[PATCH] D91803: [lld] Use -1 as tombstone value for discarded code ranges

[David Blaikie via Phabricator via llvm-commits]

dblaikie added inline comments.


================
Comment at: lld/wasm/InputFiles.cpp:196
+    if ((isa<FunctionSymbol>(sym) || isa<DataSymbol>(sym)) && !sym->isLive()) {
+      return tombstone ? tombstone : reloc.Addend;
+    }
----------------
MaskRay wrote:
> dblaikie wrote:
> > Eric wrote:
> > > dblaikie wrote:
> > > > sbc100 wrote:
> > > > > So setting the `tombstone` to zero means we should include the `Addend` ?
> > > > Yeah, I guess that's beyond my debug info purview - but I'd suggest checking what bfd ld does here & maybe going with that, rather than what gold does/lld used to do. Which is probably absolute 0 rather than addend. For broader compatibility (& probably make this code a bit less subtle - avoiding the tombstone of zero not really being zero)
> > > Yes, this was based on MaskRay@'s comment on my initial commit. If there is not agreement on this perhaps bring discussion back to the email thread?
> > Ah, [[ https://reviews.llvm.org/D91803?vs=on&id=306711#2405969 | this ]] one?
> > 
> > > The change does not seem right. For non-debug sections (when --allow-undefined is set), addend; .debug_ranges/.debug_loc => -2; other .debug_* => -1
> > 
> > @MaskRay is that what ld.bfd does? ("addend" for non-debug sections)
> Yes for "addend" for non-debug sections. This makes subtraction work.
Ah, fair enough - thanks for the context!




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  https://reviews.llvm.org/D91803/new/

https://reviews.llvm.org/D91803