• 无参数
  clang -S test2.c -o test2.s
• i386
  clang -arch i386 -S test2.c -o test2.s
• arm
  clang -arch arm -S test2.c -o test2.s
• arm64
  clang -arch arm64 -S test2.c -o test2.s
• armv7
  clang -arch armv7 -S test2.c -o test2.s

== HELP ==
<pre>
OVERVIEW: clang LLVM compiler

USAGE: clang [options] <inputs>

OPTIONS:
-### Print the commands to run for this compilation
--analyze Run the static analyzer
-arcmt-migrate-emit-errors
Emit ARC errors even if the migrator can fix them
-arcmt-migrate-report-output <value>
Output path for the plist report
-cl-kernel-arg-info OpenCL only. This option allows the compiler to store information about the arguments of a kernel(s)
-cxx-isystem <directory>
Add directory to the C++ SYSTEM include search path
-c Only run preprocess, compile, and assemble steps
-dD Print macro definitions in -E mode in addition to normal output
-dependency-dot <value> Filename to write DOT-formatted header dependencies to
-dependency-file <value>
Filename (or -) to write dependency output to
-dM Print macro definitions in -E mode instead of normal output
-emit-ast Emit Clang AST files for source inputs
-emit-llvm Use the LLVM representation for assembler and object files
-E Only run the preprocessor
-faltivec Enable AltiVec vector initializer syntax
-fansi-escape-codes Use ANSI escape codes for diagnostics
-fapple-kext Use Apple's kernel extensions ABI
-fapple-pragma-pack Enable Apple gcc-compatible #pragma pack handling
-fblocks Enable the 'blocks' language feature
-fborland-extensions Accept non-standard constructs supported by the Borland compiler
-fbounds-checking Enable run-time bounds checks
-fcolor-diagnostics Use colors in diagnostics
-fcomment-block-commands=<arg>
Treat each comma separated argument in <arg> as a documentation comment block command
-fcxx-exceptions Enable C++ exceptions
-fdata-sections Place each data in its own section (ELF Only)
-fdebug-types-section Place debug types in their own section (ELF Only)
-fdelayed-template-parsing
Parse templated function definitions at the end of the translation unit
-fdiagnostics-parseable-fixits
Print fix-its in machine parseable form
-fdiagnostics-print-source-range-info
Print source range spans in numeric form
-fdiagnostics-show-name Print diagnostic name
-fdiagnostics-show-note-include-stack
Display include stacks for diagnostic notes
-fdiagnostics-show-option
Print option name with mappable diagnostics
-fdiagnostics-show-template-tree
Print a template comparison tree for differing templates
-fdollars-in-identifiers
Allow '$' in identifiers
-femit-all-decls Emit all declarations, even if unused
-fexceptions Enable support for exception handling
-ffast-math Enable the frontend's 'fast-math' mode. This has no effect on optimizations, but provides a preprocessor macro FAST_MATH the same as GCC's -ffast-math flag
-ffixed-r9 Reserve the r9 register (ARM only)
-ffp-contract=<value> Form fused FP ops (e.g. FMAs): fast (everywhere) | on (according to FP_CONTRACT pragma, default) | off (never fuse)
-ffreestanding Assert that the compilation takes place in a freestanding environment
-ffunction-sections Place each function in its own section (ELF Only)
-fgnu-keywords Allow GNU-extension keywords regardless of language standard
-fgnu-runtime Generate output compatible with the standard GNU Objective-C runtime
-fgnu89-inline Use the gnu89 inline semantics
-finstrument-functions Generate calls to instrument function entry and exit
-fmath-errno Require math functions to indicate errors by setting errno
-fmodule-map-file= <file>
Load this module map file
-fmodule-maps Read module maps to understand the structure of library headers
-fmodule-name= <name> Specify the name of the module to build
-fmodules-cache-path=<directory>
Specify the module cache path
-fmodules-decluse Require declaration of modules used within a module
-fmodules-ignore-macro=<value>
Ignore the definition of the given macro when building and loading modules
-fmodules-prune-after=<seconds>
Specify the interval (in seconds) after which a module file will be considered unused
-fmodules-prune-interval=<seconds>
Specify the interval (in seconds) between attempts to prune the module cache
-fmodules Enable the 'modules' language feature
-fms-compatibility Enable Microsoft compatibility mode
-fms-extensions Accept some non-standard constructs supported by the Microsoft compiler
-fmsc-version=<value> Version of the Microsoft C/C++ compiler to report in _MSC_VER (0 = don't define it (default))
-fno-access-control Disable C++ access control
-fno-assume-sane-operator-new
Don't assume that C++'s global operator new can't alias any pointer
-fno-autolink Disable generation of linker directives for automatic library linking
-fno-builtin-<value> Disable implicit builtin knowledge of a specific function
-fno-builtin Disable implicit builtin knowledge of functions
-fno-common Compile common globals like normal definitions
-fno-constant-cfstrings Disable creation of CodeFoundation-type constant strings
-fno-diagnostics-fixit-info
Do not include fixit information in diagnostics
-fno-dollars-in-identifiers
Disallow '$' in identifiers
-fno-elide-constructors Disable C++ copy constructor elision
-fno-elide-type Do not elide types when printing diagnostics
-fno-lax-vector-conversions
Disallow implicit conversions between vectors with a different number of elements or different element types
-fno-math-builtin Disable implicit builtin knowledge of math functions
-fno-merge-all-constants
Disallow merging of constants
-fno-objc-infer-related-result-type
do not infer Objective-C related result type based on method family
-fno-operator-names Do not treat C++ operator name keywords as synonyms for operators
-fno-rtti Disable generation of rtti information
-fno-sanitize-blacklist Don't use blacklist file for sanitizers
-fno-sanitize-recover Disable sanitizer check recovery
-fno-show-column Do not include column number on diagnostics
-fno-show-source-location
Do not include source location information with diagnostics
-fno-signed-char Char is unsigned
-fno-spell-checking Disable spell-checking
-fno-standalone-debug Limit debug information produced to reduce size of debug binary
-fno-threadsafe-statics Do not emit code to make initialization of local statics thread safe
-fno-unroll-loops Turn off loop unroller
-fno-use-cxa-atexit Don't use __cxa_atexit for calling destructors
-fno-use-init-array Don't use .init_array instead of .ctors
-fobjc-arc-exceptions Use EH-safe code when synthesizing retains and releases in -fobjc-arc
-fobjc-arc Synthesize retain and release calls for Objective-C pointers
-fobjc-exceptions Enable Objective-C exceptions
-fobjc-gc-only Use GC exclusively for Objective-C related memory management
-fobjc-gc Enable Objective-C garbage collection
-fobjc-runtime=<value> Specify the target Objective-C runtime kind and version
-fpack-struct=<value> Specify the default maximum struct packing alignment
-fpascal-strings Recognize and construct Pascal-style string literals
-fpcc-struct-return Override the default ABI to return all structs on the stack
-fprofile-instr-generate
Generate instrumented code to collect execution counts
-fprofile-instr-use=<value>
Use instrumentation data for profile-guided optimization
-freg-struct-return Override the default ABI to return small structs in registers
-fsanitize-address-zero-base-shadow
Make AddressSanitizer map shadow memory at zero offset
-fsanitize-blacklist=<value>
Path to blacklist file for sanitizers
-fsanitize-memory-track-origins
Enable origins tracking in MemorySanitizer
-fsanitize=<check> Enable runtime instrumentation for bug detection: undefined (miscellaneous undefined behavior)
-fshort-enums Allocate to an enum type only as many bytes as it needs for the declared range of possible values
-fshort-wchar Force wchar_t to be a short unsigned int
-fshow-overloads=<value>
Which overload candidates to show when overload resolution fails: best|all; defaults to all
-fslp-vectorize-aggressive
Enable the BB vectorization passes
-fslp-vectorize Enable the superword-level parallelism vectorization passes
-fstandalone-debug Emit full debug info for all types used by the program
-fstrict-enums Enable optimizations based on the strict definition of an enum's value range
-ftrap-function=<value> Issue call to specified function rather than a trap instruction
-ftrapv-handler=<function name>
Specify the function to be called on overflow
-ftrapv Trap on integer overflow
-funroll-loops Turn on loop unroller
-fuse-init-array Use .init_array instead of .ctors
-fvectorize Enable the loop vectorization passes
-fvisibility-inlines-hidden
Give inline C++ member functions default visibility by default
-fvisibility-ms-compat Give global types 'default' visibility and global functions and variables 'hidden' visibility by default
-fvisibility=<value> Set the default symbol visibility for all global declarations
-fwrapv Treat signed integer overflow as two's complement
-fwritable-strings Store string literals as writable data
-F <value> Add directory to framework include search path
--gcc-toolchain=<value> Use the gcc toolchain at the given directory
-gdwarf-2 Generate source level debug information with dwarf version 2
-gdwarf-3 Generate source level debug information with dwarf version 3
-gdwarf-4 Generate source level debug information with dwarf version 4
-gline-tables-only Emit debug line number tables only
-g Generate source level debug information
-help Display available options
-H Show header includes and nesting depth
-idirafter <value> Add directory to AFTER include search path
-iframework <value> Add directory to SYSTEM framework search path
-imacros <file> Include macros from file before parsing
-include-pch <file> Include precompiled header file
-include <file> Include file before parsing
-index-header-map Make the next included directory (-I or -F) an indexer header map
-iprefix <dir> Set the -iwithprefix/-iwithprefixbefore prefix
-iquote <directory> Add directory to QUOTE include search path
-isysroot <dir> Set the system root directory (usually /)
-isystem <directory> Add directory to SYSTEM include search path
-iwithprefixbefore <dir>
Set directory to include search path with prefix
-iwithprefix <dir> Set directory to SYSTEM include search path with prefix
-iwithsysroot <directory>
Add directory to SYSTEM include search path, absolute paths are relative to -isysroot
-I <value> Add directory to include search path
-mcrc Allow use of CRC instructions (ARM only)
-mfp32 Use 32-bit floating point registers (MIPS only)
-mfp64 Use 64-bit floating point registers (MIPS only)
-MG Add missing headers to dependency list
--migrate-xct Apply modifications and produces temporary files to migrate to XCTest framework
--migrate Run the migrator
-mllvm <value> Additional arguments to forward to LLVM's option processing
-mms-bitfields Set the default structure layout to be compatible with the Microsoft compiler standard
-mmsa Enable MSA ASE (MIPS only)
-mno-global-merge Disable merging of globals
-mno-implicit-float Don't generate implicit floating point instructions
-mno-msa Disable MSA ASE (MIPS only)
-mno-unaligned-access Force all memory accesses to be aligned (ARM only)
-mnocrc Disallow use of CRC instructions (ARM only)
-momit-leaf-frame-pointer
Omit frame pointer setup for leaf functions
-MP Create phony target for each dependency (other than main file)
-mqdsp6-compat Enable hexagon-qdsp6 backward compatibility
-MQ <value> Specify target to quote for dependency
-mrelax-all (integrated-as) Relax all machine instructions
-mrtd Make StdCall calling convention the default
-msoft-float Use software floating point
-mstack-alignment=<value>
Set the stack alignment
-mstackrealign Force realign the stack at entry to every function
-MT <value> Specify target for dependency
-munaligned-access Allow memory accesses to be unaligned (ARM only)
-nobuiltininc Disable builtin #include directories
-nostdinc++ Disable standard #include directories for the C++ standard library
-ObjC++ Treat source input files as Objective-C++ inputs
-objcmt-atomic-property Make migration to 'atomic' properties
-objcmt-migrate-all Enable migration to modern ObjC
-objcmt-migrate-annotation
Enable migration to property and method annotations
-objcmt-migrate-designated-init
Enable migration to infer NS_DESIGNATED_INITIALIZER for initializer methods
-objcmt-migrate-instancetype
Enable migration to infer instancetype for method result type
-objcmt-migrate-literals
Enable migration to modern ObjC literals
-objcmt-migrate-ns-macros
Enable migration to NS_ENUM/NS_OPTIONS macros
-objcmt-migrate-property
Enable migration to modern ObjC property
-objcmt-migrate-protocol-conformance
Enable migration to add protocol conformance on classes
-objcmt-migrate-readonly-property
Enable migration to modern ObjC readonly property
-objcmt-migrate-readwrite-property
Enable migration to modern ObjC readwrite property
-objcmt-migrate-subscripting
Enable migration to modern ObjC subscripting
-objcmt-ns-nonatomic-iosonly
Enable migration to use NS_NONATOMIC_IOSONLY macro for setting property's 'atomic' attribute
-objcmt-returns-innerpointer-property
Enable migration to annotate property with NS_RETURNS_INNER_POINTER
-objcmt-whitelist-dir-path=<value>
Only modify files with a filename contained in the provided directory path
-ObjC Treat source input files as Objective-C inputs
-o <file> Write output to <file>
-pg Enable mcount instrumentation
-pipe Use pipes between commands, when possible
-print-file-name=<file> Print the full library path of <file>
-print-ivar-layout Enable Objective-C Ivar layout bitmap print trace
-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
-pthread Support POSIX threads in generated code
-P Disable linemarker output in -E mode
-Qunused-arguments Don't emit warning for unused driver arguments
-relocatable-pch Whether to build a relocatable precompiled header
-rewrite-legacy-objc Rewrite Legacy Objective-C source to C++
-rewrite-objc Rewrite Objective-C source to C++
-save-temps Save intermediate compilation results
-serialize-diagnostics <value>
Serialize compiler diagnostics to a file
-std=<value> Language standard to compile for
-stdlib=<value> C++ standard library to use
-S Only run preprocess and compilation steps
--target=<value> Generate code for the given target
-time Time individual commands
-traditional-cpp Enable some traditional CPP emulation
-trigraphs Process trigraph sequences
-undef undef all system defines
-verify Verify output using a verifier
-v Show commands to run and use verbose output
-Wa,<arg> Pass the comma separated arguments in <arg> to the assembler
-Wl,<arg> Pass the comma separated arguments in <arg> to the linker
-working-directory <value>
Resolve file paths relative to the specified directory
-Wp,<arg> Pass the comma separated arguments in <arg> to the preprocessor
-W<warning> Enable the specified warning
-w Suppress all warnings
-Xanalyzer <arg> Pass <arg> to the static analyzer
-Xassembler <arg> Pass <arg> to the assembler
-Xclang <arg> Pass <arg> to the clang compiler
-Xlinker <arg> Pass <arg> to the linker
-Xpreprocessor <arg> Pass <arg> to the preprocessor
-x <language> Treat subsequent input files as having type <language>

</pre>