for gcc/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
PR debug/53671
PR debug/49888
* alias.c (memrefs_conflict_p): Improve handling of AND for
alignment.
===================================================================
@@ -2097,25 +2097,32 @@ memrefs_conflict_p (int xsize, rtx x, in
break;
}
- /* Treat an access through an AND (e.g. a subword access on an Alpha)
- as an access with indeterminate size. Assume that references
- besides AND are aligned, so if the size of the other reference is
- at least as large as the alignment, assume no other overlap. */
+ /* Deal with alignment ANDs by adjusting offset and size so as to
+ cover the maximum range, without taking any previously known
+ alignment into account. */
if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1)))
{
- if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1)))
- xsize = -1;
- return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), ysize, y, c);
+ HOST_WIDE_INT sc = INTVAL (XEXP (x, 1));
+ unsigned HOST_WIDE_INT uc = sc;
+ if (xsize > 0 && sc < 0 && -uc == (uc & -uc))
+ {
+ xsize -= sc + 1;
+ c -= sc;
+ return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)),
+ ysize, y, c);
+ }
}
if (GET_CODE (y) == AND && CONST_INT_P (XEXP (y, 1)))
{
- /* ??? If we are indexing far enough into the array/structure, we
- may yet be able to determine that we can not overlap. But we
- also need to that we are far enough from the end not to overlap
- a following reference, so we do nothing with that for now. */
- if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1)))
- ysize = -1;
- return memrefs_conflict_p (xsize, x, ysize, canon_rtx (XEXP (y, 0)), c);
+ HOST_WIDE_INT sc = INTVAL (XEXP (y, 1));
+ unsigned HOST_WIDE_INT uc = sc;
+ if (ysize > 0 && sc < 0 && -uc == (uc & -uc))
+ {
+ ysize -= sc + 1;
+ c += sc;
+ return memrefs_conflict_p (xsize, x,
+ ysize, canon_rtx (XEXP (y, 0)), c);
+ }
}
if (CONSTANT_P (x))