[PATCH] middle-end/96453 - relax gimple_expand_vec_cond_expr

[Richard Biener]

This relaxes the condition under which we also try NE_EXPR
for a fake generated compare in addition to LT_EXPR given
the fact the verification ICEd when it failed but obviously
was only implemented for constants.  Thus the patch removes
the verification and the restriction to constant operands.

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

2020-09-23  Richard Biener  <rguent...@suse.de>

        PR middle-end/96453
        * gimple-isel.cc (gimple_expand_vec_cond_expr): Remove
        LT_EXPR -> NE_EXPR verification and also apply it for
        non-constant masks.

        * gcc.dg/pr96453.c: New testcase.
---
 gcc/gimple-isel.cc             | 15 ++-------------
 gcc/testsuite/gcc.dg/pr96453.c | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 13 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr96453.c

diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc
index b330cf4c20e..97922632afd 100644
--- a/gcc/gimple-isel.cc
+++ b/gcc/gimple-isel.cc
@@ -138,22 +138,11 @@ gimple_expand_vec_cond_expr (gimple_stmt_iterator *gsi,
   if (icode == CODE_FOR_nothing)
     {
       if (tcode == LT_EXPR
-         && op0a == op0
-         && TREE_CODE (op0) == VECTOR_CST)
+         && op0a == op0)
        {
          /* A VEC_COND_EXPR condition could be folded from EQ_EXPR/NE_EXPR
             into a constant when only get_vcond_eq_icode is supported.
-            Verify < 0 and != 0 behave the same and change it to NE_EXPR.  */
-         unsigned HOST_WIDE_INT nelts;
-         if (!VECTOR_CST_NELTS (op0).is_constant (&nelts))
-           {
-             if (VECTOR_CST_STEPPED_P (op0))
-               gcc_unreachable ();
-             nelts = vector_cst_encoded_nelts (op0);
-           }
-         for (unsigned int i = 0; i < nelts; ++i)
-           if (tree_int_cst_sgn (vector_cst_elt (op0, i)) == 1)
-             gcc_unreachable ();
+            Try changing it to NE_EXPR.  */
          tcode = NE_EXPR;
        }
       if (tcode == EQ_EXPR || tcode == NE_EXPR)
diff --git a/gcc/testsuite/gcc.dg/pr96453.c b/gcc/testsuite/gcc.dg/pr96453.c
new file mode 100644
index 00000000000..f758e7ec77a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr96453.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-Og -fno-early-inlining -fno-tree-ccp -fno-tree-dce" } */
+/* { dg-additional-options "-mavx -mno-sse4.2" { target x86_64-*-* i?86-*-* } 
} */
+
+typedef int __attribute__ ((__vector_size__ (16))) U;
+typedef unsigned long __attribute__ ((__vector_size__ (16))) V;
+
+static inline int
+bar (unsigned long e, V f)
+{
+  V g = f != e;
+  (union {U b;}){(U) g};
+}
+
+void
+foo (void)
+{
+  int j = bar (8, (V) { });
+  for (unsigned i;; i[&j])
+    ;
+}
-- 
2.26.2