Assembly Language & Computer Architecture

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There are 4 stages to turn source code into a binary:

1. Preprocessing (clang -E main.i)). This expands macros.
2. Compiling (clang -S main.s)). This turns code into assembly.
3. Assembling (clang -c main.o). This turns code into objects.
4. Linking: (ld main). This creates the main executable.

• Machine code with debug symbols (-g) allows you to produce a disassembly of the code.

Why look at assembly?

• The compiler made an error - sometimes bugs show up only at higher optimization levels.
• reverse engineering.

Your computer’s instruction set architecture (ISA) has four main concepts:

• Registers
• Instructions
• Data Types
• Memory Addressing

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