[mlir] Fix use-after-move issues

[noclowns]

This patch addresses two use-after-move issues:

1. Timing.cpp A variable was std::moved and then immediately passed to an assert() check. Since the moved-from state made the assertion condition trivially true, the check was effectively useless. The assert() is removed.

2. Query.cpp The matcher object was moved-from and then subsequently used as if it still retained valid state. The fix ensures no subsequent use for the moved-from variable.

Testing:
ninja check-mlir

[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: Slava Gurevich (noclowns)

Changes

This patch addresses two use-after-move issues:

1. Timing.cpp A variable was std::moved and then immediately passed to an assert() check. Since the moved-from state made the assertion condition trivially true, the check was effectively useless. The assert() is removed.

2. Query.cpp The matcher object was moved-from and then subsequently used as if it still retained valid state. The fix removes the std::move to preserve the original object. It is possible to restructure the surrounding logic to maintain the move semantics, but doing so would reduce clarity. If needed, such restructuring can be considered later based on performance profiling.

Testing:
ninja check-mlir

---

Full diff: https://github.com/llvm/llvm-project/pull/165660.diff

2 Files Affected:

• (modified) mlir/lib/Query/Query.cpp (+1-1)
• (modified) mlir/lib/Support/Timing.cpp (-1)

diff --git a/mlir/lib/Query/Query.cpp b/mlir/lib/Query/Query.cpp
index 375e82050a481..f391734def000 100644
--- a/mlir/lib/Query/Query.cpp
+++ b/mlir/lib/Query/Query.cpp
@@ -121,7 +121,7 @@ LogicalResult MatchQuery::run(llvm::raw_ostream &os, QuerySession &qs) const {
   Operation *rootOp = qs.getRootOp();
   int matchCount = 0;
   matcher::MatchFinder finder;
-  auto matches = finder.collectMatches(rootOp, std::move(matcher));
+  auto matches = finder.collectMatches(rootOp, matcher);
 
   // An extract call is recognized by considering if the matcher has a name.
   // TODO: Consider making the extract more explicit.
diff --git a/mlir/lib/Support/Timing.cpp b/mlir/lib/Support/Timing.cpp
index fb6f82c283df5..16306d72815f7 100644
--- a/mlir/lib/Support/Timing.cpp
+++ b/mlir/lib/Support/Timing.cpp
@@ -319,7 +319,6 @@ class TimerImpl {
   void mergeChildren(AsyncChildrenMap &&other) {
     for (auto &thread : other) {
       mergeChildren(std::move(thread.second));
-      assert(thread.second.empty());
     }
     other.clear();
   }