[mlir][complex] Canonicalization for consecutive complex.neg

Consecutive complex.neg are redundant so that we can canonicalize them to the original operands.

Reviewed By: pifon2a

Differential Revision: https://reviews.llvm.org/D128781

1 files changed, 14 insertions, 0 deletions

diff --git a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
index 0390a00cf684..00dbb564481e 100644
--- a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
+++ b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
@@ -125,6 +125,20 @@ OpFoldResult AddOp::fold(ArrayRef<Attribute> operands) {
 }
 
 //===----------------------------------------------------------------------===//
+// NegOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult NegOp::fold(ArrayRef<Attribute> operands) {
+  assert(operands.size() == 1 && "unary op takes 1 operand");
+
+  // complex.neg(complex.neg(a)) -> a
+  if (auto negOp = getOperand().getDefiningOp<NegOp>())
+    return negOp.getOperand();
+
+  return {};
+}
+
+//===----------------------------------------------------------------------===//
 // TableGen'd op method definitions
 //===----------------------------------------------------------------------===//