VECT: Support loop len control on EXTRACT_LAST vectorization

Hi, @Richi and @Richard, base on previous disscussion, I simpily fix issuses for
powerpc and s390 with your suggestions:

-  machine_mode len_load_mode = get_len_load_store_mode
-    (loop_vinfo->vector_mode, true).require ();
-  machine_mode len_store_mode = get_len_load_store_mode
-    (loop_vinfo->vector_mode, false).require ();
+  machine_mode len_load_mode, len_store_mode;
+  if (!get_len_load_store_mode (loop_vinfo->vector_mode, true)
+        .exists (&len_load_mode))
+    return false;
+  if (!get_len_load_store_mode (loop_vinfo->vector_mode, false)
+        .exists (&len_store_mode))
+    return false;

Co-Authored-By: Kewen.Lin <linkw@linux.ibm.com>

gcc/ChangeLog:

	* tree-vect-loop.cc (vect_verify_loop_lens): Add exists check.
	(vectorizable_live_operation): Add live vectorization for length loop
	control.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/partial/live-1.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/live_run-1.c: New test.

3 files changed, 138 insertions, 20 deletions

diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live-1.c
new file mode 100644
index 0000000..75fa2eb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live-1.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-march=rv32gcv -mabi=ilp32d --param riscv-autovec-preference=scalable -fdump-tree-optimized-details" } */
+
+#include <stdint-gcc.h>
+
+#define EXTRACT_LAST(TYPE)                                                     \
+  TYPE __attribute__ ((noinline, noclone))                                     \
+  test_##TYPE (TYPE *x, int n, TYPE value)                                     \
+  {                                                                            \
+    TYPE last;                                                                 \
+    for (int j = 0; j < n; ++j)                                                \
+      {                                                                        \
+	last = x[j];                                                           \
+	x[j] = last * value;                                                   \
+      }                                                                        \
+    return last;                                                               \
+  }
+
+#define TEST_ALL(T)                                                            \
+  T (int8_t)                                                                   \
+  T (int16_t)                                                                  \
+  T (int32_t)                                                                  \
+  T (int64_t)                                                                  \
+  T (uint8_t)                                                                  \
+  T (uint16_t)                                                                 \
+  T (uint32_t)                                                                 \
+  T (uint64_t)                                                                 \
+  T (_Float16)                                                                 \
+  T (float)                                                                    \
+  T (double)
+
+TEST_ALL (EXTRACT_LAST)
+
+/* { dg-final { scan-tree-dump-times "\.VEC_EXTRACT" 10 "optimized" } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live_run-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live_run-1.c
new file mode 100644
index 0000000..42913a1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/partial/live_run-1.c
@@ -0,0 +1,35 @@
+/* { dg-do run { target { riscv_vector } } } */
+/* { dg-additional-options "--param riscv-autovec-preference=scalable" } */
+
+#include "live-1.c"
+
+#define N 107
+#define OP 70
+
+#define TEST_LOOP(TYPE)				\
+  {						\
+    TYPE a[N];					\
+    for (int i = 0; i < N; ++i)			\
+      {						\
+	a[i] = i * 2 + (i % 3);			\
+	asm volatile ("" ::: "memory");		\
+      }						\
+    TYPE expected = a[N - 1];			\
+    TYPE res = test_##TYPE (a, N, OP);		\
+    if (res != expected)			\
+      __builtin_abort ();			\
+    for (int i = 0; i < N; ++i)			\
+      {						\
+	TYPE old = i * 2 + (i % 3);		\
+	if (a[i] != (TYPE) (old * (TYPE) OP))	\
+	  __builtin_abort ();			\
+	asm volatile ("" ::: "memory");		\
+      }						\
+  }
+
+int __attribute__ ((optimize (1)))
+main (void)
+{
+  TEST_ALL (TEST_LOOP);
+  return 0;
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 1fcd8d0..1cd6c29 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -32,6 +32,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "ssa.h"
 #include "optabs-tree.h"
+#include "memmodel.h"
+#include "optabs.h"
 #include "diagnostic-core.h"
 #include "fold-const.h"
 #include "stor-layout.h"
@@ -1465,10 +1467,13 @@ vect_verify_loop_lens (loop_vec_info loop_vinfo)
   if (LOOP_VINFO_LENS (loop_vinfo).is_empty ())
     return false;
 
-  machine_mode len_load_mode = get_len_load_store_mode
-    (loop_vinfo->vector_mode, true).require ();
-  machine_mode len_store_mode = get_len_load_store_mode
-    (loop_vinfo->vector_mode, false).require ();
+  machine_mode len_load_mode, len_store_mode;
+  if (!get_len_load_store_mode (loop_vinfo->vector_mode, true)
+	 .exists (&len_load_mode))
+    return false;
+  if (!get_len_load_store_mode (loop_vinfo->vector_mode, false)
+	 .exists (&len_store_mode))
+    return false;
 
   signed char partial_load_bias = internal_len_load_store_bias
     (IFN_LEN_LOAD, len_load_mode);
@@ -10301,17 +10306,7 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
       /* No transformation required.  */
       if (loop_vinfo && LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
 	{
-	  if (!direct_internal_fn_supported_p (IFN_EXTRACT_LAST, vectype,
-					       OPTIMIZE_FOR_SPEED))
-	    {
-	      if (dump_enabled_p ())
-		dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-				 "can't operate on partial vectors "
-				 "because the target doesn't support extract "
-				 "last reduction.\n");
-	      LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
-	    }
-	  else if (slp_node)
+	  if (slp_node)
 	    {
 	      if (dump_enabled_p ())
 		dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -10331,9 +10326,26 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
 	  else
 	    {
 	      gcc_assert (ncopies == 1 && !slp_node);
-	      vect_record_loop_mask (loop_vinfo,
-				     &LOOP_VINFO_MASKS (loop_vinfo),
-				     1, vectype, NULL);
+	      if (direct_internal_fn_supported_p (IFN_EXTRACT_LAST, vectype,
+						  OPTIMIZE_FOR_SPEED))
+		vect_record_loop_mask (loop_vinfo,
+				       &LOOP_VINFO_MASKS (loop_vinfo),
+				       1, vectype, NULL);
+	      else if (can_vec_extract_var_idx_p (
+			 TYPE_MODE (vectype), TYPE_MODE (TREE_TYPE (vectype))))
+		vect_record_loop_len (loop_vinfo,
+				      &LOOP_VINFO_LENS (loop_vinfo),
+				      1, vectype, 1);
+	      else
+		{
+		  if (dump_enabled_p ())
+		    dump_printf_loc (
+		      MSG_MISSED_OPTIMIZATION, vect_location,
+		      "can't operate on partial vectors "
+		      "because the target doesn't support extract "
+		      "last reduction.\n");
+		  LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
+		}
 	    }
 	}
       /* ???  Enable for loop costing as well.  */
@@ -10359,7 +10371,9 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
   gimple *vec_stmt;
   if (slp_node)
     {
-      gcc_assert (!loop_vinfo || !LOOP_VINFO_FULLY_MASKED_P (loop_vinfo));
+      gcc_assert (!loop_vinfo
+		  || (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
+		      && !LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo)));
 
       /* Get the correct slp vectorized stmt.  */
       vec_lhs = SLP_TREE_VEC_DEFS (slp_node)[vec_entry];
@@ -10403,7 +10417,42 @@ vectorizable_live_operation (vec_info *vinfo, stmt_vec_info stmt_info,
 
       gimple_seq stmts = NULL;
       tree new_tree;
-      if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
+      if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
+	{
+	  /* Emit:
+
+	       SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN + BIAS - 1>
+
+	     where VEC_LHS is the vectorized live-out result and MASK is
+	     the loop mask for the final iteration.  */
+	  gcc_assert (ncopies == 1 && !slp_node);
+	  gimple_seq tem = NULL;
+	  gimple_stmt_iterator gsi = gsi_last (tem);
+	  tree len
+	    = vect_get_loop_len (loop_vinfo, &gsi,
+				 &LOOP_VINFO_LENS (loop_vinfo),
+				 1, vectype, 0, 0);
+
+	  /* BIAS - 1.  */
+	  signed char biasval = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
+	  tree bias_minus_one
+	    = int_const_binop (MINUS_EXPR,
+			       build_int_cst (TREE_TYPE (len), biasval),
+			       build_one_cst (TREE_TYPE (len)));
+
+	  /* LAST_INDEX = LEN + (BIAS - 1).  */
+	  tree last_index = gimple_build (&stmts, PLUS_EXPR, TREE_TYPE (len),
+					  len, bias_minus_one);
+
+	  /* SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN + BIAS - 1>.  */
+	  tree scalar_res
+	    = gimple_build (&stmts, CFN_VEC_EXTRACT, TREE_TYPE (vectype),
+			    vec_lhs_phi, last_index);
+
+	  /* Convert the extracted vector element to the scalar type.  */
+	  new_tree = gimple_convert (&stmts, lhs_type, scalar_res);
+	}
+      else if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
 	{
 	  /* Emit: