diff options
| author | Alexandre Oliva <aoliva@redhat.com> | 2013-01-16 04:31:30 +0000 |
|---|---|---|
| committer | Alexandre Oliva <aoliva@gcc.gnu.org> | 2013-01-16 04:31:30 +0000 |
| commit | 5147bf6a236993578d316dfe7c7e7182da1cdf90 (patch) | |
| tree | f0fc6a874d85829d0f97a943b956d34c53269040 /gcc/alias.c | |
| parent | c851c76cdf52884dd5e0c7befd3c809e9d174a73 (diff) | |
| download | gcc-5147bf6a236993578d316dfe7c7e7182da1cdf90.tar.gz | |
re PR rtl-optimization/55547 (Alias analysis does not handle AND addresses correctly)
PR rtl-optimization/55547
PR rtl-optimization/53827
PR debug/53671
PR debug/49888
* alias.c (memrefs_conflict_p): Set sizes to negative after
AND adjustments.
From-SVN: r195227
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index df328ec9d73..9a386dde382 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -2080,14 +2080,20 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c) /* Deal with alignment ANDs by adjusting offset and size so as to cover the maximum range, without taking any previously known - alignment into account. */ + alignment into account. Make a size negative after such an + adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we + assume a potential overlap, because they may end up in contiguous + memory locations and the stricter-alignment access may span over + part of both. */ if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1))) { HOST_WIDE_INT sc = INTVAL (XEXP (x, 1)); unsigned HOST_WIDE_INT uc = sc; - if (xsize > 0 && sc < 0 && -uc == (uc & -uc)) + if (sc < 0 && -uc == (uc & -uc)) { - xsize -= sc + 1; + if (xsize > 0) + xsize = -xsize; + xsize += sc + 1; c -= sc + 1; return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), ysize, y, c); @@ -2097,9 +2103,11 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c) { HOST_WIDE_INT sc = INTVAL (XEXP (y, 1)); unsigned HOST_WIDE_INT uc = sc; - if (ysize > 0 && sc < 0 && -uc == (uc & -uc)) + if (sc < 0 && -uc == (uc & -uc)) { - ysize -= sc + 1; + if (ysize > 0) + ysize = -ysize; + ysize += sc + 1; c += sc + 1; return memrefs_conflict_p (xsize, x, ysize, canon_rtx (XEXP (y, 0)), c); |