Predefined Macros and Built-in Variables

Predefined Macros

Like other language compilers, the BiSheng Compiler has some predefined macros for developers to write programs.

Predefined Macros	Default Value	Description
__CCE_IS_AICORE__	1	The value is 1 on the device, which can be used to distinguish device code from host code.
__DAV_CUBE__	-	Isolates Cube-side code.
__DAV_VEC__	-	Isolates Vector-side code.
__NPU_ARCH__	-	Distinguishes between device-side and host-side code, while isolating code for different architectures on the device side.

**Table 1** Mapping between AI processor models and __NPU_ARCH__
AI processor Model	__NPU_ARCH__
Atlas 350 Accelerator Card	3510
Atlas A3 training product / Atlas A3 inference product	2201
Atlas A2 training product / Atlas A2 inference product	2201
Atlas 200I/500 A2 inference product	3002
Atlas inference product	2002
Atlas training product	1001

Note:

Tightly coupled cores (CUBE and VEC not separated): The compiler defines both __DAV_CUBE__ and __DAV_VEC__.
Loosely coupled cores (CUBE and VEC separated): The compiler defines __DAV_CUBE__ when compiling CUBE and __DAV_VEC__ when compiling VEC.
CUBE-only cores: Only __DAV_CUBE__ is defined.
VECTOR-only cores: Only __DAV_VEC__ is defined.

Built-in Variables

The following variables are built-in variables of the BiSheng Compiler. The variable names defined by developers in programs cannot be the same as the built-in variable names. Additionally, built-in variables are usually used by the framework and remain imperceptible to developers. To obtain the core ID or number of cores, use the corresponding Ascend C API.

**Table 2** Built-in variable list
Built-in Variable	Description
block_idx	Current core ID, which is a logical value in the core and remains imperceptible to developers. The core ID used during programming can be obtained by calling GetBlockIdx.
block_num	Number of used cores, which is a logical value in the core and remains imperceptible to developers. The number of cores used for programming can be obtained by calling GetBlockNum.

Parent topic: AI Core Programming Guide