Inline asm 联立计算 rdx:rax
Webb6 okt. 2010 · 一、 优点. 使用内联汇编可以在 C/C++ 代码中嵌入 汇编语言 指令,而且不需要额外的汇编和连接步骤。. 在 Visual C++ 中,内联汇编是内置的编译器,因此不需要配置诸如 MASM 一类的独立汇编工具。. 这里,我们就以 Visual Studio .NET 2003 为背景,介绍在 Visual C++ 中 ... Webb19 jan. 2024 · 回到最开始的 add () 函数,我们可以为其中的内联汇编添加限制符如下: int res; asm ( "mov %%rdi, %%rax;" "add %%rsi, %%rax;" : "=a"(res) : "D"(i), "S"(j) : ); 上面这段汇编代码,是从输入的寄存器 rdi 中读取变量 i 、寄存器 rsi 中读取变量 j ,运算后将结果输出到寄存器 rax 中的变量 res 。 除了 rdi, rsi, rax 这三个寄存器,其他寄存器并没有 …
Inline asm 联立计算 rdx:rax
Did you know?
Webb用 gcc 做到这一点的正确方法是使用寄存器约束: uint64_t rax = 0, rbx = 0 ; __asm__ ( "" : "=a" (rax), "=b" (rbx) ::); /* make rax and rbx take on the current values in those registers */ 请注意,您不需要任何实际指令——约束告诉 gcc 在什么都不做之后,值 rax 将在 rax 中,而 rbx 的值将在 rbx 中。 你可以使用约束 a, b, c, d, S 和 D (后两个用于 %rsi 和 … Webb11 okt. 2024 · 一般用途暫存區(General Purpose Register ; GPR),可分為 RAX、RBX、RCX、RDX、R8~R15。 稍微來介紹一下常見的暫存器(64位元): RAX 特殊用途:存放運算結果,執行乘法及除法指令時,會自動使用; RBX 特殊用途:基底定址法的基底暫存器; RCX 特殊用途:做迴圈的計數器
Webb整数返回值存放在 rax 或者 rdx:rax 中,浮点数返回值存放在 xmm0 或者 xmm1:xmm0 中。 下面是一个用来展示如何保存和恢复寄存器的程序: fib.asm Webb25 maj 2024 · Instruction List是汇编指令序列。. 它可以是空的,比如:__asm__ __volatile__ (""); 或__asm__ ("");都是完全合法的内联汇编表达式,只不过这两条语句没有什么意义。. 但并非所有Instruction List为空的内联汇编表达式都是没有意义的,比如:__asm__ ("":::"memory"); 就非常有意义 ...
Webb第 1 章. SIMD 和 SSE/AVX. SIMD (Single Instruction, Multiple Data),即单指令多数据,顾名思义,是通过一条指令对多条数据进行同时操作。. 据维基百科说,最早得到广泛应用的SIMD指令集是Intel的MMX指令集,共包含57条指令。. MMX提供了8个64位的寄存器 (MM0 - MM7),每个寄存器 ... Webb18 jan. 2024 · On x64, (%rax, %edx, 4) is not a legal combination. Consult the processor manual for a list of valid addressing modes. My guess is that you meant (%rax, %rdx, 4). 其他推荐答案. Most likely cause of your problem is the use of an explicit 32bit integer type in the %3 operand. You haven't shown the constraints list for your inline assembly.
Webb5 maj 2011 · Summary: Inline asm for rdtsc generates silly code Status: RESOLVED FIXED Alias: None Product: gcc Classification: Unclassified Component: rtl-optimization (show ... %rdx movq %rdx, %rax ret for the asm testcase, which isn't as bad as 4.6, but isn't perfect. What ...
Webb12 apr. 2024 · 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, etc.). counties power contactWebbScope. 内联装配可以用两种方式之一来使用。. 随着 asm! 宏,汇编代码在函数范围内发出,并集成到编译器生成的函数汇编代码中。. 此汇编代码必须遵守 严格的规则 以避免未定义的行为。. 请注意,在某些情况下,编译器可能会选择将汇编代码作为单独的函数 ... brentwood cineplex tickethttp://rk700.github.io/2024/01/19/inline-assembly-constraints/ counties on eastern shore marylandWebb1 juni 2024 · 系统调用 (Syscall) 系统调用是指程序向系统内核请求服务,系统调用因操作系统的不同而不同,因为不同的操作系统使用不同的内核。. 所有系统调用都有一个与之关联的ID (一个数字) 系统调用的输入接受一个参数列表。. 寄存器参数顺序表. 这是一个非常重要的 … counties on eastern shore vaWebb24 nov. 2012 · Constraints are used when you tell GCC to allocate registers for insn operands, the constraints define the acceptable register class from which to draw registers. The clobbers, on the other hand, tell GCC about registers, which are modified by the insns, in the cases where it's not evident from the input/output constraints, for … counties.orgWebbThese instructions that use DX:AX, EDX:EAX and RDX:RAX as source or destination still exists in long mode. But this support is at least for 64bit code completely lost/broken while there is no int128_t. As you said: "The "A" constraint supposed to be used for a _PAIR_." But as I tried to show, GCC does not use any pair in most cases. asm("…" counties pukekoheWebbActually, the GCC supports two forms of inline assembly statements: basic; extended. The basic form consists of only two things: the __asm__ keyword and the string with valid assembler instructions. For example it may look something like this: __asm__ ("movq $3, %rax\t\n" "movq %rsi, %rdi"); The asm keyword may be used in place of __asm__ ... brentwood cinema burnaby