[LLVMdev] Execution Engine: CodeGenOpt level

[Caldarale, Charles R]

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of nlamee at cs.mcgill.ca
> Subject: [LLVMdev] Execution Engine: CodeGenOpt level

> How can I dynamically change the code generation optimization level (e.g.,
> None) of a JIT in other to recompile a function with a new optimization
> level (e.g., Default)?

We set the optimization level with a PassManagerBuilder, which is initialized for each function compilation:

    PassManagerBuilder PMBuilder;
...
    PMBuilder.OptLevel = conf.value_of(CF_OPTLEVEL);
    PMBuilder.SizeLevel = conf.is_set(CF_OPTSIZE) ? 1 : 0;
    PMBuilder.DisableUnitAtATime = !conf.is_set(CF_OPTUNIT);
    PMBuilder.DisableUnrollLoops = !conf.is_set(CF_UNROLL);
    PMBuilder.DisableSimplifyLibCalls = !conf.is_set(CF_SIMPLIB);
    if (Opt != CodeGenOpt::None) {
        PMBuilder.Inliner = createFunctionInliningPass(Opt == CodeGenOpt::Aggressive ? 250 : 200);
    }
    pFPasses = new FunctionPassManager(pMod);
    pFPasses->add(new TargetData(*TD));
    PMBuilder.populateFunctionPassManager(*pFPasses);
    pFPasses->doInitialization();
    pFPasses->run(*pFun);
    pFPasses->doFinalization();
    delete pFPasses;
    pMPasses = new PassManager();
    pMPasses->add(new TargetData(*TD));
    pMPasses->add(createCFGSimplificationPass());
    pMPasses->add(createBlockPlacementPass());
    PMBuilder.populateModulePassManager(*pMPasses);
    pMPasses->run(*pMod);
    delete pMPasses;

(There is likely some redundancy and unnecessary steps in the above.)

 - Chuck


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