mehdi_amini added inline comments.
================ Comment at: llvm/test/tools/gold/X86/opt-level.ll:53 + ; CHECK-O1-OLDPM: select + ; The new PM does not do as many optimizations at O1 + ; CHECK-O1-NEWPM: phi ---------------- tejohnson wrote: > chandlerc wrote: > > tejohnson wrote: > > > tejohnson wrote: > > > > mehdi_amini wrote: > > > > > This is intended? I'm surprised the two PMs don't have the same list > > > > > of passes for a given opt level? > > > > I'm really not sure. I did compare the post-link LTO pipelines of both > > > > PMs at O0/O1/O2 and confirmed that the old PM is doing many more passes > > > > than the new PM at O1. Probably a question for @chandlerc ? In any > > > > case, I didn't want to address it here since it is orthogonal. > > > Some more info: > > > > > > This is the regular LTO post-link pipeline, ThinLTO post-link pipeline > > > uses essentially the same as a normal opt pipeline so would be consistent > > > at -O1. > > > > > > The optimization missing from the new PM regular LTO post link pipeline > > > that affects this test is SimplifyCFG. This and a few other optimizations > > > are added in the old PM at O1 via > > > PassManagerBuilder::addLateLTOOptimizationPasses. Note that > > > PassManagerBuilder::addLTOOptimizationPasses does exit early at -O1 > > > (similar to where we exit early in the new PM for the regular LTO post > > > link compilation). But the "late" LTO optimization passes are added > > > unconditionally above -O0. Is this correct/desired? There isn't an > > > equivalent in the new PM. > > I don't think it was intentional, but I'm not sure I would directly > > replicate it if it requires adding an entirely new customization point. Is > > their some simpler way of getting equivalent results at O1? > Yeah we can presumably just add those optimizations to the -O1 early exit > path in PassBuilder::buildLTODefaultPipeline. I can send a patch (but would > like to get this one in as it is a bugfix and orthogonal). (I fully agree it is orthogonal, I just spotted this as a separate bug indeed, thanks for fixing!) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D61022/new/ https://reviews.llvm.org/D61022 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
