clang及参数和生成中间代码
Clang是一个C语言、C++、Objective-C、Objective-C++语言的轻量级编译器。源代码发布于BSD协议下。Clang将支持其普通lambda表达式、返回类型的简化处理以及更好的处理constexpr关键字。
Clang是一个C++编写、基于LLVM、发布于LLVM BSD许可证下的C/C++/Objective-C/Objective-C++编译器。它与GNU C语言规范几乎完全兼容（当然，也有部分不兼容的内容，包括编译命令选项也会有点差异），并在此基础上增加了额外的语法特性，比如C函数重载（通过__attribute__((overloadable))来修饰函数），其目标（之一）就是超越GCC。
Clang 的开发背景
由于 GNU 编译器套装 (GCC) 系统庞大，而且 Apple 大量使用的 Objective-C 在 GCC 中优先级较低，同时 GCC 作为一个纯粹的编译系统，与 IDE 配合并不优秀，Apple 决定从零开始写 C family 的前端，也就是基于 LLVM 的 Clang 了。Clang 由 Apple 公司开发，源代码授权使用 BSD 的开源授权。
相比于 GCC，Clang 具有如下优点：
编译速度快：在某些平台上，Clang 的编译速度显著的快过 GCC。
占用内存小：Clang 生成的 AST 所占用的内存是 GCC 的五分之一左右。
模块化设计：Clang 采用基于库的模块化设计，易于 IDE 集成及其他用途的重用。
诊断信息可读性强：在编译过程中，Clang 创建并保留了大量详细的元数据 (metadata)，有利于调试和错误报告。
设计清晰简单，容易理解，易于扩展增强。与代码基础古老的 GCC 相比，学习曲线平缓。
当前 Clang 还处在不断完善过程中，相比于 GCC, Clang 在以下方面还需要加强：
支持更多语言：GCC 除了支持 C/C++/Objective-C, 还支持 Fortran/Pascal/Java/Ada/Go 和其他语言。Clang 目前支持的语言有 C/C++/Objective-C/Objective-C++。
加强对 C++ 的支持：Clang 对 C++ 的支持依然落后于 GCC，Clang 还需要加强对 C++ 提供全方位支持。
支持更多平台：GCC 流行的时间比较长，已经被广泛使用，对各种平台的支持也很完备。Clang 目前支持的平台有 Linux/Windows/Mac OS。
命令行
zzx:clang zzx$ clang -help
OVERVIEW: clang LLVM compiler
USAGE: clang [options]
OPTIONS:
-### Print (but do not run) the commands to run for this compilation
--analyzer-output
Static analyzer report output format (html|plist|plist-multi-file|plist-html|text).
--analyze Run the static analyzer
-arcmt-migrate-emit-errors
Emit ARC errors even if the migrator can fix them
-arcmt-migrate-report-output
Output path for the plist report
-cl-denorms-are-zero OpenCL only. Allow denormals to be flushed to zero.
-cl-fast-relaxed-math OpenCL only. Sets -cl-finite-math-only and -cl-unsafe-math-optimizations, and defines __FAST_RELAXED_MATH__.
-cl-finite-math-only OpenCL only. Allow floating-point optimizations that assume arguments and results are not NaNs or +-Inf.
-cl-fp32-correctly-rounded-divide-sqrt
OpenCL only. Specify that single precision floating-point divide and sqrt used in the program source are correctly rounded.
-cl-kernel-arg-info OpenCL only. Generate kernel argument metadata.
-cl-mad-enable OpenCL only. Allow use of less precise MAD computations in the generated binary.
-cl-no-signed-zeros OpenCL only. Allow use of less precise no signed zeros computations in the generated binary.
-cl-opt-disable OpenCL only. This option disables all optimizations. By default optimizations are enabled.
-cl-single-precision-constant
OpenCL only. Treat double precision floating-point constant as single precision constant.
-cl-std= OpenCL language standard to compile for.
-cl-strict-aliasing OpenCL only. This option is added for compatibility with OpenCL 1.0.
-cl-unsafe-math-optimizations
OpenCL only. Allow unsafe floating-point optimizations. Also implies -cl-no-signed-zeros and -cl-mad-enable.
--cuda-compile-host-device
Compile CUDA code for both host and device (default). Has no effect on non-CUDA compilations.
--cuda-device-only Compile CUDA code for device only
--cuda-gpu-arch= CUDA GPU architecture (e.g. sm_35). May be specified more than once.
--cuda-host-only Compile CUDA code for host only. Has no effect on non-CUDA compilations.
--cuda-noopt-device-debug
Enable device-side debug info generation. Disables ptxas optimizations.
--cuda-path= CUDA installation path
-cxx-isystem
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 Filename to write DOT-formatted header dependencies to
-dependency-file
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
-fapinotes-cache-path=
Specify the API notes cache path
-fapinotes-modules Enable module-based external API notes support
-fapinotes-swift-version=
Specify the Swift version to use when filtering API notes
-fapinotes Enable external API notes support
-fapple-kext Use Apple's kernel extensions ABI
-fapple-pragma-pack Enable Apple gcc-compatible #pragma pack handling
-fapplication-extension Restrict code to those available for App Extensions
-fblocks Enable the 'blocks' language feature
-fborland-extensions Accept non-standard constructs supported by the Borland compiler
-fbuild-session-file=
Use the last modification time of as the build session timestamp
-fbuild-session-timestamp= in seconds>
Time when the current build session started
-fcolor-diagnostics Use colors in diagnostics
-fcomment-block-commands=
Treat each comma separated argument in as a documentation comment block command
-fcoverage-mapping Generate coverage mapping to enable code coverage analysis
-fcuda-approx-transcendentals
Use approximate transcendental functions
-fcuda-flush-denormals-to-zero
Flush denormal floating point values to zero in CUDA device mode.
-fcxx-exceptions Enable C++ exceptions
-fdata-sections Place each data in its own section (ELF Only)
-fdebug-prefix-map=
remap file source paths in debug info
-fdebug-types-section Place debug types in their own section (ELF Only)
-fdeclspec Allow __declspec as a keyword
-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-hotness
Enable profile hotness information in diagnostic line
-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
-fembed-bitcode-marker Embed placeholder LLVM IR data as a marker
-fembed-bitcode= Embed LLVM bitcode (option: off, all, bitcode, marker)
-fembed-bitcode Embed LLVM IR bitcode as data
-femit-all-decls Emit all declarations, even if unused
-femulated-tls Use emutls functions to access thread_local variables
-fexceptions Enable support for exception handling
-ffast-math Allow aggressive, lossy floating-point optimizations
-ffixed-r9 Reserve the r9 register (ARM only)
-ffixed-x18 Reserve the x18 register (AArch64 only)
-ffp-contract= 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
-fimplicit-module-maps Implicitly search the file system for module map files.
-finline-functions Inline suitable functions
-finline-hint-functions Inline functions wich are (explicitly or implicitly) marked inline
-finstrument-functions Generate calls to instrument function entry and exit
-fintegrated-as Enable the integrated assembler
-flto-jobs= Controls the backend parallelism of -flto=thin (default of 0 means the number of threads will be derived from the number of CPUs detected)
-flto= Set LTO mode to either 'full' or 'thin'
-flto Enable LTO in 'full' mode
-fmath-errno Require math functions to indicate errors by setting errno
-fmax-type-align=
Specify the maximum alignment to enforce on pointers lacking an explicit alignment
-fmodule-file= Load this precompiled module file
-fmodule-map-file=
Load this module map file
-fmodule-name= Specify the name of the module to build
-fmodules-cache-path=
Specify the module cache path
-fmodules-decluse Require declaration of modules used within a module
-fmodules-disable-diagnostic-validation
Disable validation of the diagnostic options when loading the module
-fmodules-ignore-macro=
Ignore the definition of the given macro when building and loading modules
-fmodules-prune-after=
Specify the interval (in seconds) after which a module file will be considered unused
-fmodules-prune-interval=
Specify the interval (in seconds) between attempts to prune the module cache
-fmodules-search-all Search even non-imported modules to resolve references
-fmodules-strict-decluse
Like -fmodules-decluse but requires all headers to be in modules
-fmodules-user-build-path
Specify the module user build path
-fmodules-validate-once-per-build-session
Don't verify input files for the modules if the module has been successfully validated or loaded during this build session
-fmodules-validate-system-headers
Validate the system headers that a module depends on when loading the module
-fmodules Enable the 'modules' language feature
-fms-compatibility-version=
Dot-separated value representing the Microsoft compiler version number to report in _MSC_VER (0 = don't define it (default))
-fms-compatibility Enable full Microsoft Visual C++ compatibility
-fms-extensions Accept some non-standard constructs supported by the Microsoft compiler
-fmsc-version= Microsoft compiler version number to report in _MSC_VER (0 = don't define it (default))
-fno-access-control Disable C++ access control
-fno-apinotes-modules Disable module-based external API notes support
-fno-apinotes Disable external API notes support
-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- 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-coverage-mapping Disable code coverage analysis
-fno-declspec Disallow __declspec as a keyword
-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-gnu-inline-asm Disable GNU style inline asm
-fno-integrated-as Disable the integrated assembler
-fno-jump-tables Do not use jump tables for lowering switches
-fno-lax-vector-conversions
Disallow implicit conversions between vectors with a different number of elements or different element types
-fno-lto Disable LTO mode (default)
-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-preserve-as-comments
Do not preserve comments in inline assembly
-fno-profile-generate Disable generation of profile instrumentation.
-fno-profile-instr-generate
Disable generation of profile instrumentation.
-fno-profile-instr-use Disable using instrumentation data for profile-guided optimization
-fno-reroll-loops Turn off loop reroller
-fno-rtti Disable generation of rtti information
-fno-sanitize-blacklist Don't use blacklist file for sanitizers
-fno-sanitize-cfi-cross-dso
Disable control flow integrity (CFI) checks for cross-DSO calls.
-fno-sanitize-coverage=
Disable specified features of coverage instrumentation for Sanitizers
-fno-sanitize-memory-track-origins
Disable origins tracking in MemorySanitizer
-fno-sanitize-recover=
Disable recovery for specified sanitizers
-fno-sanitize-stats Disable sanitizer statistics gathering.
-fno-sanitize-trap=
Disable trapping for specified sanitizers
-fno-short-wchar Force wchar_t to be an unsigned int
-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-signed-zeros Allow optimizations that ignore the sign of floating point zeros
-fno-spell-checking Disable spell-checking
-fno-stack-protector Disable the use of stack protectors
-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-trigraphs Do not process trigraph sequences
-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= Specify the target Objective-C runtime kind and version
-fobjc-weak Enable ARC-style weak references in Objective-C
-fopenmp-targets=
Specify comma-separated list of triples OpenMP offloading targets to be supported
-foptimization-record-file=
Specify the file name of any generated YAML optimization record
-fpack-struct= 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
-fplugin= Load the named plugin (dynamic shared object)
-fprebuilt-module-path=<directory>
Specify the prebuilt module path
-fprofile-generate=
Generate instrumented code to collect execution counts into /default.profraw (overridden by LLVM_PROFILE_FILE env var)
-fprofile-generate Generate instrumented code to collect execution counts into default.profraw (overridden by LLVM_PROFILE_FILE env var)
-fprofile-instr-generate=
Generate instrumented code to collect execution counts into (overridden by LLVM_PROFILE_FILE env var)
-fprofile-instr-generate
Generate instrumented code to collect execution counts into default.profraw file (overriden by '=' form of option or LLVM_PROFILE_FILE env var)
-fprofile-instr-use=
Use instrumentation data for profile-guided optimization
-fprofile-sample-use=
Enable sample-based profile guided optimizations
-fprofile-use=
Use instrumentation data for profile-guided optimization. If pathname is a directory, it reads from /default.profdata. Otherwise, it reads from file .
-freciprocal-math Allow division operations to be reassociated
-freg-struct-return Override the default ABI to return small structs in registers
-freroll-loops Turn on loop reroller
-fsanitize-address-field-padding=
Level of field padding for AddressSanitizer
-fsanitize-address-use-after-scope
Enable use-after-scope detection in AddressSanitizer
-fsanitize-blacklist=
Path to blacklist file for sanitizers
-fsanitize-cfi-cross-dso
Enable control flow integrity (CFI) checks for cross-DSO calls.
-fsanitize-coverage=
Specify the type of coverage instrumentation for Sanitizers
-fsanitize-memory-track-origins=
Enable origins tracking in MemorySanitizer
-fsanitize-memory-track-origins
Enable origins tracking in MemorySanitizer
-fsanitize-memory-use-after-dtor
Enable use-after-destroy detection in MemorySanitizer
-fsanitize-recover=
Enable recovery for specified sanitizers
-fsanitize-stats Enable sanitizer statistics gathering.
-fsanitize-trap= Enable trapping for specified sanitizers
-fsanitize-undefined-strip-path-components=
Strip (or keep only, if negative) a given number of path components when emitting check metadata.
-fsanitize= Turn on runtime checks for various forms of undefined or suspicious behavior. See user manual for available checks
-fsave-optimization-record
Generate a YAML optimization record file
-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=
Which overload candidates to show when overload resolution fails: best|all; defaults to all
-fsized-deallocation Enable C++14 sized global deallocation functions
-fsjlj-exceptions Use SjLj style exceptions
-fslp-vectorize-aggressive
Enable the BB vectorization passes
-fslp-vectorize Enable the superword-level parallelism vectorization passes
-fstack-protector-all Force the usage of stack protectors for all functions
-fstack-protector-strong
Use a strong heuristic to apply stack protectors to functions
-fstack-protector Enable stack protectors for functions potentially vulnerable to stack smashing
-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
-fstrict-vtable-pointers
Enable optimizations based on the strict rules for overwriting polymorphic C++ objects
-fthinlto-index= Perform ThinLTO importing using provided function summary index
-ftrap-function= Issue call to specified function rather than a trap instruction
-ftrapv-handler=
Specify the function to be called on overflow
-ftrapv Trap on integer overflow
-ftrigraphs Process trigraph sequences
-funique-section-names Use unique names for text and data sections (ELF Only)
-funroll-loops Turn on loop unroller
-fuse-init-array Use .init_array instead of .ctors
-fveclib= Use the given vector functions library
-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= Set the default symbol visibility for all global declarations
-fwhole-program-vtables Enables whole-program vtable optimization. Requires -flto
-fwrapv Treat signed integer overflow as two's complement
-fwritable-strings Store string literals as writable data
-fxray-instruction-threshold=
Sets the minimum function size to instrument with XRay
-fxray-instrument Generate XRay instrumentation sleds on function entry and exit
-fzvector Enable System z vector language extension
-F Add directory to framework include search path
--gcc-toolchain= Use the gcc toolchain at the given directory
-gcodeview Generate CodeView debug information
-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
-gdwarf-5 Generate source-level debug information with dwarf version 5
-gline-tables-only Emit debug line number tables only
-gmodules Generate debug info with external references to clang modules or precompiled headers
-g Generate source-level debug information
-help Display available options
-H Show header includes and nesting depth
-iapinotes-modules
Add directory to the API notes search path referenced by module name
-idirafter Add directory to AFTER include search path
-iframework Add directory to SYSTEM framework search path
-imacros Include macros from file before parsing
-include-pch Include precompiled header file
-include Include file before parsing
-index-header-map Make the next included directory (-I or -F) an indexer header map
-index-ignore-system-symbols
Ignore symbols from system headers
-index-record-codegen-name
Record the codegen name for symbols
-index-store-path
Enable indexing with the specified data store path
-iprefix Set the -iwithprefix/-iwithprefixbefore prefix
-iquote Add directory to QUOTE include search path
-isysroot Set the system root directory (usually /)
-isystem-after
Add directory to end of the SYSTEM include search path
-isystem Add directory to SYSTEM include search path
-ivfsoverlay Overlay the virtual filesystem described by file over the real file system
-iwithprefixbefore
Set directory to include search path with prefix
-iwithprefix Set directory to SYSTEM include search path with prefix
-iwithsysroot
Add directory to SYSTEM include search path, absolute paths are relative to -isysroot
-I Add directory to include search path
-mabicalls Enable SVR4-style position-independent code (Mips only)
-malign-double Align doubles to two words in structs (x86 only)
-mbackchain Link stack frames through backchain on System Z
-mcrc Allow use of CRC instructions (ARM only)
-MD Write a depfile containing user and system headers
-meabi Set EABI type, e.g. 4, 5 or gnu (default depends on triple)
-mfix-cortex-a53-835769 Workaround Cortex-A53 erratum 835769 (AArch64 only)
-mfp32 Use 32-bit floating point registers (MIPS only)
-mfp64 Use 64-bit floating point registers (MIPS only)
-MF Write depfile output from -MMD, -MD, -MM, or -M to
-mgeneral-regs-only Generate code which only uses the general purpose registers (AArch64 only)
-mglobal-merge Enable merging of globals
-MG Add missing headers to depfile
-mhvx-double Enable Hexagon Double Vector eXtensions
-mhvx Enable Hexagon Vector eXtensions
-miamcu Use Intel MCU ABI
--migrate Run the migrator
-mincremental-linker-compatible
(integrated-as) Emit an object file which can be used with an incremental linker
-mios-version-min=
Set iOS deployment target
-mllvm Additional arguments to forward to LLVM's option processing
-mlong-calls Generate an indirect jump to enable jumps further than 64M
-mmacosx-version-min=
Set Mac OS X deployment target
-MMD Write a depfile containing user headers
-mms-bitfields Set the default structure layout to be compatible with the Microsoft compiler standard
-mmsa Enable MSA ASE (MIPS only)
-MM Like -MMD, but also implies -E and writes to stdout by default
-mno-abicalls Disable SVR4-style position-independent code (Mips only)
-mno-fix-cortex-a53-835769
Don't workaround Cortex-A53 erratum 835769 (AArch64 only)
-mno-global-merge Disable merging of globals
-mno-hvx-double Disable Hexagon Double Vector eXtensions
-mno-hvx Disable Hexagon Vector eXtensions
-mno-implicit-float Don't generate implicit floating point instructions
-mno-incremental-linker-compatible
(integrated-as) Emit an object file which cannot be used with an incremental linker
-mno-long-calls Restore the default behaviour of not generating long calls
-mno-movt Disallow use of movt/movw pairs (ARM only)
-mno-ms-bitfields Do not set the default structure layout to be compatible with the Microsoft compiler standard
-mno-msa Disable MSA ASE (MIPS only)
-mno-restrict-it Allow generation of deprecated IT blocks for ARMv8. It is off by default for ARMv8 Thumb mode
-mno-unaligned-access Force all memory accesses to be aligned (AArch32/AArch64 only)
-mnocrc Disallow use of CRC instructions (ARM only)
-module-dependency-dir <value>
Directory to dump module dependencies to
-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 Specify name of main file output to quote in depfile
-mrelax-all (integrated-as) Relax all machine instructions
-mrestrict-it Disallow generation of deprecated IT blocks for ARMv8. It is on by default for ARMv8 Thumb mode.
-mrtd Make StdCall calling convention the default
-msoft-float Use software floating point
-mstack-alignment=
Set the stack alignment
-mstack-probe-size=
Set the stack probe size
-mstackrealign Force realign the stack at entry to every function
-mthread-model The thread model to use, e.g. posix, single (posix by default)
-MT Specify name of main file output in depfile
-munaligned-access Allow memory accesses to be unaligned (AArch32/AArch64 only)
-MV Use NMake/Jom format for the depfile
-M Like -MD, but also implies -E and writes to stdout by default
--no-cuda-version-check Don't error out if the detected version of the CUDA install is too low for the requested CUDA gpu architecture.
--no-system-header-prefix=
Treat all #include paths starting with as not including a system header.
-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-dot-syntax
Enable migration of setter/getter messages to property-dot syntax
-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=
Only modify files with a filename contained in the provided directory path
-ObjC Treat source input files as Objective-C inputs
-o Write output to
-pg Enable mcount instrumentation
-pipe Use pipes between commands, when possible
-print-file-name= Print the full library path of
-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= Print the full program path of
-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++
-Rpass-analysis= Report transformation analysis from optimization passes whose name matches the given POSIX regular expression
-Rpass-missed= Report missed transformations by optimization passes whose name matches the given POSIX regular expression
-Rpass= Report transformations performed by optimization passes whose name matches the given POSIX regular expression
-R Enable the specified remark
-save-stats= Save llvm statistics.
-save-stats Save llvm statistics.
-save-temps= Save intermediate compilation results.
-save-temps Save intermediate compilation results
-serialize-diagnostics
Serialize compiler diagnostics to a file
-std= Language standard to compile for
-stdlib= C++ standard library to use
--system-header-prefix=
Treat all #include paths starting with as including a system header.
-S Only run preprocess and compilation steps
--target= 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-debug-info Verify the binary representation of debug output
-verify-pch Load and verify that a pre-compiled header file is not stale
-v Show commands to run and use verbose output
-Wa, Pass the comma separated arguments in to the assembler
-Wl, Pass the comma separated arguments in to the linker
-working-directory
Resolve file paths relative to the specified directory
-Wp, Pass the comma separated arguments in to the preprocessor
-W Enable the specified warning
-w Suppress all warnings
-Xanalyzer Pass to the static analyzer
-Xassembler Pass to the assembler
-Xclang Pass to the clang compiler
-Xcuda-fatbinary Pass to fatbinary invocation
-Xcuda-ptxas Pass to the ptxas assembler
-Xlinker Pass to the linker
-Xpreprocessor Pass to the preprocessor
-x Treat subsequent input files as having type
-z Pass -z to the linker 生成中间代码
2.c代码
#include 生成中间代码
clang -emit-llvm 2.c -S -o 2.o