Predefined Macro Use

The macros listed in this chapter are the Cray-specific predefined macros. To see the entire list of predefined macros, add -Wp,-list_final_macros to the cc command line.

The macros listed in this chapter are the Cray-specific predefined macros. To see the entire list of predefined macros, add -Wp,-list_final_macros to the cc command line. For example, if it is the file c.c, specify:

% cc -Wp,-list_final_macros c.c > out

Predefined macros provide information about the compilation environment. In this chapter, only those macros that begin with the underscore (_) character are defined when running in strict-conformance mode.

Any of the predefined macros except those required by the standard can be undefined by using the -U command line option; they can also be redefined by using the -D command line option.

A large set of macros is also defined in the standard header files.

Macros Required by the C and C++ Standards

The following macros are required by C and C++ standards:

__TIME__: Time of translation of the source file.
__DATE__: Date of translation of the source file.
__LINE__: Line number of the current line in the source file.
__FILE__: Name of the source file being compiled.
__STDC__: Defined as the decimal constant 1 if compilation is in strict conformance mode; defined as the decimal constant 2 if the compilation is in extended mode. This macro is defined for Cray C and C++ compilations.
__cplusplus: Defined as 1 when the compiling Cray C++ code and undefined when compiling Cray C code. The __cplusplus macro is required by the ISO C++ standard, but not the ISO C standard.

Macros Based on the Host Machine

The following macros provide information about the environment running on the host machine:

__linux: Defined as 1.
__linux__: Defined as 1.
linux: Defined as 1.
__gnu_linux__: Defined as 1.

Macros Based on the Target Machine

The following macros provide information about the characteristics of the target machine:


Macro	x86	AVX
_ADDR64	Defined as 1 if the targeted CPU has 64-bit address registers; if the targeted CPU does not have 64-bit address registers, the macro is not defined.
__LITTLE_ENDIAN__	Defined as 1.
_LITTLE_ENDIAN	Defined as 1.
_MAXVL_8	Defined as 16, the number of 8-bit elements that fit in an XMM register ("vector length").	Defined as 32, the number of 8-bit elements that fit in a YMM register ("vector length").
_MAXVL_16	Defined as 8.	Defined as 16.
_MAXVL_32	Defined as 4.	Defined as 8.
_MAXVL_64	Defined as 2.	Defined as 4.
_MAXVL_128	Defined as 0.	Defined as 2.

Macros Based on the Compiler

The following macros provide information about compiler features:

_RELEASE_MAJOR: Defined as the major release level of the compiler.
_RELEASE_MINOR: Defined as the minor release level of the compiler.
_RELEASE_STRING: Defined as a string that describes the version of the compiler.
_CRAYC: Defined as 1 to identify the Cray C and C++ compilers.

UPC Predefined Macros

The following macros provide information about UPC functions:

__UPC__: The integer constant 1, indicating a conforming implementation.
__UPC_DYNAMIC_THREADS__: The integer constant 1 in the dynamic THREADS translation environment.
__UPC_STATIC_THREADS__: The integer constant 1 in the static THREADS translation environment.