[Bug tree-optimization/83337] ICE at -O3 x86_64-linux-gnu: in interpret_rhs_expr, at tree-scalar-evolution.c:1775

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83337

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The bug is pretty obvious:
compute_access_stride
does:
  tree ref = DR_REF (dr);
  tree scev_base = build_fold_addr_expr (ref);
  tree scev = analyze_scalar_evolution (loop, scev_base);
  scev = instantiate_scev (loop_preheader_edge (loop_nest), loop, scev);
for all drs, now obviously build_fold_addr_expr is not valid on bitfields.

Untested fix:
--- gcc/gimple-loop-interchange.cc.jj   2017-12-08 12:27:11.000000000 +0100
+++ gcc/gimple-loop-interchange.cc      2017-12-09 12:18:09.209977976 +0100
@@ -1291,6 +1291,30 @@ compute_access_stride (struct loop *loop
   gcc_assert (loop == bb->loop_father);

   tree ref = DR_REF (dr);
+  if (TREE_CODE (ref) == COMPONENT_REF
+      && DECL_BIT_FIELD (TREE_OPERAND (ref, 1)))
+    {
+      /* We can't take address of bitfields.  If the bitfield is at constant
+        offset from the start of the struct, just use address of the
+        struct, for analysis of the strides that shouldn't matter.  */
+      if (!TREE_OPERAND (ref, 2)
+         || TREE_CODE (TREE_OPERAND (ref, 2)) == INTEGER_CST)
+       ref = TREE_OPERAND (ref, 0);
+      /* Otherwise, if we have a bit field representative, use that.  */
+      else if (DECL_BIT_FIELD_REPRESENTATIVE (TREE_OPERAND (ref, 1))
+              != NULL_TREE)
+       {
+         tree repr = DECL_BIT_FIELD_REPRESENTATIVE (TREE_OPERAND (ref, 1));
+         ref = build3 (COMPONENT_REF, TREE_TYPE (repr), TREE_OPERAND (ref, 0),
+                       repr, TREE_OPERAND (ref, 2));
+       }
+      /* Otherwise punt.  */
+      else
+       {
+         dr->aux = strides;
+         return;
+       }
+    }
   tree scev_base = build_fold_addr_expr (ref);
   tree scev = analyze_scalar_evolution (loop, scev_base);
   scev = instantiate_scev (loop_preheader_edge (loop_nest), loop, scev);