[llvm-dev] ORC v2 question

[Lang Hames via llvm-dev]

>
> > Well for ORCV2 there is no change before and after.
> Okay I had to put the after dump following MPM->run(*M).
> So now I get optimized IR.


Huh. I assumed FPM->run(F) actually ran the function passes. I may just be
misunderstanding how the pass manager works.

-- Lang.


On Tue, Aug 13, 2019 at 3:11 PM Dibyendu Majumdar <mobile at majumdar.org.uk>
wrote:

> On Tue, 13 Aug 2019 at 22:58, Dibyendu Majumdar <mobile at majumdar.org.uk>
> wrote:
> >
> > On Tue, 13 Aug 2019 at 22:03, Lang Hames <lhames at gmail.com> wrote:
> > > When you say your code is not getting optimized, do you mean that IR
> optimizations are not being applied, or that codegen optimizations are not
> being applied?
> > >
> > > What do you see if you dump the modules before/after running the pass
> manager on them, like this:
> > >
> > > dbgs() << "Before optimization:\n" << *M << "\n";
> > > for (auto &F : *M)
> > >   FPM->run(F);
> > > dbgs() << "Before optimization:\n" << *M << "\n";
> > >
> > > I expect that output to be the same for both ORC and ORCv2. If not
> something is going wrong with IR optimization.
> >
> > Well for ORCV2 there is no change before and after.
>
> Okay I had to put the after dump following MPM->run(*M).
> So now I get optimized IR.
>
> > I also get this message:
> >
> > JIT session error: Symbols not found: { raise_error }
> >
>
> So this must be real issue. IR is getting optimized but then codegen is
> failing.
>
> > Yes raise_error and all other extern functions are explicitly added as
> > global symbols.
> >
> > >
> > > CodeGen optimization seems a more likely culprit:
> JITTargetMachineBuilder and ExecutionEngineBuilder have different defaults
> for their CodeGen opt-level. JITTargetMachineBuilder defaults to
> CodeGenOpt::None, and ExecutionEngineBuilder default to CodeGenOpt::Default.
> > >
> > > What happens if you make the following modification to your setup?
> > >
> > > auto JTMB = llvm::orc::JITTargetMachineBuilder::detectHost();
> > > JTMB->setCodeGenOptLevel(CodeGenOpt::Default); // <-- Explicitly set
> Codegen opt level
> > > auto dataLayout = JTMB->getDefaultDataLayoutForTarget();
> > >
> >
> > No change.
> >
> > Regards
>
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