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flow.c (insn_dead_p): Don't consider two memrefs equivalent unless anti_dependence says they are.

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* flow.c (insn_dead_p): Don't consider two memrefs equivalent
	unless anti_dependence says they are.
	* alias.c (objects_must_conflict): If neither has a type specified,
	they must conflict.

From-SVN: r40420
This commit is contained in:
Richard Kenner 2001-03-12 19:09:57 +00:00 committed by Richard Kenner
parent 89c9653e9a
commit e8ea2809d0
3 changed files with 32 additions and 18 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
Mon Mar 12 14:05:32 2001 Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
* flow.c (insn_dead_p): Don't consider two memrefs equivalent
unless anti_dependence says they are.
* alias.c (objects_must_conflict): If neither has a type specified,
they must conflict.
2001-03-12 Neil Booth <neil@daikokuya.demon.co.uk>
David Billinghurst <David.Billinghurst@riotinto.com>

6
gcc/alias.c
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@ -309,6 +309,12 @@ int
objects_must_conflict_p (t1, t2)
tree t1, t2;
{
/* If neither has a type specified, we don't know if they'll conflict
because we may be using them to store objects of various types, for
example the argument and local variables areas of inlined functions. */
if (t1 == 0 && t1 == 0)
return 0;
/* If one or the other has readonly fields or is readonly,
then they may not conflict. */
if ((t1 != 0 && readonly_fields_p (t1))

37
gcc/flow.c
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@ -4420,27 +4420,28 @@ insn_dead_p (pbi, x, call_ok, notes)
/* Walk the set of memory locations we are currently tracking
and see if one is an identical match to this memory location.
If so, this memory write is dead (remember, we're walking
backwards from the end of the block to the start). */
temp = pbi->mem_set_list;
while (temp)
{
rtx mem = XEXP (temp, 0);
backwards from the end of the block to the start). Since
rtx_equal_p does not check the alias set or flags, we also
must have the potential for them to conflict (anti_dependence). */
for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
if (anti_dependence (r, XEXP (temp, 0)))
{
rtx mem = XEXP (temp, 0);
if (rtx_equal_p (mem, r))
return 1;
if (rtx_equal_p (mem, r))
return 1;
#ifdef AUTO_INC_DEC
/* Check if memory reference matches an auto increment. Only
post increment/decrement or modify are valid. */
if (GET_MODE (mem) == GET_MODE (r)
&& (GET_CODE (XEXP (mem, 0)) == POST_DEC
|| GET_CODE (XEXP (mem, 0)) == POST_INC
|| GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
&& GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
&& rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
return 1;
/* Check if memory reference matches an auto increment. Only
post increment/decrement or modify are valid. */
if (GET_MODE (mem) == GET_MODE (r)
&& (GET_CODE (XEXP (mem, 0)) == POST_DEC
|| GET_CODE (XEXP (mem, 0)) == POST_INC
|| GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
&& GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
&& rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
return 1;
#endif
temp = XEXP (temp, 1);
}
}
}
else
{