llvm dev - May 2009 - [LLVMdev] Pass to remove unused functions

In order to handle a large vector based math library I link in a fairly
large bitcode file that might or might not be needed. The problem is
that linking in this bitcode file drastically increases the amount of
compile time required. Is there a way to remove all functions that are
not used after this linking pass? Something similar to die but removes
functions from the compilation unit instead of instructions.

 

Thanks,

Micah

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On May 5, 2009, at 3:48 PM, Villmow, Micah wrote:
> In order to handle a large vector based math library I link in a  
> fairly large bitcode file that might or might not be needed. The  
> problem is that linking in this bitcode file drastically increases  
> the amount of compile time required. Is there a way to remove all  
> functions that are not used after this linking pass? Something  
> similar to die but removes functions from the compilation unit  
> instead of instructions.
>
The -globaldce pass will remove dead internal globals and functions.

-Chris
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I thought this pass would do it, but when I run it over my bc file the
output file is the same as the input file.

 

The issue I guess  is a little different. When I link in the huge bc
file with the tiny bc file, I only want the resulting bc file to have
the function definitions that the tiny bc file requires and not every
function in the huge bc file.

 

Any idea's how to do this with the current llvm toolset?

 

Thanks,

Micah

 

 

 

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
On Behalf Of Chris Lattner
Sent: Tuesday, May 05, 2009 3:53 PM
To: LLVM Developers Mailing List
Subject: Re: [LLVMdev] Pass to remove unused functions

 

 

On May 5, 2009, at 3:48 PM, Villmow, Micah wrote:





In order to handle a large vector based math library I link in a fairly
large bitcode file that might or might not be needed. The problem is
that linking in this bitcode file drastically increases the amount of
compile time required. Is there a way to remove all functions that are
not used after this linking pass? Something similar to die but removes
functions from the compilation unit instead of instructions.

 

 

The -globaldce pass will remove dead internal globals and functions.

 

-Chris

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