Fix pointer comparison

[josesimoes]

Description

• Handled code to properly compare arrays with storage pointers.

Motivation and Context

• Now properly handles this comparison. This has surfaced when adding unit tests for ReadOnlySpan<T>.
• Related with Support for generics <T> Home#782.

How Has This Been Tested?

• [tested against Merge generics support in mscorlib CoreLibrary#245].

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dev Containers (changes related with Dev Containers, has no impact on code or features)
• Dependencies/declarations (update dependencies or assembly declarations and changes associated, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist

• My code follows the code style of this project (only if there are changes in source code).
• My changes require an update to the documentation (there are changes that require the docs website to be updated).
• I have updated the documentation accordingly (the changes require an update on the docs in this repo).
• I have read the CONTRIBUTING document.
• I have tested everything locally and all new and existing tests passed (only if there are changes in source code).

Summary by CodeRabbit

• Bug Fixes
  • Enhanced array value comparison logic to improve performance and ensure accurate results when evaluating equivalent arrays.

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Walkthrough

Modified the CompareValues_Pointers function in the CLR runtime to add an upfront equality check for identical pointers and introduce special-case handling for comparing single-dimensional arrays with storage pointers. If applicable conditions are met, the function compares storage pointer values; otherwise, it retains existing default pointer comparison logic.

Changes

Cohort / File(s)	Summary
Pointer comparison logic src/CLR/Core/CLR_RT_HeapBlock.cpp	Added upfront equality check for identical pointers. Introduced special-case path for single-dimensional arrays (DATATYPE_SZARRAY) with REFLECTION_STORAGE_PTR to compare storage pointer values directly. Retained existing pointer comparison fallback logic.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• Review the placement and correctness of the new upfront equality check
• Verify the SZARRAY special-case logic handles both valid and invalid storage pointers appropriately
• Ensure the fallback pointer comparison logic remains unaffected and compatible with the new early-return paths

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix pointer comparison' clearly summarizes the main change - it directly addresses the bug fix in the CompareValues_Pointers function where pointer comparison logic was enhanced for arrays with storage pointers.

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[josesimoes]

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Actionable comments posted: 1

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between b295724 and a3d84a6.

📒 Files selected for processing (1)

• src/CLR/Core/CLR_RT_HeapBlock.cpp (1 hunks)

🧰 Additional context used

🧠 Learnings (1)

📚 Learning: 2025-01-22T03:38:57.394Z

Learnt from: josesimoes
Repo: nanoframework/nf-interpreter PR: 3074
File: src/CLR/Core/GarbageCollector_Info.cpp:107-167
Timestamp: 2025-01-22T03:38:57.394Z
Learning: In nanoFramework's memory management code, DataSize() validation is comprehensively handled through CLR_RT_HeapCluster::ValidateBlock() and other caller code. Additional size checks in ValidateCluster() are redundant as the validation is already performed at multiple levels.

Applied to files:

• src/CLR/Core/CLR_RT_HeapBlock.cpp

🔇 Additional comments (1)

src/CLR/Core/CLR_RT_HeapBlock.cpp (1)

1738-1742: Early left == right return is correct and a good fast-path.