Re: [PATCH] Remove dead vector comparisons

[Martin Liška]

On 7/27/20 1:22 PM, Richard Biener wrote:
I wonder what happens if we make vector lowering not allow the compare
expanded via expand_vec_cond_expr_p?

So the following patch survives bootstrap and tests on x86_64-linux-gnu:

diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index f8bd26f2156..fe6477c8592 100644
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -419,8 +419,7 @@ expand_vector_comparison (gimple_stmt_iterator *gsi, tree 
type, tree op0,
     return NULL_TREE;
 
   tree t;
-  if (!expand_vec_cmp_expr_p (TREE_TYPE (op0), type, code)
-      && !expand_vec_cond_expr_p (type, TREE_TYPE (op0), code))
+  if (!expand_vec_cmp_expr_p (TREE_TYPE (op0), type, code))
     {
       if (VECTOR_BOOLEAN_TYPE_P (type)
          && SCALAR_INT_MODE_P (TYPE_MODE (type))

and provides a reasonable BIT_FIELD_REF expansion on the problematic s390x 
test-case.
Is it a way to go?

Martin