[Bug target/105197] [12 Regression] SVE: wrong code with -O -ftree-vectorize

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105197

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The following improves the output from if-conversion by simplifying ~cond ? a :
b
to cond ? b : a, possibly reducing the number of conds.  Ideally if-conversion
would track predicates in a more concious way of course.

diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 7495ed653c0..dd3d5255a38 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -472,6 +472,14 @@ fold_build_cond_expr (tree type, tree cond, tree rhs, tree
lhs)
          && (integer_zerop (op1)))
        cond = op0;
     }
+  gassign *ass;
+  if (TREE_CODE (cond) == SSA_NAME
+      && (ass = dyn_cast <gassign *> (SSA_NAME_DEF_STMT (cond)))
+      && gimple_assign_rhs_code (ass) == BIT_NOT_EXPR)
+    {
+      cond = gimple_assign_rhs1 (ass);
+      std::swap (rhs, lhs);
+    }
   cond_expr = fold_ternary (COND_EXPR, type, cond, rhs, lhs);

   if (cond_expr == NULL_TREE)