[mlir][tosa] Add assembly format validation for COND_IF op

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

@@ -1167,10 +1167,61 @@ bool checkErrorIfPad(Operation *op) {
   return true;
 }
 
+// Returns true if the operation takes no input operands, excluding attributes.
+static bool isNullaryOperation(Operation *op) {
+  if (isa<tosa::ConstOp>(op) || isa<tosa::ConstShapeOp>(op) ||
+      isa<tosa::YieldOp>(op) || isa<tosa::VariableOp>(op))
+    return true;
+  return false;
+}
+
+bool checkErrorIfCondIf(Operation *op) {
+  auto ifOp = dyn_cast<tosa::IfOp>(op);
+  if (!ifOp)
+    return true;
+
+  // Whether the types and shapes of operands between the input/output list and
+  // internal regions are validated by the operation verifier. However, with
+  // support for the simplified form - where redundant operand notations are
+  // omitted - is not conformant to the specification. According to the
+  // specification, all operands passed into an operation must be explicitly
+  // declared at each operation's structure. This code section verify that the
+  // operation's form complies with this requirement.
+
+  // Returns true if the region uses no external input operands.
+  auto isNullaryRegion = [](Region &region) -> bool {
+    bool noLiveInValue = true;
+    region.walk([&noLiveInValue](Operation *op) {
+      if (!isNullaryOperation(op)) {
+        noLiveInValue = false;
+        return WalkResult::interrupt();
+      }
+      return WalkResult::advance();
+    });
+    return noLiveInValue;
+  };
+
+  mlir::Region &thenGraph = ifOp.getThenGraph();
+  mlir::Region &elseGraph = ifOp.getElseGraph();
+  bool isThenGraphNullaryRegion = isNullaryRegion(thenGraph);
+  bool isElseGraphNullaryRegion = isNullaryRegion(elseGraph);
+  bool isInputListEmpty = ifOp.getInputList().size() == 0;
+
+  if ((isInputListEmpty != isThenGraphNullaryRegion) ||
+      (isInputListEmpty != isElseGraphNullaryRegion)) {
+    op->emitOpError()
+        << "the current simplified form is not strictly conformant to the "
+           "spec, please use the generic format\n";
+    return false;
+  }
+
+  return true;
+}
+
 LogicalResult TosaValidation::applyErrorIfCheck(Operation *op) {
   if (!checkErrorIfResize(op) || !checkErrorIfMul(op) ||
       !checkErrorIfTable(op) || !checkErrorIfRescale(op) ||
-      !checkErrorIfPad(op))
+      !checkErrorIfPad(op) || !checkErrorIfCondIf(op))
     return failure();
   return success();
 }

mlir/test/Dialect/Tosa/error_if_check.mlir

@@ -225,3 +225,17 @@ func.func @test_error_i32_unsigned_output(%arg0: tensor<1xi8>) -> tensor<1xi32>
   %0 = tosa.rescale %arg0, %multiplier, %shift, %input_zp, %output_zp {scale32 = false, rounding_mode = "SINGLE_ROUND", per_channel = false, input_unsigned = false, output_unsigned = true} : (tensor<1xi8>, tensor<1xi16>, tensor<1xi8>, tensor<1xi8>, tensor<1xi32>) -> tensor<1xi32>
   return %0 : tensor<1xi32>
 }
+
+// -----
+// CHECK-LABEL: cond_if_simplified_form
+func.func @test_cond_if_simplified_form(%arg0: tensor<f32>, %arg1: tensor<f32>, %arg2: tensor<i1>) -> tensor<f32> {
+  // expected-error@+1 {{'tosa.cond_if' op the current simplified form is not strictly conformant to the spec, please use the generic format}}
+  %0 = tosa.cond_if %arg2 -> (tensor<f32>) {
+    %1 = tosa.add %arg0, %arg1 : (tensor<f32>, tensor<f32>) -> tensor<f32>
+    tosa.yield %1 : tensor<f32>
+  } else {
+    %1 = tosa.sub %arg0, %arg1 : (tensor<f32>, tensor<f32>) -> tensor<f32>
+    tosa.yield %1 : tensor<f32>
+  }
+  return %0 : tensor<f32>
+}