On Jan 15, 2013, Richard Henderson <r...@redhat.com> wrote:
> On 01/15/2013 08:24 AM, Aldy Hernandez wrote:
>> Ok, it's really an alias.c bug, but it is Alpha, and aoliva has already
>> provided an unreviewed patch...
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55547
> The patch in #C4 is ok.
Thanks, I'm checking it in (first patch below), but reviewing the logic
that uses negative sizes, I found a number of places that should use the
absolute value, and others in which being conservative about negative
sizes is unnecessary (e.g., when dealing with CONST_INT addresses).
That was implemented and regstrapped on x86_64-linux-gnu. Uros, would
you give the second patch a spin on alpha to make sure it doesn't
regress? Ok to install it?
Restore negative sizes for AND alignment
From: Alexandre Oliva <aol...@redhat.com>
for gcc/ChangeLog
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.
---
gcc/alias.c | 18 +++++++++++++-----
1 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/gcc/alias.c b/gcc/alias.c
index df328ec..9a386dd 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);
Be conservative about negative sizes on symbols, use abs elsewhere
From: Alexandre Oliva <aol...@redhat.com>
for gcc/ChangeLog
PR rtl-optimization/55547
PR rtl-optimization/53827
PR debug/53671
PR debug/49888
* alias.c (memrefs_conflict_p): Use abs of sizes all over,
retaining the conservative special case for symbolic
constants.
---
gcc/alias.c | 21 ++++++++++++---------
1 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/gcc/alias.c b/gcc/alias.c
index 9a386dd..d51ba09 100644
--- a/gcc/alias.c
+++ b/gcc/alias.c
@@ -1976,21 +1976,21 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
else if (GET_CODE (x) == LO_SUM)
x = XEXP (x, 1);
else
- x = addr_side_effect_eval (x, xsize, 0);
+ x = addr_side_effect_eval (x, abs (xsize), 0);
if (GET_CODE (y) == HIGH)
y = XEXP (y, 0);
else if (GET_CODE (y) == LO_SUM)
y = XEXP (y, 1);
else
- y = addr_side_effect_eval (y, ysize, 0);
+ y = addr_side_effect_eval (y, abs (ysize), 0);
if (rtx_equal_for_memref_p (x, y))
{
- if (xsize <= 0 || ysize <= 0)
+ if (xsize == 0 || ysize == 0)
return 1;
- if (c >= 0 && xsize > c)
+ if (c >= 0 && abs (xsize) - c > 0)
return 1;
- if (c < 0 && ysize+c > 0)
+ if (c < 0 && abs (ysize) + c > 0)
return 1;
return 0;
}
@@ -2063,7 +2063,8 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
y0 = canon_rtx (XEXP (y, 0));
if (rtx_equal_for_memref_p (x0, y0))
return (xsize == 0 || ysize == 0
- || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
+ || (c >= 0 && abs (xsize) - c > 0)
+ || (c < 0 && abs (ysize) + c > 0));
/* Can't properly adjust our sizes. */
if (!CONST_INT_P (x1))
@@ -2119,8 +2120,9 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
if (CONST_INT_P (x) && CONST_INT_P (y))
{
c += (INTVAL (y) - INTVAL (x));
- return (xsize <= 0 || ysize <= 0
- || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0));
+ return (xsize == 0 || ysize == 0
+ || (c >= 0 && abs (xsize) - c > 0)
+ || (c < 0 && abs (ysize) + c > 0));
}
if (GET_CODE (x) == CONST)
@@ -2139,7 +2141,8 @@ memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c)
if (CONSTANT_P (y))
return (xsize <= 0 || ysize <= 0
|| (rtx_equal_for_memref_p (x, y)
- && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0))));
+ && ((c >= 0 && abs (xsize) - c > 0)
+ || (c < 0 && abs (ysize) + c > 0))));
return -1;
}
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer
