[Mlir-commits] [mlir] [mlir][scf] Align `scf.while` `before` block args in canonicalizer (PR #76195)

[Matthias Springer]

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@@ -3872,14 +3872,89 @@ struct WhileRemoveDuplicatedResults : public OpRewritePattern<WhileOp> {
     return success();
   }
 };
+
+/// If both ranges contain same values return mappping indices from args1 to
+/// args2. Otherwise return std::nullopt
+static std::optional<SmallVector<unsigned>> getArgsMapping(ValueRange args1,
+                                                           ValueRange args2) {
+  if (args1.size() != args2.size())
+    return std::nullopt;
+
+  SmallVector<unsigned> ret(args1.size());
+  for (auto &&[i, arg1] : llvm::enumerate(args1)) {
+    auto it = llvm::find(args2, arg1);
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matthias-springer wrote:

The value range could contain the same value multiple times. eg if the same value is yielded multiple times from the before block. I think then this function no longer returns a permutation. actually, maybe that is fine...

https://github.com/llvm/llvm-project/pull/76195