From ccf975059c037ec51ce3b0170105fb2e4fecf2a0 Mon Sep 17 00:00:00 2001
From: Kai Sasaki <lewuathe@gmail.com>
Date: Wed, 7 Sep 2022 14:55:28 +0200
Subject: [PATCH] [mlir][complex] Canonicalization for complex.sub adding same
 numbers

Canonicalization for complex.sub adding same numbers. This canonicalization supports the case like complex.sub(complex.add(a, b), b) -> a.

Reviewed By: pifon2a

Differential Revision: https://reviews.llvm.org/D133397
---
 mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td |  2 ++
 mlir/lib/Dialect/Complex/IR/ComplexOps.cpp         | 15 +++++++++++++++
 mlir/test/Dialect/Complex/canonicalize.mlir        | 11 +++++++++++
 3 files changed, 28 insertions(+)

diff --git a/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td b/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
index 44a6952..defdf37 100644
--- a/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
+++ b/mlir/include/mlir/Dialect/Complex/IR/ComplexOps.td
@@ -531,6 +531,8 @@ def SubOp : ComplexArithmeticOp<"sub"> {
     %a = complex.sub %b, %c : complex<f32>
     ```
   }];
+
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
index cfc2e00..59f58fd 100644
--- a/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
+++ b/mlir/lib/Dialect/Complex/IR/ComplexOps.cpp
@@ -139,6 +139,21 @@ OpFoldResult AddOp::fold(ArrayRef<Attribute> operands) {
 }
 
 //===----------------------------------------------------------------------===//
+// SubOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult SubOp::fold(ArrayRef<Attribute> operands) {
+  assert(operands.size() == 2 && "binary op takes 2 operands");
+
+  // complex.sub(complex.add(a, b), b) -> a
+  if (auto add = getLhs().getDefiningOp<AddOp>())
+    if (getRhs() == add.getRhs())
+      return add.getLhs();
+
+  return {};
+}
+
+//===----------------------------------------------------------------------===//
 // NegOp
 //===----------------------------------------------------------------------===//
 
diff --git a/mlir/test/Dialect/Complex/canonicalize.mlir b/mlir/test/Dialect/Complex/canonicalize.mlir
index d57dc69..54cbf21 100644
--- a/mlir/test/Dialect/Complex/canonicalize.mlir
+++ b/mlir/test/Dialect/Complex/canonicalize.mlir
@@ -133,4 +133,15 @@ func.func @complex_add_zero() -> complex<f32> {
   // CHECK-NEXT: return %[[CPLX:.*]] : complex<f32>
   %add = complex.add %complex1, %complex2 : complex<f32>
   return %add : complex<f32>
+}
+
+// CHECK-LABEL: func @complex_sub_add_lhs
+func.func @complex_sub_add_lhs() -> complex<f32> {
+  %complex1 = complex.constant [1.0 : f32, 0.0 : f32] : complex<f32>
+  %complex2 = complex.constant [0.0 : f32, 2.0 : f32] : complex<f32>
+  // CHECK: %[[CPLX:.*]] = complex.constant [1.000000e+00 : f32, 0.000000e+00 : f32] : complex<f32>
+  // CHECK-NEXT: return %[[CPLX:.*]] : complex<f32>
+  %add = complex.add %complex1, %complex2 : complex<f32>
+  %sub = complex.sub %add, %complex2 : complex<f32>
+  return %sub : complex<f32>
 }
\ No newline at end of file
-- 
2.7.4