[llvm-dev] Function optimization pass

[Philip Pfaffe via llvm-dev]

The managers need to be created in a specific order. I recommend checking
out how the opt tool sets up its pipeline. Specifically the implementation
of `llvm::runPassPipeline`.

Cheers,
Philip

On Tue, Aug 21, 2018 at 7:38 PM Ta Thanh Dinh <tathanhdinh at gmail.com> wrote:

> I've managed somehow to pass the fp_manager.run using:
>
> auto loop_manager = llvm::LoopAnalysisManager{};
> auto cgscc_manager = llvm::CGSCCAnalysisManager{};
> auto mod_manager = llvm::ModuleAnalysisManager{};
>
> pass_builder.registerModuleAnalyses(mod_manager);
> pass_builder.registerCGSCCAnalyses(cgscc_manager);
> pass_builder.registerFunctionAnalyses(fa_manager);
> pass_builder.registerLoopAnalyses(loop_manager);
> pass_builder.crossRegisterProxies(loop_manager, fa_manager, cgscc_manager,
> mod_manager);
>
> auto fp_manager =
> pass_builder.buildFunctionSimplificationPipeline(llvm::PassBuilder::OptimizationLevel::O2,
> llvm::PassBuilder::ThinLTOPhase::None, true);
>
> fp_manager.run(*lift_func, fa_manager);
>
> ...print module...
>
> but the program still crashes when the object `fa_manager` (of class
> FunctionAnalysisManager) is destroyed!!!
>
> Le mar. 21 août 2018 à 14:32, Ta Thanh Dinh <tathanhdinh at gmail.com> a
> écrit :
>
>> Hi Philip,
>>
>> Thanks for the response. Under llvm-5.0.2 and llvm-6.0.1 in Debug mode,
>> the crash hit at the same assertion:
>>
>> /usr/local/include/llvm/IR/PassManager.h:689: typename PassT::Result&
>> llvm::AnalysisManager<IRUnitT, ExtraArgTs>::getResult(IRUnitT&, ExtraArgTs
>> ...) [with PassT =
>> llvm::InnerAnalysisManagerProxy<llvm::AnalysisManager<llvm::Loop,
>> llvm::LoopStandardAnalysisResults&>, llvm::Function>; IRUnitT =
>> llvm::Function; ExtraArgTs = {}; typename PassT::Result =
>> llvm::InnerAnalysisManagerProxy<llvm::AnalysisManager<llvm::Loop,
>> llvm::LoopStandardAnalysisResults&>, llvm::Function>::Result]: Assertion
>> `AnalysisPasses.count(PassT::ID()) && "This analysis pass was not
>> registered prior to being queried"' failed.
>>
>> I'm new to llvm optimization and I still don't know which analysis
>> managers should be created and populated in this case. Many thanks for any
>> help.
>>
>>
>> Le mar. 21 août 2018 à 14:00, Philip Pfaffe <philip.pfaffe at gmail.com> a
>> écrit :
>>
>>> Can you tell us more about the crash? I.e., do you have a stack dump?
>>> Does it hit an assertion (if your LLVM is built in Debug mode/has
>>> assertions enabled)?
>>>
>>> Generally, PassBuilder and passes likely assume a full stack of analysis
>>> managers. You should thus create and populate all of them, not just
>>> FunctionAM, and cross-register their proxies.
>>>
>>> Cheers,
>>> Philip
>>>
>>> On Mon, Aug 20, 2018 at 7:29 PM Ta Thanh Dinh via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>>> This question has been submitted to stackoverflow (
>>>> https://stackoverflow.com/questions/51934964/function-optimization-pass)
>>>> but someone suggested me that it should be submitted to llvm-dev mailing
>>>> list instead. I'm sorry for the duplication.
>>>>
>>>> I am trying to use PassBulider and FunctionPassManager to optimize a
>>>> function in a module, what I have done is:
>>>>
>>>>
>>>> mod = ...load module from LLVM IR bitcode file go_back.bc...
>>>>
>>>> auto lift_func = mod->getFunction("go_back");
>>>> if (not lift_func) {
>>>>     llvm::errs() << "Error: cannot get function\n";
>>>>     return 0;
>>>> }
>>>>
>>>> auto pass_builder = llvm::PassBuilder{};
>>>> auto fa_manager = llvm::FunctionAnalysisManager{};
>>>>
>>>> pass_builder.registerFunctionAnalyses(fa_manager);
>>>> auto fp_manager =
>>>> pass_builder.buildFunctionSimplificationPipeline(llvm::PassBuilder::OptimizationLevel::O2);
>>>>
>>>> fp_manager.run(*lift_func, fa_manager);
>>>>
>>>> ...print mod...
>>>>
>>>>
>>>> but the program crashes always at fp_manager.run. Strange enough,
>>>> LLVM's opt tool (which uses legacy optimization API) works without any
>>>> problem, i.e if I run
>>>>
>>>> opt -O2 go_back.bc -o go_back_o2.bc
>>>>
>>>> then I get a new module where the (single) function go_back is
>>>> optimized.
>>>>
>>>> Many thanks for any response.
>>>>
>>>> NB. The disassembled LLVM bitcode is at
>>>> https://gist.github.com/tathanhdinh/23470452910da9f73b857b2e6a12f144
>>>> if anyone wants to take a look.
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>>
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