7 ms·

First official release of LLVM Flang

92 points by seekdeep 2y ago

aragilar 2y ago
There doesn't appear to be a link to the release notes, it would be nice to know what are the current limitations.
- pklausler 2y ago
  Language-wise, it's all of F'2018 less coarrays and "LEN" derived type parameters, plus a pile of portable &/or popular language extensions.
  - aragilar 2y ago
    Also, it would be good to know how well it handles older codes of the f77/g77 era (as gfortran is not always well behaved on those).
    - pklausler 2y ago
      Really well, actually. Unless you have a pre-'77 code that requires each DO loop execute at least one iteration, you should be fine.
HexDecOctBin 2y ago
Now someone go convince the C committee to stop trying to turn C into Fortran.
- froh 2y ago
  Q from out of the loop: what are you referring to? and if you could enlighten me how that then is a problem?
  - jabl 2y ago
    Not the OP, but I'll take a stab at it. In C99, C added the 'restrict' qualifier for pointers, which would make function arguments marked with it behave a bit like procedure arguments in Fortran. Idea being to allow the compiler to optimize more aggressively. Not specifically about making C more like Fortran, but there's been a lot of work over the years clarifying what compilers can and cannot assume. More recently, a lot of work going into things like 'pointer provenance', again in an effort to clarify where more aggressive optimizations can be done. And things like when can NULL checks be elided etc. Some people resent all this and just want C to be more like a 'portable macro-assembler'.
    - froh 2y ago
      thanks for clarifying. this makes more sense than the unspecific Fortran bashing. and as long as C gets features you may but don't have to use, so what?
pandemic_region 2y ago
> Whilst many alternative programming languages have come and gone, it [Fortran] has regained its popularity for writing high performance codes. I don't understand why sometimes people pluralize "code". It sounds a bit silly but maybe it's just me.
- enriquto 2y ago
  it's a fairly common usage in numeric computing. If you read, for example, the wikipedia entries for "computational fluid dynamics" you'll see that they consistently speak of "codes" when referring to programs. https://en.wikipedia.org/wiki/Computational_fluid_dynamics https://en.wikipedia.org/wiki/Computational_fluid_dynamics
  - kergonath 2y ago
    Same for computational Chemistry, computational Physics (solid state, neutronics, astrophysics), etc.
- bradrn 2y ago
  As someone doing research in physics, I’ve noticed this usage before. It seems fairly frequent outside CS [EDIT: and as the sibling comment says, specifically in numerical computing]. From what I’ve gathered, for them ‘code’ has become a count noun, such that ‘a code’ means something like ‘a piece of code’ or even ‘a program’, and the plural ‘codes’ follows from that.
- thenoblesunfish 2y ago
  It's because the types of things people write in Fortran (high performance science codes, for example) tend to be monolithic, single-purpose programs. It comes from a time when a code really was basically one compilation unit (and doing that is such a nice simplification that I support it, for science). With code written for the web, shared through package managers, etc. it makes more sense to use the uncountable noun instead of the countable one.
  - gpvos 2y ago
wiz21c 2y ago
How compatible is it with the current code bases developped under proprietary compilers ?
- melodyogonna 2y ago
  It says in the article that some of these companies contribute their test suite
- pklausler 2y ago
  My approach throughout was to maximize portability of existing code to this new compiler. The list of extensions that are supported is quite long (https://flang.llvm.org/docs/Extensions.html https://flang.llvm.org/docs/Extensions.html), and the general policy is to support anything that people need so long as the feature is well defined and portable among compilers that support it.
deng 2y ago
Congratulations to the team, this has been a long time coming. I still think that modern Fortran is actually a great language to write numerical code, especially when doing lots of linear algebra. Granted, it was many years ago, but I still remember struggling with C++ and libraries like Eigen, and one day, confronted yet again with agonizing slow compile times and error messages that look like binary, I ditched C++ for good and moved to Fortran95. Not only could I pretty much copy&paste a lot of stuff from my Matlab prototype, the resulting binary was actually faster than C++ with Eigen. Not sure if I would use it today for new projects, probably Julia would be the better choice nowadays.
- accurrent 2y ago
  IF we can get modern fortran working on top of GPUs via spir-v that would be really awesome. Modern Fortran is so nice for numerics.
deleted 2y ago
[deleted]
jmclnx 2y ago
Congratulations, next is COBOL ? I am serious, we really need a free COBOL compiler. Yes, GNU now has a front end for COBOL, so LLVM turn. Maybe IBM and the Navy Department will help.
- lproven 2y ago
  Good news! https://www.theregister.com/2025/03/13/gcc_15_is_close/ https://www.theregister.com/2025/03/13/gcc_15_is_close/

92 points by seekdeep 2y ago

aragilar 2y ago

There doesn't appear to be a link to the release notes, it would be nice to know what are the current limitations.

pklausler 2y ago
Language-wise, it's all of F'2018 less coarrays and "LEN" derived type parameters, plus a pile of portable &/or popular language extensions.
- aragilar 2y ago
  Also, it would be good to know how well it handles older codes of the f77/g77 era (as gfortran is not always well behaved on those).
  - pklausler 2y ago
    Really well, actually. Unless you have a pre-'77 code that requires each DO loop execute at least one iteration, you should be fine.

HexDecOctBin 2y ago

Now someone go convince the C committee to stop trying to turn C into Fortran.

froh 2y ago
Q from out of the loop: what are you referring to? and if you could enlighten me how that then is a problem?
- jabl 2y ago
  Not the OP, but I'll take a stab at it. In C99, C added the 'restrict' qualifier for pointers, which would make function arguments marked with it behave a bit like procedure arguments in Fortran. Idea being to allow the compiler to optimize more aggressively. Not specifically about making C more like Fortran, but there's been a lot of work over the years clarifying what compilers can and cannot assume. More recently, a lot of work going into things like 'pointer provenance', again in an effort to clarify where more aggressive optimizations can be done. And things like when can NULL checks be elided etc. Some people resent all this and just want C to be more like a 'portable macro-assembler'.
  - froh 2y ago
    thanks for clarifying. this makes more sense than the unspecific Fortran bashing. and as long as C gets features you may but don't have to use, so what?

pandemic_region 2y ago

> Whilst many alternative programming languages have come and gone, it [Fortran] has regained its popularity for writing high performance codes. I don't understand why sometimes people pluralize "code". It sounds a bit silly but maybe it's just me.

enriquto 2y ago
it's a fairly common usage in numeric computing. If you read, for example, the wikipedia entries for "computational fluid dynamics" you'll see that they consistently speak of "codes" when referring to programs. https://en.wikipedia.org/wiki/Computational_fluid_dynamics https://en.wikipedia.org/wiki/Computational_fluid_dynamics
- kergonath 2y ago
  Same for computational Chemistry, computational Physics (solid state, neutronics, astrophysics), etc.
bradrn 2y ago
As someone doing research in physics, I’ve noticed this usage before. It seems fairly frequent outside CS [EDIT: and as the sibling comment says, specifically in numerical computing]. From what I’ve gathered, for them ‘code’ has become a count noun, such that ‘a code’ means something like ‘a piece of code’ or even ‘a program’, and the plural ‘codes’ follows from that.
thenoblesunfish 2y ago
It's because the types of things people write in Fortran (high performance science codes, for example) tend to be monolithic, single-purpose programs. It comes from a time when a code really was basically one compilation unit (and doing that is such a nice simplification that I support it, for science). With code written for the web, shared through package managers, etc. it makes more sense to use the uncountable noun instead of the countable one.
- gpvos 2y ago

wiz21c 2y ago

How compatible is it with the current code bases developped under proprietary compilers ?

melodyogonna 2y ago
It says in the article that some of these companies contribute their test suite
pklausler 2y ago
My approach throughout was to maximize portability of existing code to this new compiler. The list of extensions that are supported is quite long (https://flang.llvm.org/docs/Extensions.html https://flang.llvm.org/docs/Extensions.html), and the general policy is to support anything that people need so long as the feature is well defined and portable among compilers that support it.

deng 2y ago

Congratulations to the team, this has been a long time coming. I still think that modern Fortran is actually a great language to write numerical code, especially when doing lots of linear algebra. Granted, it was many years ago, but I still remember struggling with C++ and libraries like Eigen, and one day, confronted yet again with agonizing slow compile times and error messages that look like binary, I ditched C++ for good and moved to Fortran95. Not only could I pretty much copy&paste a lot of stuff from my Matlab prototype, the resulting binary was actually faster than C++ with Eigen. Not sure if I would use it today for new projects, probably Julia would be the better choice nowadays.

accurrent 2y ago
IF we can get modern fortran working on top of GPUs via spir-v that would be really awesome. Modern Fortran is so nice for numerics.

deleted 2y ago

[deleted]

jmclnx 2y ago

Congratulations, next is COBOL ? I am serious, we really need a free COBOL compiler. Yes, GNU now has a front end for COBOL, so LLVM turn. Maybe IBM and the Navy Department will help.

lproven 2y ago
Good news! https://www.theregister.com/2025/03/13/gcc_15_is_close/ https://www.theregister.com/2025/03/13/gcc_15_is_close/