https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63546
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #3)
> OK, the problem seems to be that dwarf2out tries to produce RTL for a
> variable that is optimized out. This happens here:
>
> /* Try harder to get a rtl. If this symbol ends up not being emitted
> in the current CU, resolve_addr will remove the expression referencing
> it. */
> if (rtl == NULL_RTX
> && TREE_CODE (decl) == VAR_DECL
> && !DECL_EXTERNAL (decl)
> && TREE_STATIC (decl)
> && DECL_NAME (decl)
> && !DECL_HARD_REGISTER (decl)
> && DECL_MODE (decl) != VOIDmode)
> {
> rtl = make_decl_rtl_for_debug (decl);
> if (!MEM_P (rtl)
> || GET_CODE (XEXP (rtl, 0)) != SYMBOL_REF
> || SYMBOL_REF_DECL (XEXP (rtl, 0)) != decl)
> rtl = NULL_RTX;
> }
>
> producing RTL brings the function in, because it wants to work out its
> section that breaks. I do not think dwarf2out really needs RTL for variable
> that was never output.
>
> Shall we kludge around and make make_decl_rtl-for_debug to not ICE but
> return sort of random RTL or shall we just prevent this path with
> reference_to_unused check?
>
> For Martin and Trevor, I think safe workaround is to just comment out this
> path.
Commenting that out will severely decrease debug info quality.
Yes, dwarf2out really needs a RTL for those, and some that will not affect
-fcompare-debug, with the right (mangled?) name of the var and various other
attributes on the MEM.
