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* [Bug tree-optimization/59287] New: points-to analysis confused by union accesses
@ 2013-11-25 15:17 rguenth at gcc dot gnu.org
2013-11-26 9:04 ` [Bug tree-optimization/59287] " rguenth at gcc dot gnu.org
2013-11-26 9:05 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-11-25 15:17 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59287
Bug ID: 59287
Summary: points-to analysis confused by union accesses
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
static void
get_constraint_for_component_ref (tree t, vec<ce_s> *results,
bool address_p, bool lhs_p)
{
...
/* Handle type-punning through unions. If we are extracting a pointer
from a union via a possibly type-punning access that pointer
points to anything, similar to a conversion of an integer to
a pointer. */
if (!lhs_p)
{
tree u;
for (u = t;
TREE_CODE (u) == COMPONENT_REF || TREE_CODE (u) == ARRAY_REF;
u = TREE_OPERAND (u, 0))
if (TREE_CODE (u) == COMPONENT_REF
&& TREE_CODE (TREE_TYPE (TREE_OPERAND (u, 0))) == UNION_TYPE)
{
struct constraint_expr temp;
temp.offset = 0;
temp.var = anything_id;
temp.type = ADDRESSOF;
results->safe_push (temp);
return;
}
}
has the adverse affect that if you have code like
foo (TREE_CODE (t))
then it makes ANYTHING escape ... which is the worst thing that can happen.
The above shouldn't be necessary.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/59287] points-to analysis confused by union accesses
2013-11-25 15:17 [Bug tree-optimization/59287] New: points-to analysis confused by union accesses rguenth at gcc dot gnu.org
@ 2013-11-26 9:04 ` rguenth at gcc dot gnu.org
2013-11-26 9:05 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-11-26 9:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59287
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue Nov 26 09:04:44 2013
New Revision: 205380
URL: http://gcc.gnu.org/viewcvs?rev=205380&root=gcc&view=rev
Log:
2013-11-26 Richard Biener <rguenther@suse.de>
PR tree-optimization/59287
* tree-ssa-structalias.c (get_constraint_for_component_ref):
Remove no longer necessary special-casing of union accesses.
* gcc.dg/tree-ssa/alias-29.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.dg/tree-ssa/alias-29.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-structalias.c
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/59287] points-to analysis confused by union accesses
2013-11-25 15:17 [Bug tree-optimization/59287] New: points-to analysis confused by union accesses rguenth at gcc dot gnu.org
2013-11-26 9:04 ` [Bug tree-optimization/59287] " rguenth at gcc dot gnu.org
@ 2013-11-26 9:05 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-11-26 9:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59287
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Known to work| |4.9.0
Resolution|--- |FIXED
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-11-25 15:17 [Bug tree-optimization/59287] New: points-to analysis confused by union accesses rguenth at gcc dot gnu.org
2013-11-26 9:04 ` [Bug tree-optimization/59287] " rguenth at gcc dot gnu.org
2013-11-26 9:05 ` rguenth at gcc dot gnu.org
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