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PipeBarrier(ISASI)

Function Usage

Blocks a pipeline. This synchronization operation needs to be inserted between the same pipelines with data dependency.

Prototype

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template <pipe_t pipe>
__aicore__ inline void PipeBarrier()

Parameters

Table 1 Parameters

Parameter

Input/Output

Description

pipe

Input

Template parameter, indicating the type of blocked pipelines.

For details about supported pipelines, see Hardware Pipelines.

Returns

None

Availability

Atlas Training Series Product

Constraints

The synchronization between Scalar pipelines is automatically ensured by the hardware. If PipeBarrier<PIPE_S>() is called, a hardware error occurs.

Example

In the following example, the input dst0Local of the Mul instruction is the output of the Add instruction. The two vector operation instructions depend on each other. Therefore, PipeBarrier needs to be inserted to ensure the execution sequence of the two instructions.

Figure 1 The Mul instruction and the Add instruction are in a serial relationship. The Mul instruction can be executed only after the Add instruction is executed.
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AscendC::LocalTensor<half> src0Local;
AscendC::LocalTensor<half> src1Local;
AscendC::LocalTensor<half> src2Local;
AscendC::LocalTensor<half> dst0Local;
AscendC::LocalTensor<half> dst1Local;

AscendC::Add(dst0Local, src0Local, src1Local, 512);
AscendC::PipeBarrier<PIPE_V>();
AscendC::Mul(dst1Local, dst0Local, src2Local, 512);