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How exactly do you get away with not using the 32-bit subset of AMD64 ASM? "32-bit x86 code" just means "code that does not use any of the AMD64 ISA." (And at
by 15155 4y ago
How exactly do you get away with not using the 32-bit subset of AMD64 ASM?
"32-bit x86 code" just means "code that does not use any of the AMD64 ISA." (And at this point, probably SSE2+ and a handful of other extensions.)
GP is correct: anyone that "knows" AMD64 assembly inherently must know 32-bit ASM because one must use the original x86 registers, instructions, etc. for the vast majority of tasks.
People are still constantly running what was formerly known as "32-bit x86 code" in their 64-bit applications.
- saagarjha 4y agoI read “learned 32-bit first” as “learned on i386 machines”, not “learned what the 32-bit instructions do on 64-bit computers”. There’s a big difference between these two, because the way you write code for a machine that doesn’t do 64-bit is quite different, since you have many more registers, the calling convention is pretty different, etc.