[Bug target/116104] [15 Regression] GCN vs. "[rtl-optimization/116037] Explicitly track if a destination was skipped in ext-dce"

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116104

--- Comment #2 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
Created attachment 58772
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58772&action=edit
'20000629-1.i'

Jeff, you're of course very welcome to have a look, but note that I didn't
assign you this PR -- as I said:

(In reply to myself from comment #0)
> I can't tell if this is an issue in 'RTL pass: ext_dce' or in the GCN back end.

Andrew (in CC) knows the latter one best.

That said, I'm attaching a simple reproducer, per
'gcc.c-torture/compile/20000629-1.c'.  With a '--target=amdgcn-amdhsa' build of
'make all-gcc', run:

    $ gcc/cc1 -fpreprocessed 20000629-1.i -quiet -march=gfx908 -O2 -w -version
-o 20000629-1.s