re PR target/92908 (wrong code with -Og -fno-tree-fre -mavx512bw and vector compare)

	PR target/92908
	* simplify-rtx.c (simplify_relational_operation): Punt for vector
	cmp_mode and scalar mode, if simplify_relational_operation returned
	const_true_rtx.
	(simplify_const_relational_operation): Change VOID_mode in function
	comment to VOIDmode.

	* gcc.target/i386/avx512bw-pr92908.c: New test.

From-SVN: r279369

gcc/ChangeLog

+2019-12-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/92908
+	* simplify-rtx.c (simplify_relational_operation): Punt for vector
+	cmp_mode and scalar mode, if simplify_relational_operation returned
+	const_true_rtx.
+	(simplify_const_relational_operation): Change VOID_mode in function
+	comment to VOIDmode.
+
 2019-12-13  Kewen Lin  <linkw@gcc.gnu.org>
 
 	* config/rs6000/rs6000.c (adjust_vectorization_cost): New function.

gcc/simplify-rtx.c

@@ -5037,6 +5037,15 @@ simplify_relational_operation (enum rtx_code code, machine_mode mode,
 	  return NULL_RTX;
 #endif
 	}
+      /* For vector comparison with scalar int result, it is unknown
+	 if the target means here a comparison into an integral bitmask,
+	 or comparison where all comparisons true mean const_true_rtx
+	 whole result, or where any comparisons true mean const_true_rtx
+	 whole result.  For const0_rtx all the cases are the same.  */
+      if (VECTOR_MODE_P (cmp_mode)
+	  && SCALAR_INT_MODE_P (mode)
+	  && tem == const_true_rtx)
+	return NULL_RTX;
 
       return tem;
     }
@@ -5383,7 +5392,7 @@ comparison_result (enum rtx_code code, int known_results)
 }
 
 /* Check if the given comparison (done in the given MODE) is actually
-   a tautology or a contradiction.  If the mode is VOID_mode, the
+   a tautology or a contradiction.  If the mode is VOIDmode, the
    comparison is done in "infinite precision".  If no simplification
    is possible, this function returns zero.  Otherwise, it returns
    either const_true_rtx or const0_rtx.  */

gcc/testsuite/ChangeLog

+2019-12-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/92908
+	* gcc.target/i386/avx512bw-pr92908.c: New test.
+
 2019-12-13  Andrew Pinski  <apinski@marvell.com>
 
 	* gcc.c-torture/execute/pr86659-1.c: New test.

gcc/testsuite/gcc.target/i386/avx512bw-pr92908.c

+/* PR target/92908 */
+/* { dg-do run } */
+/* { dg-options "-Og -fno-tree-fre -mavx512bw" } */
+/* { dg-require-effective-target avx512bw } */
+
+#define AVX512BW
+#include "avx512f-helper.h"
+
+typedef unsigned short V __attribute__ ((__vector_size__ (64)));
+
+V v;
+
+void
+TEST (void)
+{
+  int i;
+  v = (V) v == v;
+  for (i = 0; i < 32; i++)
+    if (v[i] != 0xffff)
+      abort ();
+}