Last week, I wrote three blogs about the situation with starting child processes on Unix and being notified of their exit. I raised several problems with the current implementation, which I have tried to solve and I have now a proposal for. If you haven’t yet, you should take some time to read the previous …
Tag Archive: low-level
Mar 28
Restricting what you can do
I usually write about C++, since it’s the programming language that I use on my daily work. Today, however, I’m talking about its nearest cousin: C. In specific, about a certain keyword introduced by the C99 standard, which was issued over 12 years ago. Usually, the C standard plays catch-up with the C++ standard (like …
Feb 22
The value of passing by value
I’ve written in the past about how passing certain types by value in C++ would be more efficient than passing by constant reference. But it turns out that the ABI rules are somewhat more complex than what I said back in 2008. Time to investigate. This is also prompted by the discussion on qreal on …
Jan 19
Update and benchmark on the dynamic library proposals
My last blog on the dynamic libraries on Linux attracted over 15000 visits, which was quite unexpected (it’s 15x more than the usual traffic). It got linked from reddit and ycombinator and comments there and in the previous post have raised some interesting questions I’ll try to answer. LD_PRELOAD First, a quck background: LD_PRELOAD and …
Jan 16
Sorry state of dynamic libraries on Linux
Last week, we identified a bug in Qt with Olivier‘s new signal-slot syntax. Upon further investigation, it turns out it’s not a Qt issue, but an ABI one. Which prompted me to investigate more and decide that dynamic libraries need a big overhaul on Linux. tl;dr (a.k.a. Executive Summary) Shared libraries on Linux are linked …
Jan 10
Architectures and ABIs detailed
Yesterday I wrote about instruction set and ABI manuals. Today I’d like to go into details about the ABIs I listed there. This was done mostly as a summary for me: it’s tiresome to search for the information in the manuals, especially since some of the manuals are PDFs without links. For example, I never …
Jan 09
Assembly developer’s library
Every now and then, when coding in C++, I find myself needing to know some assembly to understand what’s going on. Sometimes, it’s because I am actually writing assembly code, such as when I was writing the new atomic classes for Qt. More often, it’s because I need to read the assembly generated by the …
Jul 20
Table-driven methods with no relocations
The other day, someone in the qt-interest mailing list posted the link to an article entitled: How to make fewer errors at the stage of code writing, the third part in a series of articles about writing better code. In this particular article, the author ran a static code-checker tool on the Qt source code …