On Thu, Apr 4, 2013 at 3:33 PM, Yuri Rumyantsev <ysrum...@gmail.com> wrote:
> Hi Richard,
>
> You slightly change behavior of find_base_term, namely before your fix we
> have the following code:
>
> if (REG_P (tmp1) && REG_POINTER (tmp1))
> {
> rtx base = find_base_term (tmp1);
> if (base)
> return base;
> }
>
> but in your fix you added the following checks on base:
>
> tmp1 = find_base_term (tmp1);
> if (tmp1 != NULL_RTX
> && ((REG_P (tmp1) && REG_POINTER (tmp1))
> || known_base_value_p (tmp1)))
> return tmp1;
> Why you added these checks since function arguments may not considered as
> bases.
If you continue down the original function there is (quoted fully)
/* If either operand is known to be a pointer, then use it
to determine the base term. */
if (REG_P (tmp1) && REG_POINTER (tmp1))
{
rtx base = find_base_term (tmp1);
if (base)
return base;
}
if (REG_P (tmp2) && REG_POINTER (tmp2))
{
rtx base = find_base_term (tmp2);
if (base)
return base;
}
/* Neither operand was known to be a pointer. Go ahead and find the
base term for both operands. */
tmp1 = find_base_term (tmp1);
tmp2 = find_base_term (tmp2);
so we call find_base_term on tmp1 anyway, and after the modification
tmp1 = find_base_term (tmp1);
if (tmp1 != NULL_RTX
&& ((REG_P (tmp1) && REG_POINTER (tmp1))
|| known_base_value_p (tmp1)))
return tmp1;
we take it if it is non-NULL and ... ah, I see. We now check
REG_P/REG_POINTER on the new value. That was indeed
unintended.
I'll fix it like below.
Richard.
2013-04-04 Richard Biener <rguent...@suse.de>
* alias.c (find_base_term): Fix thinko in previous change.
Index: gcc/alias.c
===================================================================
--- gcc/alias.c (revision 197480)
+++ gcc/alias.c (working copy)
@@ -1687,16 +1687,16 @@ find_base_term (rtx x)
term is from a pointer or is a named object or a special address
(like an argument or stack reference), then use it for the
base term. */
- tmp1 = find_base_term (tmp1);
- if (tmp1 != NULL_RTX
+ rtx base = find_base_term (tmp1);
+ if (base != NULL_RTX
&& ((REG_P (tmp1) && REG_POINTER (tmp1))
- || known_base_value_p (tmp1)))
- return tmp1;
- tmp2 = find_base_term (tmp2);
- if (tmp2 != NULL_RTX
+ || known_base_value_p (base)))
+ return base;
+ base = find_base_term (tmp2);
+ if (base != NULL_RTX
&& ((REG_P (tmp2) && REG_POINTER (tmp2))
- || known_base_value_p (tmp2)))
- return tmp2;
+ || known_base_value_p (base)))
+ return base;
/* We could not determine which of the two operands was the
base register and which was the index. So we can determine
