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jiajia Qian
60858fce9e
The previous OpenCL implementation of UMat::diag() relied on a sequence of operations involving buffer initialization followed by copy/transpose on an aliased diag() view. Although these operations were enqueued on an in-order command queue, this implicitly assumed memory visibility between kernels operating on aliased regions of the same buffer. According to the OpenCL specification, in-order command queues only guarantee command scheduling order, while memory visibility between commands is only established through explicit command-level synchronization points (e.g. events, barriers, or clFinish).Under OpenCL’s relaxed memory model, such assumptions are not guaranteed without an explicit command-level synchronization point, and can lead to data races and incorrect results, especially for very small matrices (e.g. 1x1). The issue is more likely to be exposed on Mesa-based drivers when the GPU is running at lower frequencies (e.g. 500 MHz). This change introduces a dedicated OpenCL kernel to construct the diagonal matrix in a single kernel invocation, avoiding intermediate aliasing and eliminating the need for implicit ordering assumptions. If the OpenCL path is unavailable or unsupported, the implementation transparently falls back to the CPU path. Signed-off-by: jiajia Qian <jiajia.qian@nxp.com>
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