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 …

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 …

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, …

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.

• 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 …

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)? …

Nov 18, 2009 · The old 32-bit registers have been extended to 64 bits, the r registers (rax, rbx, rsp and so on). In addition, there's some extra general purpose registers r8 through r15 which can also be …

Dec 11, 2022 · RAX and RCX are call-clobbered so it's normal they don't keep their value; notice how their values before call come from an LEA and a load from a local on the stack. (What registers are …

With the old names all registers remain the same size, just like when x86-16 was extended to x86-32. To access 64-bit integer registers you use the new names with R-prefix such as rax, rbx... Register …

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...