CSCE 434 Lecture 31

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Lecture Slides

Have proposal for optimization (pp6) by next Friday

Heap Management

There are numerous techniques, but the main goal is to not let the heap touch the stack

Scheme 2

free(p)

…

If more than one page is needed:

• sbrk system call (slow: context switching and copying) to reserve new page
• system reserves page in the page table, but does not put it on the address bus (load it into cache)
• memory only loads when it needs to be written

What is DMA?

Intermediate Representations

Lecture Slides

A compile-time data structure (mainly used for performing optimizations)

1. Divide code into manageable pieces
2. Allow complete pass before code is emitted; lets compiler consider more than one option
3. Isolation between front-end and back-end
4. simplifies handling of multiple architectures
5. Allows for machine-independent optimization

Properties

• ease/cost of generation and manipulation
• level of abstraction (crucial consideration)
• freedom of expression
• size of typical procedure
• original or derivative

Subtle considerations