[Relax][Test] Cover default GPU pipeline scheduling for R.power/elementwise kernels

[cchung100m]

Hi Commiters,

PR #19384 fixed routing in vm_build.py:249-265 but no regression test was added. This PR adds regression coverage for GPU scheduling of legalized elementwise ops for issue #19548.

Closes the test coverage gap:

1. Device-Free Test: Verifies CUDA pipeline produces thread-bound kernels
2. GPU-Test: end-to-end compile + execute, verify numerical correctness

[gemini-code-assist]

Code Review

This pull request adds unit tests to verify that the default CUDA pipeline correctly schedules and thread-binds an elementwise R.power kernel, preventing memory verification failures during compilation. The review feedback identifies two critical issues in the newly added tests: a syntax error on line 199 where the assignment operator = is missing (mod seq(PowerModule)), and a NameError on line 202 due to using an undefined tir name instead of tvm.tirx.PrimFunc.

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The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
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[cchung100m]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds tests to verify that the default CUDA pipeline correctly schedules and thread-binds an elementwise R.power kernel with a scalar constant operand, preventing VerifyMemory build failures. Feedback was provided to make the test assertion more robust by filtering for the specific "power" PrimFunc, avoiding potential failures if future legalization passes introduce host-side helper functions without thread bindings.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.