[PATCH V3] SCCVN: Add LEN_MASK_STORE and fix LEN_STORE

[juzhe.zhong@rivai.ai]

From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

Hi, Richi. It seems that we use nunits which is len + bias to iterate then we can
simplify the codes.

Also, I fixed behavior of len_store,

Before this patch:
   (len - bias) * BITS_PER_UNIT
After this patch:
   (len + bias) * BITS_PER_UNIT
   
gcc/ChangeLog:

        * tree-ssa-sccvn.cc (vn_reference_lookup_3): Add LEN_MASK_STORE and fix LEN_STORE.

---
 gcc/tree-ssa-sccvn.cc | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 11061a374a2..d66e75460ed 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -3304,6 +3304,16 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	  if (!tree_fits_uhwi_p (len) || !tree_fits_shwi_p (bias))
 	    return (void *)-1;
 	  break;
+	case IFN_LEN_MASK_STORE:
+	  len = gimple_call_arg (call, 2);
+	  bias = gimple_call_arg (call, 5);
+	  if (!tree_fits_uhwi_p (len) || !tree_fits_shwi_p (bias))
+	    return (void *)-1;
+	  mask = gimple_call_arg (call, internal_fn_mask_index (fn));
+	  mask = vn_valueize (mask);
+	  if (TREE_CODE (mask) != VECTOR_CST)
+	    return (void *)-1;
+	  break;
 	default:
 	  return (void *)-1;
 	}
@@ -3344,6 +3354,16 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 	      tree vectype = TREE_TYPE (def_rhs);
 	      unsigned HOST_WIDE_INT elsz
 		= tree_to_uhwi (TYPE_SIZE (TREE_TYPE (vectype)));
+	      poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (vectype);
+	      if (len)
+		{
+		  /* Since the following while condition known_lt
+		     (mask_idx, nunits) will exit the while loop
+		     when mask_idx > nunits.coeffs[0], we pick the
+		     MIN (nunits.coeffs[0], len + bias).  */
+		  nunits = MIN (nunits.coeffs[0],
+				tree_to_uhwi (len) + tree_to_shwi (bias));
+		}
 	      if (mask)
 		{
 		  HOST_WIDE_INT start = 0, length = 0;
@@ -3373,7 +3393,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 			length += elsz;
 		      mask_idx++;
 		    }
-		  while (known_lt (mask_idx, TYPE_VECTOR_SUBPARTS (vectype)));
+		  while (known_lt (mask_idx, nunits));
 		  if (length != 0)
 		    {
 		      pd.rhs_off = start;
@@ -3389,7 +3409,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *data_,
 		{
 		  pd.offset = offset2i;
 		  pd.size = (tree_to_uhwi (len)
-			     + -tree_to_shwi (bias)) * BITS_PER_UNIT;
+			     + tree_to_shwi (bias)) * BITS_PER_UNIT;
 		  if (BYTES_BIG_ENDIAN)
 		    pd.rhs_off = pd.size - tree_to_uhwi (TYPE_SIZE (vectype));
 		  else
-- 
2.36.3