re PR tree-optimization/22615 (ICE in first_vi_for_offset, at tree-ssa-structalias...

2005-08-14  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/22615

	* tree-ssa-structalias.c (solution_set_add): Handle
	first_vi_for_offset returning NULL.
	(do_da_constraint): Ditto.
	(do_sd_constraint): Ditto.
	(do_ds_constraint): Ditto
	(find_func_aliases): Ditto.
	(build_constraint_graph): RHS is allowed be ANYTHING.
	(first_vi_for_offset): Return NULL if we couldn't find anything at
	the offset.

From-SVN: r103083

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fb927823d838b16ad742e3306b80b71f6d874bbb..9b8f86cc5a58a2497d9f1e39d09ce262d6873bb8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2005-08-14  Daniel Berlin  <dberlin@dberlin.org>
+
+       Fix PR tree-optimization/22615
+       
+       * tree-ssa-structalias.c (solution_set_add): Handle
+       first_vi_for_offset returning NULL. 
+       (do_da_constraint): Ditto.
+       (do_sd_constraint): Ditto.
+       (do_ds_constraint): Ditto
+       (find_func_aliases): Ditto.
+       (build_constraint_graph): RHS is allowed be ANYTHING.
+       (first_vi_for_offset): Return NULL if we couldn't find anything at
+       the offset.
+       
 2005-08-14  Ulrich Weigand  <uweigand@de.ibm.com>
 
        * config/s390/s390.c (s390_canonicalize_comparison): Prefer register

diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr22615.C b/gcc/testsuite/g++.dg/tree-ssa/pr22615.C
new file mode 100644 (file)
index 0000000..a8936c4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr22615.C
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+/* Ensure that we don't crash when people decide to return the address of padding.  */
+
+struct A
+{
+    char c;
+      int i;
+};
+
+A a;
+
+struct B
+{
+    char c, d;
+};
+
+union C
+{
+    A *p;
+      B *q;
+
+        C() : p(&a) {}
+         char& foo() { return q->d; }
+};
+void bar() { C().foo() = 0; }
+

diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 13b9751288ff442dad4b4bd1bad42d1986d2d355..cad485abd77dc21d31ac950b6370b04ec090d71e 100644 (file)
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -612,6 +612,8 @@ solution_set_add (bitmap set, unsigned HOST_WIDE_INT offset)
        {
          unsigned HOST_WIDE_INT fieldoffset = get_varinfo (i)->offset + offset;
          varinfo_t v = first_vi_for_offset (get_varinfo (i), fieldoffset);
+         if (!v)
+           continue;
          bitmap_set_bit (result, v->id);
        }
       else if (get_varinfo (i)->is_artificial_var 
@@ -997,7 +999,7 @@ build_constraint_graph (void)
          /* x = &y */
          bitmap_set_bit (get_varinfo (lhs.var)->solution, rhs.var);
        }
-      else if (rhs.var > anything_id && lhs.var > anything_id)
+      else if (lhs.var > anything_id)
        {
          /* Ignore 0 weighted self edges, as they can't possibly contribute
             anything */
@@ -1332,6 +1334,8 @@ do_da_constraint (constraint_graph_t graph ATTRIBUTE_UNUSED,
          unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + offset;
 
          v = first_vi_for_offset (get_varinfo (j), fieldoffset);
+         if (!v)
+           continue;
          t = v->node;
          sol = get_varinfo (t)->solution;
          if (!bitmap_bit_p (sol, rhs))
@@ -1375,6 +1379,8 @@ do_sd_constraint (constraint_graph_t graph, constraint_t c,
          unsigned int t;
 
          v = first_vi_for_offset (get_varinfo (j), fieldoffset);         
+         if (!v)
+           continue;
          t = v->node;
          if (int_add_graph_edge (graph, lhs, t, 0))
            flag |= bitmap_ior_into (sol, get_varinfo (t)->solution);     
@@ -1419,6 +1425,8 @@ do_ds_constraint (constraint_graph_t graph, constraint_t c, bitmap delta)
          unsigned HOST_WIDE_INT fieldoffset = get_varinfo (j)->offset + loff;
 
          v = first_vi_for_offset (get_varinfo (j), fieldoffset);
+         if (!v)
+           continue;
          t = v->node;
          if (int_add_graph_edge (graph, t, rhs, roff))
            {
@@ -2878,7 +2886,7 @@ find_func_aliases (tree t, struct alias_info *ai)
    OFFSET.
    Effectively, walk the chain of fields for the variable START to find the
    first field that overlaps with OFFSET.
-   Abort if we can't find one.  */
+   Return NULL if we can't find one.  */
 
 static varinfo_t 
 first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
@@ -2894,8 +2902,7 @@ first_vi_for_offset (varinfo_t start, unsigned HOST_WIDE_INT offset)
        return curr;
       curr = curr->next;
     }
-
-  gcc_unreachable ();
+  return NULL;
 }