GCC 的简单使用
GNU C Compiler
gcc --version
gcc test.c
# 默认生成 a.out 可执行文件
gcc -o run test.c
# 生成名为 run 的可执行文件
gcc -Wall test.c
# -Wall 编译失败时输出报错信息
编译过程：预处理、编译、汇编、链接
- 预处理器 cpp
- 汇编器 as
- 链接器 ld
1. 预处理
展开源代码中的宏
# 预处理 gcc -E (Only run the preprocessor)
gcc -E -o test.i test.c
# 默认不会保留预处理阶段的中间产物，可以利用 -E 选项保留中间输出文件，以观察预处理结果
gcc -E -C -o test.i test.c
# 添加注释信息，便于理解
2. 编译
编译器的核心任务是把 C 程序翻译成机器的汇编语言（每种 CPU 架构都有不同的汇编语言）
# RTL
实际上，GCC 是一个适合多种 CPU 架构的编译器，不会把C程序直接翻译成目的机器的汇编语言，而是一种介于C语言和汇编语言之间的一个中介语言（RTL，寄存器传输语言）；
# 编译 gcc -S (Only run preprocess and compilation steps)
gcc -S test.c
# gcc默认会把汇编语言输出到临时文件，并且在汇编器执行完后立即删除
# 使用 -S 可以保留编译产物 test.s (名称相同，以 .s 结尾)
gcc -S -fverbose-asm test.c
# 添加注释
3. 汇编
因为每个机器架构都有自己的汇编语言，GCC 调用宿主系统的汇编器，把汇编语言翻译成可执行的二进制文件。
# 汇编 gcc -c (Only run preprocess, compile, and assemble steps)
gcc -c test.c
# 默认产生文件 test.o（此时还不能直接执行），链接器执行完后会自动删除对象文件
gcc -g -o test -Wa,-a=test.list,-L test.c
#
4. 链接
链接器把多个二进制对象文件链接成单一的可执行文件，（标准链接库的大部分内容一般被放在 libc.a 中，或放在动态链接的共享版本 libc.so 中）
文件类型：
.cC 语言源代码，在编译之前要先进行预处理.iC 程序预处理的结果，可以被编译.hC 语言头文件.s汇编语言.S有 C 预处理指令的汇编语言
gcc -help
OVERVIEW: clang LLVM compiler
USAGE: clang [options] <inputs>
OPTIONS:
-### Print (but do not run) the commands to run for this compilation
--analyzer-output <value>
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 <value>
Output path for the plist report
-B <dir> Add <dir> to search path for binaries and object files used implicitly
-CC Include comments from within macros in preprocessed output
-cfguard Emit tables required for Windows Control Flow Guard.
-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=<value> OpenCL language standard to compile for.
-cl-strict-aliasing OpenCL only. This option is added for compatibility with OpenCL 1.0.
-cl-uniform-work-group-size
OpenCL only. Defines that the global work-size be a multiple of the work-group size specified to clEnqueueNDRangeKernel
-cl-unsafe-math-optimizations
OpenCL only. Allow unsafe floating-point optimizations. Also implies -cl-no-signed-zeros and -cl-mad-enable.
--config <value> Specifies configuration file
--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=<value> 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-include-ptx=<value>
Include PTX for the follwing GPU architecture (e.g. sm_35) or 'all'. May be specified more than once.
--cuda-noopt-device-debug
Enable device-side debug info generation. Disables ptxas optimizations.
--cuda-path-ignore-env Ignore environment variables to detect CUDA installation
--cuda-path=<value> CUDA installation path
-cxx-isystem <directory>
Add directory to the C++ SYSTEM include search path
-C Include comments in preprocessed output
-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
-dI Print include directives in -E mode in addition to normal output
-dM Print macro definitions in -E mode instead of normal output
-D <macro>=<value> Define <macro> to <value> (or 1 if <value> omitted)
-emit-ast Emit Clang AST files for source inputs
-emit-llvm Use the LLVM representation for assembler and object files
-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang<value>
Trivial automatic variable initialization to zero is only here for benchmarks, it'll eventually be removed, and I'm OK with that because I'm only using it to benchmark
-E Only run the preprocessor
-faddrsig Emit an address-significance table
-faligned-allocation Enable C++17 aligned allocation functions
-fallow-editor-placeholders
Treat editor placeholders as valid source code
-fansi-escape-codes Use ANSI escape codes for diagnostics
-fapinotes-cache-path=<directory>
Does nothing; API notes are no longer cached separately from modules
-fapinotes-modules Enable module-based external API notes support
-fapinotes-swift-version=<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=<file>
Use the last modification time of <file> as the build session timestamp
-fbuild-session-timestamp=<time since Epoch in seconds>
Time when the current build session started
-fbuiltin-module-map Load the clang builtins module map file.
-fc++-static-destructors
Enable C++ static destructor registration (the default)
-fcf-protection=<value> Instrument control-flow architecture protection. Options: return, branch, full, none.
-fcf-protection Enable cf-protection in 'full' mode
-fchar8_t Enable C++ builtin type char8_t
-fclang-abi-compat=<version>
Attempt to match the ABI of Clang <version>
-fcolor-diagnostics Use colors in diagnostics
-fcomment-block-commands=<arg>
Treat each comma separated argument in <arg> as a documentation comment block command
-fcomplete-member-pointers
Require member pointer base types to be complete if they would be significant under the Microsoft ABI
-fcoroutines-ts Enable support for the C++ Coroutines TS
-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.
-fcuda-rdc Generate relocatable device code, also known as separate compilation mode.
-fcuda-short-ptr Use 32-bit pointers for accessing const/local/shared address spaces.
-fcxx-exceptions Enable C++ exceptions
-fdata-sections Place each data in its own section (ELF Only)
-fdebug-info-for-profiling
Emit extra debug info to make sample profile more accurate.
-fdebug-macro Emit macro debug information
-fdebug-prefix-map=<value>
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
-fdelete-null-pointer-checks
Treat usage of null pointers as undefined behavior.
-fdiagnostics-absolute-paths
Print absolute paths in diagnostics
-fdiagnostics-hotness-threshold=<number>
Prevent optimization remarks from being output if they do not have at least this profile count
-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
-fdigraphs Enable alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:' (default)
-fdiscard-value-names Discard value names in LLVM IR
-fdollars-in-identifiers
Allow '$' in identifiers
-fdouble-square-bracket-attributes
Enable '[[]]' attributes in all C and C++ language modes
-fdwarf-exceptions Use DWARF style exceptions
-fembed-bitcode-marker Embed placeholder LLVM IR data as a marker
-fembed-bitcode=<option>
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
-fenable-matrix Enable matrix data type and related builtin functions
-fexceptions Enable support for exception handling
-fexperimental-isel Enables the experimental global instruction selector
-fexperimental-new-pass-manager
Enables an experimental new pass manager in LLVM.
-ffast-math Allow aggressive, lossy floating-point optimizations
-ffine-grained-bitfield-accesses
Use separate accesses for consecutive bitfield runs with legal widths and alignments.
-ffixed-point Enable fixed point types
-ffixed-r19 Reserve register r19 (Hexagon only)
-ffixed-r9 Reserve the r9 register (ARM only)
-ffixed-x18 Reserve the x18 register (AArch64 only)
-ffixed-x20 Reserve the x20 register (AArch64 only)
-fforce-emit-vtables Emits more virtual tables to improve devirtualization
-fforce-enable-int128 Enable support for int128_t type
-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
-fimplicit-module-maps Implicitly search the file system for module map files.
-finline-functions Inline suitable functions
-finline-hint-functions Inline functions which are (explicitly or implicitly) marked inline
-finstrument-function-entry-bare
Instrument function entry only, after inlining, without arguments to the instrumentation call
-finstrument-functions-after-inlining
Like -finstrument-functions, but insert the calls after inlining
-finstrument-functions Generate calls to instrument function entry and exit
-fintegrated-as Enable the integrated assembler
-flto-jobs=<value> 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=<value> 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=<value>
Specify the maximum alignment to enforce on pointers lacking an explicit alignment
-fmerge-all-constants Allow merging of constants
-fmodule-file=[<name>=]<file>
Specify the mapping of module name to precompiled module file, or load a module file if name is omitted.
-fmodule-map-file=<file>
Load this module map file
-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-disable-diagnostic-validation
Disable validation of the diagnostic options when loading the 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-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-ts Enable support for the C++ Modules TS
-fmodules-user-build-path <directory>
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=<value>
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=<value> Microsoft compiler version number to report in _MSC_VER (0 = don't define it (default))
-fnew-alignment=<align> Specifies the largest alignment guaranteed by '::operator new(size_t)'
-fno-access-control Disable C++ access control
-fno-addrsig Don't emit an address-significance table
-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-<value> Disable implicit builtin knowledge of a specific function
-fno-builtin Disable implicit builtin knowledge of functions
-fno-c++-static-destructors
Disable C++ static destructor registration
-fno-char8_t Disable C++ builtin type char8_t
-fno-common Compile common globals like normal definitions
-fno-complete-member-pointers
Do not require member pointer base types to be complete if they would be significant under the Microsoft ABI
-fno-constant-cfstrings Disable creation of CodeFoundation-type constant strings
-fno-coverage-mapping Disable code coverage analysis
-fno-crash-diagnostics Disable auto-generation of preprocessed source files and a script for reproduction during a clang crash
-fno-debug-info-for-profiling
Do not emit extra debug info for sample profiler.
-fno-debug-macro Do not emit macro debug information
-fno-declspec Disallow __declspec as a keyword
-fno-delayed-template-parsing
Disable delayed template parsing
-fno-delete-null-pointer-checks
Do not treat usage of null pointers as undefined behavior.
-fno-diagnostics-fixit-info
Do not include fixit information in diagnostics
-fno-digraphs Disallow alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:'
-fno-discard-value-names
Do not discard value names in LLVM IR
-fno-dollars-in-identifiers
Disallow '$' in identifiers
-fno-double-square-bracket-attributes
Disable '[[]]' attributes in all C and C++ language modes
-fno-elide-constructors Disable C++ copy constructor elision
-fno-elide-type Do not elide types when printing diagnostics
-fno-experimental-isel Disables the experimental global instruction selector
-fno-experimental-new-pass-manager
Disables an experimental new pass manager in LLVM.
-fno-fine-grained-bitfield-accesses
Use large-integer access for consecutive bitfield runs.
-fno-fixed-point Disable fixed point types
-fno-force-enable-int128
Disable support for int128_t type
-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-plt Do not use the PLT to make function calls
-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-register-global-dtors-with-atexit
Don't use atexit or __cxa_atexit to register global destructors
-fno-reroll-loops Turn off loop reroller
-fno-rtlib-add-rpath Do not add -rpath with architecture-specific resource directory to the linker flags
-fno-rtti-data Control emission of RTTI data
-fno-rtti Disable generation of rtti information
-fno-sanitize-address-poison-class-member-array-new-cookie
Disable poisoning array cookies when using class member operator new[] in AddressSanitizer
-fno-sanitize-address-use-after-scope
Disable use-after-scope detection in AddressSanitizer
-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=<value>
Disable specified features of coverage instrumentation for Sanitizers
-fno-sanitize-memory-track-origins
Disable origins tracking in MemorySanitizer
-fno-sanitize-memory-use-after-dtor
Disable use-after-destroy detection in MemorySanitizer
-fno-sanitize-recover=<value>
Disable recovery for specified sanitizers
-fno-sanitize-stats Disable sanitizer statistics gathering.
-fno-sanitize-thread-atomics
Disable atomic operations instrumentation in ThreadSanitizer
-fno-sanitize-thread-func-entry-exit
Disable function entry/exit instrumentation in ThreadSanitizer
-fno-sanitize-thread-memory-access
Disable memory access instrumentation in ThreadSanitizer
-fno-sanitize-trap=<value>
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-check Disable stack checking
-fno-stack-protector Disable the use of stack protectors
-fno-stack-size-section Don't emit section containing metadata on function stack sizes
-fno-standalone-debug Limit debug information produced to reduce size of debug binary
-fno-strict-float-cast-overflow
Relax language rules and try to match the behavior of the target's native float-to-int conversion instructions
-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-runtime=<value> Specify the target Objective-C runtime kind and version
-fobjc-weak Enable ARC-style weak references in Objective-C
-fopenmp-simd Emit OpenMP code only for SIMD-based constructs.
-fopenmp-targets=<value>
Specify comma-separated list of triples OpenMP offloading targets to be supported
-fopenmp Parse OpenMP pragmas and generate parallel code.
-foptimization-record-file=<value>
Specify the file name of any generated YAML optimization record
-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
-fplt Use the PLT to make function calls
-fplugin=<dsopath> Load the named plugin (dynamic shared object)
-fprebuilt-module-path=<directory>
Specify the prebuilt module path
-fprofile-generate=<directory>
Generate instrumented code to collect execution counts into <directory>/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=<file>
Generate instrumented code to collect execution counts into <file> (overridden by LLVM_PROFILE_FILE env var)
-fprofile-instr-generate
Generate instrumented code to collect execution counts into default.profraw file (overridden by '=' form of option or LLVM_PROFILE_FILE env var)
-fprofile-instr-use=<value>
Use instrumentation data for profile-guided optimization
-fprofile-sample-accurate
Specifies that the sample profile is accurate
-fprofile-sample-use=<value>
Enable sample-based profile guided optimizations
-fprofile-use=<pathname>
Use instrumentation data for profile-guided optimization. If pathname is a directory, it reads from <pathname>/default.profdata. Otherwise, it reads from file <pathname>.
-fptrauth-calls Enable signing and authentication of all indirect calls
-fptrauth-intrinsics Enable pointer-authentication intrinsics
-fptrauth-returns Enable signing and authentication of return addresses
-fptrauth-soft Enable software lowering of pointer authentication
-freciprocal-math Allow division operations to be reassociated
-freg-struct-return Override the default ABI to return small structs in registers
-fregister-global-dtors-with-atexit
Use atexit or __cxa_atexit to register global destructors
-frelaxed-template-template-args
Enable C++17 relaxed template template argument matching
-freroll-loops Turn on loop reroller
-frtlib-add-rpath Add -rpath with architecture-specific resource directory to the linker flags
-fsanitize-address-field-padding=<value>
Level of field padding for AddressSanitizer
-fsanitize-address-globals-dead-stripping
Enable linker dead stripping of globals in AddressSanitizer
-fsanitize-address-poison-class-member-array-new-cookie
Enable poisoning array cookies when using class member operator new[] in AddressSanitizer
-fsanitize-address-use-after-scope
Enable use-after-scope detection in AddressSanitizer
-fsanitize-blacklist=<value>
Path to blacklist file for sanitizers
-fsanitize-cfi-cross-dso
Enable control flow integrity (CFI) checks for cross-DSO calls.
-fsanitize-cfi-icall-generalize-pointers
Generalize pointers in CFI indirect call type signature checks
-fsanitize-coverage=<value>
Specify the type of coverage instrumentation for Sanitizers
-fsanitize-memory-track-origins=<value>
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=<value>
Enable recovery for specified sanitizers
-fsanitize-stats Enable sanitizer statistics gathering.
-fsanitize-thread-atomics
Enable atomic operations instrumentation in ThreadSanitizer (default)
-fsanitize-thread-func-entry-exit
Enable function entry/exit instrumentation in ThreadSanitizer (default)
-fsanitize-thread-memory-access
Enable memory access instrumentation in ThreadSanitizer (default)
-fsanitize-trap=<value> Enable trapping for specified sanitizers
-fsanitize-undefined-strip-path-components=<number>
Strip (or keep only, if negative) a given number of path components when emitting check metadata.
-fsanitize=<check> 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
-fseh-exceptions Use SEH style exceptions
-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
-fsized-deallocation Enable C++14 sized global deallocation functions
-fsjlj-exceptions Use SjLj style exceptions
-fslp-vectorize Enable the superword-level parallelism vectorization passes
-fsplit-dwarf-inlining Provide minimal debug info in the object/executable to facilitate online symbolication/stack traces in the absence of .dwo/.dwp files when using Split DWARF
-fstack-check Enable stack checking
-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
-fstack-size-section Emit section containing metadata on function stack sizes
-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-float-cast-overflow
Assume that overflowing float-to-int casts are undefined (default)
-fstrict-return Always treat control flow paths that fall off the end of a non-void function as unreachable
-fstrict-vtable-pointers
Enable optimizations based on the strict rules for overwriting polymorphic C++ objects
-fthinlto-index=<value> Perform ThinLTO importing using provided function summary index
-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
-ftrigraphs Process trigraph sequences
-ftrivial-auto-var-init=<value>
Initialize trivial automatic stack variables: uninitialized (default) | pattern
-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=<value> Use the given vector functions library
-fvectorize Enable the loop vectorization passes
-fvisibility-inlines-hidden
Give inline C++ member functions hidden 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
-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-always-emit-customevents
Determine whether to always emit __xray_customevent(...) calls even if the function it appears in is not always instrumented.
-fxray-always-emit-typedevents
Determine whether to always emit __xray_typedevent(...) calls even if the function it appears in is not always instrumented.
-fxray-always-instrument= <value>
DEPRECATED: Filename defining the whitelist for imbuing the 'always instrument' XRay attribute.
-fxray-attr-list= <value>
Filename defining the list of functions/types for imbuing XRay attributes.
-fxray-instruction-threshold= <value>
Sets the minimum function size to instrument with XRay
-fxray-instrumentation-bundle= <value>
Select which XRay instrumentation points to emit. Options: all, none, function, custom. Default is 'all'.
-fxray-instrument Generate XRay instrumentation sleds on function entry and exit
-fxray-link-deps Tells clang to add the link dependencies for XRay.
-fxray-modes= <value> List of modes to link in by default into XRay instrumented binaries.
-fxray-never-instrument= <value>
DEPRECATED: Filename defining the whitelist for imbuing the 'never instrument' XRay attribute.
-fzvector Enable System z vector language extension
-F <value> Add directory to framework include search path
--gcc-toolchain=<value> 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
-gembed-source Embed source text in DWARF debug sections
-gline-tables-only Emit debug line number tables only
-gmodules Generate debug info with external references to clang modules or precompiled headers
-gno-embed-source Restore the default behavior of not embedding source text in DWARF debug sections
-gz=<value> DWARF debug sections compression type
-gz DWARF debug sections compression type
-G <size> Put objects of at most <size> bytes into small data section (MIPS / Hexagon)
-g Generate source-level debug information
--help-hidden Display help for hidden options
-help Display available options
--hip-device-lib-path=<value>
HIP device library path
--hip-device-lib=<value>
HIP device library
--hip-link Link clang-offload-bundler bundles for HIP
-H Show header includes and nesting depth
-I- Restrict all prior -I flags to double-quoted inclusion and remove current directory from include path
-iapinotes-modules <directory>
Add directory to the API notes search path referenced by module name
-idirafter <value> Add directory to AFTER include search path
-iframeworkwithsysroot <directory>
Add directory to SYSTEM framework search path, absolute paths are relative to -isysroot
-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
-index-ignore-system-symbols
Ignore symbols from system headers
-index-record-codegen-name
Record the codegen name for symbols
-index-store-path <value>
Enable indexing with the specified data store path
-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-after <directory>
Add directory to end of the SYSTEM include search path
-isystem <directory> Add directory to SYSTEM include search path
-ivfsoverlay <value> Overlay the virtual filesystem described by file over the real file system
-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 <dir> Add directory to include search path
-L <dir> Add directory to library 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/Mips only)
-MD Write a depfile containing user and system headers
-meabi <value> Set EABI type, e.g. 4, 5 or gnu (default depends on triple)
-membedded-data Place constants in the .rodata section instead of the .sdata section even if they meet the -G <size> threshold (MIPS)
-mexecute-only Disallow generation of data access to code sections (ARM only)
-mextern-sdata Assume that externally defined data is in the small data if it meets the -G <size> threshold (MIPS)
-mfentry Insert calls to fentry at function entry (x86 only)
-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 <file> Write depfile output from -MMD, -MD, -MM, or -M to <file>
-mgeneral-regs-only Generate code which only uses the general purpose registers (AArch64 only)
-mglobal-merge Enable merging of globals
-mgpopt Use GP relative accesses for symbols known to be in a small data section (MIPS)
-MG Add missing headers to depfile
-mhvx-length=<value> Set Hexagon Vector Length
-mhvx=<value> Enable Hexagon 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
-mindirect-jump=<value> Change indirect jump instructions to inhibit speculation
-mios-version-min=<value>
Set iOS deployment target
-MJ <value> Write a compilation database entry per input
-mllvm <value> Additional arguments to forward to LLVM's option processing
-mlocal-sdata Extend the -G behaviour to object local data (MIPS)
-mlong-calls Generate branches with extended addressability, usually via indirect jumps.
-mmacosx-version-min=<value>
Set Mac OS X deployment target
-mmadd4 Enable the generation of 4-operand madd.s, madd.d and related instructions.
-MMD Write a depfile containing user headers
-mmemops Enable generation of memop instructions
-mms-bitfields Set the default structure layout to be compatible with the Microsoft compiler standard
-mmsa Enable MSA ASE (MIPS only)
-mmt Enable MT 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-crc Disallow use of CRC instructions (Mips only)
-mno-embedded-data Do not place constants in the .rodata section instead of the .sdata if they meet the -G <size> threshold (MIPS)
-mno-execute-only Allow generation of data access to code sections (ARM only)
-mno-extern-sdata Do not assume that externally defined data is in the small data if it meets the -G <size> threshold (MIPS)
-mno-fix-cortex-a53-835769
Don't workaround Cortex-A53 erratum 835769 (AArch64 only)
-mno-global-merge Disable merging of globals
-mno-gpopt Do not use GP relative accesses for symbols known to be in a small data section (MIPS)
-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-local-sdata Do not extend the -G behaviour to object local data (MIPS)
-mno-long-calls Restore the default behaviour of not generating long calls
-mno-madd4 Disable the generation of 4-operand madd.s, madd.d and related instructions.
-mno-memops Disable generation of memop instructions
-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-mt Disable MT ASE (MIPS only)
-mno-neg-immediates Disallow converting instructions with negative immediates to their negation or inversion.
-mno-nvj Disable generation of new-value jumps
-mno-nvs Disable generation of new-value stores
-mno-outline Disable function outlining (AArch64 only)
-mno-packets Disable generation of instruction packets
-mno-relax Disable linker relaxation
-mno-restrict-it Allow generation of deprecated IT blocks for ARMv8. It is off by default for ARMv8 Thumb mode
-mno-stack-arg-probe Disable stack probes which are enabled by default
-mno-unaligned-access Force all memory accesses to be aligned (AArch32/AArch64 only)
-mno-xnack Disable XNACK (AMDGPU only)
-mnocrc Disallow use of CRC instructions (ARM only)
-mnvj Enable generation of new-value jumps
-mnvs Enable generation of new-value stores
-module-dependency-dir <value>
Directory to dump module dependencies to
-module-file-info Provide information about a particular module file
-momit-leaf-frame-pointer
Omit frame pointer setup for leaf functions
-moutline Enable function outlining (AArch64 only)
-mpackets Enable generation of instruction packets
-mpie-copy-relocations Use copy relocations support for PIE builds
-mprefer-vector-width=<value>
Specifies preferred vector width for auto-vectorization. Defaults to 'none' which allows target specific decisions.
-MP Create phony target for each dependency (other than main file)
-mqdsp6-compat Enable hexagon-qdsp6 backward compatibility
-MQ <value> Specify name of main file output to quote in depfile
-mrelax-all (integrated-as) Relax all machine instructions
-mrelax Enable linker relaxation
-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=<value>
Set the stack alignment
-mstack-arg-probe Enable stack probes
-mstack-probe-size=<value>
Set the stack probe size
-mstackrealign Force realign the stack at entry to every function
-mthread-model <value> The thread model to use, e.g. posix, single (posix by default)
-mtp=<value> Read thread pointer from coprocessor register (ARM only)
-MT <value> 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
-mxnack Enable XNACK (AMDGPU only)
-M Like -MD, but also implies -E and writes to stdout by default
--no-cuda-gpu-arch=<value>
Remove GPU architecture (e.g. sm_35) from the list of GPUs to compile for. 'all' resets the list to its default value.
--no-cuda-include-ptx=<value>
Do not include PTX for the follwing GPU architecture (e.g. sm_35) or 'all'. May be specified more than once.
--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=<prefix>
Treat all #include paths starting with <prefix> 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=<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
--precompile Only precompile the input
-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 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-resource-dir Print the resource directory pathname
-print-search-dirs Print the paths used for finding libraries and programs
-pthread Support POSIX threads in generated code
--ptxas-path=<value> Path to ptxas (used for compiling CUDA code)
-P Disable linemarker output in -E mode
-Qn Do not emit metadata containing compiler name and version
-Qunused-arguments Don't emit warning for unused driver arguments
-Qy Emit metadata containing compiler name and version
-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=<value> Report transformation analysis from optimization passes whose name matches the given POSIX regular expression
-Rpass-missed=<value> Report missed transformations by optimization passes whose name matches the given POSIX regular expression
-Rpass=<value> Report transformations performed by optimization passes whose name matches the given POSIX regular expression
-rtlib=<value> Compiler runtime library to use
-R<remark> Enable the specified remark
-save-stats=<value> Save llvm statistics.
-save-stats Save llvm statistics.
-save-temps=<value> Save intermediate compilation results.
-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
--system-header-prefix=<prefix>
Treat all #include paths starting with <prefix> as including a system header.
-S Only run preprocess and compilation steps
-target-variant <value> Generate code that may run on a particular variant of the deployment target
--target=<value> Generate code for the given target
-Tbss <addr> Set starting address of BSS to <addr>
-Tdata <addr> Set starting address of DATA to <addr>
-time Time individual commands
-traditional-cpp Enable some traditional CPP emulation
-trigraphs Process trigraph sequences
-Ttext <addr> Set starting address of TEXT to <addr>
-T <script> Specify <script> as linker script
-undef undef all system defines
-U <macro> Undefine macro <macro>
--verify-debug-info Verify the binary representation of debug output
-verify-pch Load and verify that a pre-compiled header file is not stale
--version Print version information
-v Show commands to run and use verbose output
-Wa,<arg> Pass the comma separated arguments in <arg> to the assembler
-Wdeprecated Enable warnings for deprecated constructs and define __DEPRECATED
-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
-Xcuda-fatbinary <arg> Pass <arg> to fatbinary invocation
-Xcuda-ptxas <arg> Pass <arg> to the ptxas assembler
-Xlinker <arg> Pass <arg> to the linker
-Xopenmp-target=<triple> <arg>
Pass <arg> to the target offloading toolchain identified by <triple>.
-Xopenmp-target <arg> Pass <arg> to the target offloading toolchain.
-Xpreprocessor <arg> Pass <arg> to the preprocessor
-x <language> Treat subsequent input files as having type <language>
-z <arg> Pass -z <arg> to the linker