[BugFix][OpenCL] Guard QCOM perf hint behind USE_OPENCL_EXTN_QCOM to avoid undefined symbol on non-QCOM runtimes

[ping-ee]

This PR is a re-open of #18581

The previous PR was created while Jenkins CI was experiencing a disk space issue and the CI job did not trigger.

PR Description

Recent OpenCL-Headers update (KhronosGroup/OpenCL-Headers#277
) added QCOM perf-hint definitions (CL_CONTEXT_PERF_HINT_QCOM, clSetPerfHintQCOM) to cl_ext.h.

These macros are now defined even on platforms whose OpenCL runtimes (e.g., PoCL, ICD loaders) do not implement the QCOM extension.

TVM previously enabled the perf-hint code path solely based on the presence of CL_CONTEXT_PERF_HINT_QCOM, causing link errors such as:

undefined symbol: clSetPerfHintQCOM

This PR guards the QCOM perf-hint logic behind USE_OPENCL_EXTN_QCOM, matching the behavior of other QCOM-specific OpenCL paths (e.g., SetNativePtr).

Effects

Prevents accidental linking against unsupported QCOM symbols on non-QCOM runtimes.
Keeps QCOM builds fully functional when USE_OPENCL_EXTN_QCOM is explicitly enabled.
Aligns TVM’s extension handling across OpenCL code paths.

[gemini-code-assist]

Summary of Changes

Hello @ping-ee, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical linking issue within the OpenCL runtime where QCOM-specific performance hint functions were inadvertently included in builds on platforms lacking QCOM OpenCL extensions. By introducing an additional conditional compilation flag, USE_OPENCL_EXTN_QCOM, the change ensures that these QCOM-specific calls are only compiled when explicitly enabled, thereby preventing undefined symbol errors and maintaining proper functionality for both QCOM and non-QCOM OpenCL environments.

Highlights

• Bug Fix: Resolves a linking error where clSetPerfHintQCOM caused undefined symbol errors on non-QCOM OpenCL runtimes.
• Conditional Compilation: The QCOM performance hint logic is now guarded by USE_OPENCL_EXTN_QCOM in addition to CL_CONTEXT_PERF_HINT_QCOM.
• Consistency: Aligns the handling of QCOM-specific OpenCL extensions with other existing QCOM-specific code paths in TVM.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a linkage error that occurs on non-Qualcomm OpenCL runtimes. The issue arises because QCOM-specific macros are now defined in standard OpenCL headers, but the corresponding functions are not available to link against on unsupported platforms. By adding the USE_OPENCL_EXTN_QCOM build flag to the preprocessor guard, the code for setting performance hints is now only compiled when targeting Qualcomm devices, which is the correct behavior. The change is minimal, well-justified, and consistent with how other QCOM-specific extensions are handled in the codebase. The fix is sound and I have no further suggestions.

[ping-ee]

This PR reopens #18581 with the same commits.
The previous PR did not trigger Jenkins CI due to a disk space issue.