[WIP] Don't use IterType::gatherscatter with gather

[naoyam]

No description provided.

[naoyam]

!test --diff

[github-actions]

Description

• Removed unnecessary IterType::GatherScatter usage

• Simplified IterDomainBuilder in gather function

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Changes walkthrough 📝

	Relevant files
Enhancement	indexing.cpp Simplify IterDomainBuilder usage                                                  csrc/ops/indexing.cpp Removed IterType::GatherScatter assignment in IterDomainBuilder Simplified out_domain construction in gather function +1/-7

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🧪 No relevant tests

⚡ Recommended focus areas for review Performance Impact The change removes the specific IterType::GatherScatter setting for IterDomain. This might affect the performance of gather operations, especially if GatherScatter was used for optimization purposes. out_domain.push_back(IterDomainBuilder(idx_domain_ptr).build());