diff options
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 35 |
1 files changed, 21 insertions, 14 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index c11b13f..b6aca34 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -2097,25 +2097,32 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c) 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)) |