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re PR tree-optimization/22071 (ICE in first_vi_for_offset, at tree-ssa-structalias.c:2506)

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2005-06-29  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/22071

	* tree-ssa-structalias.c (offset_overlaps_with_access): New
	function.
	(get_constraint_for_component_ref): Use it.

From-SVN: r101516
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Daniel Berlin 2005-07-01 19:45:23 +00:00 • committed by Daniel Berlin
parent 7523dc31c3
commit dd68d9887b
3 changed files with 62 additions and 2 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2005-06-29 Daniel Berlin <dberlin@dberlin.org>
Fix PR tree-optimization/22071
* tree-ssa-structalias.c (offset_overlaps_with_access): New
function.
(get_constraint_for_component_ref): Use it.
2005-07-01 Andrew Pinski <pinskia@physics.uc.edu>
PR other/22264

14
gcc/testsuite/g++.dg/tree-ssa/pr22071.C Normal file
View file

@ -0,0 +1,14 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
/* This code ends up taking the address of part of the structure that is padding,
and because there is no real field there, the structure alias analyzer would
abort. */
struct empty_class {};
struct class1 : empty_class
{
class1() {}
empty_class value_;
};
struct lambda : class1 { };
lambda _1;

42
gcc/tree-ssa-structalias.c
View file

@ -1940,6 +1940,25 @@ bitpos_of_field (const tree fdecl)
}
/* Return true if an access to [ACCESSPOS, ACCESSSIZE]
overlaps with a field at [FIELDPOS, FIELDSIZE] */
static bool
offset_overlaps_with_access (const unsigned HOST_WIDE_INT fieldpos,
const unsigned HOST_WIDE_INT fieldsize,
const unsigned HOST_WIDE_INT accesspos,
const unsigned HOST_WIDE_INT accesssize)
{
if (fieldpos == accesspos && fieldsize == accesssize)
return true;
if (accesspos >= fieldpos && accesspos <= (fieldpos + fieldsize))
return true;
if (accesspos < fieldpos && (accesspos + accesssize > fieldpos))
return true;
return false;
}
/* Given a COMPONENT_REF T, return the constraint_expr for it. */
static struct constraint_expr
@ -2000,8 +2019,27 @@ get_constraint_for_component_ref (tree t)
we may have to do something cute here. */
if (result.offset < get_varinfo (result.var)->fullsize)
result.var = first_vi_for_offset (get_varinfo (result.var),
result.offset)->id;
{
/* It's also not true that the constraint will actually start at the
right offset, it may start in some padding. We only care about
setting the constraint to the first actual field it touches, so
walk to find it. */
varinfo_t curr;
for (curr = get_varinfo (result.var); curr; curr = curr->next)
{
if (offset_overlaps_with_access (curr->offset, curr->size,
result.offset, bitsize))
{
result.var = curr->id;
break;
}
}
/* assert that we found *some* field there. The user couldn't be
accessing *only* padding. */
gcc_assert (curr);
}
else
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Access to past the end of variable, ignoring\n");