* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
@ 2009-02-18 17:05 ` jakub at gcc dot gnu dot org
2009-02-18 17:24 ` jakub at gcc dot gnu dot org
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From: jakub at gcc dot gnu dot org @ 2009-02-18 17:05 UTC (permalink / raw)
To: gcc-bugs
--
jakub at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |4.4.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
2009-02-18 17:05 ` [Bug tree-optimization/39233] " jakub at gcc dot gnu dot org
@ 2009-02-18 17:24 ` jakub at gcc dot gnu dot org
2009-02-18 17:47 ` rguenth at gcc dot gnu dot org
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From: jakub at gcc dot gnu dot org @ 2009-02-18 17:24 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from jakub at gcc dot gnu dot org 2009-02-18 17:24 -------
Caused by PR31358.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
2009-02-18 17:05 ` [Bug tree-optimization/39233] " jakub at gcc dot gnu dot org
2009-02-18 17:24 ` jakub at gcc dot gnu dot org
@ 2009-02-18 17:47 ` rguenth at gcc dot gnu dot org
2009-02-18 17:51 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-18 17:47 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from rguenth at gcc dot gnu dot org 2009-02-18 17:47 -------
I will have a look.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-02-18 17:47:42
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (2 preceding siblings ...)
2009-02-18 17:47 ` rguenth at gcc dot gnu dot org
@ 2009-02-18 17:51 ` rguenth at gcc dot gnu dot org
2009-02-18 17:53 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-18 17:51 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from rguenth at gcc dot gnu dot org 2009-02-18 17:50 -------
Confirmed on x86_64 with -O2.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
GCC target triplet| |x86_64-*-*
Known to work| |4.3.3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (3 preceding siblings ...)
2009-02-18 17:51 ` rguenth at gcc dot gnu dot org
@ 2009-02-18 17:53 ` rguenth at gcc dot gnu dot org
2009-02-18 18:47 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-18 17:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from rguenth at gcc dot gnu dot org 2009-02-18 17:53 -------
This one also fails on i?86-*-*:
extern void abort (void);
__attribute__((noinline)) void
foo (void *p)
{
long l = (long) p;
if (l < 0 || l > 6)
abort ();
}
int
main ()
{
short i;
for (i = 6; i >= 0; i--)
foo ((void *) (long) i);
return 0;
}
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
GCC target triplet|x86_64-*-* |x86_64-*-*, i?86-*-*
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (4 preceding siblings ...)
2009-02-18 17:53 ` rguenth at gcc dot gnu dot org
@ 2009-02-18 18:47 ` rguenth at gcc dot gnu dot org
2009-02-18 18:56 ` jakub at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-18 18:47 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from rguenth at gcc dot gnu dot org 2009-02-18 18:47 -------
This patch fixes it, with unknown side-effects. It should be ok for
the common sizetype extensions due to POINTER_PLUS_EXPR (sizetype is
unsigned for sane languages).
Index: tree-scalar-evolution.c
===================================================================
--- tree-scalar-evolution.c (revision 144265)
+++ tree-scalar-evolution.c (working copy)
@@ -2799,6 +2799,14 @@ simple_iv (struct loop *loop, gimple stm
|| chrec_contains_symbols_defined_in_loop (iv->base, loop->num))
return false;
+ /* If we folded casts and the result is a type where overflow is
+ undefined the IV may not be simple as it can have introduced
+ undefined overflow that wasn't there before. */
+ if (folded_casts
+ && (TYPE_OVERFLOW_UNDEFINED (type)
+ || POINTER_TYPE_P (type)))
+ return false;
+
iv->no_overflow = !folded_casts && TYPE_OVERFLOW_UNDEFINED (type);
return true;
The following patch would be slightly less intrusive (only affects IVOPTs),
but possibly other passes might be affected by the same bug. OTOH it
doesn't affect number-of-iterations analysis, which the above does.
Index: tree-ssa-loop-ivopts.c
===================================================================
--- tree-ssa-loop-ivopts.c (revision 144265)
+++ tree-ssa-loop-ivopts.c (working copy)
@@ -887,6 +887,14 @@ determine_biv_step (gimple phi)
if (!simple_iv (loop, phi, name, &iv, true))
return NULL_TREE;
+ /* If the IV may overflow and the result is a type we know does not
+ overflow we may have introduced undefined overflow. Do not use
+ that induction variable. */
+ if (!iv.no_overflow
+ && (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (name))
+ || POINTER_TYPE_P (TREE_TYPE (name))))
+ return NULL_TREE;
+
return integer_zerop (iv.step) ? NULL_TREE : iv.step;
}
@@ -992,6 +1000,15 @@ find_givs_in_stmt_scev (struct ivopts_da
if (!simple_iv (loop, stmt, lhs, iv, true))
return false;
+
+ /* If the IV may overflow and the result is a type we know does not
+ overflow we may have introduced undefined overflow. Do not use
+ that induction variable. */
+ if (!iv->no_overflow
+ && (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (lhs))
+ || POINTER_TYPE_P (TREE_TYPE (lhs))))
+ return false;
+
iv->base = expand_simple_operations (iv->base);
if (contains_abnormal_ssa_name_p (iv->base)
in the end someone finally should sit down and make overflowing/non-overflowing
arithmetic explicit in the IL.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (5 preceding siblings ...)
2009-02-18 18:47 ` rguenth at gcc dot gnu dot org
@ 2009-02-18 18:56 ` jakub at gcc dot gnu dot org
2009-02-18 19:56 ` rguenth at gcc dot gnu dot org
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From: jakub at gcc dot gnu dot org @ 2009-02-18 18:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from jakub at gcc dot gnu dot org 2009-02-18 18:56 -------
Would it be possible for known loop bounds to still use pointer etc. ivopts if
we can ensure the overflow doesn't happen on that interval (+-1)? Say if the
same testcase goes for (i = 16; i >= 10; i--) instead of for (i = 6; i >= 0;
i--)?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (6 preceding siblings ...)
2009-02-18 18:56 ` jakub at gcc dot gnu dot org
@ 2009-02-18 19:56 ` rguenth at gcc dot gnu dot org
2009-02-21 13:08 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-18 19:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from rguenth at gcc dot gnu dot org 2009-02-18 19:56 -------
I'm sure it is somehow possible, maybe we can use scev_probably_wraps_p
in simple_iv. I will check that.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (7 preceding siblings ...)
2009-02-18 19:56 ` rguenth at gcc dot gnu dot org
@ 2009-02-21 13:08 ` rguenth at gcc dot gnu dot org
2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-21 13:08 UTC (permalink / raw)
To: gcc-bugs
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P1
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
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2009-02-21 13:08 ` rguenth at gcc dot gnu dot org
@ 2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-24 11:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from rguenth at gcc dot gnu dot org 2009-02-24 11:05 -------
Fixed.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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* [Bug tree-optimization/39233] [4.4 Regression] ivopts + vrp miscompilation
2009-02-18 17:05 [Bug tree-optimization/39233] New: [4.4 Regression] ivopts + vrp miscompilation jakub at gcc dot gnu dot org
` (9 preceding siblings ...)
2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
@ 2009-02-24 11:05 ` rguenth at gcc dot gnu dot org
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From: rguenth at gcc dot gnu dot org @ 2009-02-24 11:05 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from rguenth at gcc dot gnu dot org 2009-02-24 11:05 -------
Subject: Bug 39233
Author: rguenth
Date: Tue Feb 24 11:05:15 2009
New Revision: 144405
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=144405
Log:
2009-02-24 Richard Guenther <rguenther@suse.de>
Zdenek Dvorak <ook@ucw.cz>
PR tree-optimization/39233
* tree-ssa-loop-ivopts.c (add_candidate_1): Do not except pointers
from converting them to a generic type.
* gcc.c-torture/execute/pr39233.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.c-torture/execute/pr39233.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-loop-ivopts.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39233
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