[MLIR][NFC] fix name operand -> op

[bondhugula]

Summary

The wrong name was confusing to read. value.getUsers() yields
Operation *s.

Depends on D77483.

[stephenneuendorffer]

mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp

182–183

This seems like a bad idea to me, since you're shadowing another outer op.

[bondhugula]

Rename op -> userOp

mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp

182–183

I hadn't even noticed - thanks! Fixed.

[rriddle]

mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp

181–182

Can you change this to just op->getUsers()? It is cleaner and more efficient.

[bondhugula]

mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp

181–182

Yes, but we should do that in another patch - this is meant to be a rename only. There are other instances (two in this file) and about five more in other files that use such a 2-d iteration that could all be replaced.

mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp

while (!worklist.empty()) {
       // list. Also remove `op` and nested ops from worklist.
       originalOperands.assign(op->operand_begin(), op->operand_end());
       auto preReplaceAction = [&](Operation *op) {
         // Add the operands to the worklist for visitation.
         addToWorklist(originalOperands);
 
         // Add all the users of the result to the worklist so we make sure
         // to revisit them.
         for (auto result : op->getResults())
-          for (auto *operand : result.getUsers())
-            addToWorklist(operand);
+          for (auto *userOp : result.getUsers())
+            addToWorklist(userOp);
 
         notifyOperationRemoved(op);
       };
 
       // Try to fold this op.
       if (succeeded(folder.tryToFold(op, collectOps, preReplaceAction))) {
         changed = true;
         continue;