diff options
Diffstat (limited to 'gcc/fwprop.c')
| -rw-r--r-- | gcc/fwprop.c | 32 |
1 files changed, 27 insertions, 5 deletions
diff --git a/gcc/fwprop.c b/gcc/fwprop.c index c4587d7..d8cb9fa 100644 --- a/gcc/fwprop.c +++ b/gcc/fwprop.c @@ -999,10 +999,27 @@ try_fwprop_subst (df_ref use, rtx *loc, rtx new_rtx, rtx_insn *def_insn, making a new one if one does not already exist. */ if (set_reg_equal) { - if (dump_file) - fprintf (dump_file, " Setting REG_EQUAL note\n"); + /* If there are any paradoxical SUBREGs, don't add REG_EQUAL note, + because the bits in there can be anything and so might not + match the REG_EQUAL note content. See PR70574. */ + subrtx_var_iterator::array_type array; + FOR_EACH_SUBRTX_VAR (iter, array, *loc, NONCONST) + { + rtx x = *iter; + if (SUBREG_P (x) && paradoxical_subreg_p (x)) + { + set_reg_equal = false; + break; + } + } - note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (new_rtx)); + if (set_reg_equal) + { + if (dump_file) + fprintf (dump_file, " Setting REG_EQUAL note\n"); + + note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (new_rtx)); + } } } @@ -1300,14 +1317,19 @@ forward_propagate_and_simplify (df_ref use, rtx_insn *def_insn, rtx def_set) that isn't mentioned in USE_SET, as the note would be invalid otherwise. We also don't want to install a note if we are merely propagating a pseudo since verifying that this pseudo isn't dead - is a pain; moreover such a note won't help anything. */ + is a pain; moreover such a note won't help anything. + If the use is a paradoxical subreg, make sure we don't add a + REG_EQUAL note for it, because it is not equivalent, it is one + possible value for it, but we can't rely on it holding that value. + See PR70574. */ set_reg_equal = (note == NULL_RTX && REG_P (SET_DEST (use_set)) && !REG_P (src) && !(GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))) && !reg_mentioned_p (SET_DEST (use_set), - SET_SRC (use_set))); + SET_SRC (use_set)) + && !paradoxical_subreg_p (DF_REF_REG (use))); } if (GET_MODE (*loc) == VOIDmode) |