[PATCH] middle-end/97579 - lower VECTOR_BOOLEAN_TYPE_P VEC_COND_EXPRs

[Richard Biener]

This makes sure to lower VECTOR_BOOLEAN_TYPE_P typed VEC_COND_EXPRs
so we don't try to use vcond to expand those.  That's especially
improtant for x86 integer mode boolean vectors but eventually
as well for aarch64 / gcn VnBImode ones.

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

2020-11-25  Richard Biener  <rguenther@suse.de>

	PR middle-end/97579
	* gimple-isel.cc (gimple_expand_vec_cond_expr): Lower
	VECTOR_BOOLEAN_TYPE_P VEC_COND_EXPRs.

	* gcc.dg/pr97579.c: New testcase.
---
 gcc/gimple-isel.cc             | 21 +++++++++++++++++++--
 gcc/testsuite/gcc.dg/pr97579.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr97579.c

diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc
index b5362cc4b01..eac1f62e1ff 100644
--- a/gcc/gimple-isel.cc
+++ b/gcc/gimple-isel.cc
@@ -37,6 +37,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssa-dce.h"
 #include "memmodel.h"
 #include "optabs.h"
+#include "gimple-fold.h"
 
 /* Expand all ARRAY_REF(VIEW_CONVERT_EXPR) gimple assignments into calls to
    internal function based on vector type of selected expansion.
@@ -134,6 +135,24 @@ gimple_expand_vec_cond_expr (gimple_stmt_iterator *gsi,
   lhs = gimple_assign_lhs (stmt);
   machine_mode mode = TYPE_MODE (TREE_TYPE (lhs));
 
+  /* Lower mask typed VEC_COND_EXPRs to bitwise operations.  Those can
+     end up generated by folding and at least for integer mode masks
+     we cannot expect vcond expanders to exist.  We lower a ? b : c
+     to (b & a) | (c & ~a).  */
+  if (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (lhs)))
+    {
+      gcc_assert (types_compatible_p (TREE_TYPE (op0), TREE_TYPE (op1)));
+      gimple_seq stmts = NULL;
+      tree type = TREE_TYPE (lhs);
+      location_t loc = gimple_location (stmt);
+      tree tem0 = gimple_build (&stmts, loc, BIT_AND_EXPR, type, op1, op0);
+      tree tem1 = gimple_build (&stmts, loc, BIT_NOT_EXPR, type, op0);
+      tree tem2 = gimple_build (&stmts, loc, BIT_AND_EXPR, type, op2, tem1);
+      tree tem3 = gimple_build (&stmts, loc, BIT_IOR_EXPR, type, tem0, tem2);
+      gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+      return gimple_build_assign (lhs, tem3);
+    }
+
   gcc_assert (!COMPARISON_CLASS_P (op0));
   if (TREE_CODE (op0) == SSA_NAME)
     {
@@ -198,7 +217,6 @@ gimple_expand_vec_cond_expr (gimple_stmt_iterator *gsi,
   cmp_op_mode = TYPE_MODE (TREE_TYPE (op0a));
   unsignedp = TYPE_UNSIGNED (TREE_TYPE (op0a));
 
-
   gcc_assert (known_eq (GET_MODE_NUNITS (mode),
 			GET_MODE_NUNITS (cmp_op_mode)));
 
@@ -246,7 +264,6 @@ gimple_expand_vec_exprs (void)
 	{
 	  gimple *g = gimple_expand_vec_cond_expr (&gsi,
 						   &vec_cond_ssa_name_uses);
-
 	  if (g != NULL)
 	    {
 	      tree lhs = gimple_assign_lhs (gsi_stmt (gsi));
diff --git a/gcc/testsuite/gcc.dg/pr97579.c b/gcc/testsuite/gcc.dg/pr97579.c
new file mode 100644
index 00000000000..5cd5427a528
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97579.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 --param=max-unswitch-insns=1024" } */
+/* { dg-additional-options "-mavx512vl" { target x86_64-*-* i?86-*-* } } */
+
+int bad_odd_rows_0_0, rows_bad_row1, rows_bad_group_okay, calc_rows_row2;
+
+int
+rows_bad() {
+  int i, in_zeroes;
+  char block;
+  i = 0;
+  for (; i < 5; i++)
+    if (rows_bad_row1 & i)
+      in_zeroes = 0;
+    else {
+      if (!in_zeroes)
+        in_zeroes = 1;
+      if (block & 1)
+        rows_bad_group_okay = 1;
+    }
+  if (in_zeroes)
+    return rows_bad_group_okay;
+}
+
+void
+calc_rows() {
+  for (; calc_rows_row2; calc_rows_row2++) {
+    rows_bad();
+    bad_odd_rows_0_0 = rows_bad();
+  }
+}
-- 
2.26.2