[LLVMdev] How to use LLVM optimizations with clang

[Abdul Wahid Memon]

Thanks alot Duncan.

Regards

Shahzad

On Tue, Jun 12, 2012 at 1:38 PM, Duncan Sands <baldrick at free.fr> wrote:
> Hi,
>
>
>> I executed the following command line
>>
>> llc -O3 comb.ll.bc -debug-pass=Arguments
>>
>> and got
>>
>> Pass Arguments:  -targetdata -targetpassconfig -no-aa -tbaa
>> -targetlibinfo -basicaa -collector-metadata -machinemoduleinfo
>> -machine-branch-prob -preverify -domtree -verify -loops -loop-simplify
>> -scalar-evolution -loop-simplify -iv-users -loop-reduce -gc-lowering
>> -unreachableblockelim -codegenprepare -stack-protector -preverify
>> -domtree -verify -loops -branch-prob -expand-isel-pseudos
>> -tailduplication -opt-phis -localstackalloc -dead-mi-elimination
>> -machinedomtree -machine-loops -machinelicm -machine-cse -machine-sink
>> -peephole-opts -unreachable-mbb-elimination -livevars
>> -phi-node-elimination -twoaddressinstruction -processimpdefs
>> -slotindexes -liveintervals -livedebugvars -simple-register-coalescing
>> -calcspillweights -livestacks -virtregmap -edge-bundles
>> -spill-code-placement -stack-slot-coloring -machinelicm -edge-bundles
>> -prologepilog -branch-folder -tailduplication -machine-cp
>> -postrapseudos -machinedomtree -machine-loops -post-RA-sched
>> -gc-analysis -machine-block-freq -block-placement2 -machinedomtree
>> -machine-loops
>>
>> Now, how can I specify these optimization manually along with llc like
>> we did with opt tool?
>
>
> you can't.
>
> Ciao, Duncan.
>
>
>>
>> Regards
>>
>> Shahzad
>>
>> On Tue, Jun 12, 2012 at 1:23 PM, Duncan Sands<baldrick at free.fr>  wrote:
>>>
>>> Hi,
>>>
>>>
>>> On 12/06/12 13:09, Abdul Wahid Memon wrote:
>>>>
>>>>
>>>> Thanks alot. How can we view those optimization which are enabled when
>>>> we
>>>> do
>>>>
>>>> llc -O3 comb.ll
>>>
>>>
>>>
>>> llc -O3 comb.ll -debug-pass=Arguments
>>>
>>>
>>>>
>>>> Are these the same as the ones produced by the following command line
>>>
>>>
>>>
>>> no, as I mentioned before they are of a completely different nature
>>> to the optimizations that opt does.
>>>
>>> Ciao, Duncan.
>>>
>>>
>>>>
>>>> llvm-as<    /dev/null | opt -O3 -disable-output -debug-pass=Arguments
>>>>
>>>> Regards
>>>>
>>>> Shahzad
>>>>
>>>> On Tue, Jun 12, 2012 at 1:01 PM, Duncan Sands<baldrick at free.fr>
>>>>  wrote:
>>>>>>
>>>>>>
>>>>>> Yes. But how exactly code generation (optimized one) be done without
>>>>>> clang. Is it possible that we can specify those optimization
>>>>>> (individual ones instead of standard ones like -O3) some how when
>>>>>> generating code as is done by clang or llc?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> llc comb.ll
>>>>> gcc -o comb comb.s
>>>>>
>>>>> Variants:
>>>>>  llc -O0 comb.ll
>>>>>  llc -O3 comb.ll
>>>>> etc
>>>>>
>>>>> Note that the codegen level optimizations done by llc have nothing to
>>>>> do
>>>>> with
>>>>> the IR level optimizations of the kind performed by opt.
>>>>>
>>>>> Ciao, Duncan.
>>>
>>>
>>>
>