1
A syntax-directed definition (SDD) is a context-free grammar together with
Correct Answer
attributes and semantic rules
☑ MCQ PRACTICE
Compiler Design Unit 3
Practice objective questions for quick revision and examination preparation. Try answering each question before revealing the answer.
Compiler Design MCQs - Unit 3
2
An attribute whose value is computed from the attribute values of its children is
Correct Answer
synthesized
3
An attribute whose value is computed from its parent and siblings is
Correct Answer
inherited
4
An S-attributed definition uses only
Correct Answer
synthesized attributes
5
In an L-attributed definition, an inherited attribute may depend on the parent and the
Correct Answer
siblings to its left
6
S-attributed definitions can be evaluated in
Correct Answer
bottom-up (post-order) fashion
7
A dependency graph is used to find
Correct Answer
a valid order of evaluating attributes
8
A parse tree that shows the values of its attributes is called an
Correct Answer
annotated parse tree
9
A syntax-directed translation scheme is a grammar with
Correct Answer
semantic actions embedded in the production bodies
10
In a postfix SDT, the actions are placed
Correct Answer
at the right end of the production
11
A directed acyclic graph (DAG) for an expression helps to
Correct Answer
identify common subexpressions
12
In three-address code, each instruction contains at most
Correct Answer
one operator on the right side
13
Three-address code can be implemented as
Correct Answer
quadruples, triples and indirect triples
14
A quadruple has how many fields?
Correct Answer
four
15
A triple has how many fields?
Correct Answer
three
16
Indirect triples use
Correct Answer
a list of pointers to triples
17
Type checking ensures that
Correct Answer
operands are of compatible types for the operator
18
A type conversion done automatically by the compiler is called
Correct Answer
implicit conversion (coercion)
19
Backpatching is used to
Correct Answer
fill in jump targets that are not known when the jump is generated
20
Boolean expressions in control-flow statements are translated using
Correct Answer
jumping code
21
A switch statement can be implemented using
Correct Answer
a jump table or a sequence of conditional jumps
22
In three-address code for procedure calls, the instruction param x is used to
Correct Answer
pass an actual parameter
23
An advantage of intermediate code is that
Correct Answer
it makes the compiler easier to retarget to other machines
24
For a = b + c * d, the three-address code uses how many temporary variables?
Correct Answer
2
25
Two types are structurally equivalent if
Correct Answer
they have the same structure
Fill in the Blanks
26
A syntax-directed definition is a context-free grammar with attributes and ______ rules.
Correct Answer
semantic
27
An attribute computed from the attributes of its children is called ______.
Correct Answer
synthesized
28
An attribute computed from its parent and siblings is called ______.
Correct Answer
inherited
29
An S-attributed definition uses only ______ attributes.
Correct Answer
synthesized
30
A ______ graph is used to decide the order of evaluating attributes.
Correct Answer
dependency
31
A parse tree that shows the attribute values at each node is called an ______ parse tree.
Correct Answer
annotated
32
A ______ for an expression identifies its common subexpressions.
Correct Answer
DAG (directed acyclic graph)
33
In three-address code, there is at most ______ operator on the right side of an instruction.
Correct Answer
one
34
Three-address code can be stored as quadruples, triples and ______.
Correct Answer
indirect triples
35
A quadruple has ______ fields.
Correct Answer
four
36
______ is the technique of filling in jump targets after they become known.
Correct Answer
Backpatching
37
A type conversion inserted automatically by the compiler is called ______ conversion.
Correct Answer
implicit
38
In an L-attributed definition, an inherited attribute may depend on the parent and the ______ siblings.
Correct Answer
left
39
Intermediate code is independent of the ______ machine.
Correct Answer
target
40
Boolean expressions in control flow are translated using ______ code.
Correct Answer
jumping