Here is a table showing the relationship between registers in IA-32 and x64 architectures:
Figure 3: Registers used in the x86 architecture
r8 to r15 are available only in x64 and not in IA-32, and spl, bpl, sil, and dil can be accessed only in x64.
The first four registers (rax, rbx, rcx, and rdx) are General-Purpose Registers (GPRs), but some of them have the following special use cases for certain instructions:
- rax/eax: This is used to store information and it's a special register for some calculations
- rcx/ecx: This is used as a counter register in loop instructions
- rdx/edx: This is used in division to return the modulus
In x64, the registers from r8 to r15 are also GPRs that were added to the available GPRs.
The rsp/esp register is used as a stack pointer that points to the top of the stack. Its value decreases when there's a value getting pushed to the stack, and increases, when there's a value getting pulled out from the stack. The rbp/ebp register is...
