What is the purpose of the RBP register in x86_64 assembler?
网页2017年1月29日 · 165. rbp is the frame pointer on x86_64. In your generated code, it gets a snapshot of the stack pointer (rsp) so that when adjustments are made to rsp (i.e. reserving space for local variables or push ing values on to the stack), local variables and function parameters are still accessible from a constant offset from rbp.
What is the "-4" for in assembler: movl $1, -4(%rbp)
网页2020年9月29日 · 2. -4 / -8 / -12 bytes relative to the address held in rbp, which is the pointer to the top of the stack (which grows downward). 4 bytes / 32 bits because that is the size of int on your machine. answered Sep 29, 2020 at 14:58.
Why are RBP and RSP called general-purpose registers?
网页2016年4月10日 · 63. According to Intel, in x64, the following registers are called general-purpose registers (RAX, RBX, RCX, RDX, RBP, RSI, RDI, RSP and R8-R15). In the article Understanding C by learning assembly, it's written that RBP and RSP are special-purpose registers (RBP points to the base of the current stack frame and RSP points to the top of …
x86 - What does the following assembly instruction do addsd
网页2012年5月1日 · 9. I'm trying to figure out what the assembly instruction actually does. addsd -8(%rbp), %xmm0. I know that it's a floating point addition on an x86-64 machine with SSE2. Also, I know that %xmm0 is a register. However, what I'm not sure of is what -8 (%rbp) means. The manuals are a bit confusing on that. Basically, the question is, does -8 ...
What does the R stand for in RAX, RBX, RCX, RDX, RSI, RDI, RBP, …
网页Closed 7 years ago. The x86 assembler language has had to change as the x86 processor architecture has changed from 8bit to 16bit to 32bit and now 64bit. I know that in 32bit assembler register names (EAX, EBX, etc.), the E prefix for each of the names stands for Extended meaning the 32bit form of the register rather than the 16bit form (AX, BX ...
Understanding %rip register in intel assembly - Stack Overflow
网页Feb 13, 2017 at 23:23. 1. movb $0x4,0x0 will store byte value 4 into memory at absolute address 0. movb $0x4,0x0(%rip) will store byte value 4 into memory at absolute address rip + 0, ie. at relative-to-RIP address 0. It's same as using other registers for addressing, like movb $4,0(%edi).
assembly - "mov rbp, rsp" in function prologue - Stack Overflow
网页2021年5月8日 · It moves the value from rbp to the memory location which rsp points to (after being decremented by 8). – Nate Eldredge. May 8, 2021 at 16:53. push rbp decrements rsp by 8 and then writes the prior value of rbp to the memory pointed to by rsp. mov rbp, rsp then loads the new rsp value into the rbp register. – ecm.
Allocating variables on the stack in x86 assembly. rbp and rsp vs …
网页You are compiling for 64-bit, so rbp and rsp are just the 64-bit equivalents to the 32-bit ebp and esp variables. . Even in 64-bit code you often see the 32-bit (e**) registers used when possible - but you won't see that with rsp or rbp usually 1 since they hold pointers that almost always need to be 64-b
Why RBP instead of another register as a frame pointer?
网页2021年3月28日 · So there are plenty of duplicates for the part about when / why to use a frame pointer at all. The interesting part is whether a register other than RBP could have been chosen. The only things special about RBP are that leave can compactly do RSP=RBP + pop RBP; and that a (%rbp) addressing mode requires an explicit disp8 or disp32 (with …
assembly - Is RBP/EBP register really necessary to support Variable ...
网页2016年6月2日 · (That said, %rbp is a good choice because there is no addressing mode for (%rbp), you have to use 0(%rbp). This makes %rbp a poor choice for a general purpose pointer, but it's okay as a frame pointer because you never need to access (%rbp) since all it contains is the previous frame pointer.)