diff options
Diffstat (limited to 'gcc/cse.c')
| -rw-r--r-- | gcc/cse.c | 21 |
1 files changed, 15 insertions, 6 deletions
@@ -6238,23 +6238,32 @@ cse_insn (insn, libcall_insn) { rtx prev = prev_nonnote_insn (insn); + /* Do not swap the registers around if the previous instruction + attaches a REG_EQUIV note to REG1. + + ??? It's not entirely clear whether we can transfer a REG_EQUIV + from the pseudo that originally shadowed an incoming argument + to another register. Some uses of REG_EQUIV might rely on it + being attached to REG1 rather than REG2. + + This section previously turned the REG_EQUIV into a REG_EQUAL + note. We cannot do that because REG_EQUIV may provide an + uninitialised stack slot when REG_PARM_STACK_SPACE is used. */ + if (prev != 0 && GET_CODE (prev) == INSN && GET_CODE (PATTERN (prev)) == SET - && SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl)) + && SET_DEST (PATTERN (prev)) == SET_SRC (sets[0].rtl) + && ! find_reg_note (prev, REG_EQUIV, NULL_RTX)) { rtx dest = SET_DEST (sets[0].rtl); rtx src = SET_SRC (sets[0].rtl); - rtx note = find_reg_note (prev, REG_EQUIV, NULL_RTX); + rtx note; validate_change (prev, &SET_DEST (PATTERN (prev)), dest, 1); validate_change (insn, &SET_DEST (sets[0].rtl), src, 1); validate_change (insn, &SET_SRC (sets[0].rtl), dest, 1); apply_change_group (); - /* If REG1 was equivalent to a constant, REG0 is not. */ - if (note) - PUT_REG_NOTE_KIND (note, REG_EQUAL); - /* If there was a REG_WAS_0 note on PREV, remove it. Move any REG_WAS_0 note on INSN to PREV. */ note = find_reg_note (prev, REG_WAS_0, NULL_RTX); |