https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67671
Bug ID: 67671
Summary: restrict pointer reference looses restrict
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
Consider test-case test.c:
...
void
f (int *__restrict__ &__restrict__ p)
{
*p = 1;
}
...
When compiling the test-case with g++ -O2, we find one clique/base annotation
at ealias:
...
void f(int* __restrict__&) (intD.9 * restrict & restrict pD.2252)
{
intD.9 * _3;
# VUSE <.MEM_1(D)>
# PT = nonlocal escaped
_3 = MEM[(intD.9 * restrict &)p_2(D) clique 1 base 1];
# .MEM_4 = VDEF <.MEM_1(D)>
*_3 = 1;
...
If we write an equivalent example using a struct with pointer field instead:
...
struct ps {
int *__restrict__ p;
}
f (struct ps &__restrict__ ps)
{
*(ps.p) = 1;
}
...
we get two clique/base annotations at ealias (after fixing PR67666).
I think the two examples are similar enough to expect two clique/base
annotations at ealias for the first example.
Using this demonstrator patch, we manage that:
...
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 94016b9..fa7108a 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -5684,6 +5684,9 @@ create_variable_info_for_1 (tree decl, const char *name)
vi->fullsize = tree_to_uhwi (declsize);
vi->size = vi->fullsize;
vi->is_full_var = true;
+ if (POINTER_TYPE_P (TREE_TYPE (decl))
+ && TYPE_RESTRICT (TREE_TYPE (decl)))
+ vi->only_restrict_pointers = 1;
fieldstack.release ();
return vi;
}
...
