llvm dev - Dec 2014 - [LLVMdev] Reproducing clang -O3 with opt

This is probably a trivial question but the way I used to do this turns out to
be flawed.

I used run clang with -O0 -emit-llvm and then use the resulting IR with opt -O3.
The problem is that clang at -O0 does not generate TBAA metadata so the passes
run by opt behave differently.

What’s the recommended way of doing this?

Thanks,
Adam

On 03.12.2014 09:19, Adam Nemet wrote:
> This is probably a trivial question but the way I used to do this turns out
to be flawed.
>
> I used run clang with -O0 -emit-llvm and then use the resulting IR with opt
-O3.  The problem is that clang at -O0 does not generate TBAA metadata so the
passes run by opt behave differently.
>
> What’s the recommended way of doing this?
I normally run 'clang -O3 -mllvm -disable-llvm-optzns' followed by
'opt
-O3'.

Tobias

----- Original Message -----
> From: "Adam Nemet" <anemet at apple.com>
> To: "LLVM Dev" <llvmdev at cs.uiuc.edu>
> Sent: Wednesday, December 3, 2014 2:19:04 AM
> Subject: [LLVMdev] Reproducing clang -O3 with opt
> 
> This is probably a trivial question but the way I used to do this
> turns out to be flawed.
> 
> I used run clang with -O0 -emit-llvm and then use the resulting IR
> with opt -O3.  The problem is that clang at -O0 does not generate
> TBAA metadata so the passes run by opt behave differently.
> 
> What’s the recommended way of doing this?
Run clang -O3 -mllvm -disable-llvm-optzns -emit-llvm

 -Hal
> 
> Thanks,
> Adam
> 
> 
> _______________________________________________
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> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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> 
-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory

Great, thanks!

> On Dec 3, 2014, at 12:37 AM, Tobias Grosser <tobias at grosser.es>
wrote:
> 
>> On 03.12.2014 09:19, Adam Nemet wrote:
>> This is probably a trivial question but the way I used to do this turns
out to be flawed.
>> 
>> I used run clang with -O0 -emit-llvm and then use the resulting IR with
opt -O3.  The problem is that clang at -O0 does not generate TBAA metadata so
the passes run by opt behave differently.
>> 
>> What’s the recommended way of doing this?
> 
> I normally run 'clang -O3 -mllvm -disable-llvm-optzns' followed by
'opt -O3'.
> 
> Tobias