https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100232
Tom de Vries <vries at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |amonakov at gcc dot gnu.org
--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
In expand_GOMP_SIMT_XCHG_BFLY, we have a subreg target:
...
(gdb) call debug_rtx ( target )
(subreg/s/u:QI (reg:SI 40 [ _61 ]) 0)
...
During expand_insn, the operands are legitimized, and this changes the state of
the output operand to:
...
(gdb) call debug_rtx ( ops[0].value )
(reg:QI 57)
...
So the value is written to reg 57, but never actually copied back to reg 40.
Tentative fix:
...
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index dd7173126fb..28ae3ed167a 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -361,6 +361,8 @@ expand_GOMP_SIMT_XCHG_BFLY (internal_fn, gcall *stmt)
create_input_operand (&ops[2], idx, SImode);
gcc_assert (targetm.have_omp_simt_xchg_bfly ());
expand_insn (targetm.code_for_omp_simt_xchg_bfly, 3, ops);
+ if (ops[0].value != target)
+ emit_move_insn (target, ops[0].value);
}
/* Exchange between SIMT lanes according to given source lane index. */
...
