4.8.1. Predefined macros

Table 4.18 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 4.18. Predefined macros

NameValueWhen defined
__arm__-

Always defined for the ARM compiler, even when you specify the --thumb option.

See also __ARMCC_VERSION.

__ARMCC_VERSIONver

Always defined. It is a decimal number, and is guaranteed to increase between releases. The format is PVtbbb where:

  • P is the major version

  • V is the minor version

  • t is the patch release

  • bbb is the build number.

Note

Use this to distinguish between RVCT 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_ARM1

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__dateAlways defined.
__EDG__-

Always defined.

__EDG_IMPLICIT_USING_STD-

In C++ mode when you specify the --implicit_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 RVCT or RVDS version number.

__EXCEPTIONS1

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__nameAlways 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__verIn 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__numAlways 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__.

__NO_INLINE__-

When you specify the --no_inline option in GNU mode.

__OPTIMISE_LEVELnum

Always set to 2 by default, unless you change the optimization level using the -Onum option.

__OPTIMISE_SPACE-

When you specify the -Ospace option.

__OPTIMISE_TIME-

When you specify the -Otime option.

__OPTIMIZE__-

When -O1 or -O2 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_int4

For sizeof(int), but available in preprocessor expressions.

__sizeof_long4

For sizeof(long), but available in preprocessor expressions.

__sizeof_ptr4

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.

__TARGET_ARCH_ARMnumThe number of the ARM base architecture of the target CPU irrespective of whether the compiler is compiling for ARM or Thumb.
__TARGET_ARCH_THUMBnumThe 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.
__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 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_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 --fpu=softvfp+vfpv2 or --fpu=softvfp+vfpv3, __TARGET_FPU_SOFTVFP_VFPV2 or __TARGET_FPU_SOFTVFP_VFPV3 is also set.

See ‑‑fpu=name for more information.

__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.
__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.

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