Think In Geek

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Walk-through flang – Part 2

In the previous installment of this series we saw basically how to install flang and we ran a simple smoke test. In this post we will see a high level overview of what happens when we compile a Fortran program using flang. We will also compare it with what usually happens with clang.

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Walk-through flang – Part 1

Flang is an open source project to create a Fortran compiler for LLVM. It is based on NVIDIA/PGI Fortran and it has been released under Apache License 2.0. In this series we will do a walk-through the code of this compiler and how it has been integrated in the existing LLVM infrastructure.

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10 years of Think In Geek

10 years ago Bernat (brafales) started this blog. This is still his blog though he is a bit busy these days and he cannot publish as much as he wants.

All in all, without his initiative this blog would not exist. As would not exist many of the posts I published here since 2012, when Bernat insisted that I should collaborate. I guess his persistence has somehow paid off 🙂

Consider this post a very small celebration of those 10 years. Hopefully we will be able to celebrate many more years.

Compilers as a memory error detectors

This is a small anecdote of something that happened me the other day.
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Exploring AArch64 assembler – Chapter 8

In the last chapter we saw how to call a function. We mentioned a special memory called the stack but we did not delve into it. Let’s see in this chapter how we can use the stack and why it is important in function calls.

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A small Telegram Bot in Go

I started using Telegram a few years ago. Most of the time I don’t use it much to have 1 to 1 conversations but rather chat in a small group of friends which I’ve known for a while now. Every now and then, we share some links to Twitter on that group, and unfortunately the Telegram official clients preview mode don’t support previewing Twitter messages with more than one image.

Take this test message as an example:

The moment I link this to a Telegram chat, this is the result:

Which is not ideal, as sometimes the message doesn’t make much sense when only one of the images is displayed.

Turns out I’ve been learning some Go over the last few months as well, so I wondered if I could write a small Telegram Bot to help me with that. I needed something to which I could send a Twitter link, and gave me back either the default Twitter preview in Telegram, or a custom made one with all the images of the message, in case there were more than one.
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ARM assembler in Raspberry Pi – Chapter 27

We saw in the previous chapter what is the process required to build a program from different compilation units. This process happened before we obtained the final program. The question is, can this process happen when the program runs? This is, is it possible to dynamically link a program?

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Whose is this optimization?

Today we will toy around a very simple optimization in clang and discuss a bit about separation of concerns when optimizing code.

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Exploring AArch64 assembler – Chapter 7

In the previous installment of this series we saw how to alter the sequencing of our programs. Today we will see how we can reuse instructions by means of branches. Let’s talk about functions.

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Compilation of array expressions in Fortran

As I stated in my previous post, Fortran 90 improved the array capabilities of Fortran. Today we will discuss what are the challenges when compiling array expressions.

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