Add check for casting bundle with elements in different directions

lib/Dialect/FIRRTL/FIRRTLOps.cpp

@@ -5730,25 +5730,43 @@ LogicalResult HWStructCastOp::verify() {
 LogicalResult BitCastOp::verify() {
   auto inTypeBits = getBitWidth(getInput().getType(), /*ignoreFlip=*/true);
   auto resTypeBits = getBitWidth(getType());
-  if (inTypeBits.has_value() && resTypeBits.has_value()) {
-    // Bitwidths must match for valid bit
-    if (*inTypeBits == *resTypeBits) {
-      // non-'const' cannot be casted to 'const'
-      if (containsConst(getType()) && !isConst(getOperand().getType()))
-        return emitError("cannot cast non-'const' input type ")
-               << getOperand().getType() << " to 'const' result type "
-               << getType();
-      return success();
-    }
+  if (!inTypeBits.has_value())
+    return emitError("bitwidth cannot be determined for input operand type ")
+           << getInput().getType();
+  if (!resTypeBits.has_value())
+    return emitError("bitwidth cannot be determined for result type ")
+           << getType();
+  // Bitwidths must match for valid bit
+  if (*inTypeBits != *resTypeBits)
     return emitError("the bitwidth of input (")
            << *inTypeBits << ") and result (" << *resTypeBits
            << ") don't match";
+
+  // non-'const' cannot be casted to 'const'
+  if (containsConst(getType()) && !isConst(getOperand().getType()))
+    return emitError("cannot cast non-'const' input type ")
+           << getOperand().getType() << " to 'const' result type " << getType();
+
+  if (auto bundleType = dyn_cast<BundleType>(getInput().getType())) {
+    auto elts = bundleType.getElements();
+    if (any_of(elts, [&](BundleType::BundleElement elt) {
+          return elt.isFlip != elts.front().isFlip;
+        }))
+      return emitError("cannot cast input bundle type with elements in "
+                       "different directions ")
+             << getInput().getType();
   }
-  if (!inTypeBits.has_value())
-    return emitError("bitwidth cannot be determined for input operand type ")
-           << getInput().getType();
-  return emitError("bitwidth cannot be determined for result type ")
-         << getType();
+  if (auto openBundleType = dyn_cast<OpenBundleType>(getInput().getType())) {
+    auto elts = openBundleType.getElements();
+    if (any_of(elts, [&](OpenBundleType::BundleElement elt) {
+          return elt.isFlip != elts.front().isFlip;
+        }))
+      return emitError("cannot cast input open bundle type with elements in "
+                       "different directions ")
+             << getInput().getType();
+  }
+
+  return success();
 }
 
 //===----------------------------------------------------------------------===//

test/Dialect/FIRRTL/bitcast-bundle-different-diretions.mlir

@@ -0,0 +1,17 @@
+// RUN: circt-opt %s --lower-firrtl-to-hw --verify-diagnostics
+
+firrtl.circuit "BitcastBundle" {
+  firrtl.module @BitcastBundle(in %input_0: !firrtl.uint<8>, out %output_0: !firrtl.uint<8>) {
+    %io = firrtl.wire : !firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>
+    %0 = firrtl.subfield %io[input_0] : !firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>
+    firrtl.connect %0, %input_0 : !firrtl.uint<8>
+    %1 = firrtl.subfield %io[output_0] : !firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>
+    firrtl.connect %output_0, %1 : !firrtl.uint<8>
+    %2 = firrtl.subfield %io[output_0] : !firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>
+    // expected-error @below {{cannot cast input bundle type with elements in different directions '!firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>'}}
+    %3 = firrtl.bitcast %io : (!firrtl.bundle<input_0 flip: uint<8>, output_0: uint<8>>) -> !firrtl.uint<16>
+    %4 = firrtl.bits %3 7 to 0 : (!firrtl.uint<16>) -> !firrtl.uint<8>
+    %_GEN_0 = firrtl.node interesting_name %4 : !firrtl.uint<8>
+    firrtl.connect %2, %_GEN_0 : !firrtl.uint<8>
+  }
+}