Conversational x86 ASM: Learning to Appreciate Your Compiler • Matt Godbolt • YOW! 2020

Assembly language isn’t as scary as it seems - it’s a way to understand what your computer is actually executing and appreciate what compilers do for you

Most x86 assembly instructions have a destination operand (which is also usually a source) and one or more source operands that can be registers, memory locations, or constants

Registers have different names based on size - RAX/EAX/AX/AL refer to 64/32/16/8 bits of the same register. The first 8 registers have special names (RAX, RBX etc) while additional ones are numbered (R8-R15)

Function calling conventions (ABI) specify which registers are used for parameters and return values - on Linux x86-64, RDI holds the first parameter, RSI the second, etc. Return values go in RAX

Common instructions include MOV (copy), arithmetic (ADD/SUB/MUL), comparisons (CMP/TEST), and jumps (JE/JNE). Memory access can often be combined with arithmetic in x86

Modern compilers are extremely good at optimizing code - they can transform loops, eliminate redundant operations, and use specialized instructions (like LEA for address calculations)

Writing maintainable high-level code and trusting the compiler is generally better than trying to outsmart it with manual optimizations

Tools like Compiler Explorer help developers understand assembly output and verify compiler optimizations by showing the mapping between source code and assembly

Benchmarking is essential but challenging - looking at assembly can help develop intuition about performance but actual measurements are required

Assembly knowledge is particularly valuable in performance-critical domains like games, finance and systems programming, but the principles apply broadly