[mlir] Remove unused local variables (NFC) (#167107)

Identified with bugprone-unused-local-non-trivial-variable.

Author: kazutakahirata

mlir/lib/Dialect/Affine/Utils/Utils.cpp

@@ -1327,9 +1327,6 @@ LogicalResult mlir::affine::replaceAllMemRefUsesWith(
   assert(cast<MemRefType>(oldMemRef.getType()).getElementType() ==
          cast<MemRefType>(newMemRef.getType()).getElementType());
 
-  std::unique_ptr<DominanceInfo> domInfo;
-  std::unique_ptr<PostDominanceInfo> postDomInfo;
-
   // Walk all uses of old memref; collect ops to perform replacement. We use a
   // DenseSet since an operation could potentially have multiple uses of a
   // memref (although rare), and the replacement later is going to erase ops.

mlir/lib/Dialect/Linalg/Transforms/TilingInterfaceImpl.cpp

@@ -216,8 +216,6 @@ struct LinalgOpTilingInterface
       SmallVectorImpl<OpFoldResult> &iterDomainSizes) const {
     auto linalgOp = cast<LinalgOp>(op);
 
-    std::optional<SmallVector<OpFoldResult>> iterationSpaceOffsets,
-        iterationSpaceSizes;
     SmallVector<AffineMap> indexingMaps =
         llvm::map_to_vector(operandNumbers, [&](unsigned operandNumber) {
           OpOperand &opOperand = linalgOp->getOpOperand(operandNumber);

mlir/lib/Dialect/OpenACC/Transforms/ACCImplicitData.cpp

@@ -571,7 +571,6 @@ Operation *ACCImplicitData::generateDataClauseOpForCandidate(
                                          /*structured=*/true, /*implicit=*/true,
                                          accSupport.getVariableName(var));
     } else {
-      SmallVector<Value> bounds;
       auto copyinOp =
           acc::CopyinOp::create(builder, loc, var,
                                 /*structured=*/true, /*implicit=*/true,

mlir/lib/Dialect/SCF/Transforms/ParallelForToNestedFors.cpp

@@ -44,7 +44,6 @@ mlir::scf::parallelForToNestedFors(RewriterBase &rewriter,
          lowerBounds.size() == steps.size() &&
          "Mismatched parallel loop bounds");
 
-  SmallVector<Value> ivs;
   scf::LoopNest loopNest =
       scf::buildLoopNest(rewriter, loc, lowerBounds, upperBounds, steps);