[PATCH] tree-optimization/106196 - properly update virtual SSA for vector stores

[Richard Biener via Gcc-patches]

The following properly handles aggregate returns of the const marked
STORE_LANES internal function to update virtual SSA form on-the-fly
rather than relying on a costly virtual SSA rewrite.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

        PR tree-optimization/106196
        * tree-vect-stmts.cc (vect_finish_stmt_generation): Properly
        handle aggregate returns of calls for VDEF updates.

        * gcc.dg/torture/pr106196.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr106196.c | 14 ++++++++++++++
 gcc/tree-vect-stmts.cc                  |  6 ++++--
 2 files changed, 18 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr106196.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr106196.c 
b/gcc/testsuite/gcc.dg/torture/pr106196.c
new file mode 100644
index 00000000000..56723de42c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr106196.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-ftree-vectorize -fno-vect-cost-model" } */
+
+extern char a[];
+char *b;
+void e() {
+  char *d;
+  int c;
+  d = a;
+  for (; c; c++) {
+    d[2] = d[1] = d[0] = b[c];
+    d += 3;
+  }
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 72107afc883..3db6620dd42 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -1638,8 +1638,10 @@ vect_finish_stmt_generation (vec_info *vinfo,
              && ((is_gimple_assign (vec_stmt)
                   && !is_gimple_reg (gimple_assign_lhs (vec_stmt)))
                  || (is_gimple_call (vec_stmt)
-                     && !(gimple_call_flags (vec_stmt)
-                          & (ECF_CONST|ECF_PURE|ECF_NOVOPS)))))
+                     && (!(gimple_call_flags (vec_stmt)
+                           & (ECF_CONST|ECF_PURE|ECF_NOVOPS))
+                         || (gimple_call_lhs (vec_stmt)
+                             && !is_gimple_reg (gimple_call_lhs 
(vec_stmt)))))))
            {
              tree new_vdef = copy_ssa_name (vuse, vec_stmt);
              gimple_set_vdef (vec_stmt, new_vdef);
-- 
2.35.3