[llvm-branch-commits] [llvm] [StructuralHash] Support Differences (PR #112638)

[Kyungwoo Lee via llvm-branch-commits]

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@@ -100,8 +233,20 @@ class StructuralHashImpl {
     if (const auto *ComparisonInstruction = dyn_cast<CmpInst>(&Inst))
       Hashes.emplace_back(ComparisonInstruction->getPredicate());
 
-    for (const auto &Op : Inst.operands())
-      Hashes.emplace_back(hashOperand(Op));
+    unsigned InstIdx = 0;
+    if (IndexInstruction) {
+      InstIdx = IndexInstruction->size();
+      IndexInstruction->insert({InstIdx, const_cast<Instruction *>(&Inst)});
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kyulee-com wrote:

Instruction is inserted once by design in this pass. In fact, this map `IndexInstruction` itself can't catch the duplication as the key is `index`, not `Instruction *`.  Anyhow, replaced `insert` by `trace_emplace` for efficiency.

https://github.com/llvm/llvm-project/pull/112638