vect: Allow same precision for bit-precision conversions.

In PR111794 we miss a vectorization because on riscv type precision and
mode precision differ for mask types.  We can still vectorize when
allowing assignments with the same precision for dest and source which
is what this patch does.

gcc/ChangeLog:

	PR tree-optimization/111794
	* tree-vect-stmts.cc (vectorizable_assignment): Add
	same-precision exception for dest and source.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/slp-mask-1.c: New test.
	* gcc.target/riscv/rvv/autovec/slp-mask-run-1.c: New test.

3 files changed, 56 insertions, 5 deletions

diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-1.c
new file mode 100644
index 0000000..ee1baa5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-std=gnu99 -O3 -march=rv64gcv -mabi=lp64d --param=riscv-autovec-preference=scalable -fdump-tree-slp-details" } */
+
+void
+__attribute__ ((noipa))
+f (int *restrict x, short *restrict y, int *restrict res)
+{
+  res[0] = x[0] == 1 & y[0] == 2;
+  res[1] = x[1] == 1 & y[1] == 2;
+  res[2] = x[2] == 1 & y[2] == 2;
+  res[3] = x[3] == 1 & y[3] == 2;
+  res[4] = x[4] == 1 & y[4] == 2;
+  res[5] = x[5] == 1 & y[5] == 2;
+  res[6] = x[6] == 1 & y[6] == 2;
+  res[7] = x[7] == 1 & y[7] == 2;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorizing stmts using SLP" 1 "slp2" } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-run-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-run-1.c
new file mode 100644
index 0000000..b3469c4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/slp-mask-run-1.c
@@ -0,0 +1,31 @@
+/* { dg-do run { target { riscv_v } } } */
+/* { dg-additional-options "-std=gnu99 -O3 -march=rv64gcv -mabi=lp64d --param=riscv-autovec-preference=scalable" } */
+
+#include <malloc.h>
+#include <stdio.h>
+
+#include "slp-mask-1.c"
+
+#define SZ 8
+
+__attribute__ ((optimize ("1")))
+int main ()
+{
+  int *a = malloc (SZ * sizeof (*a));
+  short *b = malloc (SZ * sizeof (*b));
+  int *res = malloc (SZ * sizeof (*res));
+  int *ref = malloc (SZ * sizeof (*ref));
+
+  for (int i = 0; i < SZ; i++)
+    {
+      a[i] = i & 1;
+      b[i] = 2;
+      ref[i] = a[i] == 1 & b[i] == 2;
+    }
+
+  f (a, b, res);
+
+  for (int i = 0; i < SZ; i++)
+    if (res[i] != ref[i])
+      __builtin_abort ();
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 99ba75e..a920076 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -6058,14 +6058,16 @@ vectorizable_assignment (vec_info *vinfo,
       /* But a conversion that does not change the bit-pattern is ok.  */
       && !(INTEGRAL_TYPE_P (TREE_TYPE (scalar_dest))
 	   && INTEGRAL_TYPE_P (TREE_TYPE (op))
-	   && (TYPE_PRECISION (TREE_TYPE (scalar_dest))
+	   && (((TYPE_PRECISION (TREE_TYPE (scalar_dest))
 	       > TYPE_PRECISION (TREE_TYPE (op)))
-	   && TYPE_UNSIGNED (TREE_TYPE (op))))
+	     && TYPE_UNSIGNED (TREE_TYPE (op)))
+	       || (TYPE_PRECISION (TREE_TYPE (scalar_dest))
+		   == TYPE_PRECISION (TREE_TYPE (op))))))
     {
       if (dump_enabled_p ())
-        dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-                         "type conversion to/from bit-precision "
-                         "unsupported.\n");
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "type conversion to/from bit-precision "
+			 "unsupported.\n");
       return false;
     }