[Bug tree-optimization/78847] pointer arithmetic from c++ ranged-based for loop not optimized

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78847

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
A simple fold-const.c "fix" is the following:

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 245276)
+++ gcc/fold-const.c    (working copy)
@@ -785,7 +785,9 @@ split_tree (location_t loc, tree in, tre
                  the value is not affected.  For reals, the value might be
                  affected, so we can't.  */
               && ((code == PLUS_EXPR && TREE_CODE (in) == MINUS_EXPR)
-                  || (code == MINUS_EXPR && TREE_CODE (in) == PLUS_EXPR))))
+                  || (code == MINUS_EXPR
+                      && (TREE_CODE (in) == PLUS_EXPR
+                          || TREE_CODE (in) == POINTER_PLUS_EXPR)))))
     {
       tree op0 = TREE_OPERAND (in, 0);
       tree op1 = TREE_OPERAND (in, 1);

I'm giving it bootstrap/regtest - that would be likely a quite beneficial
change for all the middle-end machinery still using GENERIC...