Subject: system programming and compiler construction

Topic: Assemblers

Difficulty: Medium

Two pass translation

• Two pass translations consist of pass I and pass II.

• Generally, LC processing performed in the first pass and symbols defined in the program entered into the symbol table, hence first pass performs analysis of the source program.

• So, two pass translation of assembly lang. the program can handle forward reference easily.

• The second pass synthesizes the target form using the address information found in the symbol table.

• Moreover, The first pass constructs an intermediate representation of the source program and that will be used by the second pass.

• IR consists of two main components: data structure + IC (intermediate code)

Single-pass translation

• Similarly, A one-pass assembler requires 1 scan of the source program to generate machine code.

• Moreover, The process of forwarding references talked using a process called back patching. The operand field of an instruction containing forward references left blank initially.

• Also, A table of instruction containing forward references maintained separately called table of