[llvm] [LLVM-Reduce] - Distinct Metadata Reduction (PR #96072)

[Michal Paszkowski via llvm-commits]

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+//===- ReduceDistinctMetadata.cpp - Specialized Delta Pass
+//------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===------------------------------------------------------------------------------===//
+//
+// This file implements two functions used by the Generic Delta Debugging
+// Algorithm, which are used to reduce unnamed distinct metadata nodes.
+//
+//===------------------------------------------------------------------------------===//
+
+#include "ReduceDistinctMetadata.h"
+#include "Delta.h"
+#include "llvm/ADT/Sequence.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/InstIterator.h"
+#include <algorithm>
+#include <queue>
+#include <set>
+
+using namespace llvm;
+
+// Traverse the graph breadth-first and try to remove unnamed metadata nodes
+void BFS_removal(MDNode *root,
+                 std::set<std::pair<unsigned int, MDNode *>> &nodesToDelete,
+                 MDNode *tmp, Oracle &O, Module &Program) {
+  std::queue<MDNode *> q{};
+  std::set<MDNode *>
+      visited{}; // Keep track of visited nodes not to get into loops
+  q.push(root);
+
+  while (!q.empty()) {
+    MDNode *current = q.front();
+    q.pop();
+
+    // Mark the nodes for removal
+    for (unsigned int i = 0; i < current->getNumOperands(); ++i) {
+      Metadata *operand = current->getOperand(i).get();
+      if (isa_and_nonnull<MDNode>(operand)) {
+        if (std::find(visited.begin(), visited.end(), operand) ==
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michalpaszkowski wrote:

Using std::find on std::set might be inefficient. You could use visited.find(operand) != visited.end().

https://github.com/llvm/llvm-project/pull/96072