Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Intel C/C++ compilers complete adoption of LLVM

software.intel.com

Post reply on HN
Print view View original

111–120 of 169 posts

Re: Intel C/C++ compilers complete adoption of LLVM

#111

Post by pjmlp »

ip26 wrote: post #93
jasonhansel wrote: post #79

This is exactly why I've been concerned about LLVM's use of a non-copyleft license: unlike with GCC, vendors can create their own proprietary extensions and optimizations without contributing them back to the community. (In the past, people have dismissed such concerns, saying that it would be impractical for anyone to actually do such a thing. But this project by Intel shows that it isn't just possible--in fact, it'…

Why is this worse than totally proprietary & closed source icc?

Leeching on the work that Johnny/Jane dev might have contributed to LLVM as part of their PhD thesis in compiler optimisations.

Re: Intel C/C++ compilers complete adoption of LLVM

#112

Post by ok123456 »

trasz wrote: post #87
dhosek wrote: post #86

It's still a little strange to me the whole free compiler thing. I used to pay hundreds of dollars each for, first Turbo C/C++, then Borland C/C++ and Zortech C/C++. I think IBM's C/C++ for OS/2 was the first time the compiler came free with an OS that I had on my computer and I was literally shocked that it included—for free—the GUI for building GUI applications. I guess being old is what makes me perfectly fine wit…

Early Unix systems came with bundled compiler toolchain. I think it was the SunOS which unbundled it first.

It's wasn't much of a prize. At school, the Sun C++ compiler, required for the OOP class, was responsible for a lot of people switching out of CS.

Re: Intel C/C++ compilers complete adoption of LLVM

#113

Post by pjmlp »

justicezyx wrote: post #97
yakubin wrote: post #48

Earlier quoted context omitted.

Because reinventing the wheel is how progress is made. You car isn't made with wheels from 17th century.

Who told you reinventing wheel is how progress made? Can we be precise here? I never had a memory about a major technical progress being reinventing the wheel.

So your car wheels are still made of wood with metal roundings?

Re: Intel C/C++ compilers complete adoption of LLVM

#114

Post by dragontamer »

floatboth wrote: post #55
ytch wrote: post #19

Earlier quoted context omitted.

Yeah, I guess LLVM is preferred mostly because license. Companies can keep their optimizations in secrets. Just like why Playststion's OS is based on BSD.

It's nearly impossible to keep optimizations secret. They are the easiest thing in the world to reverse engineer: just look at the output assembly. (And you can't exactly output obfuscated assembly because that would make the performance worse, nullifying the benefits of the optimizations.)

I don't get it.

Looking at output assembly language won't tell me anything about the algorithms behind solving the register allocation problem (aka: live data problem, which is a knapsack problem and/or graph-coloring problem IIRC).

I'd be able to see that yes, compilers are good at deciding which registers should hold which data. But that's not sufficient at actually learning how the algorithm / register selection process works.

Re: Intel C/C++ compilers complete adoption of LLVM

#115

Post by justicezyx »

pjmlp wrote: post #113
justicezyx wrote: post #97

Earlier quoted context omitted.

Who told you reinventing wheel is how progress made? Can we be precise here? I never had a memory about a major technical progress being reinventing the wheel.

So your car wheels are still made of wood with metal roundings?

If modern tires are considered reinventing the wooden wheels, sure, then reinventing wheel is the main form of making progress. But I doubt that's how people thinking about reinventing wheel, when they use that phrase to mock others of wasting energy inventing something that has already a very-well-working alternative.

Re: Intel C/C++ compilers complete adoption of LLVM

#116

Post by jabl »

justicezyx wrote: post #96
xamolxix wrote: post #8

Earlier quoted context omitted.

I disagree. Competition is good. Don't want to end up with every C/C++ compiler being a clang skin in the same way as (almost) every browser is a chrome skin. And for what it's worth cl compiles faster for me than even clang-cl. I like having both available though.

Well competition is good for consumers but is not for the actual market players. And what's the point of competing in the compiler space?

> And what's the point of competing in the compiler space?

To an extent, processor vendors sell CPU's based on how they perform on SPEC{int,fpu}. So what matters is not how fast your HW is, but rather on how fast the combination of HW + compiler is.

Re: Intel C/C++ compilers complete adoption of LLVM

#117

Post by CalChris »

MauranKilom wrote: post #18
OskarS wrote: post #9

I'm not sure I love this. I mean, LLVM is awesome and everthing, but software monocultures are pretty bad. It's not like the situation is dire yet (given that there are also GCC and MSVC), but you can imagine a situation in a couple of years when Microsoft goes "yeah, we're also gonna go with LLVM now" and also GCC starting to fade away. It's a bit concerning. Also: if icc is going to go with LLVM as a backend, then…

> Also: if icc is going to go with LLVM as a backend, then what is the point of using icc at all? Why not just use clang? From the blog post: " Not all our optimization techniques get upstreamed—sometimes because they are too new, sometimes because they are very specific for Intel architecture. This is to be expected and is consistent with other compilers that have adopted LLVM. " I don't see any good technical reaso…

The Intel post didn't say "Other compilers also don't upstream everything". So you shouldn't put that in quotes.

However, that is an actual argument. This isn't GCC where that would be required. This is LLVM where that is allowed. This is a choice, Intel's choice, because LLVM allows that, and it's probably at the corner case level of an Intel-specific icc-specific feature, as in, not particularly generally useful.

There is a benefit of this for normal LLVM development as well. It means that Intel is responsible for maintaining it and normal LLVM developers aren't. If I do something that breaks something in the LLVM AMD GPU backend, that's on me. If I do something that breaks something in Intel's code, that's on them.

Re: Intel C/C++ compilers complete adoption of LLVM

#118

Post by bigbillheck »

xamolxix wrote: post #8
xvilka wrote: post #5

Absolutely sensible move. Time for Microsoft to do the same with MSVC.

I disagree. Competition is good. Don't want to end up with every C/C++ compiler being a clang skin in the same way as (almost) every browser is a chrome skin. And for what it's worth cl compiles faster for me than even clang-cl. I like having both available though.

> Don't want to end up with every C/C++ compiler being a clang skin

I've wasted too much of my life dealing with compiler differences, and I certainly do want that.

Re: Intel C/C++ compilers complete adoption of LLVM

#119

Post by Ar-Curunir »

pjmlp wrote: post #14
OskarS wrote: post #9

I'm not sure I love this. I mean, LLVM is awesome and everthing, but software monocultures are pretty bad. It's not like the situation is dire yet (given that there are also GCC and MSVC), but you can imagine a situation in a couple of years when Microsoft goes "yeah, we're also gonna go with LLVM now" and also GCC starting to fade away. It's a bit concerning. Also: if icc is going to go with LLVM as a backend, then…

Because not everything on icc is going to be upstreamed to clang, thanks license. It is not like clang is enjoying C++ Builder RAD abilities, PS 4 and 5 optimizations, or bitcode format used by watchOS.

I don’t think the license meaningfully changes anything. For example: rustc has a WIP GCC backend, despite not being GPL. I imagine icc could do something similar

Re: Intel C/C++ compilers complete adoption of LLVM

#120

Post by pjmlp »

justicezyx wrote: post #115
pjmlp wrote: post #113

Earlier quoted context omitted.

So your car wheels are still made of wood with metal roundings?

If modern tires are considered reinventing the wooden wheels, sure, then reinventing wheel is the main form of making progress. But I doubt that's how people thinking about reinventing wheel, when they use that phrase to mock others of wasting energy inventing something that has already a very-well-working alternative.

So you would drive a chariot on the same places as a four wheel traction drive Jeep?
Post reply on HN