[PATCH] RISC-V: Make liveness be aware of rgroup number of LENS[dynamic LMUL]

[Juzhe-Zhong <juzhe.zhong@rivai.ai>]

This patch fixes the following situation:
vl4re16.v       v12,0(a5)
...
vl4re16.v       v16,0(a3)
vs4r.v  v12,0(a5)
...
vl4re16.v       v4,0(a0)
vs4r.v  v16,0(a3)
...
vsetvli a3,zero,e16,m4,ta,ma
...
vmv.v.x v8,t6
vmsgeu.vv       v2,v16,v8
vsub.vv v16,v16,v8
vs4r.v  v16,0(a5)
...
vs4r.v  v4,0(a0)
vmsgeu.vv       v1,v4,v8
...
vsub.vv v4,v4,v8
slli    a6,a4,2
vs4r.v  v4,0(a5)
...
vsub.vv v4,v12,v8
vmsgeu.vv       v3,v12,v8
vs4r.v  v4,0(a5)
...

There are many spills which are 'vs4r.v'.  The root cause is that we don't count
vector REG liveness referencing the rgroup controls.

_29 = _25->iatom[0]; is transformed into the following vect statement with 4 different loop_len (loop_len_74, loop_len_75, loop_len_76, loop_len_77).

  vect__29.11_78 = .MASK_LEN_LOAD (vectp_sb.9_72, 32B, { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }, loop_len_74, 0);
  vect__29.12_80 = .MASK_LEN_LOAD (vectp_sb.9_79, 32B, { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }, loop_len_75, 0);
  vect__29.13_82 = .MASK_LEN_LOAD (vectp_sb.9_81, 32B, { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }, loop_len_76, 0);
  vect__29.14_84 = .MASK_LEN_LOAD (vectp_sb.9_83, 32B, { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }, loop_len_77, 0);

which are the LENS number (LOOP_VINFO_LENS (loop_vinfo).length ()).

Count liveness according to LOOP_VINFO_LENS (loop_vinfo).length () to compute liveness more accurately:

vsetivli	zero,8,e16,m1,ta,ma
vmsgeu.vi	v19,v14,8
vadd.vi	v18,v14,-8
vmsgeu.vi	v17,v1,8
vadd.vi	v16,v1,-8
vlm.v	v15,0(a5)
...

Tested no regression, ok for trunk ?

	PR target/113112

gcc/ChangeLog:

	* config/riscv/riscv-vector-costs.cc (compute_nregs_for_mode): Add rgroup info.
	(max_number_of_live_regs): Ditto.
	(has_unexpected_spills_p): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/costmodel/riscv/rvv/pr113112-5.c: New test.

---
 gcc/config/riscv/riscv-vector-costs.cc        | 34 +++++++++++++++----
 .../vect/costmodel/riscv/rvv/pr113112-5.c     | 24 +++++++++++++
 2 files changed, 52 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr113112-5.c

diff --git a/gcc/config/riscv/riscv-vector-costs.cc b/gcc/config/riscv/riscv-vector-costs.cc
index 1199b3af067..12d3b57aff6 100644
--- a/gcc/config/riscv/riscv-vector-costs.cc
+++ b/gcc/config/riscv/riscv-vector-costs.cc
@@ -373,13 +373,17 @@ compute_local_live_ranges (
    E.g. If mode = SImode, biggest_mode = DImode, LMUL = M4.
 	Then return RVVM4SImode (LMUL = 4, element mode = SImode).  */
 static unsigned int
-compute_nregs_for_mode (machine_mode mode, machine_mode biggest_mode, int lmul)
+compute_nregs_for_mode (loop_vec_info loop_vinfo, machine_mode mode,
+			machine_mode biggest_mode, int lmul)
 {
+  unsigned int rgroup_size = LOOP_VINFO_LENS (loop_vinfo).is_empty ()
+			       ? 1
+			       : LOOP_VINFO_LENS (loop_vinfo).length ();
   unsigned int mode_size = GET_MODE_SIZE (mode).to_constant ();
   unsigned int biggest_size = GET_MODE_SIZE (biggest_mode).to_constant ();
   gcc_assert (biggest_size >= mode_size);
   unsigned int ratio = biggest_size / mode_size;
-  return MAX (lmul / ratio, 1);
+  return MAX (lmul / ratio, 1) * rgroup_size;
 }
 
 /* This function helps to determine whether current LMUL will cause
@@ -393,7 +397,7 @@ compute_nregs_for_mode (machine_mode mode, machine_mode biggest_mode, int lmul)
        mode.
      - Third, Return the maximum V_REGs are alive of the loop.  */
 static unsigned int
-max_number_of_live_regs (const basic_block bb,
+max_number_of_live_regs (loop_vec_info loop_vinfo, const basic_block bb,
 			 const hash_map<tree, pair> &live_ranges,
 			 unsigned int max_point, machine_mode biggest_mode,
 			 int lmul)
@@ -412,7 +416,7 @@ max_number_of_live_regs (const basic_block bb,
 	{
 	  machine_mode mode = TYPE_MODE (TREE_TYPE (var));
 	  unsigned int nregs
-	    = compute_nregs_for_mode (mode, biggest_mode, lmul);
+	    = compute_nregs_for_mode (loop_vinfo, mode, biggest_mode, lmul);
 	  live_vars_vec[i] += nregs;
 	  if (live_vars_vec[i] > max_nregs)
 	    {
@@ -687,6 +691,24 @@ update_local_live_ranges (
 		dump_printf_loc (MSG_NOTE, vect_location,
 				 "Add perm indice %T, start = 0, end = %d\n",
 				 sel, max_point);
+	      if (!LOOP_VINFO_LENS (loop_vinfo).is_empty ()
+		  && LOOP_VINFO_LENS (loop_vinfo).length () > 1)
+		{
+		  /* If we are vectorizing a permutation when the rgroup number
+		     > 1, we will need additional mask to shuffle the second
+		     vector.  */
+		  tree mask = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+					  get_identifier ("vect_perm_mask"),
+					  boolean_type_node);
+		  pair &live_range
+		    = live_ranges->get_or_insert (mask, &existed_p);
+		  gcc_assert (!existed_p);
+		  live_range = pair (0, max_point);
+		  if (dump_enabled_p ())
+		    dump_printf_loc (MSG_NOTE, vect_location,
+				     "Add perm mask %T, start = 0, end = %d\n",
+				     mask, max_point);
+		}
 	    }
 	}
     }
@@ -730,8 +752,8 @@ has_unexpected_spills_p (loop_vec_info loop_vinfo)
 		continue;
 	      /* We prefer larger LMUL unless it causes register spillings. */
 	      unsigned int nregs
-		= max_number_of_live_regs (bb, (*iter).second, max_point,
-					   biggest_mode, lmul);
+		= max_number_of_live_regs (loop_vinfo, bb, (*iter).second,
+					   max_point, biggest_mode, lmul);
 	      if (nregs > max_nregs)
 		max_nregs = nregs;
 	    }
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr113112-5.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr113112-5.c
new file mode 100644
index 00000000000..117d54f68f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr113112-5.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -ftree-vectorize --param riscv-autovec-lmul=dynamic --param riscv-autovec-preference=fixed-vlmax -fno-schedule-insns -fno-schedule-insns2" } */
+
+typedef struct {
+  int iatom[3];
+  int blocknr;
+} t_sortblock;
+
+#define DIM 3
+
+void foo (int ncons, t_sortblock *sb, int *iatom)
+{
+ int i, m;
+
+ for(i=0; (i<ncons); i++,iatom+=3)
+   for(m=0; (m<DIM); m++)
+     iatom[m]=sb[i].iatom[m];
+}
+
+/* { dg-final { scan-assembler {e32,m2} } } */
+/* { dg-final { scan-assembler-not {vs1r} } } */
+/* { dg-final { scan-assembler-not {vs2r} } } */
+/* { dg-final { scan-assembler-not {vs4r} } } */
+/* { dg-final { scan-assembler-not {vs8r} } } */
-- 
2.36.3