Intermediate Representation
We can represent intermediate code in two ways:
- High-Level Intermediate Representation: High-level intermediate code representation is very close to the source language itself. It can quickly generate from the source code, and we can easily apply code modifications to enhance performance. But for target machine optimization, it is less preferred.
- Low-Level Intermediate Representation: This one is close to the target machine, making it suitable for register and memory allocation, instruction set selection, etc. It is ideal for machine-dependent optimizations.
Also See, Top Down Parsing
Intermediate code can be language-specific (e.g., Byte Code for Java) or language-independent (three-address code).
Postfix Notation
The standard (infix) way of writing the sum of a & b is with the operator in the middle: a + b
We put the operator at the right end of the phrase in postfix notation, as ab +. In general, if p1 and p2 are any postfix expressions and + is any binary operator, the outcome of applying + to the values signified by p1 and p2 is p1p2 +, which is postfix notation. Because the operators' location and arity(number of arguments) allow only one way to decode a postfix expression, it requires no parentheses in postfix notation. The operator comes after the operand in postfix notation.
For Example The postfix representation of the expression (A/(B-C)*D+E) is: ABC-/D*E+.
“Recommended Topic, procedure call in compiler design“
Three-Address Code
A statement involving three references(two for operands and one for result) is known as a three address statement. A sequence of three address statements is known as a three-address code. Three address statements are a = b op c, where a, b, and c will have address (memory location). Sometimes a statement might contain less than three references, but it is still called a three-address statement.
For Example: The three-address code for the expression a * -b + b / c :
tmp1 = -b
tmp2 = a * tmp1
tmp3 = c
tmp4 = b / tmp3
tmp5 = tmp2 + tmp4
tmp1, tmp2, tmp3, tmp4, tmp5 are temporary variables.
Syntax Tree
The syntax tree is nothing other than a reduced form of a parse tree. We move the operator and keyword nodes of the parse tree to their parents, and the single link in the syntax tree replaces a chain of single productions. The internal and child nodes are operators and operands, respectively. Forming a syntax tree put parentheses in the expression makes it easy to recognize which operand should come first.
Example 1: (a*b)+(d*e)
Example 2: (a+b)*(c*(d+e))
Frequently Asked Questions
What is intermediate language or code in compiler design?
Many compilers utilize a medium-level language as a stepping-stone between high-level and low-level machine code. Such stepping-stone languages are called intermediate languages or Intermediate codes.
What is the disadvantage of the intermediate language?
The disadvantage of intermediate language is speed. In most cases, interpreting the intermediate form will be a lot slower than executing translated code directly. However, the approach has seen some success, e.g., with Java.
What do you understand by just-in-time compilation in intermediate language?
We can eliminate some speed penalties by translating the intermediate code to machine code immediately before or during the program's execution. This hybrid form is called just-in-time compilation, and we often use it for executing the intermediate code for Java.
What is the purpose of intermediate representation?
The data structure or code utilized internally by a compiler or virtual machine to represent source code is an intermediate representation (IR). We made an IR that allows for additional processing like optimization and translation.
What are some other names and examples of intermediate language?
The CPU cannot directly execute a language generated from programming source code. Being platform-independent, the intermediate language (IL) is also called bytecode, p-code, pseudocode, or pseudo-language. Examples of intermediate languages are assembly languages, such as PL/I, BASIC, and Fortran.
Conclusion
This article teaches about intermediate language. We also discussed the characteristics, benefits, and applications of the Intermediate language in compiler design.
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