[Bug] Error in cross_compilation_and_rpc.py tutorial: incorrect variable used in sch.split

[HGboda]

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Expected behavior

The OpenCL example in the cross-compilation and RPC tutorial should use the correct variable names and properly bind loops to GPU thread hierarchy. Specifically, after getting the loop variable x and splitting it into xo and xi, the code should use these variables correctly in subsequent operations.

Actual behavior

The tutorial code contains variable name errors and incorrect loop binding:

Line 237 uses an undefined variable i in sch.split(i, [None, 32]) instead of using the previously defined variable x.
Lines 238-239 incorrectly bind the same variable x to both "blockIdx.x" and "threadIdx.x", instead of binding the outer loop xo to "blockIdx.x" and the inner loop xi to "threadIdx.x".

Environment

TVM from GitHub repository (latest main branch)
Operating System: Linux

Steps to reproduce

Open the tutorial file at docs/how_to/tutorials/cross_compilation_and_rpc.py
Look at the run_opencl() function around line 236-239:

(x,) = sch.get_loops(block=sch.get_block("B"))
xo, xi = sch.split(i, [None, 32]) # Error: 'i' is undefined
sch.bind(x, "blockIdx.x") # Error: should use 'xo'
sch.bind(x, "threadIdx.x") # Error: should use 'xi'

Triage

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[tqchen]

Thanks @HGboda do you mind to send a PR to fix? i think it is a matter of chaanging i => x and use xo and xi below.

[tqchen]

cc @tlopex

[HGboda]

Thank you for your response! I’d be happy to submit a PR to fix this issue. I will make the necessary changes and open a PR soon.

[tqchen]

fixed by #17743