tree-optimization/104782 - adjust PR101636 fix

This reverts the reversion of r10-5979 amending the CTOR case
with a comment as to why the conversion is not necessary there.
It also adds a testcase (but not for the CTOR case).

2022-03-07  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/104782
	* tree-vect-slp.cc (vectorize_slp_instance_root_stmt):
	Re-instantiate r10-5979 fix, add comment.

	* gcc.dg/vect/pr104782.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/vect/pr104782.c b/gcc/testsuite/gcc.dg/vect/pr104782.c
new file mode 100644 (file)
index 0000000..7b8ca6c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr104782.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O3" } */
+/* { dg-additional-options "-march=armv8.2-a+sve -msve-vector-bits=128" { target aarch64-*-* } } */
+
+int a, b, c;
+static int d;
+short *q;
+void f() {
+  int *p = &d;
+  b = 9;
+  for (b = 9; b; b--) {
+    a = 2;
+    for (c = 2; c <= 9; c++) {
+      for (int i = 0; i < 3; i++)
+        *p |= (*q)++;
+    }
+  }
+}

diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index f9bbc872a99f00ea088ffde8192aabff8c3f0c0a..4ac2b70303c94e8f111fe41df39ac727cf8cc462 100644 (file)
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -7382,6 +7382,10 @@ vectorize_slp_instance_root_stmt (slp_tree node, slp_instance instance)
          gimple *child_stmt = SLP_TREE_VEC_STMTS (node)[0];
          tree vect_lhs = gimple_get_lhs (child_stmt);
          tree root_lhs = gimple_get_lhs (instance->root_stmts[0]->stmt);
+         if (!useless_type_conversion_p (TREE_TYPE (root_lhs),
+                                         TREE_TYPE (vect_lhs)))
+           vect_lhs = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (root_lhs),
+                              vect_lhs);
          rstmt = gimple_build_assign (root_lhs, vect_lhs);
        }
       else if (SLP_TREE_NUMBER_OF_VEC_STMTS (node) > 1)
@@ -7392,6 +7396,9 @@ vectorize_slp_instance_root_stmt (slp_tree node, slp_instance instance)
          vec<constructor_elt, va_gc> *v;
          vec_alloc (v, nelts);
 
+         /* A CTOR can handle V16HI composition from VNx8HI so we
+            do not need to convert vector elements if the types
+            do not match.  */
          FOR_EACH_VEC_ELT (SLP_TREE_VEC_STMTS (node), j, child_stmt)
            CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                                    gimple_get_lhs (child_stmt));