diff --git a/mlir/lib/Dialect/GPU/Transforms/AllReduceLowering.cpp b/mlir/lib/Dialect/GPU/Transforms/AllReduceLowering.cpp
--- a/mlir/lib/Dialect/GPU/Transforms/AllReduceLowering.cpp
+++ b/mlir/lib/Dialect/GPU/Transforms/AllReduceLowering.cpp
@@ -157,10 +157,12 @@
   /// Returns an accumulator factory using either the op attribute or the body
   /// region.
   AccumulatorFactory getFactory() {
-    if (!reduceOp.body().empty())
-      return getFactory(reduceOp.body());
-    if (reduceOp.op())
-      return getFactory(*reduceOp.op());
+    auto body = reduceOp.body();
+    if (!body.empty())
+      return getFactory(body);
+    auto opAttr = reduceOp.op();
+    if (opAttr)
+      return getFactory(*opAttr);
     return AccumulatorFactory();
   }
 
@@ -186,7 +188,7 @@
       // Replace all gpu.yield ops with branch out of body.
       for (; block != split; block = block->getNextNode()) {
         Operation *terminator = block->getTerminator();
-        if (!llvm::isa<gpu::YieldOp>(terminator))
+        if (!isa<gpu::YieldOp>(terminator))
           continue;
         rewriter.setInsertionPointToEnd(block);
         rewriter.replaceOpWithNewOp<BranchOp>(
@@ -297,13 +299,13 @@
             createIf(
                 shuffleOp.getResult(1),
                 [&] {
-                  return llvm::SmallVector<Value , 1>{
+                  return SmallVector<Value , 1>{
                       accumFactory(value, shuffleOp.getResult(0))};
                 },
                 [&] { return llvm::makeArrayRef(value); });
             value = rewriter.getInsertionBlock()->getArgument(0);
           }
-          return llvm::SmallVector<Value , 1>{value};
+          return SmallVector<Value , 1>{value};
         },
         // Generate a reduction over the entire subgroup. This is a specialization
         // of the above reduction with unconditional accumulation.
@@ -315,7 +317,7 @@
                                                     offset, subgroupSize, xorAttr);
             value = accumFactory(value, shuffleOp.getResult(0));
           }
-          return llvm::SmallVector<Value , 1>{value};
+          return SmallVector<Value , 1>{value};
         });
     return rewriter.getInsertionBlock()->getArgument(0);
   }
@@ -344,7 +346,7 @@
 
   PatternMatchResult matchAndRewrite(Operation *op,
                                      PatternRewriter &rewriter) const override {
-    auto funcOp = llvm::cast<gpu::GPUFuncOp>(op);
+    auto funcOp = cast<gpu::GPUFuncOp>(op);
     auto callback = [&](gpu::AllReduceOp reduceOp) {
       GpuAllReduceRewriter(funcOp, reduceOp, rewriter).rewrite();
       return WalkResult::interrupt();