diff options
Diffstat (limited to 'gcc/expmed.c')
| -rw-r--r-- | gcc/expmed.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/gcc/expmed.c b/gcc/expmed.c index b7f55a7..d7f8e9a 100644 --- a/gcc/expmed.c +++ b/gcc/expmed.c @@ -3356,13 +3356,20 @@ expand_mult_const (machine_mode mode, rtx op0, HOST_WIDE_INT val, tem = gen_lowpart (nmode, op0); } - insn = get_last_insn (); - wide_int wval_so_far - = wi::uhwi (val_so_far, - GET_MODE_PRECISION (as_a <scalar_mode> (nmode))); - rtx c = immed_wide_int_const (wval_so_far, nmode); - set_dst_reg_note (insn, REG_EQUAL, gen_rtx_MULT (nmode, tem, c), - accum_inner); + /* Don't add a REG_EQUAL note if tem is a paradoxical SUBREG. + In that case, only the low bits of accum would be guaranteed to + be equal to the content of the REG_EQUAL note, the upper bits + can be anything. */ + if (!paradoxical_subreg_p (tem)) + { + insn = get_last_insn (); + wide_int wval_so_far + = wi::uhwi (val_so_far, + GET_MODE_PRECISION (as_a <scalar_mode> (nmode))); + rtx c = immed_wide_int_const (wval_so_far, nmode); + set_dst_reg_note (insn, REG_EQUAL, gen_rtx_MULT (nmode, tem, c), + accum_inner); + } } } |