Compiler phases (PL/I example): resolving symbolic addresses (labels) and generating machine code belongs to which phase?

Introduction / Context:Compilers pass source through multiple phases: lexical analysis, parsing, semantic analysis, optimization, and code generation. This item pinpoints the phase responsible for turning intermediate representation into target code and resolving label addresses.

Given Data / Assumptions:

• Source language: PL/I (representative of HLLs).
• Activities: assign final addresses/labels and emit machine code.
• Focus on phase naming, not toolchain packaging.

Concept / Approach:

• Code generation maps IR to machine instructions and fixes branch targets/labels.
• Syntax analysis only parses structure; storage assignment plans memory layout but doesn’t emit target code.
• “Assembly and output” is an output step but address resolution in HLL compilers is classically part of code generation and later relocation.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• Assembly and output: Output format step; not the principal phase for label resolution in HLL compilation.
• Storage assignment: Memory layout planning, not code emission.
• Syntax analysis: Parsing only; no machine code.
• None of the above: Incorrect; code generation is correct.

Common Pitfalls:

• Assuming parsing includes address resolution; it does not.

Final Answer: