[llvm] r359426 - [DebugInfo] Terminate more location-list ranges at the end of blocks

[Eric Christopher via llvm-commits]

To follow up:

You can see the slowdown on just about any TU in clang. SemaExpr.cpp
is pretty good, if you compile it under asan it's even more evident.
Use -ftime-passes to the compiler before and after.

Hope that helps!

-eric

On Wed, May 8, 2019 at 4:51 PM Eric Christopher <echristo at gmail.com> wrote:
>
> On Wed, May 8, 2019 at 4:39 PM Eric Christopher <echristo at gmail.com> wrote:
> >
> > On Wed, May 8, 2019 at 4:38 PM Adrian Prantl <aprantl at apple.com> wrote:
> > >
> > >
> > >
> > > > On May 8, 2019, at 4:31 PM, Eric Christopher <echristo at gmail.com> wrote:
> > > >
> > > > This is really going to scale poorly - it might just be showing
> > > > algorithmic problems later in the pipeline, but the amount of extra
> > > > work this causes is going to be huge.
> > > >
> > > > We should definitely back this out for now and come up with some other
> > > > thoughts on how to approach this.
> > >
> > > Sure thing! I understand it may be difficult to share a reproducer, but if you can share any details about what passes blow up (or perhaps even share a sample/profile of clang) that would be useful for the redesign.
> > >
> >
> > Absolutely. Jordan's working on it now. :)
>
> Done thusly:
>
> echristo at athyra ~/r/llvm-project> git llvm push
> Pushing 1 commit:
>   4efc39ba75a Temporarily Revert "[DebugInfo] Terminate more
> location-list ranges at the end of blocks" as it was causing
> significant compile time regressions.
> Sending        llvm/trunk/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
> Sending        llvm/trunk/lib/CodeGen/LiveDebugValues.cpp
> Sending        llvm/trunk/test/DebugInfo/COFF/pieces.ll
> Sending        llvm/trunk/test/DebugInfo/MIR/AArch64/implicit-def-dead-scope.mir
> Sending        llvm/trunk/test/DebugInfo/X86/fission-ranges.ll
> Deleting       llvm/trunk/test/DebugInfo/X86/live-debug-values-constprop.mir
> Transmitting file data .....done
> Committing transaction...
> Committed revision 360301.
> Committed 4efc39ba75a to svn.
>
> Sorry for the inconvenience!
>
> -eric