llvm dev - Jun 2009 - [LLVMdev] Some understanding of LLVM vs gCC vs Intel C++ Compilers

Hi All,

I have spent a better part of my 32 years on this earth writing  
Solaris software and more recently leaving that and returning back to  
Mac OS.

I obviously know about GCC and the Intel C++ Compilers.

I am looking to have more freedom and flexibility along with producing  
better quality software.

How does LLVm fit in?

I know that it is a C/C++ Compiler, but how do I use it? Is it  
Makefile based?

Does it replace GCC?

Can one build full OS X applications with it? (What I mean is dont  
need to use XCode or anything if I dont want to)

I would totally appreciate advice!

Thanks,

-Jason

----- Original Message ----
> From: Jason Todd Slack-Moehrle <mailinglists at mailnewsrss.com>
> To: llvmdev at cs.uiuc.edu
> Sent: Sunday, June 14, 2009 8:09:03 PM
> Subject: [LLVMdev] Some understanding of LLVM vs gCC vs Intel C++ Compilers
> 
> Hi All,
Hello Jason,
> I know that it is a C/C++ Compiler, but how do I use it? Is it  
> Makefile based?
> 
Wrong.  LLVM-GCC is a frontend for LLVM that converts C/C++ code into the
intermediate representation that is LLVM.
> Does it replace GCC?
> 
It uses a special version of GCC currently to generate its bitcode from C/C++. 
There is a GCC replacement called Clang that is coming up but not mature yet.

LLVM stands for Low-Level Virtual Machine.  It is an open-source,
cross-architecture compiler infrastructure.  It runs on and generates code for
MacOSX 10.4+ for both PPC and Intel, Windows XP+, Linux on several processor
types, and others in the works.

With some effort, it is possible to write a compiler to generate bitcode that
will run on any processor independently of the one it was written on.  It does
not have a thick abstraction layer like .NET or Java, however.  For that
extension you'll want to look into VMKit which is another implementation of
Java and .NET using LLVM.  Anther compiler that is going to use the LLVM
architecture is Google's Unladen Swallow project which aims to make the
Python programming language execute 5 times faster.

I hope this answers some of you questions,

--Sam

On Jun 14, 2009, at 6:09 PM, Jason Todd Slack-Moehrle
wrote:
> Hi All,
Hi Jason,

Sam's response is right on for general guidance, here is some mac- 
specific guidance.
> I have spent a better part of my 32 years on this earth writing
> Solaris software and more recently leaving that and returning back to
> Mac OS.
>
> I obviously know about GCC and the Intel C++ Compilers.
>
> I am looking to have more freedom and flexibility along with producing
> better quality software.
>
> How does LLVm fit in?
The llvm project provides two open source compilers, llvm-gcc and  
clang.  Clang is considered production quality on the mac for C and  
ObjC.  llvm-gcc on the mac supports c/objc/c++/objc++.  Apple  
productizes these and ships them with the Xcode installation.
> I know that it is a C/C++ Compiler, but how do I use it? Is it
> Makefile based?
>
> Does it replace GCC?
Both llvm-gcc and clang work as drop in replacements for GCC.  They  
take the same command line options etc, and are both quite usable on  
the command line.
> Can one build full OS X applications with it? (What I mean is dont
> need to use XCode or anything if I dont want to)
Yes, absolutely.

-Chris

Hi Chris,

Thanks for the response.
>> How does LLVm fit in?
>
> The llvm project provides two open source compilers, llvm-gcc and
> clang.  Clang is considered production quality on the mac for C and
> ObjC.  llvm-gcc on the mac supports c/objc/c++/objc++.  Apple
> productizes these and ships them with the Xcode installation.
>
>> I know that it is a C/C++ Compiler, but how do I use it? Is it
>> Makefile based?
>>
>> Does it replace GCC?
>
> Both llvm-gcc and clang work as drop in replacements for GCC.  They
> take the same command line options etc, and are both quite usable on
> the command line.
Can you provide advice on why Intel C++ compilers vs LLVM-GCC vs just  
normal GCC? Like benefits to one over the others? Pros and Cons, etc,  
etc...

Best,
-Jason

Thanks to Sam。
    As a fresh man on compiler, this mail helps me a lot :)

On Mon, Jun 15, 2009 at 9:46 AM, Samuel Crow<samuraileumas at yahoo.com>
wrote:
>
>
>
>
>
> ----- Original Message ----
>> From: Jason Todd Slack-Moehrle <mailinglists at mailnewsrss.com>
>> To: llvmdev at cs.uiuc.edu
>> Sent: Sunday, June 14, 2009 8:09:03 PM
>> Subject: [LLVMdev] Some understanding of LLVM vs gCC vs Intel C++
Compilers
>>
>> Hi All,
>
> Hello Jason,
>
>> I know that it is a C/C++ Compiler, but how do I use it? Is it
>> Makefile based?
>>
>
> Wrong.  LLVM-GCC is a frontend for LLVM that converts C/C++ code into the
intermediate representation that is LLVM.
>
>> Does it replace GCC?
>>
>
> It uses a special version of GCC currently to generate its bitcode from
C/C++.  There is a GCC replacement called Clang that is coming up but not mature
yet.
>
> LLVM stands for Low-Level Virtual Machine.  It is an open-source,
cross-architecture compiler infrastructure.  It runs on and generates code for
MacOSX 10.4+ for both PPC and Intel, Windows XP+, Linux on several processor
types, and others in the works.
>
> With some effort, it is possible to write a compiler to generate bitcode
that will run on any processor independently of the one it was written on.  It
does not have a thick abstraction layer like .NET or Java, however.  For that
extension you'll want to look into VMKit which is another implementation of
Java and .NET using LLVM.  Anther compiler that is going to use the LLVM
architecture is Google's Unladen Swallow project which aims to make the
Python programming language execute 5 times faster.
>
> I hope this answers some of you questions,
>
> --Sam
>
>
>
>
> _______________________________________________
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> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


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