[PATCH] Fix PR91069

[Richard Biener]

Late FRE uncovered a bug in vec-perm folding.

Boostrap / regtest running on x86_64-unknown-linux-gnu.

Richard.

2019-07-03  Richard Biener  <rguent...@suse.de>

        PR middle-end/91069
        * match.pd (vec_perm -> bit_insert): Fix element read from
        first vector.

        * gcc.dg/pr91069.c: New testcase.

Index: gcc/match.pd
===================================================================
--- gcc/match.pd        (revision 272958)
+++ gcc/match.pd        (working copy)
@@ -5520,7 +5520,7 @@ (define_operator_list COND_TERNARY
                   first vector we only can insert the first elt from
                   the first vector.  */
                at = 0;
-               if ((ins = fold_read_from_vector (cop0, 0)))
+               if ((ins = fold_read_from_vector (cop0, sel[0])))
                  op0 = op1;
              }
            else
Index: gcc/testsuite/gcc.dg/pr91069.c
===================================================================
--- gcc/testsuite/gcc.dg/pr91069.c      (nonexistent)
+++ gcc/testsuite/gcc.dg/pr91069.c      (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+
+typedef double v2df __attribute__((vector_size(16)));
+typedef long v2di __attribute__((vector_size(16)));
+
+void foo (v2df *res, v2df *src)
+{
+  v2df x = *src;
+  *res = __builtin_shuffle ((v2df) { 1.0, 0.0 }, x, (v2di) { 1, 3 });
+}
+
+int main()
+{
+  v2df x = (v2df) { 0.0, 2.0 };
+  foo (&x, &x);
+  if (x[0] != 0.0 || x[1] != 2.0)
+    __builtin_abort ();
+  return 0;
+}