[Pass] InitMemRef fragments dynamic-shape Var pointers, breaking roundtrip structural equality

[huxinyuan1215]

Category

Bug (Pass)

Component

Passes / Transforms — InitMemRef

Description

InitMemRef pass fragments dynamic-shape Var pointers. Before the pass, a single Var("M") shared_ptr is used across all param types, return types, and body. After the pass, each occurrence gets a different Var pointer with the same name and type, breaking structural_equal bijection.

This caused the RoundtripInstrument to suppress Variable pointer mismatch errors via string matching in instruments.py.

Root Cause

In ProcessNormalVar() (src/ir/transforms/init_memref.cpp), when a Var has a non-ShapedType (e.g. ScalarType(INDEX) for dynamic-shape dimensions like M, N), the function still creates a new Var via make_shared<Var>(...) even though the type is unchanged. This new pointer is cached in var_map_, but every call to CloneTypeWithMemRefAndRemapExprs on a param/body type re-encounters the original Var and creates a fresh copy.

Fix

Return the original Var pointer for non-ShapedType variables in ProcessNormalVar(), since they don't need MemRef initialization:

} else {
    return var;  // Preserve pointer identity for scalar/index Vars
}

Location

• src/ir/transforms/init_memref.cpp:162-176 — ProcessNormalVar()
• python/pypto/ir/instruments.py:100-107 — suppression to be removed

Priority

Medium