[Mlir-commits] [mlir] [MLIR] Fix use-after-move for DEBUG builds (PR #164763)

[Slava Gurevich]

https://github.com/noclowns created https://github.com/llvm/llvm-project/pull/164763

Fix use-after-move issues that occur only in DEBUG builds.

In one, constructor arguments are moved in the initializer list to initialize member variables, but the function body mistakenly accesses the moved-from arguments instead of the corresponding class members with identical names. While this is a UB, here it actually renders the affected asserts ineffective, since the comparisons operate on two hollowed-out objects, by implementation.

In a second fix, a variable is moved from within an assert, introducing a side effect that alters its subsequent use and causes divergence between DEBUG and RELEASE builds.

Testing:
ninja check-llvm
ninja check-llvm-unit

>From ccfee53ff378c159d593371809fe26a01f253263 Mon Sep 17 00:00:00 2001
From: Slava Gurevich <sgurevich at gmail.com>
Date: Wed, 22 Oct 2025 21:39:40 -0700
Subject: [PATCH] [MLIR] Fix use-after-move for DEBUG builds Fix use-after-move
 issues that occur only in DEBUG builds.

In one, constructor arguments are moved in the initializer list to initialize member variables, but the function body mistakenly accesses the moved-from arguments instead of the corresponding class members with identical names.
While this is a UB, here it actually renders the affected asserts ineffective, since the comparisons operate on two hollowed-out objects, by implementation.

In a second fix, a variable is moved from within an assert, introducing a side effect that alters its subsequent use and causes divergence between DEBUG and RELEASE builds.

Testing:
ninja check-llvm
ninja check-llvm-unit
---
 mlir/include/mlir/Dialect/SparseTensor/IR/SparseTensor.h    | 6 ++----
 .../SparseTensor/Transforms/Utils/IterationGraphSorter.cpp  | 6 +++---
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/mlir/include/mlir/Dialect/SparseTensor/IR/SparseTensor.h b/mlir/include/mlir/Dialect/SparseTensor/IR/SparseTensor.h
index d0a3f01afe871..43e48a6d34026 100644
--- a/mlir/include/mlir/Dialect/SparseTensor/IR/SparseTensor.h
+++ b/mlir/include/mlir/Dialect/SparseTensor/IR/SparseTensor.h
@@ -158,16 +158,14 @@ namespace sparse_tensor {
 /// Convenience method to abbreviate casting `getType()`.
 template <typename T>
 inline RankedTensorType getRankedTensorType(T &&t) {
-  assert(static_cast<bool>(std::forward<T>(t)) &&
-         "getRankedTensorType got null argument");
+  assert(static_cast<bool>(t) && "getRankedTensorType got null argument");
   return dyn_cast<RankedTensorType>(std::forward<T>(t).getType());
 }
 
 /// Convenience method to abbreviate casting `getType()`.
 template <typename T>
 inline MemRefType getMemRefType(T &&t) {
-  assert(static_cast<bool>(std::forward<T>(t)) &&
-         "getMemRefType got null argument");
+  assert(static_cast<bool>(t) && "getMemRefType got null argument");
   return cast<MemRefType>(std::forward<T>(t).getType());
 }
 
diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/Utils/IterationGraphSorter.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/Utils/IterationGraphSorter.cpp
index 73e0f3d2891d7..c70fd3b010406 100644
--- a/mlir/lib/Dialect/SparseTensor/Transforms/Utils/IterationGraphSorter.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/Utils/IterationGraphSorter.cpp
@@ -159,12 +159,12 @@ IterationGraphSorter::IterationGraphSorter(
       loop2OutLvl(loop2OutLvl), iterTypes(std::move(iterTypes)),
       strategy(strategy) {
   // One map per tensor.
-  assert(loop2InsLvl.size() == ins.size());
+  assert(this->loop2InsLvl.size() == this->ins.size());
   // All the affine maps have the same number of dimensions (loops).
   assert(llvm::all_equal(llvm::map_range(
-      loop2InsLvl, [](AffineMap m) { return m.getNumDims(); })));
+      this->loop2InsLvl, [](AffineMap m) { return m.getNumDims(); })));
   // The number of results of the map should match the rank of the tensor.
-  assert(llvm::all_of(llvm::zip(loop2InsLvl, ins), [](auto mvPair) {
+  assert(llvm::all_of(llvm::zip(this->loop2InsLvl, this->ins), [](auto mvPair) {
     auto [m, v] = mvPair;
     return m.getNumResults() == cast<ShapedType>(v.getType()).getRank();
   }));