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Cool. The author has set himself a huge task if he wants to build something like LLVM. An alternative would be to participate in a project with similar goals th

by Rochus 2y ago

Cool. The author has set himself a huge task if he wants to build something like LLVM. An alternative would be to participate in a project with similar goals that is already quite progressed, such as QBE or Eigen (https://github.com/EigenCompilerSuite/ https://github.com/EigenCompilerSuite/) ; both so far lack of optimizers. I consider Eigen very attractive because it supports much more targets and includes assemblers and linkers for all targets. I see the advantage in having a C implementation; Eigen is unfortunately developed in C++17, but I managed to backport the parts I'm using to a moderate C++11 subset (https://github.com/rochus-keller/Eigen https://github.com/rochus-keller/Eigen). There are different front-ends available, two C compilers among them. And - as mentioned - an optimizer would be great. EDIT: just found this podcast where the author gives more informations about the project goals and history (at least the beginning of the podcast is interesting): https://www.youtube.com/watch?v=f2khyLEc-Hw https://www.youtube.com/watch?v=f2khyLEc-Hw

wffurr 2y ago
What’s unfortunate about C++17? It has some nice features that build on C++11’s safety and ergonomic improvements.
- Rochus 2y ago
  You need a large, modern C++ compiler and standard library, which are not available for most older systems, and you're inviting an excess of dependencies because not all compilers support all parts of the newer C++ standards (in the same way), and require a lot more resources and newer versions of APIs and libraries, which further limits their usability on older systems. Furthermore, C89 and C++98 are much easier to bootstrap than a colossus like LLVM and Clang. The few "nice features" are perhaps enticing, but the costs they incur are disproportionate.
- o11c 2y ago
  For reference, GCC 4.7 (released March 2012) was the last build of GCC that is written in C, and supports almost all of the C++11 language (4.8.1, written in C++, finished the last bits) and a fair amount of the library. If you have to work on a system that hasn't been updated since 2014 or so (since it's fair enough to avoid the .0 releases), getting support for later C++ standards is significantly more complicated.
lerno 2y ago
The QBE author has said that good compilation speed was not a design goal. It also outputs asm which then has to be run through GCC or Clang, which nullifies any benefit of being a standalone backend.
- Rochus 2y ago
  > that good compilation speed was not a design goal Not sure how this relates to my statement. I was talking about an optimizer, not about compilation speed. I'm neither using QBE, but Eigen, for good reasons.

by Rochus 2y ago

wffurr 2y ago

What’s unfortunate about C++17? It has some nice features that build on C++11’s safety and ergonomic improvements.

Rochus 2y ago
You need a large, modern C++ compiler and standard library, which are not available for most older systems, and you're inviting an excess of dependencies because not all compilers support all parts of the newer C++ standards (in the same way), and require a lot more resources and newer versions of APIs and libraries, which further limits their usability on older systems. Furthermore, C89 and C++98 are much easier to bootstrap than a colossus like LLVM and Clang. The few "nice features" are perhaps enticing, but the costs they incur are disproportionate.
o11c 2y ago
For reference, GCC 4.7 (released March 2012) was the last build of GCC that is written in C, and supports almost all of the C++11 language (4.8.1, written in C++, finished the last bits) and a fair amount of the library. If you have to work on a system that hasn't been updated since 2014 or so (since it's fair enough to avoid the .0 releases), getting support for later C++ standards is significantly more complicated.

lerno 2y ago

The QBE author has said that good compilation speed was not a design goal. It also outputs asm which then has to be run through GCC or Clang, which nullifies any benefit of being a standalone backend.

Rochus 2y ago
> that good compilation speed was not a design goal Not sure how this relates to my statement. I was talking about an optimizer, not about compilation speed. I'm neither using QBE, but Eigen, for good reasons.