[LLVMdev] Reproducing clang -O3 with opt

[Adam Nemet]

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