Table of Contents

[TOC]

Pre-defined C/C++ Compiler Macros

The macros are found here:

General guidelines are found here:

Please send updates/corrections to predef-contribute.

Introduction

C and C++ compilers automatically define certain macros that can be used to check for compiler or operating system features. This is useful when writing portable software.

These pages lists various pre-defined compiler macros that can be used to identify standards, compilers, operating systems, hardware architectures, and even basic run-time libraries at compile-time.

For example, if we want to use a generic or opaque pointer type, we use void pointers. However, ancient K&R compilers (from the time before the first ANSI C standard) do not support void pointers. Instead we can define our own type:

#if defined(__STDC__) || defined(__cplusplus) || defined(_MSC_EXTENSIONS)
typedef void * t_pointer;
#else
typedef char * t_pointer;
#endif

Another example, Microsoft Visual C++ version 4.2 added a pragma to reduce compilation times by only including a file once (if _MSC_VER is not defined then it will evaluate to 0 (zero) — however, some compilers may complain about an undefined macro)

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
#pragma once
#endif

The macros contained in these pages have been obtained through vendor documentation, the defines script, contributors, and third-party source code. No guarantee about the correctness of the macros is given.

An often-used alternative is Autoconf, which is a more powerful tool to examine various types of features, including compilation options. However, Autoconf is fairly Unix-centric, and requires a Unix layer on other platforms (e.g. Cygwin on Windows). Other alternatives are Buildtool, CMake, SCons, PMK, Jam, Ant, and Bakefile.

Architectures

Alpha

Type Macro Description
Identification __alpha__ Defined by GNU C
Version __alpha_ev'V'__ V = Version
Identification __alpha Defined by DEC C
Identification _M_ALPHA Defined by Visual Studio
Example
CPU Macro
Alpha EV4 __alpha_ev4__
Alpha EV5 __alpha_ev5__
Alpha EV6 __alpha_ev6__

AMD64

Type Macro Description
Identification __amd64__ __amd64 __x86_64__ __x86_64 Defined by GNU C and Sun Studio
Identification _M_X64 _M_AMD64 Defined by Visual Studio

Notice that x32 can be detected by checking if the CPU uses the ILP32 data model.

ARM

Type Macro Description
Identification __arm__ Defined by GNU C and RealView
Identification __thumb__ Defined by GNU C and RealView in Thumb mode
Version __ARM_ARCH_'V'__ V = Version Defined by GNU C 1
Identification __TARGET_ARCH_ARM __TARGET_ARCH_THUMB Defined by RealView
Version __TARGET_ARCH_ARM = V __TARGET_ARCH_THUMB = V V = Version
Version __TARGET_ARCH_'VR' VR = Version and Revision
Identification _ARM Defined by ImageCraft C
Identification _M_ARM Defined by Visual Studio
Identification _M_ARMT Defined by Visual Studio in Thumb mode
Version _M_ARM = V V = Version
Identification __arm Defined by Diab
Example
CPU Macro _M_ARM
ARM 2 __ARM_ARCH_2__  
ARM 3 __ARM_ARCH_3__ __ARM_ARCH_3M__  
ARM 4T __ARM_ARCH_4T__ __TARGET_ARM_4T  
ARM 5 __ARM_ARCH_5__ __ARM_ARCH_5E__ 5
ARM 5T __ARM_ARCH_5T__ __ARM_ARCH_5TE__ __ARM_ARCH_5TEJ__  
ARM 6 __ARM_ARCH_6__ __ARM_ARCH_6J__ __ARM_ARCH_6K__ __ARM_ARCH_6Z__ __ARM_ARCH_6ZK__ 6
ARM 6T2 __ARM_ARCH_6T2__  
ARM 7 __ARM_ARCH_7__ __ARM_ARCH_7A__ __ARM_ARCH_7R__ __ARM_ARCH_7M__ __ARM_ARCH_7S__ 7

ARM64

Type Macro Description
Identification __aarch64__ Defined by GNU C 1

Blackfin

Type Macro Description
Identification __bfin __BFIN__ Defined by GNU C

Convex

Type Macro Description
Identification __convex__ Defined by GNU C
Version __convex_'V'__ V = Version
Example
CPU Macro
Convex C1 __convex_c1__
Convex C2 __convex_c2__
Convex C32xx series __convex_c32__
Convex C34xx series __convex_c34__
Convex C38xx series __convex_c38__

Epiphany

Type Macro  
Identification __epiphany__  

HP/PA RISC

Type Macro Description
Identification __hppa__ Defined by GNU C
Identification __HPPA__ Defined by Stratus VOS C
Identification __hppa  
Version _PA_RISC'V'_'R' V = Version R = Revision

See also OpenPA.net.

Example
CPU Macro
PA RISC 1.0 _PA_RISC1_0
PA RISC 1.1 _PA_RISC1_1 __HPPA11__ __PA7100__
PA RISC 2.0 _PA_RISC2_0 __RISC2_0__ __HPPA20__ __PA8000__

Intel x86

Type Macro Format Description
Identification i386 __i386 __i386__   Defined by GNU C
Version __i386__ __i486__ __i586__ __i686__   Defined by GNU C
Identification __i386   Defined by Sun Studio
Identification __i386 __IA32__   Defined by Stratus VOS C
Identification _M_I86   Only defined for 16-bits architectures Defined by Visual Studio, Digital Mars, and Watcom C/C++ (see note below)
Identification _M_IX86   Only defined for 32-bits architectures Defined by Visual Studio, Intel C/C++, Digital Mars, and Watcom C/C++
Version _M_IX86 V00 V = Version
Identification __X86__   Defined by Watcom C/C++
Identification _X86_   Defined by MinGW32
Identification __THW_INTEL__   Defined by XL C/C++
Identification __I86__   Defined by Digital Mars
Version __I86__ V V = Version
Identification __INTEL__   Defined by CodeWarrior
Identification __386   Defined by Diab

Notice that Watcom C/C++ defines _M_IX86 for both 16-bits and 32-bits architectures. Use __386__ or _M_I386 to detect 32-bits architectures in this case.

Notice that the Stratus VOS is big-endian on IA32, so these macros cannot be used to detect endianness if __VOS__ is set.

Example
CPU _M_IX86 __I86__
80386 300 3
80486 400 4
Pentium 500 5
Pentium Pro/II 600 6

Intel Itanium (IA-64)

Type Macro Format Description
Identification __ia64__ _IA64 __IA64__   Defined by GNU C
Identification __ia64   Defined by HP aCC
Identification _M_IA64   Defined by Visual Studio
Identification _M_IA64   Defined by Intel C/C++
Version _M_IA64 ?  
Identification __itanium__   Defined by Intel C/C++
Example
CPU _M_IA64 (Intel C/C++)
  64100

Motorola 68k

Type Macro Description
Identification __m68k__ Defined by GNU C
Version __mc'V'__ __mc'V' mc'V' V = Version
Identification M68000 Defined by SAS/C
Identification __MC68K__ Defined by Stratus VOS C
Version __MC'V'__ V = Version
Example
CPU Macro
68000 __mc68000__ __MC68000__
68010 __mc68010__
68020 __mc68020__ __MC68020__
68030 __mc68030__ __MC68030__
68040 __mc68040__
68060 __mc68060__

MIPS

Type Macro Description
Identification __mips__ mips Defined by GNU C
Version _MIPS_ISA = _MIPS_ISA_MIPS'V' V = MIPS ISA level
Version _R3000 _R4000 _R5900  
Identification __mips Defined by MIPSpro and GNU C
Version __mips The value indicates the MIPS ISA (Instruction Set Architecture) level
Version __MIPS_ISA'V'__ V = MIPS ISA level
Identification __MIPS__ Defined by Metrowerks
Example
CPU _MIPS_ISA GNU C Macro __mips MIPSpro Macro
R2000 _MIPS_ISA_MIPS1   1  
R3000 _MIPS_ISA_MIPS1 _R3000 1  
R6000 _MIPS_ISA_MIPS2   2 __MIPS_ISA2__
R4000   _R4000    
R4400 _MIPS_ISA_MIPS3   3 __MIPS_ISA3__
R8000 _MIPS_ISA_MIPS4   4 __MIPS_ISA4__
R10000 _MIPS_ISA_MIPS4   4 __MIPS_ISA4__

PowerPC

Type Macro Description
Identification __powerpc __powerpc__ __powerpc64__ __POWERPC__ __ppc__ __ppc64__ __PPC__ __PPC64__ _ARCH_PPC _ARCH_PPC64 Defined by GNU C
Version __ppc'V'__ V = Version
Identification _M_PPC Defined by Visual Studio
Version _M_PPC ?
Identification _ARCH_PPC _ARCH_PPC64 Defined by XL C/C++
Version _ARCH_'V' V = Version
Version __PPCGECKO__ Gekko Defined by CodeWarrior
Version __PPCBROADWAY__ Broadway Defined by CodeWarrior
Version _XENON Xenon
Identification __ppc Defined by Diab
Example
CPU _M_PPC Macro XL Macro
PowerPC 440     _ARCH_440
PowerPC 450     _ARCH_450
PowerPC 601 601 __ppc601__ _ARCH_601
PowerPC 603 603 __ppc603__ _ARCH_603
PowerPC 604 604 __ppc604__ _ARCH_604
PowerPC 620 620    

Pyramid 9810

Type Macro
Identification pyr

RS/6000

Type Macro Description
Identification __THW_RS6000 Defined by XL C/C++
Identification _IBMR2  
Identification _POWER  
Identification _ARCH_PWR _ARCH_PWR2 _ARCH_PWR3 _ARCH_PWR4  

SPARC

Type Macro Description
Identification __sparc__ Defined by GNU C
Identification __sparc Defined by Sun Studio
Version __sparc_v8__ __sparc_v9__ Defined by GNU C
Version __sparcv8 __sparcv9 Defined by Sun Studio
Example
CPU Sun Studio Macro GNU C Macro
SPARC v8 (SuperSPARC) __sparcv8 __sparc_v8__
SPARC v9 (UltraSPARC) __sparcv9 __sparc_v9__

SuperH

Type Macro Description
Identification __sh__ Defined by GNU C
Version __sh1__ __sh2__ __sh3__ __SH3__ __SH4__ __SH5__  

SystemZ

Type Macro Description
Identification __370__ __THW_370__ Identifies System/370 Defined by XL C/C++
Identification __s390__ Identifies System/390 Defined by GNU C
Identification __s390x__ Identifies z/Architecture Defined by GNU C
Identification __zarch__ Identifies z/Architecture Defined by clang
Identification __SYSC_ZARCH__ Identifies z/Architecture Defined by Systems/C

TMS320

Type Macro Description
Identification _TMS320C2XX __TMS320C2000__ C2000 series
Identification _TMS320C5X __TMS320C55X__ C5000 series
Identification _TMS320C6X __TMS320C6X__ C6000 series
Example
DSP Macro
C28xx _TMS320C28X
C54x _TMS320C5XX
C55x __TMS320C55X__
C6200 _TMS320C6200
C6400 _TMS320C6400
C6400+ _TMS320C6400_PLUS
C6600 _TMS320C6600
C6700 _TMS320C6700
C6700+ _TMS320C6700_PLUS
C6740 _TMS320C6740

TMS470

Type Macro
Identification __TMS470__

Data Models

Data type LP32 ILP32 LP64 LLP64 ILP64 SILP64
char 8 8 8 8 8 8
short 16 16 16 16 16 64
int 16 32 32 32 64 64
long 32 32 64 32 64 64
long long     64 64 64 64
pointer 32 32 64 64 64 64

ILP32

Macro Description
_ILP32 Defined by HP aCC and Sun Studio
__ILP32__ Defined by GNU C

LP64

Macro Description
_LP64 Defined by HP aCC and Sun Studio
__LP64__ Defined by GNU C

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