[mlir][spirv] Add folder for LogicalNotEqual

[ThomasRaoux]

Summary

Add a folder for LogicalNotEqual when rhs is false. This pattern shows
up after lowering to SPIRV.

mlir/include/mlir/Dialect/SPIRV/IR/SPIRVLogicalOps.td

let description = [{
 
     #### Example:
 
     ```mlir
     %2 = spirv.LogicalNotEqual %0, %1 : i1
     %2 = spirv.LogicalNotEqual %0, %1 : vector<4xi1>
     ```
   }];
+  let hasFolder = true;
 }
 
 // -----
 
 def SPIRV_LogicalOrOp : SPIRV_LogicalBinaryOp<"LogicalOr",
                                           SPIRV_Bool,
                                           [Commutative,
                                            UsableInSpecConstantOp]> {

mlir/lib/Dialect/SPIRV/IR/SPIRVCanonicalization.cpp

if (Optional<bool> rhs = getScalarOrSplatBoolAttr(operands.back())) {
     if (!*rhs)
       return operands.back();
   }
 
   return Attribute();
 }
 
 //===----------------------------------------------------------------------===//
+// spirv.LogicalNotEqualOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult spirv::LogicalNotEqualOp::fold(ArrayRef<Attribute> operands) {
+  assert(operands.size() == 2 &&
+         "spirv.LogicalNotEqual should take two operands");
+
+  if (Optional<bool> rhs = getScalarOrSplatBoolAttr(operands.back())) {
+    // x && false = x
+    if (!rhs.value())
+      return getOperand1();
+  }
+
+  return Attribute();
+}
+
+//===----------------------------------------------------------------------===//
 // spirv.LogicalNot
 //===----------------------------------------------------------------------===//
 
 void spirv::LogicalNotOp::getCanonicalizationPatterns(
     RewritePatternSet &results, MLIRContext *context) {
   results
       .add<ConvertLogicalNotOfIEqual, ConvertLogicalNotOfINotEqual,
            ConvertLogicalNotOfLogicalEqual, ConvertLogicalNotOfLogicalNotEqual>(

mlir/test/Dialect/SPIRV/Transforms/canonicalize.mlir

 func.func @convert_logical_not_to_not_equal(%arg0: vector<3xi64>, %arg1: vector<3xi64>) -> vector<3xi1> {
   // CHECK: %[[RESULT:.*]] = spirv.INotEqual {{%.*}}, {{%.*}} : vector<3xi64>
   // CHECK-NEXT: spirv.ReturnValue %[[RESULT]] : vector<3xi1>
   %2 = spirv.IEqual %arg0, %arg1 : vector<3xi64>
   %3 = spirv.LogicalNot %2 : vector<3xi1>
   spirv.ReturnValue %3 : vector<3xi1>
 }
 
+
+// -----
+
+//===----------------------------------------------------------------------===//
+// spirv.LogicalNotEqual
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @convert_logical_not_equal_false
+// CHECK-SAME: %[[ARG:.+]]: vector<4xi1>
+func.func @convert_logical_not_equal_false(%arg: vector<4xi1>) -> vector<4xi1> {
+  %cst = spirv.Constant dense<false> : vector<4xi1>
+  // CHECK: spirv.ReturnValue %[[ARG]] : vector<4xi1>
+  %0 = spirv.LogicalNotEqual %arg, %cst : vector<4xi1>
+  spirv.ReturnValue %0 : vector<4xi1>
+}
+
 // -----
 
 func.func @convert_logical_not_to_equal(%arg0: vector<3xi64>, %arg1: vector<3xi64>) -> vector<3xi1> {
   // CHECK: %[[RESULT:.*]] = spirv.IEqual {{%.*}}, {{%.*}} : vector<3xi64>
   // CHECK-NEXT: spirv.ReturnValue %[[RESULT]] : vector<3xi1>
   %2 = spirv.INotEqual %arg0, %arg1 : vector<3xi64>
   %3 = spirv.LogicalNot %2 : vector<3xi1>
   spirv.ReturnValue %3 : vector<3xi1>