> -----Original Message----- > From: jing...@apple.com [mailto:jing...@apple.com] > Sent: Wednesday, October 10, 2018 2:20 PM > To: Vedant Kumar > Cc: Robinson, Paul; Vedant Kumar via llvm-commits; LLDB; Matthias Braun > Subject: Re: [lldb-dev] [llvm] r343874 - DwarfDebug: Pick next location in > case of missing location at block begin > > > > > On Oct 10, 2018, at 9:54 AM, Vedant Kumar <v...@apple.com> wrote: > > > >> On Oct 10, 2018, at 9:16 AM, Matthias Braun <ma...@braunis.de> wrote: > >> > >> So I haven't worked much on debug info, but here's the explanation for > my patches: > >> My original motivation was getting rid of code some code in the llvm > codegen that for spills and reloads just picked the next debug location > around. That just seemed wrong to me, as spills and reloads really are > bookkeeping, we just move values around between registers and memory and > none of it is related to anything the user wrote in the source program. So > not assigning any debug information felt right for these instructions. > Then people noticed line table bloat because of this and I guess we > assumed that having exact line-0 annotations isn't that useful that it > warrants bloating the debug information... > > > > Right. This doesn't seem any more arbitrary than reusing the previous > instruction location, which we do all the time. I think it's a reasonable > tradeoff.
For spills and reloads, the next valid source location might be reasonable. For top-of-block instructions, I really don't think so; we had this issue in FastISel, some years back, and ultimately went with line-0 at top of block because it caused way fewer problems than hoisting the next valid source location. Please revert, and make top-of-block not work the same as spills and reloads. --paulr _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
