diff options
Diffstat (limited to 'gcc/lower-subreg.c')
| -rw-r--r-- | gcc/lower-subreg.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/gcc/lower-subreg.c b/gcc/lower-subreg.c index a11e535..abe7180 100644 --- a/gcc/lower-subreg.c +++ b/gcc/lower-subreg.c @@ -1087,12 +1087,21 @@ resolve_simple_move (rtx set, rtx_insn *insn) emit_clobber (dest); for (i = 0; i < words; ++i) - emit_move_insn (simplify_gen_subreg_concatn (word_mode, dest, - dest_mode, - i * UNITS_PER_WORD), - simplify_gen_subreg_concatn (word_mode, src, - orig_mode, - i * UNITS_PER_WORD)); + { + rtx t = simplify_gen_subreg_concatn (word_mode, dest, + dest_mode, + i * UNITS_PER_WORD); + /* simplify_gen_subreg_concatn can return (const_int 0) for + some sub-objects of paradoxical subregs. As a source operand, + that's fine. As a destination it must be avoided. Those are + supposed to be don't care bits, so we can just drop that store + on the floor. */ + if (t != CONST0_RTX (word_mode)) + emit_move_insn (t, + simplify_gen_subreg_concatn (word_mode, src, + orig_mode, + i * UNITS_PER_WORD)); + } } if (real_dest != NULL_RTX) |