Compilers Alignment Alex Aiken Alignment Most modern machines are - - PowerPoint PPT Presentation

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Jun 22, 2023 211 likes •270 views

Compilers Alignment Alex Aiken Alignment Most modern machines are 32 or 64 bit 8 bits in a byte 4 or 8 bytes in a word Machines are either byte or word addressable Alex Aiken Alignment Data is word aligned if it begins at a

SLIDE 1

Alex Aiken

Compilers

Alignment

SLIDE 2

Alex Aiken

Alignment

Most modern machines are 32 or 64 bit

– 8 bits in a byte – 4 or 8 bytes in a word – Machines are either byte or word addressable

SLIDE 3

Alex Aiken

Alignment

Data is word aligned if it begins at a word boundary
Most machines have some alignment restrictions

– Or performance penalties for poor alignment

SLIDE 4

Alex Aiken

Alignment

Example: A string

“Hello” Takes 5 characters (without a terminating \0)

To word align next word, add 3 “padding” characters to

the string

The padding is not part of the string, it’s just unused

Compilers

Alignment

Alignment

– 8 bits in a byte – 4 or 8 bytes in a word – Machines are either byte or word addressable

Alignment

– Or performance penalties for poor alignment

Alignment

“Hello” Takes 5 characters (without a terminating \0)

the string

memory