On 8/31/20 10:01 AM, Richard Biener wrote:
On Fri, Aug 28, 2020 at 4:18 PM Martin Liška <mli...@suse.cz> wrote:

Hey.

The patch is about VEC_COND_EXP comparison of a SSA_NAME with a constant
that is artifact of -fno-tree-ccp.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?

Err, no - we shouldn't do this at RTL expansion time.  And piecewise
expansion is gross - in this the case is a constant boolean vector IIRC
(not sure what mode?)

Yes, it's:

(gdb) p op0.typed.type
$11 = <vector_type 0x7ffff743a1f8>
(gdb) p mode
$13 = E_DImode

and TYPE_MODE (TREE_TYPE (op0)) is E_BLKmode

and ISEL only tries matching up with
a comparison operand.  But ISEL should also handle matching up with
a constant "boolean vector" ("boolean vector"s are artifacts of VEC_COND_EXPRs,
but some targets allow bitwise arithmetic on them...).  So the compensation
needs to happen in ISEL, recognizing

  _1 = {0}
  _2 = _1 ? ...;

as

  _2 = .VCOND (0 == 0, ...)

Do we really want to do a scalar arguments of .VCOND? Note that in PR96453
(a similar bug), we end up with:

  _5 = { -1, -1 };
  _6 = VEC_COND_EXPR <_5, { -1, -1 }, { 0, 0 }>;

Thanks for hints,
Martin


or so.

Richard.

Thanks,
Martin

gcc/ChangeLog:

         PR tree-optimization/96466
         * gimple-fold.c (expand_cmp_piecewise): New.
         * gimple-fold.h (nunits_for_known_piecewise_op): New.
         (expand_cmp_piecewise): Moved from ...
         * tree-vect-generic.c (expand_vector_comparison): ... here.
         (nunits_for_known_piecewise_op): Moved to gimple-fold.h.
         * gimple-isel.cc (gimple_expand_vec_cond_expr): Use
         expand_cmp_piecewise fallback for constants.

gcc/testsuite/ChangeLog:

         PR tree-optimization/96466
         * gcc.dg/vect/pr96466.c: New test.
---
   gcc/gimple-fold.c                   | 28 ++++++++++++++++++++
   gcc/gimple-fold.h                   | 14 ++++++++++
   gcc/gimple-isel.cc                  | 10 ++++---
   gcc/testsuite/gcc.dg/vect/pr96466.c | 18 +++++++++++++
   gcc/tree-vect-generic.c             | 41 ++---------------------------
   5 files changed, 69 insertions(+), 42 deletions(-)
   create mode 100644 gcc/testsuite/gcc.dg/vect/pr96466.c

diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index dcc1b56a273..86d5d0ed7d8 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -8056,3 +8056,31 @@ gimple_stmt_integer_valued_real_p (gimple *stmt, int 
depth)
         return false;
       }
   }
+
+tree
+expand_cmp_piecewise (gimple_stmt_iterator *gsi, tree type, tree op0, tree op1)
+{
+  tree inner_type = TREE_TYPE (TREE_TYPE (op0));
+  tree part_width = vector_element_bits_tree (TREE_TYPE (op0));
+  tree index = bitsize_int (0);
+  int nunits = nunits_for_known_piecewise_op (TREE_TYPE (op0));
+  int prec = GET_MODE_PRECISION (SCALAR_TYPE_MODE (type));
+  tree ret_type = build_nonstandard_integer_type (prec, 1);
+  tree ret_inner_type = boolean_type_node;
+  int i;
+  tree t = build_zero_cst (ret_type);
+
+  if (TYPE_PRECISION (ret_inner_type) != 1)
+    ret_inner_type = build_nonstandard_integer_type (1, 1);
+  for (i = 0; i < nunits;
+       i++, index = int_const_binop (PLUS_EXPR, index, part_width))
+    {
+      tree a = tree_vec_extract (gsi, inner_type, op0, part_width, index);
+      tree b = tree_vec_extract (gsi, inner_type, op1, part_width, index);
+      tree result = gimplify_build2 (gsi, NE_EXPR, ret_inner_type, a, b);
+      t = gimplify_build3 (gsi, BIT_INSERT_EXPR, ret_type, t, result,
+                          bitsize_int (i));
+    }
+
+  return gimplify_build1 (gsi, VIEW_CONVERT_EXPR, type, t);
+}
diff --git a/gcc/gimple-fold.h b/gcc/gimple-fold.h
index 0ed1d1ffe83..7e843b34f53 100644
--- a/gcc/gimple-fold.h
+++ b/gcc/gimple-fold.h
@@ -147,6 +147,20 @@ gimple_build_vector (gimple_seq *seq, tree_vector_builder 
*builder)
   extern bool gimple_stmt_nonnegative_warnv_p (gimple *, bool *, int = 0);
   extern bool gimple_stmt_integer_valued_real_p (gimple *, int = 0);

+/* Return the number of elements in a vector type TYPE that we have
+   already decided needs to be expanded piecewise.  We don't support
+   this kind of expansion for variable-length vectors, since we should
+   always check for target support before introducing uses of those.  */
+
+static inline unsigned int
+nunits_for_known_piecewise_op (const_tree type)
+{
+  return TYPE_VECTOR_SUBPARTS (type).to_constant ();
+}
+
+extern tree expand_cmp_piecewise (gimple_stmt_iterator *gsi, tree lhs,
+                                 tree op0, tree op1);
+
   /* In gimple-match.c.  */
   extern tree gimple_simplify (enum tree_code, tree, tree,
                              gimple_seq *, tree (*)(tree));
diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc
index b330cf4c20e..32e3bc31f7f 100644
--- a/gcc/gimple-isel.cc
+++ b/gcc/gimple-isel.cc
@@ -33,8 +33,8 @@ along with GCC; see the file COPYING3.  If not see
   #include "gimplify-me.h"
   #include "gimplify.h"
   #include "tree-cfg.h"
-#include "bitmap.h"
   #include "tree-ssa-dce.h"
+#include "gimple-fold.h"

   /* Expand all VEC_COND_EXPR gimple assignments into calls to internal
      function based on type of selected expansion.  */
@@ -119,8 +119,12 @@ gimple_expand_vec_cond_expr (gimple_stmt_iterator *gsi,
         /* Fake op0 < 0.  */
         else
         {
-         gcc_assert (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (op0)))
-                     == MODE_VECTOR_INT);
+         if (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (op0))) != MODE_VECTOR_INT)
+           {
+             tree t = expand_cmp_piecewise (gsi, TREE_TYPE (lhs), op0, op1);
+             return gimple_build_assign (lhs, NOP_EXPR, t);
+           }
+
           op0a = op0;
           op0b = build_zero_cst (TREE_TYPE (op0));
           tcode = LT_EXPR;
diff --git a/gcc/testsuite/gcc.dg/vect/pr96466.c 
b/gcc/testsuite/gcc.dg/vect/pr96466.c
new file mode 100644
index 00000000000..8cca5e12ff2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr96466.c
@@ -0,0 +1,18 @@
+/* PR tree-optimization/96466 */
+/* { dg-do compile } */
+/* { dg-options "-Og -finline-functions-called-once -fno-tree-ccp" } */
+
+typedef unsigned long __attribute__ ((__vector_size__ (8))) V;
+
+V
+bar (unsigned long x, V v)
+{
+  v &= x >= v;
+  return (V) v;
+}
+
+V
+foo (void)
+{
+  return bar (5, (V) 4441221375);
+}
diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index 6d5d65195ae..b01aa301baa 100644
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -42,20 +42,11 @@ along with GCC; see the file COPYING3.  If not see
   #include "insn-config.h"
   #include "tree-ssa-dce.h"
   #include "recog.h"            /* FIXME: for insn_data */
+#include "gimple-fold.h"


   static void expand_vector_operations_1 (gimple_stmt_iterator *, bitmap);

-/* Return the number of elements in a vector type TYPE that we have
-   already decided needs to be expanded piecewise.  We don't support
-   this kind of expansion for variable-length vectors, since we should
-   always check for target support before introducing uses of those.  */
-static unsigned int
-nunits_for_known_piecewise_op (const_tree type)
-{
-  return TYPE_VECTOR_SUBPARTS (type).to_constant ();
-}
-
   /* Return true if TYPE1 has more elements than TYPE2, where either
      type may be a vector or a scalar.  */

@@ -427,35 +418,7 @@ expand_vector_comparison (gimple_stmt_iterator *gsi, tree 
type, tree op0,
                        TYPE_VECTOR_SUBPARTS (type)
                        * GET_MODE_BITSIZE (SCALAR_TYPE_MODE
                                                 (TREE_TYPE (type)))))
-       {
-         tree inner_type = TREE_TYPE (TREE_TYPE (op0));
-         tree part_width = vector_element_bits_tree (TREE_TYPE (op0));
-         tree index = bitsize_int (0);
-         int nunits = nunits_for_known_piecewise_op (TREE_TYPE (op0));
-         int prec = GET_MODE_PRECISION (SCALAR_TYPE_MODE (type));
-         tree ret_type = build_nonstandard_integer_type (prec, 1);
-         tree ret_inner_type = boolean_type_node;
-         int i;
-         location_t loc = gimple_location (gsi_stmt (*gsi));
-         t = build_zero_cst (ret_type);
-
-         if (TYPE_PRECISION (ret_inner_type) != 1)
-           ret_inner_type = build_nonstandard_integer_type (1, 1);
-         warning_at (loc, OPT_Wvector_operation_performance,
-                     "vector operation will be expanded piecewise");
-         for (i = 0; i < nunits;
-              i++, index = int_const_binop (PLUS_EXPR, index, part_width))
-           {
-             tree a = tree_vec_extract (gsi, inner_type, op0, part_width,
-                                        index);
-             tree b = tree_vec_extract (gsi, inner_type, op1, part_width,
-                                        index);
-             tree result = gimplify_build2 (gsi, code, ret_inner_type, a, b);
-             t = gimplify_build3 (gsi, BIT_INSERT_EXPR, ret_type, t, result,
-                                  bitsize_int (i));
-           }
-         t = gimplify_build1 (gsi, VIEW_CONVERT_EXPR, type, t);
-       }
+       t = expand_cmp_piecewise (gsi, type, op0, op1);
         else
         t = expand_vector_piecewise (gsi, do_compare, type,
                                      TREE_TYPE (TREE_TYPE (op0)), op0, op1,
--
2.28.0


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