Move code that stubs out IFN_MASK_LOADs

vectorizable_mask_load_store replaces scalar IFN_MASK_LOAD calls with
dummy assignments, so that they never survive vectorisation.  This patch
moves the code to vect_transform_loop instead, so that we only change
the scalar statements once all of them have been vectorised.

This makes it easier to handle other types of functions that need
stubbing out, and also makes it easier to handle groups and patterns.

2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* tree-vect-loop.c (vect_transform_loop): Stub out scalar
	IFN_MASK_LOAD calls here rather than...
	* tree-vect-stmts.c (vectorizable_mask_load_store): ...here.

From-SVN: r256210

gcc/ChangeLog

 2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	* tree-vect-loop.c (vect_transform_loop): Stub out scalar
+	IFN_MASK_LOAD calls here rather than...
+	* tree-vect-stmts.c (vectorizable_mask_load_store): ...here.
+
+2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 

gcc/tree-vect-loop.c

@@ -7810,6 +7810,25 @@ vect_transform_loop (loop_vec_info loop_vinfo)
 	      gsi_next (&si);
 	    }
 	}		        /* stmts in BB */
+
+      /* Stub out scalar statements that must not survive vectorization.
+	 Doing this here helps with grouped statements, or statements that
+	 are involved in patterns.  */
+      for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
+	   !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gcall *call = dyn_cast <gcall *> (gsi_stmt (gsi));
+	  if (call && gimple_call_internal_p (call, IFN_MASK_LOAD))
+	    {
+	      tree lhs = gimple_get_lhs (call);
+	      if (!VECTOR_TYPE_P (TREE_TYPE (lhs)))
+		{
+		  tree zero = build_zero_cst (TREE_TYPE (lhs));
+		  gimple *new_stmt = gimple_build_assign (lhs, zero);
+		  gsi_replace (&gsi, new_stmt, true);
+		}
+	    }
+	}
     }				/* BBs in loop */
 
   /* The vectorization factor is always > 1, so if we use an IV increment of 1.

gcc/tree-vect-stmts.c

@@ -2347,20 +2347,6 @@ vectorizable_mask_load_store (gimple *stmt, gimple_stmt_iterator *gsi,
 	    STMT_VINFO_RELATED_STMT (prev_stmt_info) = new_stmt;
 	  prev_stmt_info = vinfo_for_stmt (new_stmt);
 	}
-
-      /* Ensure that even with -fno-tree-dce the scalar MASK_LOAD is removed
-	 from the IL.  */
-      if (STMT_VINFO_RELATED_STMT (stmt_info))
-	{
-	  stmt = STMT_VINFO_RELATED_STMT (stmt_info);
-	  stmt_info = vinfo_for_stmt (stmt);
-	}
-      tree lhs = gimple_call_lhs (stmt);
-      new_stmt = gimple_build_assign (lhs, build_zero_cst (TREE_TYPE (lhs)));
-      set_vinfo_for_stmt (new_stmt, stmt_info);
-      set_vinfo_for_stmt (stmt, NULL);
-      STMT_VINFO_STMT (stmt_info) = new_stmt;
-      gsi_replace (gsi, new_stmt, true);
       return true;
     }
   else if (vls_type != VLS_LOAD)
@@ -2477,23 +2463,6 @@ vectorizable_mask_load_store (gimple *stmt, gimple_stmt_iterator *gsi,
 	}
     }
 
-  if (vls_type == VLS_LOAD)
-    {
-      /* Ensure that even with -fno-tree-dce the scalar MASK_LOAD is removed
-	 from the IL.  */
-      if (STMT_VINFO_RELATED_STMT (stmt_info))
-	{
-	  stmt = STMT_VINFO_RELATED_STMT (stmt_info);
-	  stmt_info = vinfo_for_stmt (stmt);
-	}
-      tree lhs = gimple_call_lhs (stmt);
-      new_stmt = gimple_build_assign (lhs, build_zero_cst (TREE_TYPE (lhs)));
-      set_vinfo_for_stmt (new_stmt, stmt_info);
-      set_vinfo_for_stmt (stmt, NULL);
-      STMT_VINFO_STMT (stmt_info) = new_stmt;
-      gsi_replace (gsi, new_stmt, true);
-    }
-
   return true;
 }