[mlir][tosa] Add custom operand getters for select op (#145921)

The select op has 3 inputs: input1, input2, input3 to according to the
tosa specification. However, use of getInput1(), getInput2() and
getInput3() in the codebase can be confusing and hinder readability.
This commit adds custom getters to help improve readability:
  - input1 -> getPred()
  - input2 -> getOnTrue()
  - input3 -> getOnFalse()

They should be preferred as they are more descriptive, however, the ODS
generated getters (getInputX()) may still be used.

Unfortunately the custom getters don't propagate to Adaptors such as
`FoldAdaptor`, so the ODS generated getters must be used.

mlir/include/mlir/Dialect/Tosa/IR/TosaOps.td

@@ -1490,9 +1490,9 @@ def Tosa_SelectOp : Tosa_ElementwiseOp<"select"> {
   }];
 
   let arguments = (ins
-    Tosa_I1Tensor:$input1,
-    Tosa_Tensor:$input2,
-    Tosa_Tensor:$input3
+    Tosa_I1Tensor:$input1,  // pred
+    Tosa_Tensor:$input2,    // on true
+    Tosa_Tensor:$input3     // on false
   );
 
   let results = (outs
@@ -1512,6 +1512,13 @@ def Tosa_SelectOp : Tosa_ElementwiseOp<"select"> {
     operands attr-dict `:` `(` type($input1) `,` type($input2) `,` type($input3)
     `)` `->` type($output)
   }];
+
+  let extraClassDeclaration = [{
+    // Custom getters for readability
+    ::mlir::TypedValue<::mlir::TensorType> getPred() { return getInput1(); }
+    ::mlir::TypedValue<::mlir::TensorType> getOnTrue() { return getInput2(); }
+    ::mlir::TypedValue<::mlir::TensorType> getOnFalse() { return getInput3(); }
+  }];
 }
 
 //===----------------------------------------------------------------------===//

mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp

@@ -344,7 +344,7 @@ LogicalResult SelectOp::canonicalize(SelectOp op, PatternRewriter &rewriter) {
     return failure();
   rewriter.modifyOpInPlace(op, [&]() {
     op.getOperation()->setOperands(
-        {notOp.getInput1(), op.getInput3(), op.getInput2()});
+        {notOp.getInput1(), op.getOnFalse(), op.getOnTrue()});
   });
   return success();
 }
@@ -1510,8 +1510,8 @@ OpFoldResult SliceOp::fold(FoldAdaptor adaptor) {
 }
 
 OpFoldResult tosa::SelectOp::fold(FoldAdaptor adaptor) {
-  if (getInput2() == getInput3())
-    return getInput2();
+  if (getOnTrue() == getOnFalse())
+    return getOnTrue();
 
   auto predicate =
       llvm::dyn_cast_if_present<DenseIntElementsAttr>(adaptor.getInput1());
@@ -1520,8 +1520,8 @@ OpFoldResult tosa::SelectOp::fold(FoldAdaptor adaptor) {
 
   if (!predicate.isSplat())
     return {};
-  return predicate.getSplatValue<APInt>().getBoolValue() ? getInput2()
-                                                         : getInput3();
+  return predicate.getSplatValue<APInt>().getBoolValue() ? getOnTrue()
+                                                         : getOnFalse();
 }
 
 OpFoldResult TileOp::fold(FoldAdaptor adaptor) {

mlir/lib/Dialect/Tosa/IR/TosaOps.cpp

@@ -3829,16 +3829,16 @@ LogicalResult ReverseOp::verify() {
 
 LogicalResult tosa::SelectOp::verify() {
   // verify input2 and input3 have same element type as output
-  if (verifySameElementTypes(*this, /* inType = */ getInput2().getType(),
+  if (verifySameElementTypes(*this, /* inType = */ getOnTrue().getType(),
                              /* outType = */ getOutput().getType())
           .failed() ||
-      verifySameElementTypes(*this, /* inType = */ getInput3().getType(),
+      verifySameElementTypes(*this, /* inType = */ getOnFalse().getType(),
                              /* outType = */ getOutput().getType())
           .failed()) {
     return failure();
   }
   // verify input1 has element type of bool
-  auto predicateType = llvm::dyn_cast<ShapedType>(getInput1().getType());
+  auto predicateType = llvm::dyn_cast<ShapedType>(getPred().getType());
   if (!predicateType) {
     return emitOpError("expect shaped tensor for input1, got ")
            << getInput1().getType();

mlir/lib/Dialect/Tosa/Transforms/TosaMakeBroadcastable.cpp

@@ -169,9 +169,9 @@ struct ConvertTosaOp<tosa::SelectOp> : public OpRewritePattern<tosa::SelectOp> {
   LogicalResult matchAndRewrite(tosa::SelectOp tosaOp,
                                 PatternRewriter &rewriter) const override {
 
-    Value input1 = tosaOp.getInput1();
-    Value input2 = tosaOp.getInput2();
-    Value input3 = tosaOp.getInput3();
+    Value input1 = tosaOp.getPred();
+    Value input2 = tosaOp.getOnTrue();
+    Value input3 = tosaOp.getOnFalse();
     Value output = tosaOp.getResult();
 
     auto outputType = dyn_cast<RankedTensorType>(output.getType());

mlir/lib/Dialect/Tosa/Transforms/TosaProfileCompliance.cpp

@@ -188,8 +188,8 @@ LogicalResult ProfileInfoDepot::populateProfileInfo(tosa::RFFT2dOp op) {
 
 template <>
 LogicalResult ProfileInfoDepot::populateProfileInfo(tosa::SelectOp op) {
-  addValue(op.getInput2());
-  addValue(op.getInput3());
+  addValue(op.getOnTrue());
+  addValue(op.getOnFalse());
   addValue(op.getOutput());
   return success();
 }