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CLANG(1)			     Clang			      CLANG(1)

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

       clang [options] filename	...

       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

	      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.

	      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   <-> for more	details	 on  how  to  use  the
       static analyzer.

   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 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.

	      Specify the language standard to compile for.

	      Supported	values for the C language are:

		     ISO C 1990

		     ISO C 1990	with amendment 1

		     ISO C 1990	with GNU extensions

		     ISO C 1999

		     ISO C 1999	with GNU extensions

		     ISO C 2011

		     ISO C 2011	with GNU extensions

		     ISO C 2017

		     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:

		     ISO C++ 1998 with amendments

		     ISO C++ 1998 with amendments and GNU extensions

		     ISO C++ 2011 with amendments

		     ISO C++ 2011 with amendments and GNU extensions

		     ISO C++ 2014 with amendments

		     ISO C++ 2014 with amendments and GNU extensions

		     ISO C++ 2017 with amendments

		     ISO C++ 2017 with amendments and GNU extensions

		     Working draft for ISO C++ 2020

		     Working draft for ISO C++ 2020 with GNU extensions

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

	      Supported	values for the OpenCL language are:

		     OpenCL 1.0

		     OpenCL 1.1

		     OpenCL 1.2

		     OpenCL 2.0

	      The default OpenCL language standard is cl1.0.

	      Supported	values for the CUDA language are:

		     NVIDIA CUDA(tm)

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

	      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

	      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

	      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.

	      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).

       -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

   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 sup-
	      ported by	your application.

	      When building for	iPhone OS, specify the	minimum	 version  sup-
	      ported 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, -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-

		 -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.

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

	      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.

	      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

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

       --help Display available	options.

	      Do not emit any warnings 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 the currently used compiler runtime
	      library ("libgcc.a" or "libclang_rt.builtins.*.a").

	      Print the	full program path of name.

	      Print the	paths used for finding libraries and programs.

	      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.

	      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
	      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

	      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 builtin include directories.

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

	      These environment	variables are checked, in order, for the loca-
	      tion to  write  temporary	 files	used  during  the  compilation

       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.

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

	      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 (<>)

       2007-2018, The Clang Team

6				 Apr 11, 2018			      CLANG(1)


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