What are callee-saved registers x86?
The callee-saved registers are used for local state of the caller that needs to preserved across further function calls.
What is callee-saved register?
Callee-saved registers (AKA non-volatile registers, or call-preserved) are used to hold long-lived values that should be preserved across calls.
Is RSP A callee-saved register?
The registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14, and R15 are considered nonvolatile (callee-saved).
Which are the preserved registers?
r12 , r13 , r14 , r15 , rbx , rsp , rbp are the callee-saved registers – they have a “Yes” in the “Preserved across function calls” column. What about flags? like DF?
What is difference between caller and callee?
A caller is a function that calls another function; a callee is a function that was called. The currently-executing function is a callee, but not a caller.
Is the stack pointer callee saved?
The stack above the stack pointer is automatically preserved as long as the callee does not write to memory addresses above SP.
What is callee save and caller save?
A caller-save register must be saved and restored around any call to a subprogram. In contrast, for a callee-save register, a caller need do no extra work at a call site (the callee saves and restores the register if it is used).
Is RBP callee saved?
What is callee function?
Description. callee is a property of the arguments object. It can be used to refer to the currently executing function inside the function body of that function. This is useful when the name of the function is unknown, such as within a function expression with no name (also called “anonymous functions”).
What is the difference between callee and caller?
Is EAX a return register?
EAX: The accumulator. This register typically stores return values from functions.
Is Fastcall faster?
Since it typically saves at least four memory accesses, yes it is generally faster.
What is x86 EAX?
For example, ‘EAX’ is the accumulator register as a 32-bit value. Similarly, in the 64-bit version, the ‘E’ is replaced with an ‘R’ (register), so the 64-bit version of ‘EAX’ is called ‘RAX’. It is also possible to address the first four registers (AX, CX, DX and BX) in their size of 16-bit as two 8-bit halves.
What is Rax and EAX?
rax is the 64-bit, “long” size register. It was added in 2003 during the transition to 64-bit processors. eax is the 32-bit, “int” size register. It was added in 1985 during the transition to 32-bit processors with the 80386 CPU.
What is a Fastcall?
Microsoft Specific
The __fastcall calling convention specifies that arguments to functions are to be passed in registers, when possible. This calling convention only applies to the x86 architecture.
Does x86 have a zero register?
While the x86/x64 architectures do not have an architectural zero register it seems likely that the Sandybridge processor has a physical zero register.
What are EAX EBX ECX EDX registers?
The EAX, EBX, ECX, EDX, EBP, EDI, and ESI registers are all 32-bit general-purpose registers, used for temporary data storage and memory access. Some of CPU instructions modify specific registers.
What is __ Stdcall?
The __stdcall calling convention is used to call Win32 API functions. The callee cleans the stack, so the compiler makes vararg functions __cdecl . Functions that use this calling convention require a function prototype. The __stdcall modifier is Microsoft-specific.
What does cdecl stand for?
cdecl. The cdecl (which stands for C declaration) is a calling convention for the C programming language and is used by many C compilers for the x86 architecture. In cdecl, subroutine arguments are passed on the stack.
What registers can I use x86?
The x86 architecture has 8 General-Purpose Registers (GPR), 6 Segment Registers, 1 Flags Register and an Instruction Pointer. 64-bit x86 has additional registers.
How many registers are there in x86?
The x86 architecture contains eight 32-bit General Purpose Registers (GPRs). These registers are mainly used to perform address calculations, arithmetic and logical calculations. Four of the GPRs can be treated as a 32-bit quantity, a 16-bit quantity or as two 8-bit quantities.
What are EAX ECX Eflags ESI registers for?
The EAX, EDX, ECX, EBX, EBP, EDI, and ESI registers are 32-bit general-purpose registers, used for temporary data storage and memory access.
What is __ Fastcall?
The __fastcall calling convention specifies that arguments to functions are to be passed in registers, when possible. This calling convention only applies to the x86 architecture.
Is x86 obsolete?
Arguably, within the next 5-10 years, the x86 architecture will go obsolete. It seems extremely hard for Intel and AMD to turn this reality around. Instead, Intel and AMD seem to be in the same position, today, as Motorola and IBM were back in 1995 and 2005 when Apple decided to move its computers to Intel x86 CPUs.
Why are 32-bit called x86?
x86 is the name of the architecture that it’s built to run on (the name comes from a series of old Intel processors, the names of which all ended in 86, The first of which was the 8086). Although x86 was originally a 16-bit architecture, the version in use today is the 32-bit extension.