[Bug tree-optimization/94734] [10 Regression] Program crashes when compiled with -O2 since r10-1892-gb9ef6a2e04bfd013

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94734

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
If we don't want to revert the change completely, could we perhaps do:
--- gcc/tree-ssa-phiopt.c.jj    2020-03-19 10:23:50.542872359 +0100
+++ gcc/tree-ssa-phiopt.c       2020-04-24 10:54:10.341716841 +0200
@@ -2237,10 +2237,26 @@ cond_store_replacement (basic_block midd
      whose value is not available readily, which we want to avoid.  */
   if (!nontrap->contains (lhs))
     {
-      /* If LHS is a local variable without address-taken, we could
-        always safely move down the store.  */
-      tree base = get_base_address (lhs);
-      if (!auto_var_p (base) || TREE_ADDRESSABLE (base))
+      /* If LHS is an access to a local variable without address-taken
+        or its part and the access is provably within the bounds of the
+        local variable, we could always safely move down the store.  */
+      HOST_WIDE_INT offset, size, decl_size;
+      bool reverse;
+      tree base = get_ref_base_and_extent_hwi (lhs, &offset, &size,
+                                              &reverse);
+      if (base == NULL_TREE || !auto_var_p (base) || TREE_ADDRESSABLE (base))
+       return false;
+      if (!DECL_SIZE (base)
+         || !tree_fits_shwi_p (DECL_SIZE (base)))
+       return false;
+      decl_size = tree_to_shwi (DECL_SIZE (base));
+      if (offset < 0
+         || size < 0
+         || decl_size < 0
+         || offset >= decl_size
+         || size > decl_size
+         || ((unsigned HOST_WIDE_INT) offset + size
+             > (unsigned HOST_WIDE_INT) decl_size))
        return false;
     }

+ xfail the tests from the PR89430 because they all need the nontrap ARRAY_REF
etc. handling?
With that, in the above testcase baz is still cselim optimized , but foo and
bar are not.  bar is still miscompiled by some other optimization though (and
GCC 9 didn't do that), so we have some other regression.