diff options
author | Jeffrey A Law <law@cygnus.com> | 1999-10-18 07:52:32 +0000 |
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committer | Jeff Law <law@gcc.gnu.org> | 1999-10-18 01:52:32 -0600 |
commit | da0c310973eed951e9b61feacf2a1c73631513ba (patch) | |
tree | 50e8ee931efabb4be4bc2cec43f38c109068ddef | |
parent | 2aa437e3fb3f68175ea46d0a9cda0ed3402a6bef (diff) | |
download | gcc-da0c310973eed951e9b61feacf2a1c73631513ba.tar.gz |
combine.c (get_last_value): If the last set of a register is after subst_low_cuid...
* combine.c (get_last_value): If the last set of a register
is after subst_low_cuid, then we can not use it to determine
the register's last value.
From-SVN: r30064
-rw-r--r-- | gcc/ChangeLog | 6 | ||||
-rw-r--r-- | gcc/combine.c | 51 |
2 files changed, 8 insertions, 49 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 7e6b3e08d83..3bddf0d4bdb 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +Mon Oct 18 01:41:35 1999 Jeffrey A Law (law@cygnus.com) + + * combine.c (get_last_value): If the last set of a register + is after subst_low_cuid, then we can not use it to determine + the register's last value. + Sat Oct 16 15:20:15 1999 Jeffrey A Law (law@cygnus.com) Sat Oct 16 00:07:01 1999 Richard Henderson <rth@cygnus.com> diff --git a/gcc/combine.c b/gcc/combine.c index 0b64a86a548..57b2e8619bc 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -10834,56 +10834,9 @@ get_last_value (x) return 0; /* If the value was set in a later insn than the ones we are processing, - we can't use it even if the register was only set once, but make a quick - check to see if the previous insn set it to something. This is commonly - the case when the same pseudo is used by repeated insns. - - This does not work if there exists an instruction which is temporarily - not on the insn chain. */ - + we can't use it even if the register was only set once. */ if (INSN_CUID (reg_last_set[regno]) >= subst_low_cuid) - { - rtx insn, set; - - /* We can not do anything useful in this case, because there is - an instruction which is not on the insn chain. */ - if (subst_prev_insn) - return 0; - - /* Skip over USE insns. They are not useful here, and they may have - been made by combine, in which case they do not have a INSN_CUID - value. We can't use prev_real_insn, because that would incorrectly - take us backwards across labels. Skip over BARRIERs also, since - they could have been made by combine. If we see one, we must be - optimizing dead code, so it doesn't matter what we do. */ - for (insn = prev_nonnote_insn (subst_insn); - insn && ((GET_CODE (insn) == INSN - && GET_CODE (PATTERN (insn)) == USE) - || GET_CODE (insn) == BARRIER - || INSN_CUID (insn) >= subst_low_cuid); - insn = prev_nonnote_insn (insn)) - ; - - if (insn - && (set = single_set (insn)) != 0 - && rtx_equal_p (SET_DEST (set), x)) - { - value = SET_SRC (set); - - /* Make sure that VALUE doesn't reference X. Replace any - explicit references with a CLOBBER. If there are any remaining - references (rare), don't use the value. */ - - if (reg_mentioned_p (x, value)) - value = replace_rtx (copy_rtx (value), x, - gen_rtx_CLOBBER (GET_MODE (x), const0_rtx)); - - if (reg_overlap_mentioned_p (x, value)) - return 0; - } - else - return 0; - } + return 0; /* If the value has all its registers valid, return it. */ if (get_last_value_validate (&value, reg_last_set[regno], |