Compiler Options Grouped by Functionality

Language:

This chapter summarizes the C compiler options by function. Detailed explanations of the options and the compiler command-line syntax are provided in Table 35.

A.1 Options Summarized by Function

In this section, the compiler options are grouped by function to provide a quick reference. For a detailed description of each option, refer to C Compiler Options Reference. Some flags serve more than one purpose and appear more than once.

The options apply to all platforms except as noted. Features that are unique to SPARC-based systems are identified as (SPARC), and the features that are unique to x86/x64–based systems are identified as (x86). Options that apply to Oracle Solaris platforms only are marked (Oracle Solaris). Options for Oracle Linux-only platforms are marked (Oracle Linux).

A.1.1 Optimization and Performance Options

Table 22 Optimization and Performance Options

Option	Action
`-fast`	Selects the optimum combination of compilation options for speed of executable code.
`-fma`	Enables automatic generation of floating-point fused multiply-add instructions.
`-fsemantic-interposition` `-fno-semantic-interposition`	Control optimizations that impact interposing on global library functions.
`-library=sunperf`	Links with the Sun Performance Library.
`-p`	Prepares the object code to collect data for profiling.
`-xalias_level`	Enables the compiler to perform type-based alias analysis and optimizations.
`-xannotate`	Instructs the compiler to create binaries that can be used by the optimization and observability tools `binopt`(1), `code-analyzer`(1), `discover`(1), `collect`(1), and `uncover`(1).
`-xbuiltin`	Improves the optimization of code that calls standard library functions.
`-xdepend`	Analyzes loops for inter-iteration data dependencies and does loop restructuring.
`-xF`	Enables reordering of data and functions by the linker.
`-xglobalize`	Controls globalization of file static variables but not functions.
`-xhwcprof`	Enables compiler support for hardware counter-based profiling.
`-xinline`	Tries to inline only those functions specified.
`-xinline_param`	Manually changes the heuristics used by the compiler for deciding when to inline a function call.
`-xinline_report`	Generates a report written to standard output on the inlining of functions by the compiler.
`-xinstrument`	Compiles and instruments your program for analysis by the Thread Analyzer.
`-xipo`	Performs whole-program optimizations by invoking an interprocedural analysis component.
`-xipo_archive`	Allows crossfile optimization to include archive (`.a`) libraries.
`-xipo_build`	Reduces compile time by avoiding optimizations during the initial pass through the compiler, optimizing only at link time.
`-xkeepframe`	Prohibits stack related optimizations for the named functions.
`-xjobs`	Sets how many processes the compiler creates.
`-xlibmil`	Inlines some library routines for faster execution.
`-xlinkopt`	Performs link-time optimizations on relocatable object files.
`-xlibmopt`	Selects library of optimized math routines.
`-xmaxopt`	Limits the level of `pragma` `opt` to the level specified.
`-xnolibmil`	Does not inline math library routines.
`-xO`	Optimizes the object code.
`-xnorunpath`	Prevents inclusion of a runtime search path for shared libraries in the executable.
`-xpagesize`	Sets the preferred page size for the stack and the heap.
`-xpagesize_stack`	Sets the preferred page size for the stack.
`-xpagesize_heap`	Sets the preferred page size for the heap.
`-xpch`	Reduces compile time for applications whose source files share a common set of include files.
`–xpec`	Generates a Portable Executable Code (PEC) binary which can be used with additional tuning and troubleshooting.
`-xpchstop`	Can be used in conjunction with `-xpch` to specify the last include file of the viable prefix.
`-xprefetch`	Enables prefetch instructions.
`-xprefetch_level`	Controls the aggressiveness of automatic insertion of prefetch instructions as set by `-xprefetch=auto`
`-xprefetch_auto_type`	Controls how indirect prefetches are generated.
`-xprofile`	Collects data for a profile or uses a profile to optimize.
`-xprofile_ircache`	Improves compilation time of `-xprofile=use` phase by reusing compilation data saved from the `-xprofile=collect` phase.
`-xprofile_pathmap`	Support for multiple programs or shared libraries in a single profile directory.
`-xrestrict`	Treats pointer-valued function parameters as restricted pointers.
`-xsafe`	(SPARC) Allows the compiler to assume no memory-based traps occur.
`-xspace`	Does no optimizations or parallelization of loops that increase code size.
`-xthroughput`	Specifies that the application will be run in situations where many processes are simultaneously running on the system.
`-xunroll`	Suggests to the optimizer to unroll loops `n` times.

A.1.2 Compile-Time and Link-Time Options

The following table lists the options that must be specified both at link-time and at compile-time.

Table 23 Compile-Time and Link-Time Options

Option	Action
`-fast`	Selects the optimum combination of compilation options for speed of executable code.
`-fopenmp`	Equivalent to `-xopenmp=parallel`.
`-m32` \|`-m64`	Specifies the data type model for the compiled binary object.
`-mt`	Macro option that expands to `-D_REENTRANT` `-lthread`.
`-p`	Prepares the object code to collect data for profiling with `prof`(1)
`-xarch`	Specify instruction set architecture.
`-xautopar`	Enables automatic parallelization for multiple processors.
`-xhwcprof`	Enables compiler support for hardware counter-based profiling.
`-xipo`	Performs whole-program optimizations by invoking an interprocedural analysis component.
`-xlinkopt`	Performs link-time optimizations on relocatable object files.
`-xmemalign`	(SPARC) Specify maximum assumed memory alignment and behavior of misaligned data accesses.
`-xopenmp`	Supports the OpenMP interface for explicit parallelization including a set of source code directives, run-time library routines, and environment variables
`-xpagesize`	Sets the preferred page size for the stack and the heap.
`-xpagesize_stack`	Sets the preferred page size for the stack.
`-xpagesize_heap`	Sets the preferred page size for the heap.
`-xpatchpadding`	Reserve an area of memory before the start of each function.
`-xpg`	Prepares the object code to collect data for profiling with `gprof`(1).
`-xprofile`	Collects data for a profile or uses a profile to optimize.
`-xs`	(Oracle Solaris) Link debug information from object files into executable.
`-xvector=lib`	Enable automatic generation of calls to the vector library functions.

A.1.3 Data-Alignment Options

Table 24 Data-Alignment Options

Option	Action
`-xchar_byte_order`	Produce an integer constant by placing the characters of a multi-character character-constant in the specified byte order.
`-xdepend`	Analyzes loops for inter-iteration data dependencies and does loop restructuring.
`-xmemalign`	(SPARC) Specify maximum assumed memory alignment and behavior of misaligned data accesses.
`-xsegment_align`	Cause the driver to include a special mapfile on the link line.

A.1.4 Numerics and Floating-Point Options

Table 25 Numerics and Floating-Point Options

Option	Action
`-flteval`	(x86) Controls floating point evaluation.
`-fma`	Enables automatic generation of floating-point fused multiply-add instructions.
`-fnonstd`	Causes nonstandard initialization of floating-point arithmetic hardware.
`-fns`	Turns on nonstandard floating-point mode.
`-fprecision`	(x86) Initializes the rounding-precision mode bits in the Floating-point Control Word
`-fround`	Sets the IEEE 754 rounding mode that is established at runtime during the program initialization.
`-fsimple`	Allows the optimizer to make simplifying assumptions concerning floating-point arithmetic.
`-fsingle`	Causes the compiler to evaluate `float` expressions as single precision rather than double precision.
`-fstore`	(x86) Causes the compiler to convert the value of a floating-point expression or function to the type on the left-hand side of an assignment
`-ftrap`	Sets the IEEE 754 trapping mode in effect at startup.
`-nofstore`	(x86) Does not convert the value of a floating-point expression or function to the type on the left-hand side of an assignment
`-xdepend`	Analyzes loops for inter-iteration data dependencies and does loop restructuring.
`-xlibmieee`	Forces IEEE 754 style return values for math routines in exceptional cases.
`-xsfpconst`	Represents unsuffixed floating-point constants as single precision
`-xvector`	Enable automatic generation of calls to the vector library functions.

A.1.5 Parallelization Options

Table 26 Parallelization Options

Option	Action
`-fopenmp`	Equivalent to `-xopenmp=parallel`.
`-mt`	Macro option that expands to `-D_REENTRANT` `-lthread`.
`-xautopar`	Enables automatic parallelization for multiple processors.
`-xcheck`	Adds runtime checks for stack overflow and initializes local variables.
`-xdepend`	Analyzes loops for inter-iteration data dependencies and does loop restructuring.
`-xloopinfo`	Shows which loops are parallelized and which are not.
`-xopenmp`	Supports the OpenMP interface for explicit parallelization including a set of source code directives, run-time library routines, and environment variables
`-xreduction`	Enables reduction recognition during automatic parallelization.
`-xrestrict`	Treats pointer-valued function parameters as restricted pointers.
`-xthreadvar`	Controls the implementation of thread local variables.
`-xthroughput`	Specify that the application will be run in situations where many processes are simultaneously running on the system.
`-xvpara`	Warns about loops that have `#pragma` `MP` directives specified but might not be properly specified for parallelization.

A.1.6 Source Code Options

Table 27 Source Code Options

Option	Action
`-A`	Associates `name` as a predicate with the specified tokens as if by a `#assert` preprocessing directive.
`-ansi`	Equivalent to `-std=c89`.
`-C`	Prevents the preprocessor from removing comments, except those on the preprocessing directive lines.
`-D`	Associates `name` with the specified tokens as if by a `#define` preprocessing directive.
`-E`	Runs the source file through the preprocessor only and sends the output to `stdout`.
`-fd`	Reports K&R-style function definitions and declarations.
`-H`	Prints to standard error, one per line, the path name of each file included during the current compilation.
`-I`	Adds directories to the list that is searched for `#include` files with relative file names.
`–include`	Causes the compiler to treat the argument `filename` as if it appears in the first line of a primary source file as a `#include` preprocessor directive.
`-P`	Runs the source file through the C preprocessor only.
`-pedantic`	Enforce strict conformance with errors/warnings for non-ANSI constructs.
`-preserve_argvalues`	(x86) Save copies of register-based function arguments in the stack.
`-std`	Specify C language standard.
`-U`	Removes any initial definition of the preprocessor symbol `name`.
`-X`	The `-X` options specify varying degrees of compliance to the ISO C standard.
`-xCC`	Accepts the C++-style comments.
`-xc99`	Controls compiler recognition of supported C99 features.
`-xchar`	Helps with migration from systems where char is defined as unsigned.
`-xcsi`	Allows the C compiler to accept source code written in locales that do not conform to the ISO C source character code requirements
`-xM`	Runs only the preprocessor on the named C programs, requesting that it generate makefile dependencies and send the result to the standard output
`-xM1`	Collects dependencies like `-xM`, but excludes `/usr/include` files.
`-xMD`	Generates makefile dependencies like `-xM` but includes compilation.
`-xMF`	Specifies a filename which stores makefile dependency information.
`-xMMD`	Generates makefile dependencies but excludes system headers.
`-xP`	Prints prototypes for all K&R C functions defined in this module
`-xpg`	Prepares the object code to collect data for profiling with `gprof`(1).
`-xtrigraphs`	Determines recognition of trigraph sequences.
`-xustr`	Enables recognition of string literals composed of sixteen-bit characters.

A.1.7 Compiled Code Options

Table 28 Compiled Code Options

Option	Action
`-c`	Directs the compiler to suppress linking with `ld`(1) and to produce a `.o` file in the current working directory for each source file
`-o`	Names the output file
`-S`	Directs the compiler to produce an assembly source file but not to assemble the program.

A.1.8 Compilation Mode Options

Table 29 Compilation Mode Options

Option	Action
`-#`	Enables verbose mode, which shows how command options expand and shows each component as it is invoked.
`-###`	Shows each component as it would be invoked, but does not actually execute it. Also shows how command options expand.
`-ansi`	Equivalent to `-std=c89`.
`-features`	Enables or disables various C-language features.
`-fshort-enums`	Set the type of an `enum` to that of the smallest type capable of holding all of the enumerator values. `-fno-short-enums` can be used to reverse `-fshort_enums` specified earlier on the command line.
`-fexceptions`	Generate code to interoperate with C++ exception handling in C++ gcc compatibility modes.
`-keeptmp`	Retains temporary files created during compilation instead of deleting them automatically.
`-std`	Specify C language standard.
`-temp`	Define the directory for temporary files.
`-V`	Directs `cc` to print the name and version ID of each component as the compiler executes.
`-W`	Passes arguments to C compilation-system components.
`-X`	The `-X` options specify varying degrees of compliance to the ISO C standard.
`-xc99`	Controls compiler recognition of supported C99 features.
`-xchar`	Preserves the sign of a char
`-xhelp`	Displays on-line help information.
`-xjobs`	Sets how many processes the compiler creates.
`-xlang`	Override the default `libc` behavior as specified by the `-std` flag.
`-xpch`	Reduces compile time for applications whose source files share a common set of include files.
`-xpchstop`	Can be used in conjunction with `-xpch` to specify the last include file of the viable prefix.
`-xtime`	Reports the time and resources used by each compilation component.
`-Y`	Specifies a new directory for the location of a C compilation-system component.
`-YA`	Changes the default directory searched for components.
`-YI`	Changes the default directory searched for include files.
`-YP`	Changes the default directory for finding library files.
`-YS`	Changes the default directory for startup object files.

A.1.9 Diagnostic Options

Table 30 Diagnostic Options

Option	Action
`-errfmt`	Prefix error messages with string “error:” for ready distinction from warning messages.
`-errhdr`	Limits the warnings from header files to a specified group.
`-erroff`	Suppresses compiler warning messages.
`-errshort`	Control how much detail is in the error message produced by the compiler when it discovers a type mismatch.
`-errtags`	Displays the message tag for each warning message.
`-errwarn`	If the indicated warning message is issued, `cc` exits with a failure status.
`-pedantic`	Enforce strict conformance with errors/warnings for non-ANSI constructs.
`-v`	Directs the compiler to perform stricter semantic checks and to enable other `lint`-like checks.
`-w`	Suppresses compiler warning messages.
`-xanalyze`	Produce a static analysis of the source code that can be viewed using the Code Analyzer.
`-xe`	Performs only syntax and semantic checking on the source file, but does not produce any object or executable code.
`-xprevise`	Produce a static analysis of the source code that can be viewed using the Code Analyzer.
`-xs`	(Oracle Solaris) Link debug information from object files into executable.
`-xtransition`	Issues warnings for the differences between K&R C and Oracle Developer Studio ISO C.
`-xvpara`	Warns about loops that have `#pragma` `MP` directives specified but might not be properly specified for parallelization.

A.1.10 Debugging Options

Table 31 Debugging Options

Option	Action
`-g`	Produces additional symbol table information for the debugger.
`-g3`	Produces addition debugging information.
`-s`	Removes all symbolic debugging information from the output object file.
`-xcheck`	Adds runtime checks for stack overflow and initializes local variables.
`-xcompress`	Control compression of the debug section.
`-xcompress_format`	Specify format of compression of the debug section.
`-xdebugformat`	Generates debugging information in dwarf format.
`-xdebuginfo`	Control how much debugging and observability information is emitted.
`-xglobalize`	Control globalization of file static variables but not functions.
`-xkeep_unref`	Keep definitions of unreferenced functions and variables.
`-xpagesize`	Sets the preferred page size for the stack and the heap.
`-xpagesize_stack`	Sets the preferred page size for the stack.
`-xpagesize_heap`	Sets the preferred page size for the heap.
`-xs`	Disables Auto-Read of object files for `dbx`.
`-xvis`	(SPARC) Enables compiler recognition of the assembly-language templates defined in the VIS instruction set

A.1.11 Linking and Libraries Options

Table 32 Linking and Libraries Options Table

Option	Action
`-B`	Specifies whether bindings of libraries for linking are `static` or `dynamic`.
`-d`	Specifies dynamic or static linking in the link editor.
`-G`	Passes the option to the link editor to produce a shared object rather than a dynamically linked executable. Does not link any libraries by default.
`-h`	Assigns a name to a shared dynamic library as a way to have different versions of a library.
`-i`	Passes the option to the linker to ignore any `LD_LIBRARY_PATH` setting.
`-L`	Adds directories to the list that the linker searches for libraries.
`-l`	Links with object library `libname.so`, or `libname.a`.
`-mc`	Removes duplicate strings from the `.comment` section of the object file.
`-mr`	Removes all strings from the `.comment` section. Can also insert a `string` in that section of the object file.
`-Q`	Determines whether to emit identification information to the output file.
`-R`	Passes a colon-separated list of directories used to specify library search directories to the runtime linker.
`-shared`	Passes the `–G` option to the link editor to produce a shared object rather than a dynamically linked executable. Links default system libraries.
`-staticlib`	Specify whether linking with the Sun performance libraries will be static or dynamic.
`-xMerge`	Merges data segments into text segments.
`-xcode`	Specify code address space.
`-xlang`	Override the default `libc` behavior as specified by the `-std` flag.
`-xldscope`	Controls the default scope of variable and function definitions to create faster and safer shared libraries.
`-xnolib`	Does not link any libraries by default
`-xnolibmil`	Does not inline math library routines.
`-xpatchpadding`	Reserve an area of memory before the start of each function.
`-xsegment_align`	Cause the driver to include a special mapfile on the link line.
`-xstrconst`	This option may be deprecated in a future release. Use `–features=[no%]conststrings` instead. Inserts string literals into the read-only data section of the text segment instead of the default data segment.
`-xunboundsym`	Specify whether the program contains references to dynamically bound symbols.

A.1.12 Target Platform Options

Table 33 Target Platform Options

Option	Action
`-m32` \|`-m64`	Specifies the data type model for the compiled binary object.
`-xarch`	Specify instruction set architecture.
`-xcache`	Defines the cache properties for use by the optimizer.
`-xchip`	Specifies the target processor for use by the optimizer.
`-xregs`	Specifies the usage of registers for the generated code.
`-xtarget`	Specifies the target system for instruction set and optimization.

A.1.13 x86-Specific Options

Table 34 x86-Specific Options

Option	Action
`-flteval`	Controls floating point evaluation.
`-fprecision`	Initializes the rounding-precision mode bits in the Floating-point Control Word
`-fstore`	Causes the compiler to convert the value of a floating-point expression or function to the type on the left-hand side of an assignment
`-nofstore`	Does not convert the value of a floating-point expression or function to the type on the left-hand side of an assignment
`-preserve_argvalues`	(x86) Save copies of register-based function arguments in the stack.
`-xmodel`	Modifies the form of 64-bit objects for the Oracle Solaris x86 platforms

A.1.14 Obsolete Options

The following table lists the options that have been deprecated. Note that the compiler might still accept these options, but might not do so in future releases. Begin using the suggested alternative option as soon as possible.

Table 35 Obsolete Options Table

Option	Action
`-dalign`	Use `-xmemalign=8s` instead.
`-features=%none`	Use `features=no%` followed by the sub-option.
`-flteval`	Obsolete.
`-misalign`	Use `-xmemalign=1i` instead.
`-misalign2`	Use `-xmemalign=2i` instead.
`-p`	Use `-xpg` instead.
`-xanalyze`	Produce a static analysis of the source code that can be viewed using the Code Analyzer.
`-xarch=pentium_pro`	Obsolete. Use `-xarch=generic` instead.
`-xarch=sse`	Obsolete. Use `-xarch=generic` instead.
`-xchip=amdfam10`	Obsolete.
`-xchip=pentium`	Obsolete. Use `-xchip=generic` instead.
`-xchip=T3`	Obsolete.
`-xchip=pentium_pro`	Obsolete. Use `-xchip=generic` instead.
`-xchip=pentium3`	Obsolete. Use `-xchip=generic` instead.
`-xchip=ultraT1`	Obsolete.
`-xchip=ultraT2`	Obsolete.
`-xchip=ultraT2plus`	Obsolete.
`-xchip=sparc64vi`	Obsolete.
`-xchip=sparc64vii`	Obsolete.
`–xcrossfile`	Obsolete. Use `–xipo` instead.
`-xlicinfo`	Obsolete; there is no alternative option.
`-xnolibmopt`	Use `-xlibmopt=%none` instead.
`-xpentium`	Obsolete. Use `-xchip=generic` instead.
`-xprefetch=yes`	Use `-xprefetch=auto,explicit` instead.
`-xprefetch=no`	Use `-xprefetch=no%auto,no%explicit` instead.
`-Xs`	Obsolete. There is no alternative option. Recommend converting code to at least conform with C99.
`-xstrconst`	Use `-features=conststrings` instead.
`-Xt`	Obsolete. There is no alternative option. Recommend converting code to at least conform with C99.
`-xtarget=T3`	Obsolete.
`-xtarget=pentium`	Obsolete. Use `-xtarget=generic` instead.
`-xtarget=pentium_pro`	Obsolete. Use `-xtarget=generic` instead.
`-xtarget=pentium3`	Obsolete. Use `-xtarget=generic` instead.
`-xtarget=ultraT1`	Obsolete.
`-xtarget=ultraT2`	Obsolete.
`-xtarget=ultraT2plus`	Obsolete.
`-xtarget=ultraT3`	Obsolete.
`-xtarget=sparc64vi`	Obsolete.
`-xtarget=sparc64vii`	Obsolete.
`–xvector=yes`	Use `–xvector=lib` instead.
`–xvector=no`	Use `–xvector=none` instead.