Bug fix for comparison of large cbits and integer literals (#168)

This PR fixes a bug that caused verification failure on the generated
QUIR when comparing large cbits (> 32 bits) with integer literals. This
was caused by failing to cast to match bit width because we weren't
updating the tracked type after casting the reference to convert from
cbit to int.

Author: mbhealy

lib/Frontend/OpenQASM3/QUIRGenQASM3Visitor.cpp

@@ -1564,10 +1564,12 @@ ExpressionValueType QUIRGenQASM3Visitor::visit_(const ASTBinaryOpNode *node) {
     if (leftType.isa<quir::CBitType>()) {
       leftRef = builder.create<CastOp>(getLocation(left),
                                        builder.getIntegerType(bits), leftRef);
+      leftType = leftRef.getType();
     }
     if (rightType.isa<quir::CBitType>()) {
       rightRef = builder.create<CastOp>(getLocation(right),
                                         builder.getIntegerType(bits), rightRef);
+      rightType = rightRef.getType();
     }
     // integer types of different sizes
     if (leftType != rightType && leftType.isIntOrIndex() &&

test/Frontend/OpenQASM3/compare-bits.qasm

@@ -108,3 +108,12 @@ if (bit_two != bit_one){
 if (bit_one != bitstring[0]) {
     U(0, 0, 0) $0;
 }
+
+// MLIR-DAG: [[BIG_BITS:%.*]] = oq3.variable_load @big_bits : !quir.cbit<33>
+// MLIR-DAG: [[ZERO_32:%.*]] = arith.constant 0 : i32
+// MLIR-DAG: [[LHS:%.*]] = "oq3.cast"([[BIG_BITS]]) : (!quir.cbit<33>) -> i33
+// MLIR-DAG: [[RHS:%.*]] = "oq3.cast"([[ZERO_32]]) : (i32) -> i33
+// MLIR: [[CMP:%.*]] = arith.cmpi eq, [[LHS]], [[RHS]] : i33
+// MLIR: scf.if [[CMP]] {
+bit[33] big_bits;
+if (big_bits == 0) {}