What are the x86-64 instructions for floating-point comparisons like the cmpq for quard-word integer comparison? The SSE3 extenstions provide two instructions for comparing floating values: Instruction Based on Description ucomiss S2, S1 S1 – S2 Compare single precision ucomisd S2, S1 S1 – S2 Compare double precision As with cmpq, they follow the GAS convention […]
Posts tagged x86-64
6 posts in total.
How to get the assembly code for OCaml code generated by ocamlopt?
How to get the native assembly code (e.g. x86-64 asm) for OCaml code generated by the native ocamlopt compiler? To get the assembly code for an OCaml program, add these parameters to ocamlopt: -S -inline 20 -nodynlink An example is as follows. The OCaml program: $ cat not.ml let not x = ((x – 1) […]
x86-64 calling convention by gcc
What is the x86-64 calling convention by gcc? The calling convention of the System V AMD64 ABI is followed on GNU/Linux. The registers RDI, RSI, RDX, RCX, R8, and R9 are used for integer and memory address arguments and XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6 and XMM7 are used for floating point arguments. For […]
A Beginners’ Guide to x86-64 Instruction Encoding
The encoding of x86 and x86-64 instructions is well documented in Intel or AMD’s manuals. However, they are not quite easy for beginners to start with to learn encoding of the x86-64 instructions. In this post, I will give a list of useful manuals for understanding and studying the x86-64 instruction encoding, a brief introduction […]
Measuring Time Accurately in Programs
It is quite common to measure the time in programs using APIs like clock() and gettimeofday(). We may also want to measure the time “accurately” for certain purposes, such as measuring a small piece of code’s execution time for performance analysis, or measuring the time in time-sensitive game software. It is hard to measure the […]
x86-64 ISA / Assembly Programming References
This post collect the reference resource for x86-64 (also know as Intel 64, AMD 64) ISA / assembly language programming. x86-64 is a 64-bit extension of the Intel x86 instruction set. x86-64 Assembly Programming ∞ Introduction to Computer Systems Resources (15-213 Introduction to Computer Systems Resources from CMU) Lots materials for learning machine-level programming on […]