set  the	default	 thread-local  storage	(TLS) model to use for
	      thread-local  variables.	Valid  values  are:  "global-dynamic",
	      "local-dynamic", "initial-exec" and "local-exec".	The default is
	      "global-dynamic".	The default model can be overridden  with  the
	      tls_model	 attribute.  The  compiler  will  try to choose	a more
	      efficient	model if possible.

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

	      The default for -flto is "full", in which	the  LLVM  bitcode  is
	      suitable	for monolithic Link Time Optimization (LTO), where the
	      linker merges all	such modules into a single combined module for
	      optimization.   With  "thin",  ThinLTO  compilation  is  invoked
	      instead.

   Driver Options
       -###   Print (but do not	run) the commands to run for this compilation.

       --help Display available	options.

       -Qunused-arguments
	      Do not emit any warnings 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.

       -Xlinker	<arg>
	      Pass arg to the linker.

       -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 the currently used  compiler  runtime
	      library ("libgcc.a" or "libclang_rt.builtins.*.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.

       -save-stats, -save-stats=cwd, -save-stats=obj
	      Save internal code generation (LLVM) statistics to a file	in the
	      current directory	(-save-stats/"-save-stats=cwd")	or the	direc-
	      tory of the output file ("-save-state=obj").

       -integrated-as, -no-integrated-as
	      Used  to	enable and disable, respectively, the use of the inte-
	      grated 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, -fdiagnos-
       tics-fixit-info,	      -fdiagnostics-parseable-fixits,	    -fdiagnos-
       tics-print-source-range-info,   -fprint-source-range-info,   -fdiagnos-
       tics-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
       -D<macroname>=<value>
	      Adds an implicit #define into the	 predefines  buffer  which  is
	      read before the source file is preprocessed.

       -U<macroname>
	      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.

       -I<directory>
	      Add  the	specified  directory  to  the  search path for include
	      files.

       -F<directory>
	      Add the specified	directory to the  search  path	for  framework
	      include files.

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

       -nostdlibinc
	      Do not search the	standard system	directories for	include	files,
	      but do search compiler builtin include directories.

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

ENVIRONMENT
       TMPDIR, TEMP, TMP
	      These environment	variables are checked, in order, for the loca-
	      tion 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
	      delimiter, as used in the	PATH environment variable.

	      Empty components in the environment variable are ignored.

       C_INCLUDE_PATH,	  OBJC_INCLUDE_PATH,	 CPLUS_INCLUDE_PATH,	 OBJC-
       PLUS_INCLUDE_PATH
	      These  environment  variables  specify  additional paths,	as for
	      CPATH, which are only used when processing the appropriate  lan-
	      guage.

       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>)

COPYRIGHT
       2007-2018, The Clang Team

6				 Apr 11, 2018			      CLANG(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | BUGS | SEE ALSO | AUTHOR | COPYRIGHT

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