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Dec 9, 2020 · @RossRidge given %rax is the go-to register for storing return values, seeing it used in another way is surprising to me. It means that reading the disassembled code requires us to mentally map %rax not ...
Dec 20, 2016 · In AT&T syntax, the instruction: mov (%rax), %eax # AT&T syntax or, equivalently in Intel syntax: mov eax, DWORD PTR [rax] ; Intel syntax dereferences the memory address stored in rax, reads a 32-bit va...
Dec 13, 2013 · @DavidHeffernan: I just want to read values that are currently in those registers: RAX, RBX, RCX, RDX, RSP. RBP, RSI, RDI and print them out, thats it.
Jul 7, 2017 · The registers starting with r as in rax, rbx, etc, are the 64-bit registers introduced with the AMD64 extension to the existing 32-bit x86 ISA. That ISA extension was subsequently adopted by Intel and is...
As it is widely advertised, modern x86_64 processors have 64-bit registers that can be used in backward-compatible fashion as 32-bit registers, 16-bit registers and even 8-bit registers, for exampl...
Jul 10, 2019 · Thus (%rax) means to get the value of the pointer currently stored in %rax. What does the star decoration do on that? Does that further dereference that value (thus (%rax) is itself a pointer)? I'm havi...
• RDX:RAX register pair representing a 128-bit operand See the question and answer for x86_64 registers rax/eax/ax/al overwriting full register contents as well as Why do most x64 instructions zero the upper part of a...
Following the answer about assembly registers' sizes: First, what sizes are eax, ax, ah and their counterparts, in the 64-bit architecture? How to access a single register's byte and how to access...
Oct 3, 2021 · Either do lea rax, [rel a] or as an optimization in executables that are known to be linked into the low 32 bits of address space (like non-PIE on Linux), mov eax, a. Still, mov rax, a does work ineffici...
RAX is the full 64-bit value, with EAX and its sub-components mapped to the lower 32 bits. The upper half of 64-bit registers is only accessible in 64-bit mode, unlike 32-bit registers which can be used in any mode on...
