llvm-project/clang/docs/ClangCommandLineReference.rst

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Clang command line argument reference
=====================================
.. contents::
:local:
Introduction
============
This page lists the command line arguments currently supported by the
GCC-compatible ``clang`` and ``clang++`` drivers.
.. program:: clang
.. option:: -B<dir>, --prefix <arg>, --prefix=<arg>
Add <dir> to search path for binaries and object files used implicitly
.. option:: -F<arg>
Add directory to framework include search path
.. option:: -ObjC
Treat source input files as Objective-C inputs
.. program:: clang1
.. option:: -ObjC++
.. program:: clang
Treat source input files as Objective-C++ inputs
.. option:: -Qn
Do not emit metadata containing compiler name and version
.. option:: -Qunused-arguments
Don't emit warning for unused driver arguments
.. option:: -Qy
Emit metadata containing compiler name and version
.. option:: -Wa,<arg>,<arg2>...
Pass the comma separated arguments in <arg> to the assembler
.. option:: -Wlarge-by-value-copy=<arg>
.. option:: -Xarch\_<arg1> <arg2>
.. option:: -Xcuda-fatbinary <arg>
Pass <arg> to fatbinary invocation
.. option:: -Xcuda-ptxas <arg>
Pass <arg> to the ptxas assembler
.. option:: -Xopenmp-target <arg>
Pass <arg> to the target offloading toolchain.
.. program:: clang1
.. option:: -Xopenmp-target=<triple> <arg>
.. program:: clang
Pass <arg> to the target offloading toolchain identified by <triple>.
.. option:: -Z<arg>
.. option:: -a<arg>, --profile-blocks
.. option:: -all\_load
.. option:: -allowable\_client <arg>
.. option:: --analyze
Run the static analyzer
.. option:: --analyze-auto
.. option:: --analyzer-no-default-checks
.. option:: --analyzer-output<arg>
Static analyzer report output format (html\|plist\|plist-multi-file\|plist-html\|text).
.. option:: -ansi, --ansi
.. option:: -arch <arg>
.. program:: clang1
.. option:: -arch\_errors\_fatal
.. program:: clang
.. program:: clang2
.. option:: -arch\_only <arg>
.. program:: clang
.. option:: -arcmt-migrate-emit-errors
Emit ARC errors even if the migrator can fix them
.. option:: -arcmt-migrate-report-output <arg>
Output path for the plist report
.. option:: --autocomplete=<arg>
.. option:: -bind\_at\_load
.. option:: -bundle
.. program:: clang1
.. option:: -bundle\_loader <arg>
.. program:: clang
.. option:: -cfguard
Emit tables required for Windows Control Flow Guard.
.. option:: -client\_name<arg>
.. option:: -compatibility\_version<arg>
.. option:: --config <arg>
Specifies configuration file
.. option:: --constant-cfstrings
.. option:: -coverage, --coverage
.. option:: --cuda-compile-host-device
Compile CUDA code for both host and device (default). Has no effect on non-CUDA compilations.
.. option:: --cuda-device-only
Compile CUDA code for device only
.. option:: --cuda-gpu-arch=<arg>, --no-cuda-gpu-arch=<arg>
CUDA GPU architecture (e.g. sm\_35). May be specified more than once.
.. option:: --cuda-host-only
Compile CUDA code for host only. Has no effect on non-CUDA compilations.
.. option:: --cuda-include-ptx=<arg>, --no-cuda-include-ptx=<arg>
Include PTX for the follwing GPU architecture (e.g. sm\_35) or 'all'. May be specified more than once.
.. option:: --cuda-noopt-device-debug, --no-cuda-noopt-device-debug
Enable device-side debug info generation. Disables ptxas optimizations.
.. option:: -current\_version<arg>
.. option:: -dead\_strip
.. option:: -dependency-dot <arg>
Filename to write DOT-formatted header dependencies to
.. option:: -dependency-file <arg>
Filename (or -) to write dependency output to
.. option:: -dumpmachine
.. option:: -dumpversion
.. option:: --dyld-prefix=<arg>, --dyld-prefix <arg>
.. option:: -dylib\_file <arg>
.. option:: -dylinker
.. program:: clang1
.. option:: -dylinker\_install\_name<arg>
.. program:: clang
.. option:: -dynamic
.. option:: -dynamiclib
.. option:: -emit-ast
Emit Clang AST files for source inputs
.. option:: -exported\_symbols\_list <arg>
.. option:: -faligned-new=<arg>
.. option:: -fcuda-approx-transcendentals, -fno-cuda-approx-transcendentals
Use approximate transcendental functions
.. option:: -fcuda-flush-denormals-to-zero, -fno-cuda-flush-denormals-to-zero
Flush denormal floating point values to zero in CUDA device mode.
.. option:: -fcuda-rdc, -fno-cuda-rdc
Generate relocatable device code, also known as separate compilation mode.
.. option:: -ffixed-r19
Reserve the r19 register (Hexagon only)
.. option:: -fheinous-gnu-extensions
.. option:: -flat\_namespace
.. option:: -fopenmp-targets=<arg1>,<arg2>...
Specify comma-separated list of triples OpenMP offloading targets to be supported
.. option:: -force\_cpusubtype\_ALL
.. program:: clang1
.. option:: -force\_flat\_namespace
.. program:: clang
.. program:: clang2
.. option:: -force\_load <arg>
.. program:: clang
.. option:: -framework <arg>
.. option:: -frtlib-add-rpath, -fno-rtlib-add-rpath
Add -rpath with architecture-specific resource directory to the linker flags
.. option:: --gcc-toolchain=<arg>, -gcc-toolchain <arg>
Use the gcc toolchain at the given directory
.. option:: -gcodeview
Generate CodeView debug information
.. option:: -headerpad\_max\_install\_names<arg>
.. option:: -help, --help
Display available options
.. option:: --help-hidden
Display help for hidden options
.. option:: -image\_base <arg>
.. option:: -index-header-map
Make the next included directory (-I or -F) an indexer header map
.. option:: -init <arg>
.. option:: -install\_name <arg>
.. option:: -keep\_private\_externs
.. option:: -lazy\_framework <arg>
.. program:: clang1
.. option:: -lazy\_library <arg>
.. program:: clang
.. option:: -mbig-endian, -EB
.. option:: --migrate
Run the migrator
.. option:: -mios-simulator-version-min=<arg>, -miphonesimulator-version-min=<arg>
.. option:: -mlinker-version=<arg>
.. option:: -mlittle-endian, -EL
.. option:: -mllvm <arg>
Additional arguments to forward to LLVM's option processing
.. option:: -module-dependency-dir <arg>
Directory to dump module dependencies to
.. option:: -mtvos-simulator-version-min=<arg>, -mappletvsimulator-version-min=<arg>
.. option:: -multi\_module
.. option:: -multiply\_defined <arg>
.. program:: clang1
.. option:: -multiply\_defined\_unused <arg>
.. program:: clang
.. option:: -mwatchos-simulator-version-min=<arg>, -mwatchsimulator-version-min=<arg>
.. option:: --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.
.. option:: -no-integrated-cpp, --no-integrated-cpp
.. option:: -no\_dead\_strip\_inits\_and\_terms
.. option:: -nobuiltininc
Disable builtin #include directories
.. option:: -nocudainc
.. option:: -nocudalib
.. option:: -nodefaultlibs
.. option:: -nofixprebinding
.. option:: -nolibc
.. option:: -nomultidefs
.. option:: -nopie, -no-pie
.. option:: -noprebind
.. option:: -noseglinkedit
.. option:: -nostartfiles
.. option:: -nostdinc, --no-standard-includes
.. program:: clang1
.. option:: -nostdinc++
.. program:: clang
Disable standard #include directories for the C++ standard library
.. option:: -nostdlib, --no-standard-libraries
.. program:: clang1
.. option:: -nostdlib++
.. program:: clang
.. option:: -nostdlibinc
.. option:: -o<file>, --output <arg>, --output=<arg>
Write output to <file>
.. option:: -objcmt-atomic-property
Make migration to 'atomic' properties
.. option:: -objcmt-migrate-all
Enable migration to modern ObjC
.. option:: -objcmt-migrate-annotation
Enable migration to property and method annotations
.. option:: -objcmt-migrate-designated-init
Enable migration to infer NS\_DESIGNATED\_INITIALIZER for initializer methods
.. option:: -objcmt-migrate-instancetype
Enable migration to infer instancetype for method result type
.. option:: -objcmt-migrate-literals
Enable migration to modern ObjC literals
.. option:: -objcmt-migrate-ns-macros
Enable migration to NS\_ENUM/NS\_OPTIONS macros
.. option:: -objcmt-migrate-property
Enable migration to modern ObjC property
.. option:: -objcmt-migrate-property-dot-syntax
Enable migration of setter/getter messages to property-dot syntax
.. option:: -objcmt-migrate-protocol-conformance
Enable migration to add protocol conformance on classes
.. option:: -objcmt-migrate-readonly-property
Enable migration to modern ObjC readonly property
.. option:: -objcmt-migrate-readwrite-property
Enable migration to modern ObjC readwrite property
.. option:: -objcmt-migrate-subscripting
Enable migration to modern ObjC subscripting
.. option:: -objcmt-ns-nonatomic-iosonly
Enable migration to use NS\_NONATOMIC\_IOSONLY macro for setting property's 'atomic' attribute
.. option:: -objcmt-returns-innerpointer-property
Enable migration to annotate property with NS\_RETURNS\_INNER\_POINTER
.. option:: -objcmt-whitelist-dir-path=<arg>, -objcmt-white-list-dir-path=<arg>
Only modify files with a filename contained in the provided directory path
.. option:: -object
.. option:: -p, --profile
.. option:: -pagezero\_size<arg>
.. option:: -pg
Enable mcount instrumentation
.. option:: -pie
.. option:: -pipe, --pipe
Use pipes between commands, when possible
.. option:: -prebind
.. program:: clang1
.. option:: -prebind\_all\_twolevel\_modules
.. program:: clang
.. option:: -preload
.. option:: --print-diagnostic-categories
.. option:: -print-file-name=<file>, --print-file-name=<file>, --print-file-name <arg>
Print the full library path of <file>
.. option:: -print-ivar-layout
Enable Objective-C Ivar layout bitmap print trace
.. option:: -print-libgcc-file-name, --print-libgcc-file-name
Print the library path for the currently used compiler runtime library ("libgcc.a" or "libclang\_rt.builtins.\*.a")
.. option:: -print-multi-directory, --print-multi-directory
.. option:: -print-multi-lib, --print-multi-lib
.. option:: -print-prog-name=<name>, --print-prog-name=<name>, --print-prog-name <arg>
Print the full program path of <name>
.. option:: -print-resource-dir, --print-resource-dir
Print the resource directory pathname
.. option:: -print-search-dirs, --print-search-dirs
Print the paths used for finding libraries and programs
.. option:: -private\_bundle
.. option:: -pthread, -no-pthread
Support POSIX threads in generated code
.. option:: -pthreads
.. option:: -rdynamic
.. option:: -read\_only\_relocs <arg>
.. option:: -relocatable-pch, --relocatable-pch
Whether to build a relocatable precompiled header
.. option:: -remap
.. option:: -rewrite-legacy-objc
Rewrite Legacy Objective-C source to C++
.. option:: -rtlib=<arg>, --rtlib=<arg>, --rtlib <arg>
Compiler runtime library to use
.. option:: -save-stats=<arg>, --save-stats=<arg>, -save-stats (equivalent to -save-stats=cwd), --save-stats (equivalent to -save-stats=cwd)
Save llvm statistics.
.. option:: -save-temps=<arg>, --save-temps=<arg>, -save-temps (equivalent to -save-temps=cwd), --save-temps (equivalent to -save-temps=cwd)
Save intermediate compilation results.
.. option:: -sectalign <arg1> <arg2> <arg3>
.. option:: -sectcreate <arg1> <arg2> <arg3>
.. option:: -sectobjectsymbols <arg1> <arg2>
.. option:: -sectorder <arg1> <arg2> <arg3>
.. option:: -seg1addr<arg>
.. option:: -seg\_addr\_table <arg>
.. program:: clang1
.. option:: -seg\_addr\_table\_filename <arg>
.. program:: clang
.. option:: -segaddr <arg1> <arg2>
.. option:: -segcreate <arg1> <arg2> <arg3>
.. option:: -seglinkedit
.. option:: -segprot <arg1> <arg2> <arg3>
.. option:: -segs\_read\_<arg>
.. program:: clang1
.. option:: -segs\_read\_only\_addr <arg>
.. program:: clang
.. program:: clang2
.. option:: -segs\_read\_write\_addr <arg>
.. program:: clang
.. option:: -serialize-diagnostics <arg>, --serialize-diagnostics <arg>
Serialize compiler diagnostics to a file
.. option:: -shared, --shared
.. option:: -shared-libgcc
.. option:: -shared-libsan, -shared-libasan
.. option:: -single\_module
.. option:: -specs=<arg>, --specs=<arg>
.. option:: -static, --static
.. option:: -static-libgcc
.. option:: -static-libsan
.. option:: -static-libstdc++
.. option:: -std-default=<arg>
.. option:: -stdlib=<arg>, --stdlib=<arg>, --stdlib <arg>
C++ standard library to use
.. option:: -sub\_library<arg>
.. program:: clang1
.. option:: -sub\_umbrella<arg>
.. program:: clang
.. option:: --sysroot=<arg>, --sysroot <arg>
.. option:: --target-help
.. option:: --target=<arg>, -target <arg>
Generate code for the given target
.. option:: -time
Time individual commands
.. option:: -traditional, --traditional
.. option:: -traditional-cpp, --traditional-cpp
Enable some traditional CPP emulation
.. option:: -twolevel\_namespace
.. program:: clang1
.. option:: -twolevel\_namespace\_hints
.. program:: clang
.. option:: -umbrella <arg>
.. option:: -unexported\_symbols\_list <arg>
.. option:: -v, --verbose
Show commands to run and use verbose output
.. option:: --verify-debug-info
Verify the binary representation of debug output
.. option:: --version
Print version information
.. option:: -w, --no-warnings
Suppress all warnings
.. option:: -weak-l<arg>
.. option:: -weak\_framework <arg>
.. program:: clang1
.. option:: -weak\_library <arg>
.. program:: clang
.. program:: clang2
.. option:: -weak\_reference\_mismatches <arg>
.. program:: clang
.. option:: -whatsloaded
.. option:: -whyload
.. option:: -working-directory<arg>, -working-directory=<arg>
Resolve file paths relative to the specified directory
.. option:: -x<language>, --language <arg>, --language=<arg>
Treat subsequent input files as having type <language>
.. option:: -y<arg>
Actions
=======
The action to perform on the input.
.. option:: -E, --preprocess
Only run the preprocessor
.. option:: -S, --assemble
Only run preprocess and compilation steps
.. option:: -c, --compile
Only run preprocess, compile, and assemble steps
.. option:: -emit-llvm
Use the LLVM representation for assembler and object files
.. option:: -fsyntax-only
.. option:: -module-file-info
Provide information about a particular module file
.. option:: --precompile
Only precompile the input
.. option:: -rewrite-objc
Rewrite Objective-C source to C++
.. option:: -verify-pch
Load and verify that a pre-compiled header file is not stale
Compilation flags
=================
Flags controlling the behavior of Clang during compilation. These flags have
no effect during actions that do not perform compilation.
.. option:: -Xassembler <arg>
Pass <arg> to the assembler
.. option:: -Xclang <arg>
Pass <arg> to the clang compiler
.. option:: -fclang-abi-compat=<version>
Attempt to match the ABI of Clang <version>
.. option:: -fcomment-block-commands=<arg>,<arg2>...
Treat each comma separated argument in <arg> as a documentation comment block command
.. option:: -fdeclspec, -fno-declspec
Allow \_\_declspec as a keyword
.. option:: -fdepfile-entry=<arg>
.. option:: -fdiagnostics-fixit-info, -fno-diagnostics-fixit-info
.. option:: -fdiagnostics-format=<arg>
.. option:: -fdiagnostics-parseable-fixits
Print fix-its in machine parseable form
.. option:: -fdiagnostics-print-source-range-info
Print source range spans in numeric form
.. option:: -fdiagnostics-show-category=<arg>
.. option:: -fdiscard-value-names, -fno-discard-value-names
Discard value names in LLVM IR
.. option:: -fexperimental-isel, -fno-experimental-isel
Enables the experimental global instruction selector
.. option:: -fexperimental-new-pass-manager, -fno-experimental-new-pass-manager
Enables an experimental new pass manager in LLVM.
.. option:: -ffine-grained-bitfield-accesses, -fno-fine-grained-bitfield-accesses
Use separate accesses for bitfields with legal widths and alignments.
.. option:: -finline-functions, -fno-inline-functions
Inline suitable functions
.. option:: -finline-hint-functions
Inline functions which are (explicitly or implicitly) marked inline
.. option:: -fno-crash-diagnostics
Disable auto-generation of preprocessed source files and a script for reproduction during a clang crash
.. option:: -fno-sanitize-blacklist
Don't use blacklist file for sanitizers
.. option:: -fparse-all-comments
.. option:: -fsanitize-address-field-padding=<arg>
Level of field padding for AddressSanitizer
.. option:: -fsanitize-address-globals-dead-stripping
Enable linker dead stripping of globals in AddressSanitizer
.. option:: -fsanitize-address-poison-class-member-array-new-cookie, -fno-sanitize-address-poison-class-member-array-new-cookie
Enable poisoning array cookies when using class member operator new\[\] in AddressSanitizer
.. option:: -fsanitize-address-use-after-scope, -fno-sanitize-address-use-after-scope
Enable use-after-scope detection in AddressSanitizer
.. option:: -fsanitize-blacklist=<arg>
Path to blacklist file for sanitizers
.. option:: -fsanitize-cfi-cross-dso, -fno-sanitize-cfi-cross-dso
Enable control flow integrity (CFI) checks for cross-DSO calls.
.. option:: -fsanitize-cfi-icall-generalize-pointers
Generalize pointers in CFI indirect call type signature checks
.. option:: -fsanitize-coverage=<arg1>,<arg2>..., -fno-sanitize-coverage=<arg1>,<arg2>...
Specify the type of coverage instrumentation for Sanitizers
.. option:: -fsanitize-link-c++-runtime
.. option:: -fsanitize-memory-track-origins, -fno-sanitize-memory-track-origins
Enable origins tracking in MemorySanitizer
.. program:: clang1
.. option:: -fsanitize-memory-track-origins=<arg>
.. program:: clang
Enable origins tracking in MemorySanitizer
.. option:: -fsanitize-memory-use-after-dtor, -fno-sanitize-memory-use-after-dtor
Enable use-after-destroy detection in MemorySanitizer
.. option:: -fsanitize-minimal-runtime, -fno-sanitize-minimal-runtime
.. option:: -fsanitize-recover, -fno-sanitize-recover
.. program:: clang1
.. option:: -fsanitize-recover=<arg1>,<arg2>..., -fno-sanitize-recover=<arg1>,<arg2>...
.. program:: clang
Enable recovery for specified sanitizers
.. option:: -fsanitize-stats, -fno-sanitize-stats
Enable sanitizer statistics gathering.
.. option:: -fsanitize-thread-atomics, -fno-sanitize-thread-atomics
Enable atomic operations instrumentation in ThreadSanitizer (default)
.. option:: -fsanitize-thread-func-entry-exit, -fno-sanitize-thread-func-entry-exit
Enable function entry/exit instrumentation in ThreadSanitizer (default)
.. option:: -fsanitize-thread-memory-access, -fno-sanitize-thread-memory-access
Enable memory access instrumentation in ThreadSanitizer (default)
.. option:: -fsanitize-trap=<arg1>,<arg2>..., -fno-sanitize-trap=<arg1>,<arg2>...
Enable trapping for specified sanitizers
.. option:: -fsanitize-undefined-strip-path-components=<number>
Strip (or keep only, if negative) a given number of path components when emitting check metadata.
.. option:: -fsanitize-undefined-trap-on-error, -fno-sanitize-undefined-trap-on-error
.. option:: -fsanitize=<check>,<arg2>..., -fno-sanitize=<arg1>,<arg2>...
Turn on runtime checks for various forms of undefined or suspicious behavior. See user manual for available checks
.. option:: --param <arg>, --param=<arg>
.. option:: -std=<arg>, --std=<arg>, --std <arg>
Language standard to compile for
Preprocessor flags
~~~~~~~~~~~~~~~~~~
Flags controlling the behavior of the Clang preprocessor.
.. option:: -C, --comments
Include comments in preprocessed output
.. option:: -CC, --comments-in-macros
Include comments from within macros in preprocessed output
.. option:: -D<macro>=<value>, --define-macro <arg>, --define-macro=<arg>
Define <macro> to <value> (or 1 if <value> omitted)
.. option:: -H, --trace-includes
Show header includes and nesting depth
.. option:: -P, --no-line-commands
Disable linemarker output in -E mode
.. option:: -U<macro>, --undefine-macro <arg>, --undefine-macro=<arg>
Undefine macro <macro>
.. option:: -Wp,<arg>,<arg2>...
Pass the comma separated arguments in <arg> to the preprocessor
.. option:: -Xpreprocessor <arg>
Pass <arg> to the preprocessor
Include path management
-----------------------
Flags controlling how ``#include``\s are resolved to files.
.. option:: -I<dir>, --include-directory <arg>, --include-directory=<arg>
Add directory to include search path
.. option:: -I-, --include-barrier
Restrict all prior -I flags to double-quoted inclusion and remove current directory from include path
.. option:: --cuda-path-ignore-env
Ignore environment variables to detect CUDA installation
.. option:: --cuda-path=<arg>
CUDA installation path
.. option:: -cxx-isystem<directory>
Add directory to the C++ SYSTEM include search path
.. option:: -fbuild-session-file=<file>
Use the last modification time of <file> as the build session timestamp
.. option:: -fbuild-session-timestamp=<time since Epoch in seconds>
Time when the current build session started
.. option:: -fmodule-file=\[<name>=\]<file>
Specify the mapping of module name to precompiled module file, or load a module file if name is omitted.
.. option:: -fmodules-cache-path=<directory>
Specify the module cache path
.. option:: -fmodules-disable-diagnostic-validation
Disable validation of the diagnostic options when loading the module
.. option:: -fmodules-prune-after=<seconds>
Specify the interval (in seconds) after which a module file will be considered unused
.. option:: -fmodules-prune-interval=<seconds>
Specify the interval (in seconds) between attempts to prune the module cache
.. option:: -fmodules-user-build-path <directory>
Specify the module user build path
.. option:: -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
.. option:: -fmodules-validate-system-headers, -fno-modules-validate-system-headers
Validate the system headers that a module depends on when loading the module
.. option:: -fprebuilt-module-path=<directory>
Specify the prebuilt module path
.. option:: -idirafter<arg>, --include-directory-after <arg>, --include-directory-after=<arg>
Add directory to AFTER include search path
.. option:: -iframework<arg>
Add directory to SYSTEM framework search path
.. option:: -iframeworkwithsysroot<directory>
Add directory to SYSTEM framework search path, absolute paths are relative to -isysroot
.. option:: -imacros<file>, --imacros<file>, --imacros=<arg>
Include macros from file before parsing
.. option:: -include<file>, --include<file>, --include=<arg>
Include file before parsing
.. option:: -include-pch <file>
Include precompiled header file
.. option:: -iprefix<dir>, --include-prefix <arg>, --include-prefix=<arg>
Set the -iwithprefix/-iwithprefixbefore prefix
.. option:: -iquote<directory>
Add directory to QUOTE include search path
.. option:: -isysroot<dir>
Set the system root directory (usually /)
.. option:: -isystem<directory>
Add directory to SYSTEM include search path
.. option:: -isystem-after<directory>
Add directory to end of the SYSTEM include search path
.. option:: -ivfsoverlay<arg>
Overlay the virtual filesystem described by file over the real file system
.. option:: -iwithprefix<dir>, --include-with-prefix <arg>, --include-with-prefix-after <arg>, --include-with-prefix-after=<arg>, --include-with-prefix=<arg>
Set directory to SYSTEM include search path with prefix
.. option:: -iwithprefixbefore<dir>, --include-with-prefix-before <arg>, --include-with-prefix-before=<arg>
Set directory to include search path with prefix
.. option:: -iwithsysroot<directory>
Add directory to SYSTEM include search path, absolute paths are relative to -isysroot
.. option:: --ptxas-path=<arg>
Path to ptxas (used for compiling CUDA code)
.. option:: --system-header-prefix=<prefix>, --no-system-header-prefix=<prefix>, --system-header-prefix <arg>
Treat all #include paths starting with <prefix> as including a system header.
Dependency file generation
--------------------------
Flags controlling generation of a dependency file for ``make``-like build
systems.
.. option:: -M, --dependencies
Like -MD, but also implies -E and writes to stdout by default
.. option:: -MD, --write-dependencies
Write a depfile containing user and system headers
.. option:: -MF<file>
Write depfile output from -MMD, -MD, -MM, or -M to <file>
.. option:: -MG, --print-missing-file-dependencies
Add missing headers to depfile
.. option:: -MJ<arg>
Write a compilation database entry per input
.. option:: -MM, --user-dependencies
Like -MMD, but also implies -E and writes to stdout by default
.. option:: -MMD, --write-user-dependencies
Write a depfile containing user headers
.. option:: -MP
Create phony target for each dependency (other than main file)
.. option:: -MQ<arg>
Specify name of main file output to quote in depfile
.. option:: -MT<arg>
Specify name of main file output in depfile
.. option:: -MV
Use NMake/Jom format for the depfile
Dumping preprocessor state
--------------------------
Flags allowing the state of the preprocessor to be dumped in various ways.
.. option:: -d
.. program:: clang1
.. option:: -d<arg>
.. program:: clang
.. option:: -dA
.. option:: -dD
Print macro definitions in -E mode in addition to normal output
.. option:: -dI
Print include directives in -E mode in addition to normal output
.. option:: -dM
Print macro definitions in -E mode instead of normal output
Diagnostic flags
~~~~~~~~~~~~~~~~
Flags controlling which warnings, errors, and remarks Clang will generate.
See the :doc:`full list of warning and remark flags <DiagnosticsReference>`.
.. option:: -R<remark>
Enable the specified remark
.. option:: -Rpass-analysis=<arg>
Report transformation analysis from optimization passes whose name matches the given POSIX regular expression
.. option:: -Rpass-missed=<arg>
Report missed transformations by optimization passes whose name matches the given POSIX regular expression
.. option:: -Rpass=<arg>
Report transformations performed by optimization passes whose name matches the given POSIX regular expression
.. option:: -W<warning>, --extra-warnings, --warn-<arg>, --warn-=<arg>
Enable the specified warning
.. option:: -Wdeprecated, -Wno-deprecated
Enable warnings for deprecated constructs and define \_\_DEPRECATED
.. option:: -Wnonportable-cfstrings<arg>, -Wno-nonportable-cfstrings<arg>
Target-independent compilation options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. option:: -Wframe-larger-than=<arg>
.. option:: -fPIC, -fno-PIC
.. option:: -fPIE, -fno-PIE
.. option:: -faccess-control, -fno-access-control
.. option:: -falign-functions, -fno-align-functions
.. program:: clang1
.. option:: -falign-functions=<arg>
.. program:: clang
.. program:: clang1
.. option:: -faligned-allocation, -faligned-new, -fno-aligned-allocation
.. program:: clang
Enable C++17 aligned allocation functions
.. option:: -fallow-editor-placeholders, -fno-allow-editor-placeholders
Treat editor placeholders as valid source code
.. option:: -fallow-unsupported
.. option:: -faltivec, -fno-altivec
.. option:: -fansi-escape-codes
Use ANSI escape codes for diagnostics
.. option:: -fapple-kext, -findirect-virtual-calls, -fterminated-vtables
Use Apple's kernel extensions ABI
.. option:: -fapple-pragma-pack, -fno-apple-pragma-pack
Enable Apple gcc-compatible #pragma pack handling
.. option:: -fapplication-extension, -fno-application-extension
Restrict code to those available for App Extensions
.. option:: -fasm, -fno-asm
.. option:: -fasm-blocks, -fno-asm-blocks
.. option:: -fassociative-math, -fno-associative-math
.. option:: -fassume-sane-operator-new, -fno-assume-sane-operator-new
.. option:: -fast
.. option:: -fastcp
.. option:: -fastf
.. option:: -fasynchronous-unwind-tables, -fno-asynchronous-unwind-tables
.. option:: -fautolink, -fno-autolink
.. option:: -fblocks, -fno-blocks
Enable the 'blocks' language feature
.. option:: -fbootclasspath=<arg>, --bootclasspath <arg>, --bootclasspath=<arg>
.. option:: -fborland-extensions, -fno-borland-extensions
Accept non-standard constructs supported by the Borland compiler
.. option:: -fbracket-depth=<arg>
.. option:: -fbuiltin, -fno-builtin
.. option:: -fbuiltin-module-map
Load the clang builtins module map file.
.. option:: -fcaret-diagnostics, -fno-caret-diagnostics
.. option:: -fcf-protection=<arg>, -fcf-protection (equivalent to -fcf-protection=full)
Instrument control-flow architecture protection. Options: return, branch, full, none.
.. option:: -fclasspath=<arg>, --CLASSPATH <arg>, --CLASSPATH=<arg>, --classpath <arg>, --classpath=<arg>
.. option:: -fcolor-diagnostics, -fno-color-diagnostics
Use colors in diagnostics
.. option:: -fcommon, -fno-common
.. option:: -fcompile-resource=<arg>, --resource <arg>, --resource=<arg>
.. option:: -fconstant-cfstrings, -fno-constant-cfstrings
.. option:: -fconstant-string-class=<arg>
.. option:: -fconstexpr-backtrace-limit=<arg>
.. option:: -fconstexpr-depth=<arg>
.. option:: -fconstexpr-steps=<arg>
.. option:: -fcoroutines-ts, -fno-coroutines-ts
Enable support for the C++ Coroutines TS
.. option:: -fcoverage-mapping, -fno-coverage-mapping
Generate coverage mapping to enable code coverage analysis
.. option:: -fcreate-profile
.. option:: -fcxx-exceptions, -fno-cxx-exceptions
Enable C++ exceptions
.. option:: -fcxx-modules, -fno-cxx-modules
.. option:: -fdata-sections, -fno-data-sections
Place each data in its own section (ELF Only)
.. option:: -fdebug-info-for-profiling, -fno-debug-info-for-profiling
Emit extra debug info to make sample profile more accurate.
.. option:: -fdebug-macro, -fno-debug-macro
Emit macro debug information
.. option:: -fdebug-pass-arguments
.. option:: -fdebug-pass-structure
.. option:: -fdebug-prefix-map=<arg>
remap file source paths in debug info
.. option:: -fdebug-types-section, -fno-debug-types-section
Place debug types in their own section (ELF Only)
.. option:: -fdelayed-template-parsing, -fno-delayed-template-parsing
Parse templated function definitions at the end of the translation unit
.. option:: -fdenormal-fp-math=<arg>
.. option:: -fdiagnostics-absolute-paths
Print absolute paths in diagnostics
.. option:: -fdiagnostics-color, -fno-diagnostics-color
.. program:: clang1
.. option:: -fdiagnostics-color=<arg>
.. program:: clang
.. option:: -fdiagnostics-hotness-threshold=<number>
Prevent optimization remarks from being output if they do not have at least this profile count
.. option:: -fdiagnostics-show-hotness, -fno-diagnostics-show-hotness
Enable profile hotness information in diagnostic line
.. option:: -fdiagnostics-show-note-include-stack, -fno-diagnostics-show-note-include-stack
Display include stacks for diagnostic notes
.. option:: -fdiagnostics-show-option, -fno-diagnostics-show-option
Print option name with mappable diagnostics
.. option:: -fdiagnostics-show-template-tree
Print a template comparison tree for differing templates
.. option:: -fdollars-in-identifiers, -fno-dollars-in-identifiers
Allow '$' in identifiers
.. option:: -fdouble-square-bracket-attributes, -fno-double-square-bracket-attributes
Enable '\[\[\]\]' attributes in all C and C++ language modes
.. option:: -fdwarf-directory-asm, -fno-dwarf-directory-asm
.. option:: -fdwarf-exceptions
Use DWARF style exceptions
.. option:: -felide-constructors, -fno-elide-constructors
.. option:: -feliminate-unused-debug-symbols, -fno-eliminate-unused-debug-symbols
.. option:: -fembed-bitcode=<option>, -fembed-bitcode (equivalent to -fembed-bitcode=all), -fembed-bitcode-marker (equivalent to -fembed-bitcode=marker)
Embed LLVM bitcode (option: off, all, bitcode, marker)
.. option:: -femit-all-decls
Emit all declarations, even if unused
.. option:: -femulated-tls, -fno-emulated-tls
Use emutls functions to access thread\_local variables
.. option:: -fencoding=<arg>, --encoding <arg>, --encoding=<arg>
.. option:: -ferror-limit=<arg>
.. option:: -fescaping-block-tail-calls, -fno-escaping-block-tail-calls
.. option:: -fexceptions, -fno-exceptions
Enable support for exception handling
.. option:: -fexec-charset=<arg>
.. option:: -fextdirs=<arg>, --extdirs <arg>, --extdirs=<arg>
.. option:: -ffast-math, -fno-fast-math
Allow aggressive, lossy floating-point optimizations
.. option:: -ffinite-math-only, -fno-finite-math-only
.. option:: -ffor-scope, -fno-for-scope
.. option:: -fforce-enable-int128, -fno-force-enable-int128
Enable support for int128\_t type
.. option:: -ffp-contract=<arg>
Form fused FP ops (e.g. FMAs): fast (everywhere) \| on (according to FP\_CONTRACT pragma, default) \| off (never fuse)
.. option:: -ffreestanding
Assert that the compilation takes place in a freestanding environment
.. option:: -ffunction-sections, -fno-function-sections
Place each function in its own section (ELF Only)
.. option:: -fgnu-inline-asm, -fno-gnu-inline-asm
.. option:: -fgnu-keywords, -fno-gnu-keywords
Allow GNU-extension keywords regardless of language standard
.. option:: -fgnu-runtime
Generate output compatible with the standard GNU Objective-C runtime
.. option:: -fgnu89-inline, -fno-gnu89-inline
Use the gnu89 inline semantics
.. option:: -fhonor-infinities, -fhonor-infinites, -fno-honor-infinities
.. option:: -fhonor-nans, -fno-honor-nans
.. option:: -fhosted
.. option:: -fimplicit-module-maps, -fmodule-maps, -fno-implicit-module-maps
Implicitly search the file system for module map files.
.. option:: -fimplicit-modules, -fno-implicit-modules
.. option:: -finput-charset=<arg>
.. option:: -finstrument-function-entry-bare
Instrument function entry only, after inlining, without arguments to the instrumentation call
.. option:: -finstrument-functions
Generate calls to instrument function entry and exit
.. option:: -finstrument-functions-after-inlining
Like -finstrument-functions, but insert the calls after inlining
.. option:: -fintegrated-as, -fno-integrated-as, -integrated-as
Enable the integrated assembler
.. option:: -fjump-tables, -fno-jump-tables
.. option:: -flax-vector-conversions, -fno-lax-vector-conversions
.. option:: -flimited-precision=<arg>
.. option:: -flto, -fno-lto
Enable LTO in 'full' mode
.. option:: -flto-jobs=<arg>
Controls the backend parallelism of -flto=thin (default of 0 means the number of threads will be derived from the number of CPUs detected)
.. program:: clang1
.. option:: -flto=<arg>
.. program:: clang
Set LTO mode to either 'full' or 'thin'
.. option:: -fmacro-backtrace-limit=<arg>
.. option:: -fmath-errno, -fno-math-errno
Require math functions to indicate errors by setting errno
.. option:: -fmax-type-align=<arg>
Specify the maximum alignment to enforce on pointers lacking an explicit alignment
.. option:: -fmerge-all-constants, -fno-merge-all-constants
Allow merging of constants
.. option:: -fmessage-length=<arg>
.. option:: -fmodule-file-deps, -fno-module-file-deps
.. option:: -fmodule-map-file=<file>
Load this module map file
.. option:: -fmodule-name=<name>, -fmodule-implementation-of <arg>, -fmodule-name <arg>
Specify the name of the module to build
.. option:: -fmodules, -fno-modules
Enable the 'modules' language feature
.. option:: -fmodules-decluse, -fno-modules-decluse
Require declaration of modules used within a module
.. option:: -fmodules-ignore-macro=<arg>
Ignore the definition of the given macro when building and loading modules
.. option:: -fmodules-search-all, -fno-modules-search-all
Search even non-imported modules to resolve references
.. option:: -fmodules-strict-decluse
Like -fmodules-decluse but requires all headers to be in modules
.. option:: -fmodules-ts
Enable support for the C++ Modules TS
.. option:: -fms-compatibility, -fno-ms-compatibility
Enable full Microsoft Visual C++ compatibility
.. option:: -fms-compatibility-version=<arg>
Dot-separated value representing the Microsoft compiler version number to report in \_MSC\_VER (0 = don't define it (default))
.. option:: -fms-extensions, -fno-ms-extensions
Accept some non-standard constructs supported by the Microsoft compiler
.. option:: -fms-memptr-rep=<arg>
.. option:: -fms-volatile<arg>
.. option:: -fmsc-version=<arg>
Microsoft compiler version number to report in \_MSC\_VER (0 = don't define it (default))
.. option:: -fmudflap
.. option:: -fmudflapth
.. option:: -fnested-functions
.. option:: -fnew-alignment=<align>, -fnew-alignment <arg>
Specifies the largest alignment guaranteed by '::operator new(size\_t)'
.. option:: -fnext-runtime
.. option:: -fno-builtin-<arg>
Disable implicit builtin knowledge of a specific function
.. option:: -fno-elide-type
Do not elide types when printing diagnostics
.. option:: -fno-max-type-align
.. option:: -fno-operator-names
Do not treat C++ operator name keywords as synonyms for operators
.. option:: -fno-rtti-data
Control emission of RTTI data
.. option:: -fno-strict-modules-decluse
.. option:: -fno-working-directory
.. option:: -fnoxray-link-deps
.. option:: -fobjc-abi-version=<arg>
.. option:: -fobjc-arc, -fno-objc-arc
Synthesize retain and release calls for Objective-C pointers
.. option:: -fobjc-arc-exceptions, -fno-objc-arc-exceptions
Use EH-safe code when synthesizing retains and releases in -fobjc-arc
.. option:: -fobjc-exceptions, -fno-objc-exceptions
Enable Objective-C exceptions
.. option:: -fobjc-infer-related-result-type, -fno-objc-infer-related-result-type
.. option:: -fobjc-legacy-dispatch, -fno-objc-legacy-dispatch
.. option:: -fobjc-link-runtime
.. option:: -fobjc-nonfragile-abi, -fno-objc-nonfragile-abi
.. option:: -fobjc-nonfragile-abi-version=<arg>
.. option:: -fobjc-runtime=<arg>
Specify the target Objective-C runtime kind and version
.. option:: -fobjc-sender-dependent-dispatch
.. option:: -fobjc-weak, -fno-objc-weak
Enable ARC-style weak references in Objective-C
.. option:: -fomit-frame-pointer, -fno-omit-frame-pointer
.. option:: -fopenmp, -fno-openmp
Parse OpenMP pragmas and generate parallel code.
.. option:: -fopenmp-simd, -fno-openmp-simd
Emit OpenMP code only for SIMD-based constructs.
.. option:: -fopenmp-version=<arg>
.. program:: clang1
.. option:: -fopenmp=<arg>
.. program:: clang
.. option:: -foperator-arrow-depth=<arg>
.. option:: -foptimization-record-file=<arg>
Specify the file name of any generated YAML optimization record
.. option:: -foptimize-sibling-calls, -fno-optimize-sibling-calls
.. option:: -foutput-class-dir=<arg>, --output-class-directory <arg>, --output-class-directory=<arg>
.. option:: -fpack-struct, -fno-pack-struct
.. program:: clang1
.. option:: -fpack-struct=<arg>
.. program:: clang
Specify the default maximum struct packing alignment
.. option:: -fpascal-strings, -fno-pascal-strings, -mpascal-strings
Recognize and construct Pascal-style string literals
.. option:: -fpcc-struct-return
Override the default ABI to return all structs on the stack
.. option:: -fpch-preprocess
.. option:: -fpic, -fno-pic
.. option:: -fpie, -fno-pie
.. option:: -fplt, -fno-plt
Use the PLT to make function calls
.. option:: -fplugin=<dsopath>
Load the named plugin (dynamic shared object)
.. option:: -fpreserve-as-comments, -fno-preserve-as-comments
.. option:: -fprofile-arcs, -fno-profile-arcs
.. option:: -fprofile-dir=<arg>
.. option:: -fprofile-generate, -fno-profile-generate
Generate instrumented code to collect execution counts into default.profraw (overridden by LLVM\_PROFILE\_FILE env var)
.. program:: clang1
.. option:: -fprofile-generate=<directory>
.. program:: clang
Generate instrumented code to collect execution counts into <directory>/default.profraw (overridden by LLVM\_PROFILE\_FILE env var)
.. option:: -fprofile-instr-generate, -fno-profile-instr-generate
Generate instrumented code to collect execution counts into default.profraw file (overridden by '=' form of option or LLVM\_PROFILE\_FILE env var)
.. program:: clang1
.. option:: -fprofile-instr-generate=<file>
.. program:: clang
Generate instrumented code to collect execution counts into <file> (overridden by LLVM\_PROFILE\_FILE env var)
.. option:: -fprofile-instr-use, -fno-profile-instr-use, -fprofile-use
.. program:: clang1
.. option:: -fprofile-instr-use=<arg>
.. program:: clang
Use instrumentation data for profile-guided optimization
.. option:: -fprofile-sample-accurate, -fauto-profile-accurate, -fno-profile-sample-accurate
Specifies that the sample profile is accurate. If the sample
profile is accurate, callsites without profile samples are marked
as cold. Otherwise, treat callsites without profile samples as if
we have no profile
.. option:: -fprofile-sample-use, -fauto-profile, -fno-profile-sample-use
.. program:: clang1
.. option:: -fprofile-sample-use=<arg>, -fauto-profile=<arg>
.. program:: clang
Enable sample-based profile guided optimizations
.. program:: clang1
.. option:: -fprofile-use=<pathname>
.. program:: clang
Use instrumentation data for profile-guided optimization. If pathname is a directory, it reads from <pathname>/default.profdata. Otherwise, it reads from file <pathname>.
.. option:: -freciprocal-math, -fno-reciprocal-math
Allow division operations to be reassociated
.. option:: -freg-struct-return
Override the default ABI to return small structs in registers
.. option:: -fregister-global-dtors-with-atexit, -fno-register-global-dtors-with-atexit
Use atexit or \_\_cxa\_atexit to register global destructors
.. option:: -frelaxed-template-template-args, -fno-relaxed-template-template-args
Enable C++17 relaxed template template argument matching
.. option:: -freroll-loops, -fno-reroll-loops
Turn on loop reroller
.. option:: -fretain-comments-from-system-headers
.. option:: -frewrite-imports, -fno-rewrite-imports
.. option:: -frewrite-includes, -fno-rewrite-includes
.. option:: -frewrite-map-file <arg>
.. program:: clang1
.. option:: -frewrite-map-file=<arg>
.. program:: clang
.. option:: -fropi, -fno-ropi
.. option:: -frtti, -fno-rtti
.. option:: -frwpi, -fno-rwpi
.. option:: -fsave-optimization-record, -fno-save-optimization-record
Generate a YAML optimization record file
.. option:: -fseh-exceptions
Use SEH style exceptions
.. option:: -fshort-enums, -fno-short-enums
Allocate to an enum type only as many bytes as it needs for the declared range of possible values
.. option:: -fshort-wchar, -fno-short-wchar
Force wchar\_t to be a short unsigned int
.. option:: -fshow-column, -fno-show-column
.. option:: -fshow-overloads=<arg>
Which overload candidates to show when overload resolution fails: best\|all; defaults to all
.. option:: -fshow-source-location, -fno-show-source-location
.. option:: -fsignaling-math, -fno-signaling-math
.. option:: -fsigned-bitfields
.. option:: -fsigned-char, -fno-signed-char, --signed-char
.. option:: -fsigned-zeros, -fno-signed-zeros
.. option:: -fsized-deallocation, -fno-sized-deallocation
Enable C++14 sized global deallocation functions
.. option:: -fsjlj-exceptions
Use SjLj style exceptions
.. option:: -fslp-vectorize, -fno-slp-vectorize, -ftree-slp-vectorize
Enable the superword-level parallelism vectorization passes
.. option:: -fspell-checking, -fno-spell-checking
.. option:: -fspell-checking-limit=<arg>
.. option:: -fsplit-dwarf-inlining, -fno-split-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
.. option:: -fsplit-stack
.. option:: -fstack-protector, -fno-stack-protector
Enable stack protectors for functions potentially vulnerable to stack smashing
.. option:: -fstack-protector-all
Force the usage of stack protectors for all functions
.. option:: -fstack-protector-strong
Use a strong heuristic to apply stack protectors to functions
.. option:: -fstack-size-section, -fno-stack-size-section
Emit section containing metadata on function stack sizes
.. option:: -fstandalone-debug, -fno-limit-debug-info, -fno-standalone-debug
Emit full debug info for all types used by the program
.. option:: -fstrict-aliasing, -fno-strict-aliasing
.. option:: -fstrict-enums, -fno-strict-enums
Enable optimizations based on the strict definition of an enum's value range
.. option:: -fstrict-overflow, -fno-strict-overflow
.. option:: -fstrict-return, -fno-strict-return
Always treat control flow paths that fall off the end of a non-void function as unreachable
.. option:: -fstrict-vtable-pointers, -fno-strict-vtable-pointers
Enable optimizations based on the strict rules for overwriting polymorphic C++ objects
.. option:: -fstruct-path-tbaa, -fno-struct-path-tbaa
.. option:: -ftabstop=<arg>
.. option:: -ftemplate-backtrace-limit=<arg>
.. option:: -ftemplate-depth-<arg>
.. option:: -ftemplate-depth=<arg>
.. option:: -ftest-coverage
.. option:: -fthinlto-index=<arg>
Perform ThinLTO importing using provided function summary index
.. option:: -fthreadsafe-statics, -fno-threadsafe-statics
.. option:: -ftime-report
.. option:: -ftls-model=<arg>
.. option:: -ftrap-function=<arg>
Issue call to specified function rather than a trap instruction
.. option:: -ftrapping-math, -fno-trapping-math
.. option:: -ftrapv
Trap on integer overflow
.. option:: -ftrapv-handler <arg>
.. program:: clang1
.. option:: -ftrapv-handler=<function name>
.. program:: clang
Specify the function to be called on overflow
.. option:: -ftrigraphs, -fno-trigraphs, -trigraphs, --trigraphs
Process trigraph sequences
.. option:: -funique-section-names, -fno-unique-section-names
Use unique names for text and data sections (ELF Only)
.. option:: -funit-at-a-time, -fno-unit-at-a-time
.. option:: -funroll-loops, -fno-unroll-loops
Turn on loop unroller
.. option:: -funsafe-math-optimizations, -fno-unsafe-math-optimizations
.. option:: -funsigned-bitfields
.. option:: -funsigned-char, -fno-unsigned-char, --unsigned-char
.. option:: -funwind-tables, -fno-unwind-tables
.. option:: -fuse-cxa-atexit, -fno-use-cxa-atexit
.. option:: -fuse-init-array, -fno-use-init-array
Use .init\_array instead of .ctors
.. option:: -fuse-ld=<arg>
.. option:: -fuse-line-directives, -fno-use-line-directives
.. option:: -fveclib=<arg>
Use the given vector functions library
.. option:: -fvectorize, -fno-vectorize, -ftree-vectorize
Enable the loop vectorization passes
.. option:: -fverbose-asm, -fno-verbose-asm
.. option:: -fvisibility-inlines-hidden
Give inline C++ member functions default visibility by default
.. option:: -fvisibility-ms-compat
Give global types 'default' visibility and global functions and variables 'hidden' visibility by default
.. option:: -fvisibility=<arg>
Set the default symbol visibility for all global declarations
.. option:: -fwhole-program-vtables, -fno-whole-program-vtables
Enables whole-program vtable optimization. Requires -flto
.. option:: -fforce-emit-vtables, -fno-force-emit-vtables
In order to improve devirtualization, forces emitting of vtables even in
modules where it isn't necessary. It causes more inline virtual functions
to be emitted.
.. option:: -fwrapv, -fno-wrapv
Treat signed integer overflow as two's complement
.. option:: -fwritable-strings
Store string literals as writable data
.. option:: -fxray-always-emit-customevents, -fno-xray-always-emit-customevents
Determine whether to always emit \_\_xray\_customevent(...) calls even if the function it appears in is not always instrumented.
.. option:: -fxray-always-emit-typedevents, -fno-xray-always-emit-typedevents
Determine whether to always emit \_\_xray\_typedevent(...) calls even if the function it appears in is not always instrumented.
.. option:: -fxray-always-instrument=<arg>
DEPRECATED: Filename defining the whitelist for imbuing the 'always instrument' XRay attribute.
.. option:: -fxray-attr-list=<arg>
Filename defining the list of functions/types for imbuing XRay attributes.
.. option:: -fxray-instruction-threshold<arg>
.. program:: clang1
.. option:: -fxray-instruction-threshold=<arg>
.. program:: clang
Sets the minimum function size to instrument with XRay
.. option:: -fxray-instrument, -fno-xray-instrument
Generate XRay instrumentation sleds on function entry and exit
.. option:: -fxray-instrumentation-bundle=<arg>
Select which XRay instrumentation points to emit. Options: all, none, function, custom. Default is 'all'.
.. option:: -fxray-link-deps
Tells clang to add the link dependencies for XRay.
.. option:: -fxray-modes=<arg>
List of modes to link in by default into XRay instrumented binaries.
.. option:: -fxray-never-instrument=<arg>
DEPRECATED: Filename defining the whitelist for imbuing the 'never instrument' XRay attribute.
.. option:: -fzero-initialized-in-bss, -fno-zero-initialized-in-bss
.. option:: -fzvector, -fno-zvector, -mzvector
Enable System z vector language extension
.. option:: -pedantic, --pedantic, -no-pedantic, --no-pedantic
.. option:: -pedantic-errors, --pedantic-errors
OpenCL flags
------------
.. option:: -cl-denorms-are-zero
OpenCL only. Allow denormals to be flushed to zero.
.. option:: -cl-fast-relaxed-math
OpenCL only. Sets -cl-finite-math-only and -cl-unsafe-math-optimizations, and defines \_\_FAST\_RELAXED\_MATH\_\_.
.. option:: -cl-finite-math-only
OpenCL only. Allow floating-point optimizations that assume arguments and results are not NaNs or +-Inf.
.. option:: -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.
.. option:: -cl-kernel-arg-info
OpenCL only. Generate kernel argument metadata.
.. option:: -cl-mad-enable
OpenCL only. Allow use of less precise MAD computations in the generated binary.
.. option:: -cl-no-signed-zeros
OpenCL only. Allow use of less precise no signed zeros computations in the generated binary.
.. option:: -cl-opt-disable
OpenCL only. This option disables all optimizations. By default optimizations are enabled.
.. option:: -cl-single-precision-constant
OpenCL only. Treat double precision floating-point constant as single precision constant.
.. option:: -cl-std=<arg>
OpenCL language standard to compile for.
.. option:: -cl-strict-aliasing
OpenCL only. This option is added for compatibility with OpenCL 1.0.
.. option:: -cl-uniform-work-group-size
OpenCL only. Defines that the global work-size be a multiple of the work-group size specified to clEnqueueNDRangeKernel
.. option:: -cl-unsafe-math-optimizations
OpenCL only. Allow unsafe floating-point optimizations. Also implies -cl-no-signed-zeros and -cl-mad-enable.
Target-dependent compilation options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. option:: -G<size>, -G=<arg>, -msmall-data-threshold=<arg>
Put objects of at most <size> bytes into small data section (MIPS / Hexagon)
.. option:: -m16
.. option:: -m32
.. option:: -m64
.. option:: -mabi=<arg>
.. option:: -mabicalls, -mno-abicalls
Enable SVR4-style position-independent code (Mips only)
.. option:: -mabs=<arg>
.. option:: -malign-double
Align doubles to two words in structs (x86 only)
.. option:: -march=<arg>
.. option:: -masm=<arg>
.. option:: -mbackchain, -mno-backchain
Link stack frames through backchain on System Z
.. option:: -mcheck-zero-division, -mno-check-zero-division
.. option:: -mcmodel=<arg>
.. option:: -mcompact-branches=<arg>
.. option:: -mconsole<arg>
.. option:: -mcpu=<arg>, -mv4 (equivalent to -mcpu=hexagonv4), -mv5 (equivalent to -mcpu=hexagonv5), -mv55 (equivalent to -mcpu=hexagonv55), -mv60 (equivalent to -mcpu=hexagonv60), -mv62 (equivalent to -mcpu=hexagonv62), -mv65 (equivalent to -mcpu=hexagonv65)
.. option:: -mdefault-build-attributes<arg>, -mno-default-build-attributes<arg>
.. option:: -mdll<arg>
.. option:: -mdouble-float
.. option:: -mdsp, -mno-dsp
.. option:: -mdspr2, -mno-dspr2
.. option:: -mdynamic-no-pic<arg>
.. option:: -meabi <arg>
Set EABI type, e.g. 4, 5 or gnu (default depends on triple)
.. option:: -membedded-data, -mno-embedded-data
Place constants in the .rodata section instead of the .sdata section even if they meet the -G <size> threshold (MIPS)
.. option:: -mextern-sdata, -mno-extern-sdata
Assume that externally defined data is in the small data if it meets the -G <size> threshold (MIPS)
.. option:: -mfentry
Insert calls to fentry at function entry (x86 only)
.. option:: -mfloat-abi=<arg>
.. option:: -mfp32
Use 32-bit floating point registers (MIPS only)
.. option:: -mfp64
Use 64-bit floating point registers (MIPS only)
.. option:: -mfpmath=<arg>
.. option:: -mfpu=<arg>
.. option:: -mglobal-merge, -mno-global-merge
Enable merging of globals
.. option:: -mgpopt, -mno-gpopt
Use GP relative accesses for symbols known to be in a small data section (MIPS)
.. option:: -mhard-float
.. option:: -mhwdiv=<arg>, --mhwdiv <arg>, --mhwdiv=<arg>
.. option:: -miamcu, -mno-iamcu
Use Intel MCU ABI
.. option:: -mimplicit-float, -mno-implicit-float
.. option:: -mimplicit-it=<arg>
.. option:: -mincremental-linker-compatible, -mno-incremental-linker-compatible
(integrated-as) Emit an object file which can be used with an incremental linker
.. option:: -mindirect-jump=<arg>
Change indirect jump instructions to inhibit speculation
.. option:: -miphoneos-version-min=<arg>, -mios-version-min=<arg>
.. option:: -mips16
.. option:: -mkernel
.. option:: -mldc1-sdc1, -mno-ldc1-sdc1
.. option:: -mlocal-sdata, -mno-local-sdata
Extend the -G behaviour to object local data (MIPS)
.. option:: -mlong-calls, -mno-long-calls
Generate branches with extended addressability, usually via indirect jumps.
.. option:: -mmacosx-version-min=<arg>, -mmacos-version-min=<arg>
Set Mac OS X deployment target
.. option:: -mmadd4, -mno-madd4
Enable the generation of 4-operand madd.s, madd.d and related instructions.
.. option:: -mmcu=<arg>
.. option:: -mmicromips, -mno-micromips
.. option:: -mms-bitfields, -mno-ms-bitfields
Set the default structure layout to be compatible with the Microsoft compiler standard
.. option:: -mmsa, -mno-msa
Enable MSA ASE (MIPS only)
.. option:: -mmt, -mno-mt
Enable MT ASE (MIPS only)
.. option:: -mnan=<arg>
.. option:: -mno-mips16
.. option:: -momit-leaf-frame-pointer, -mno-omit-leaf-frame-pointer
Omit frame pointer setup for leaf functions
.. option:: -moslib=<arg>
.. option:: -mpie-copy-relocations, -mno-pie-copy-relocations
Use copy relocations support for PIE builds
.. option:: -mprefer-vector-width=<arg>
Specifies preferred vector width for auto-vectorization. Defaults to 'none' which allows target specific decisions.
.. option:: -mqdsp6-compat
Enable hexagon-qdsp6 backward compatibility
.. option:: -mrecip
.. program:: clang1
.. option:: -mrecip=<arg1>,<arg2>...
.. program:: clang
.. option:: -mred-zone, -mno-red-zone
.. option:: -mregparm=<arg>
.. option:: -mrelax-all, -mno-relax-all
(integrated-as) Relax all machine instructions
.. option:: -mrtd, -mno-rtd
Make StdCall calling convention the default
.. option:: -msingle-float
.. option:: -msoft-float, -mno-soft-float
Use software floating point
.. option:: -mstack-alignment=<arg>
Set the stack alignment
.. option:: -mstack-arg-probe, -mno-stack-arg-probe
Enable stack probes
.. option:: -mstack-probe-size=<arg>
Set the stack probe size
.. option:: -mstackrealign, -mno-stackrealign
Force realign the stack at entry to every function
.. option:: -mthread-model <arg>
The thread model to use, e.g. posix, single (posix by default)
.. option:: -mthreads<arg>
.. option:: -mthumb, -mno-thumb
.. option:: -mtune=<arg>
.. option:: -mtvos-version-min=<arg>, -mappletvos-version-min=<arg>
.. option:: -municode<arg>
.. option:: -mvx, -mno-vx
.. option:: -mwarn-nonportable-cfstrings, -mno-warn-nonportable-cfstrings
.. option:: -mwatchos-version-min=<arg>
.. option:: -mwindows<arg>
.. option:: -mx32
.. option:: -mxgot, -mno-xgot
AARCH64
-------
.. option:: -ffixed-x18
Reserve the x18 register (AArch64 only)
.. option:: -ffixed-x20
Reserve the x20 register (AArch64 only)
.. option:: -mfix-cortex-a53-835769, -mno-fix-cortex-a53-835769
Workaround Cortex-A53 erratum 835769 (AArch64 only)
.. option:: -mgeneral-regs-only
Generate code which only uses the general purpose registers (AArch64 only)
AMDGPU
------
.. option:: -mxnack, -mno-xnack
Enable XNACK (AMDGPU only)
ARM
---
.. option:: -ffixed-r9
Reserve the r9 register (ARM only)
.. option:: -mcrc
Allow use of CRC instructions (ARM only)
.. option:: -mexecute-only, -mno-execute-only, -mpure-code
Disallow generation of data access to code sections (ARM only)
.. option:: -mno-movt
Disallow use of movt/movw pairs (ARM only)
.. option:: -mno-neg-immediates
Disallow converting instructions with negative immediates to their negation or inversion.
.. option:: -mnocrc
Disallow use of CRC instructions (ARM only)
.. option:: -mrestrict-it, -mno-restrict-it
Disallow generation of deprecated IT blocks for ARMv8. It is on by default for ARMv8 Thumb mode.
.. option:: -mtp=<arg>
Read thread pointer from coprocessor register (ARM only)
.. option:: -munaligned-access, -mno-unaligned-access
Allow memory accesses to be unaligned (AArch32/AArch64 only)
Hexagon
-------
.. option:: -mieee-rnd-near
.. option:: -mpackets, -mno-packets
Enable generation of instruction packets
Hexagon
-------
.. option:: -mhvx, -mno-hvx
Enable Hexagon Vector eXtensions
.. option:: -mhvx-length=<arg>
Set Hexagon Vector Length
.. program:: clang1
.. option:: -mhvx=<arg>
.. program:: clang
Enable Hexagon Vector eXtensions
PowerPC
-------
.. option:: -maltivec, -mno-altivec
.. option:: -mcmpb, -mno-cmpb
.. option:: -mcrbits, -mno-crbits
.. option:: -mcrypto, -mno-crypto
.. option:: -mdirect-move, -mno-direct-move
.. option:: -mfloat128, -mno-float128
.. option:: -mfprnd, -mno-fprnd
.. option:: -mhtm, -mno-htm
.. option:: -minvariant-function-descriptors, -mno-invariant-function-descriptors
.. option:: -misel, -mno-isel
.. option:: -mlongcall, -mno-longcall
.. option:: -mmfocrf, -mmfcrf, -mno-mfocrf
.. option:: -mpopcntd, -mno-popcntd
.. option:: -mpower8-vector, -mno-power8-vector
.. option:: -mpower9-vector, -mno-power9-vector
.. option:: -mqpx, -mno-qpx
.. option:: -msecure-plt
.. option:: -mvsx, -mno-vsx
WebAssembly
-----------
.. option:: -mexception-handling, -mno-exception-handling
.. option:: -mnontrapping-fptoint, -mno-nontrapping-fptoint
.. option:: -msign-ext, -mno-sign-ext
.. option:: -msimd128, -mno-simd128
X86
---
.. option:: -m3dnow, -mno-3dnow
.. option:: -m3dnowa, -mno-3dnowa
.. option:: -madx, -mno-adx
.. option:: -maes, -mno-aes
.. option:: -mavx, -mno-avx
.. option:: -mavx2, -mno-avx2
.. option:: -mavx512bitalg, -mno-avx512bitalg
.. option:: -mavx512bw, -mno-avx512bw
.. option:: -mavx512cd, -mno-avx512cd
.. option:: -mavx512dq, -mno-avx512dq
.. option:: -mavx512er, -mno-avx512er
.. option:: -mavx512f, -mno-avx512f
.. option:: -mavx512ifma, -mno-avx512ifma
.. option:: -mavx512pf, -mno-avx512pf
.. option:: -mavx512vbmi, -mno-avx512vbmi
.. option:: -mavx512vbmi2, -mno-avx512vbmi2
.. option:: -mavx512vl, -mno-avx512vl
.. option:: -mavx512vnni, -mno-avx512vnni
.. option:: -mavx512vpopcntdq, -mno-avx512vpopcntdq
.. option:: -mbmi, -mno-bmi
.. option:: -mbmi2, -mno-bmi2
.. option:: -mcldemote, -mno-cldemote
.. option:: -mclflushopt, -mno-clflushopt
.. option:: -mclwb, -mno-clwb
.. option:: -mclzero, -mno-clzero
.. option:: -mcx16, -mno-cx16
.. option:: -mf16c, -mno-f16c
.. option:: -mfma, -mno-fma
.. option:: -mfma4, -mno-fma4
.. option:: -mfsgsbase, -mno-fsgsbase
.. option:: -mfxsr, -mno-fxsr
.. option:: -mgfni, -mno-gfni
.. option:: -mlwp, -mno-lwp
.. option:: -mlzcnt, -mno-lzcnt
.. option:: -mmmx, -mno-mmx
.. option:: -mmovbe, -mno-movbe
.. option:: -mmovdiri, -mno-movdiri
.. option:: -mmovdir64b, -mno-movdir64b
.. option:: -mmpx, -mno-mpx
.. option:: -mmwaitx, -mno-mwaitx
.. option:: -mpclmul, -mno-pclmul
.. option:: -mpku, -mno-pku
.. option:: -mpopcnt, -mno-popcnt
.. option:: -mprefetchwt1, -mno-prefetchwt1
.. option:: -mprfchw, -mno-prfchw
.. option:: -mrdpid, -mno-rdpid
.. option:: -mrdrnd, -mno-rdrnd
.. option:: -mrdseed, -mno-rdseed
.. option:: -mretpoline, -mno-retpoline
.. option:: -mretpoline-external-thunk, -mno-retpoline-external-thunk
.. option:: -mrtm, -mno-rtm
.. option:: -msahf, -mno-sahf
.. option:: -msgx, -mno-sgx
.. option:: -msha, -mno-sha
.. option:: -mshstk, -mno-shstk
.. option:: -msse, -mno-sse
.. option:: -msse2, -mno-sse2
.. option:: -msse3, -mno-sse3
.. option:: -msse4.1, -mno-sse4.1
.. program:: clang1
.. option:: -msse4.2, -mno-sse4.2, -msse4
.. program:: clang
.. option:: -msse4a, -mno-sse4a
.. option:: -mssse3, -mno-ssse3
.. option:: -mtbm, -mno-tbm
.. option:: -mvaes, -mno-vaes
.. option:: -mvpclmulqdq, -mno-vpclmulqdq
.. option:: -mwaitpkg, -mno-waitpkg
.. option:: -mwbnoinvd, -mno-wbnoinvd
.. option:: -mx87, -m80387, -mno-x87
.. option:: -mxop, -mno-xop
.. option:: -mxsave, -mno-xsave
.. option:: -mxsavec, -mno-xsavec
.. option:: -mxsaveopt, -mno-xsaveopt
.. option:: -mxsaves, -mno-xsaves
Optimization level
~~~~~~~~~~~~~~~~~~
Flags controlling how much optimization should be performed.
.. option:: -O<arg>, -O (equivalent to -O2), --optimize, --optimize=<arg>
.. option:: -Ofast<arg>
Debug information generation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Flags controlling how much and what kind of debug information should be
generated.
Kind and level of debug information
-----------------------------------
.. option:: -g, --debug, --debug=<arg>
Generate source-level debug information
.. option:: -gdwarf-2
Generate source-level debug information with dwarf version 2
.. option:: -gdwarf-3
Generate source-level debug information with dwarf version 3
.. option:: -gdwarf-4, -gdwarf
Generate source-level debug information with dwarf version 4
.. option:: -gdwarf-5
Generate source-level debug information with dwarf version 5
.. option:: -gfull
.. option:: -gused
Debug level
___________
.. option:: -g0
.. option:: -g2
.. option:: -g3
.. option:: -ggdb0
.. option:: -ggdb1
.. option:: -ggdb2
.. option:: -ggdb3
.. option:: -gline-tables-only, -g1, -gmlt
Emit debug line number tables only
.. option:: -gmodules
Generate debug info with external references to clang modules or precompiled headers
Debugger to tune debug information for
______________________________________
.. option:: -ggdb
.. option:: -glldb
.. option:: -gsce
Debug information flags
-----------------------
.. option:: -gcolumn-info, -gno-column-info
.. option:: -gdwarf-aranges
.. option:: -gembed-source, -gno-embed-source
Embed source text in DWARF debug sections
.. option:: -ggnu-pubnames
.. option:: -grecord-gcc-switches, -gno-record-gcc-switches
.. option:: -gsplit-dwarf
.. option:: -gstrict-dwarf, -gno-strict-dwarf
.. option:: -gz
DWARF debug sections compression type
.. program:: clang1
.. option:: -gz=<arg>
.. program:: clang
DWARF debug sections compression type
Static analyzer flags
=====================
Flags controlling the behavior of the Clang Static Analyzer.
.. option:: -Xanalyzer <arg>
Pass <arg> to the static analyzer
Fortran compilation flags
=========================
Flags that will be passed onto the ``gfortran`` compiler when Clang is given
a Fortran input.
.. option:: -A<arg>, --assert <arg>, --assert=<arg>
.. option:: -A-<arg>
.. option:: -J<arg>
.. option:: -cpp
.. option:: -faggressive-function-elimination, -fno-aggressive-function-elimination
.. option:: -falign-commons, -fno-align-commons
.. option:: -fall-intrinsics, -fno-all-intrinsics
.. option:: -fautomatic, -fno-automatic
.. option:: -fbackslash, -fno-backslash
.. option:: -fbacktrace, -fno-backtrace
.. option:: -fblas-matmul-limit=<arg>
.. option:: -fbounds-check, -fno-bounds-check
.. option:: -fcheck-array-temporaries, -fno-check-array-temporaries
.. option:: -fcheck=<arg>
.. option:: -fcoarray=<arg>
.. option:: -fconvert=<arg>
.. option:: -fcray-pointer, -fno-cray-pointer
.. option:: -fd-lines-as-code, -fno-d-lines-as-code
.. option:: -fd-lines-as-comments, -fno-d-lines-as-comments
.. option:: -fdefault-double-8, -fno-default-double-8
.. option:: -fdefault-integer-8, -fno-default-integer-8
.. option:: -fdefault-real-8, -fno-default-real-8
.. option:: -fdollar-ok, -fno-dollar-ok
.. option:: -fdump-fortran-optimized, -fno-dump-fortran-optimized
.. option:: -fdump-fortran-original, -fno-dump-fortran-original
.. option:: -fdump-parse-tree, -fno-dump-parse-tree
.. option:: -fexternal-blas, -fno-external-blas
.. option:: -ff2c, -fno-f2c
.. option:: -ffixed-form, -fno-fixed-form
.. option:: -ffixed-line-length-<arg>
.. option:: -ffpe-trap=<arg>
.. option:: -ffree-form, -fno-free-form
.. option:: -ffree-line-length-<arg>
.. option:: -ffrontend-optimize, -fno-frontend-optimize
.. option:: -fimplicit-none, -fno-implicit-none
.. option:: -finit-character=<arg>
.. option:: -finit-integer=<arg>
.. option:: -finit-local-zero, -fno-init-local-zero
.. option:: -finit-logical=<arg>
.. option:: -finit-real=<arg>
.. option:: -finteger-4-integer-8, -fno-integer-4-integer-8
.. option:: -fintrinsic-modules-path, -fno-intrinsic-modules-path
.. option:: -fmax-array-constructor=<arg>
.. option:: -fmax-errors=<arg>
.. option:: -fmax-identifier-length, -fno-max-identifier-length
.. option:: -fmax-stack-var-size=<arg>
.. option:: -fmax-subrecord-length=<arg>
.. option:: -fmodule-private, -fno-module-private
.. option:: -fpack-derived, -fno-pack-derived
.. option:: -fprotect-parens, -fno-protect-parens
.. option:: -frange-check, -fno-range-check
.. option:: -freal-4-real-10, -fno-real-4-real-10
.. option:: -freal-4-real-16, -fno-real-4-real-16
.. option:: -freal-4-real-8, -fno-real-4-real-8
.. option:: -freal-8-real-10, -fno-real-8-real-10
.. option:: -freal-8-real-16, -fno-real-8-real-16
.. option:: -freal-8-real-4, -fno-real-8-real-4
.. option:: -frealloc-lhs, -fno-realloc-lhs
.. option:: -frecord-marker=<arg>
.. option:: -frecursive, -fno-recursive
.. option:: -frepack-arrays, -fno-repack-arrays
.. option:: -fsecond-underscore, -fno-second-underscore
.. option:: -fsign-zero, -fno-sign-zero
.. option:: -fstack-arrays, -fno-stack-arrays
.. option:: -funderscoring, -fno-underscoring
.. option:: -fwhole-file, -fno-whole-file
.. option:: -imultilib <arg>
.. option:: -nocpp
.. option:: -static-libgfortran
Linker flags
============
Flags that are passed on to the linker
.. option:: -L<dir>, --library-directory <arg>, --library-directory=<arg>
Add directory to library search path
.. option:: -Mach
.. option:: -T<script>
Specify <script> as linker script
.. option:: -Tbss<addr>
Set starting address of BSS to <addr>
.. option:: -Tdata<addr>
Set starting address of DATA to <addr>
.. option:: -Ttext<addr>
Set starting address of TEXT to <addr>
.. option:: -Wl,<arg>,<arg2>...
Pass the comma separated arguments in <arg> to the linker
.. option:: -X
.. option:: -Xlinker <arg>, --for-linker <arg>, --for-linker=<arg>
Pass <arg> to the linker
.. program:: clang1
.. option:: -Z
.. program:: clang
.. option:: -e<arg>, --entry
.. option:: -filelist <arg>
.. option:: -l<arg>
.. option:: -r
.. option:: -rpath <arg>
.. option:: -s
.. option:: -t
.. option:: -u<arg>, --force-link <arg>, --force-link=<arg>
.. option:: -undef
undef all system defines
.. option:: -undefined<arg>, --no-undefined
.. option:: -z <arg>
Pass -z <arg> to the linker