ARM Compiler toolchain Compiler Reference: Compiler predefines

Compiler predefines

This section documents the predefined macros of the ARM compiler.

Predefined macros

Table 28 lists the macro names predefined by the ARM compiler for C and C++. Where the value field is empty, the symbol is only defined.

Table 28. Predefined macros

Name	Value	When defined
`__arm__`	-	Always defined for the ARM compiler, even when you specify the `--thumb` option. See also `__ARMCC_VERSION`.
`__ARM_NEON__`	-	When compiler `--cpu` and `--fpu` options indicate that NEON is available. This macro can be used to conditionally include `arm_neon.h`, to permit the use of NEON intrinsics.
`__ARMCC_VERSION`	`ver`	Always defined. It is a decimal number, and is guaranteed to increase between releases. The format is `PVbbbb` where: `P` is the major version `V` is the minor version `bbbb` is the build number. Note Use this macro to distinguish between ARM Compiler 4.1 and other tools that define `__arm__`.
`__APCS_INTERWORK`	-	When you specify the `--apcs /interwork` option or set the CPU architecture to ARMv5T or later.
`__APCS_ROPI`	-	When you specify the `--apcs /ropi` option.
`__APCS_RWPI`	-	When you specify the `--apcs /rwpi` option.
`__APCS_FPIC`	-	When you specify the `--apcs /fpic` option.
`__ARRAY_OPERATORS`	-	In C++ compiler mode, to specify that array new and delete are enabled.
`__BASE_FILE__`	`name`	Always defined. Similar to `__FILE__`, but indicates the primary source file rather than the current one (that is, when the current file is an included file).
`__BIG_ENDIAN`	-	If compiling for a big-endian target.
`_BOOL`	-	In C++ compiler mode, to specify that bool is a keyword.
`__cplusplus`	-	In C++ compiler mode.
`__CC_ARM`	1	Always set to 1 for the ARM compiler, even when you specify the `--thumb` option.
`__CHAR_UNSIGNED__`	-	In GNU mode. It is defined if and only if char is an unsigned type.
`__DATE__`	`date`	Always defined.
`__EDG__`	-	Always defined.
`__EDG_IMPLICIT_USING_STD`	-	In C++ mode when you specify the `--using_std` option.
`__EDG_VERSION__`	-	Always set to an integer value that represents the version number of the Edison Design Group (EDG) front-end. For example, version 3.8 is represented as `308`. The version number of the EDG front-end does not necessarily match the version number of the ARM compiler toolchain.
`__EXCEPTIONS`	1	In C++ mode when you specify the `--exceptions` option.
`__FEATURE_SIGNED_CHAR`	-	When you specify the `--signed_chars` option (used by `CHAR_MIN` and `CHAR_MAX`).
`__FILE__`	`name`	Always defined as a string literal.
`__FP_FAST`	-	When you specify the `--fpmode=fast` option.
`__FP_FENV_EXCEPTIONS`	-	When you specify the `--fpmode=ieee_full` or `--fpmode=ieee_fixed` options.
`__FP_FENV_ROUNDING`	-	When you specify the `--fpmode=ieee_full` option.
`__FP_IEEE`	-	When you specify the `--fpmode=ieee_full`, `--fpmode=ieee_fixed`, or `--fpmode=ieee_no_fenv` options.
`__FP_INEXACT_EXCEPTION`	-	When you specify the `--fpmode=ieee_full` option.
`__GNUC__`	`ver`	When you specify the `--gnu` option. It is an integer that shows the current major version of the GNU mode being used.
`__GNUC_MINOR__`	`ver`	When you specify the `--gnu` option. It is an integer that shows the current minor version of the GNU mode being used.
`__GNUG__`	`ver`	In GNU mode when you specify the `--cpp` option. It has the same value as `__GNUC__`.
`__IMPLICIT_INCLUDE`	-	When you specify the `--implicit_include` option.
`__INTMAX_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `intmax_t` typedef.
`__LINE__`	`num`	Always set. It is the source line number of the line of code containing this macro.
`__MODULE__`	`mod`	Contains the filename part of the value of `__FILE__`.
`__MULTIFILE`	--	When you explicitly or implicitly use the `--multifile` option.^[a]
`__NO_INLINE__`	-	When you specify the `--no_inline` option in GNU mode.
`__OPTIMISE_LEVEL`	`num`	Always set to 2 by default, unless you change the optimization level using the `-Onum` option.^[a]
`__OPTIMISE_SPACE`	-	When you specify the `-Ospace` option.
`__OPTIMISE_TIME`	-	When you specify the `-Otime` option.
`__OPTIMIZE__`	-	When `-O1`, `-O2`, or `-O3` is specified in GNU mode.
`__OPTIMIZE_SIZE__`	-	When `-Ospace` is specified in GNU mode.
`__PLACEMENT_DELETE`	-	In C++ mode to specify that placement delete (that is, an operator delete corresponding to a placement operator new, to be called if the constructor throws an exception) is enabled. This is only relevant when using exceptions.
`__PTRDIFF_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `ptrdiff_t` typedef.
`__RTTI`	-	In C++ mode when RTTI is enabled.
`__sizeof_int`	4	For `sizeof(int)`, but available in preprocessor expressions.
`__sizeof_long`	4	For `sizeof(long)`, but available in preprocessor expressions.
`__sizeof_ptr`	4	For `sizeof(void *)`, but available in preprocessor expressions.
`__SIZE_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `size_t` typedef.
`__SOFTFP__`	-	If compiling to use the software floating-point calling standard and library. Set when you specify the `--fpu=softvfp` option for ARM or Thumb, or when you specify `--fpu=softvfp+vfpv2` for Thumb.
`__STDC__`	-	In all compiler modes.
`__STDC_VERSION__`	-	Standard version information.
`__STRICT_ANSI__`	-	When you specify the `--strict` option.
`__SUPPORT_SNAN__`	-	Support for signalling NaNs when you specify `--fpmode=ieee_fixed` or `--fpmode=ieee_full`.
`__TARGET_ARCH_ARM`	`num`	The number of the ARM base architecture of the target CPU irrespective of whether the compiler is compiling for ARM or Thumb. For possible values of `__TARGET_ARCH_ARM` in relation to the ARM architecture versions, see Table 29.
`__TARGET_ARCH_THUMB`	`num`	The number of the Thumb base architecture of the target CPU irrespective of whether the compiler is compiling for ARM or Thumb. The value is defined as zero if the target does not support Thumb. For possible values of `__TARGET_ARCH_THUMB` in relation to the ARM architecture versions, see Table 29.
`__TARGET_ARCH_XX`	-	`XX` represents the target architecture and its value depends on the target architecture. For example, if you specify the compiler options `--cpu=4T` or `--cpu=ARM7TDMI` then `__TARGET_ARCH_4T` is defined.
`__TARGET_CPU_XX`	-	`XX` represents the target CPU. The value of `XX` is derived from the `--cpu` compiler option, or the default if none is specified. For example, if you specify the compiler option `--cpu=ARM7TM` then `__TARGET_CPU_ARM7TM` is defined and no other symbol starting with `__TARGET_CPU_` is defined. If you specify the target architecture, then `__TARGET_CPU_generic` is defined. If the CPU name specified with `--cpu` is in lowercase, it is converted to uppercase. For example, `--cpu=Cortex-R4` results in `__TARGET_CPU_CORTEX_R4` being defined (rather than `__TARGET_CPU_Cortex_R4`). If the processor name contains hyphen (-) characters, these are mapped to an underscore (`_`). For example, `--cpu=ARM1136JF-S` is mapped to `__TARGET_CPU_ARM1136JF_S`.
`__TARGET_FEATURE_DOUBLEWORD`	-	ARMv5T and above.
`__TARGET_FEATURE_DSPMUL`	-	If the DSP-enhanced multiplier is available, for example ARMv5TE.
`__TARGET_FEATURE_MULTIPLY`	-	If the target architecture supports the long multiply instructions `MULL` and `MULAL`.
`__TARGET_FEATURE_DIVIDE`	-	If the target architecture supports the hardware divide instruction (that is, ARMv7-M or ARMv7-R).
`__TARGET_FEATURE_MULTIPROCESSING`	-	When you specify any of the following options: `--cpu=Cortex-A9` `--cpu=Cortex-A9.no_neon` `--cpu=Cortex-A9.no_neon.no_vfp` `--cpu=Cortex-A5` `--cpu=Cortex-A5.vfp` `--cpu=Cortex-A5.neon`
`__TARGET_FEATURE_NEON`	-	When you specify any of the following options: `--cpu=Cortex-A5.neon` `--cpu=Cortex-A8` `--cpu=Cortex-A9` `--cpu=QSP`
`__TARGET_FEATURE_THUMB`	-	If the target architecture supports Thumb, ARMv4T or later.
`__TARGET_FPU_xx`	-	One of the following is set to indicate the FPU usage: `__TARGET_FPU_NONE` `__TARGET_FPU_VFP` `__TARGET_FPU_SOFTVFP` In addition, if compiling with one of the following `--fpu` options, the corresponding target name is set: `--fpu=softvfp+vfpv2`, `__TARGET_FPU_SOFTVFP_VFPV2` `--fpu=softvfp+vfpv3`, `__TARGET_FPU_SOFTVFP_VFPV3` `--fpu=softvfp+vfpv3_fp16`, `__TARGET_FPU_SOFTVFP_VFPV3_FP16` `--fpu=softvfp+vfpv3_d16`, `__TARGET_FPU_SOFTVFP_VFPV3_D16` `--fpu=softvfp+vfpv3_d16_fp16`, `__TARGET_FPU_SOFTVFP_VFPV3_D16_FP16` `--fpu=vfpv2`, `__TARGET_FPU_VFPV2` `--fpu=vfpv3`, `__TARGET_FPU_VFPV3` `--fpu=vfpv3_fp16`, `__TARGET_FPU_VFPV3_FP16` `--fpu=vfpv3_d16`, `__TARGET_FPU_VFPV3_D16` `--fpu=vfpv3_d16_fp16`, `__TARGET_FPU_VFPV3_D16_FP16` See ‑‑fpu=name for more information.
`__TARGET_PROFILE_A`		When you specify the `--cpu=7-A` option.
`__TARGET_PROFILE_R`		When you specify the `--cpu=7-R` option.
`__TARGET_PROFILE_M`		When you specify any of the following options: `--cpu=6-M` `--cpu=6S-M` `--cpu=7-M`
`__thumb__`	-	When the compiler is in Thumb mode. That is, you have either specified the `--thumb` option on the command-line or `#pragma thumb` in your source code. Note The compiler might generate some ARM code even if it is compiling for Thumb. `__thumb` and `__thumb__` become defined or undefined when using `#pragma thumb` or `#pragma arm`, but do not change in cases where Thumb functions are generated as ARM code for other reasons (for example, a function specified as `__irq`).
`__TIME__`	`time`	Always defined.
`__UINTMAX_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `uintmax_t` typedef.
`__USER_LABEL_PREFIX__`		In GNU mode. It defines an empty string. This macro is used by some of the Linux header files.
`__VERSION__`	`ver`	When you specify the `--gnu` option. It is a string that shows the current version of the GNU mode being used.
`_WCHAR_T`	-	In C++ mode, to specify that wchar_t is a keyword.
`__WCHAR_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `wchar_t` typedef.
`__WCHAR_UNSIGNED__`	-	In GNU mode when you specify the `--cpp` option. It is defined if and only if wchar_t is an unsigned type.
`__WINT_TYPE__`	-	In GNU mode. It defines the correct underlying type for the `wint_t` typedef.
^[a]ARM recommends that if you have source code reliant on the `__OPTIMISE_LEVEL` macro to determine whether or not `--multifile` is in effect, you change to using`__MULTIFILE`.

Table 29 shows the possible values for __TARGET_ARCH_THUMB (see Table 28), and how these values relate to versions of the ARM architecture.

Table 29. Thumb architecture versions in relation to ARM architecture versions

ARM architecture	`__TARGET_ARCH_ARM`	`__TARGET_ARCH_THUMB`
v4	`4`	`0`
v4T	`4`	`1`
v5T, v5TE, v5TEJ	`5`	`2`
v6, v6K, v6Z	`6`	`3`
v6T2	`6`	`4`
v6-M, v6S-M	`0`	`3`
v7-A, v7-R	`7`	`4`
v7-M, v7E-M	`0`	`4`

Function names

Table 30 lists builtin variables supported by the compiler for C and C++.

Table 30. Builtin variables

Name Value

Name	Value
`__FUNCTION__`	Holds the name of the function as it appears in the source. `__FUNCTION__` is a constant string literal. You cannot use the preprocessor to join the contents to other text to form new tokens.
`__PRETTY_FUNCTION__`	Holds the name of the function as it appears pretty printed in a language-specific fashion. `__PRETTY_FUNCTION__` is a constant string literal. You cannot use the preprocessor to join the contents to other text to form new tokens.

__FUNCTION__

Holds the name of the function as it appears in the source.

__FUNCTION__ is a constant string literal. You cannot use the preprocessor to join the contents to other text to form new tokens.

__PRETTY_FUNCTION__

Holds the name of the function as it appears pretty printed in a language-specific fashion.

__PRETTY_FUNCTION__ is a constant string literal. You cannot use the preprocessor to join the contents to other text to form new tokens.

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Compiler predefines

Predefined macros

Note

Note

Function names