[Bug tree-optimization/68659] [6 regression] FAIL: gcc.dg/graphite/id-pr45230-1.c (internal compiler error)

["vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68659

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org

--- Comment #17 from vries at gcc dot gnu.org ---
(In reply to John David Anglin from comment #11)
> Seeing this on hppa with -mschedule=7100LC.  This is with r231795.
> 
> There is null pointer exception here:
> 
> Program received signal SIGSEGV, Segmentation fault.
> translate_isl_ast_to_gimple::collect_all_ssa_names (
>     this=this@entry=0xfd703908, new_expr=0x0,
> vec_ssa=vec_ssa@entry=0xfd7044c8)
>     at ../../gcc/gcc/graphite-isl-ast-to-gimple.c:1603
> 1603	  if (TREE_CODE (new_expr) == SSA_NAME)
> (gdb) p new_expr
> $1 = (tree) 0x0

I wonder if this patch is correct (at least fixes the ICE with x86_64 -m32):
...
index d3614e4..e5b03ee 100644
--- a/gcc/graphite-isl-ast-to-gimple.c
+++ b/gcc/graphite-isl-ast-to-gimple.c
@@ -1404,6 +1404,9 @@ void translate_isl_ast_to_gimple::
 collect_all_ssa_names (tree new_expr, vec<tree> *vec_ssa)
 {

+  if (new_expr == NULL_TREE)
+    return;
+
   /* Rename all uses in new_expr.  */
   if (TREE_CODE (new_expr) == SSA_NAME)
     {
@@ -1804,6 +1807,9 @@ get_new_name (basic_block new_bb, tree op,
   if (is_constant (op))
     return op;

+  if (TREE_CODE (op) == ADDR_EXPR)
+    return op;
+
   return get_rename (new_bb, op, old_bb, phi_kind);
 }

...

We're doing collect_all_ssa_names for component_ref u2.buf. Operand 2 is
NULL_TREE, which AFAIU according to the definition of component_ref is allowed
(tree.def: Operand 2, if present, ...). This code in collect_all_ssa_names just
looks at TREE_CODE_LENGTH, which is 3 for component_ref, and for i == 2, op ==
NULL_TREE:
...
  /* Iterate over SSA_NAMES in NEW_EXPR.  */
  for (int i = 0; i < (TREE_CODE_LENGTH (TREE_CODE (new_expr))); i++)
    {
      tree op = TREE_OPERAND (new_expr, i);
      collect_all_ssa_names (op, vec_ssa);
    }
...

The first bit of the patch allows the NULL_TREE operand in
collect_all_ssa_names. But subsequently, we run into handling op == &u2.buf in
get_new_name, which results in an assert that op is not an ssa-name in
get_rename. The last bit of the patch handles that.