fix(pass): preserve dynamic-shape Var pointer identity in InitMemRef

[huxinyuan1215]

Summary

Closes #970

InitMemRef::ProcessNormalVar was creating new Var objects for non-ShapedType variables (e.g. ScalarType(INDEX) for dynamic dimensions like M, N) even though they don't need MemRef initialization. This fragmented a single shared M pointer into 4 distinct pointers across param types, return types, and body — breaking structural_equal bijection during roundtrip checks.

Fix: return the original Var for non-ShapedType variables. This also removes the last Variable pointer mismatch suppression from RoundtripInstrument — all roundtrip checks now run with zero suppressions.

Test plan

• All 3419 unit tests pass
• Verified M pointer count stays at 1 through entire pass pipeline (was 4 after InitMemRef before fix)

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: a0f7cb25-175e-4596-b981-c8c6e3b66679

📥 Commits

Reviewing files that changed from the base of the PR and between 53d9f93 and 14b69d0.

📒 Files selected for processing (2)

• python/pypto/ir/instruments.py
• src/ir/transforms/init_memref.cpp

💤 Files with no reviewable changes (1)

• python/pypto/ir/instruments.py

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📝 Walkthrough

Walkthrough

Fixes a bug where the InitMemRef pass was fragmenting dynamic-shape Var pointers by creating new instances instead of preserving the original pointer identity. Returns the original Var for non-ShapedType variables in ProcessNormalVar() and removes the downstream suppression of "Variable pointer mismatch" errors in the RoundtripInstrument.

Changes

Cohort / File(s)	Summary
InitMemRef Var Pointer Preservation src/ir/transforms/init_memref.cpp	Added explicit handling to return the original Var pointer for non-ShapedType variables instead of creating a new instance, preserving pointer identity across multiple type annotations.
RoundtripInstrument Error Suppression Removal python/pypto/ir/instruments.py	Removed special-case string matching that silently suppressed "Variable pointer mismatch" structural-equality errors; now all exceptions are re-raised as RuntimeError with printed IR included.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• PR #871: Addresses InitMemRef handling of Var pointer identity for dynamic/valid-shape-related types by preventing creation of fresh Vars and preserving original references.
• PR #460: Fixes the same pointer-identity problem for IR Vars used as dynamic/dimension variables through deduplication of DynVar→Var mappings to ensure shared pointer identity.

Suggested reviewers

• lyfne123

Poem

🐰 A pointer once fragmented, now made whole,
Dynamic shapes no longer take their toll,
No more suppression of the mismatch cry,
One Var to rule them all—no alibi! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title clearly and concisely describes the main fix: preserving Var pointer identity in InitMemRef for dynamic-shape variables, which directly matches the changeset.
Description check	✅ Passed	Description relates to the changeset, explains the bug, the fix, and references the linked issue #970.
Linked Issues check	✅ Passed	Code changes fully implement the objectives from issue #970: preserving Var pointer identity in InitMemRef and removing Variable pointer mismatch suppression from RoundtripInstrument.
Out of Scope Changes check	✅ Passed	All changes directly address the requirements in issue #970; no out-of-scope modifications detected.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[gemini-code-assist]

Code Review

This pull request addresses the "Variable pointer mismatch" issue by ensuring that non-shaped types, such as those used for dynamic-shape dimensions, preserve their pointer identity during IR mutations in InitMemRefMutator. By returning the original Var instead of creating a new one for these types, structural equality checks no longer fail due to pointer bijections. Consequently, the previous workarounds and documentation regarding this limitation in the RoundtripInstrument have been removed. I have no feedback to provide.