PipeBarrier(ISASI)

Product Support

Function

Blocks a pipeline. This synchronization 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

Returns

None

Restrictions

The synchronization between Scalar pipelines is automatically ensured by the hardware. Calling PipeBarrier<PIPE_S>() throws a hardware error.

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.

Note: This is only an example for reference. When automatic synchronization is enabled (enabled by default in kernel launch operator projects and custom operator development projects), the compiler automatically inserts the PIPE_V synchronization, and you do not need to manually insert it.

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);