PR 49742: call lhs being ignored

[Richard Sandiford]

In 49742, we have:

  vect_array.21 = LOAD_LANES (MEM[(int[512] *)vect_pin.17_56]);
  vect_var_.22_58 = vect_array.21[0];

predcom doesn't think that there are any dependencies between
the two statements, so hoists the second one as an invariant.
This in turn is because get_references_in_stmt ignores the lhs
of calls.

Tested on x86_64-linux-gnu and arm-linux-gnueabi.  OK to install?

Richard


gcc/
	PR tree-optimization/49742
	* tree-data-ref.c (get_references_in_stmt): Treat the lhs of a call
	as a potential write.

Index: gcc/tree-data-ref.c
===================================================================
--- gcc/tree-data-ref.c	2011-07-19 10:53:10.000000000 +0100
+++ gcc/tree-data-ref.c	2011-07-19 13:08:12.000000000 +0100
@@ -4158,33 +4158,37 @@ get_references_in_stmt (gimple stmt, VEC
 	  ref->pos = op1;
 	  ref->is_read = true;
 	}
-
-      if (DECL_P (*op0)
-	  || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0)))
-	{
-	  ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
-	  ref->pos = op0;
-	  ref->is_read = false;
-	}
     }
   else if (stmt_code == GIMPLE_CALL)
     {
-      unsigned i, n = gimple_call_num_args (stmt);
+      unsigned i, n;
 
+      op0 = gimple_call_lhs_ptr (stmt);
+      n = gimple_call_num_args (stmt);
       for (i = 0; i < n; i++)
 	{
-	  op0 = gimple_call_arg_ptr (stmt, i);
+	  op1 = gimple_call_arg_ptr (stmt, i);
 
-	  if (DECL_P (*op0)
-	      || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0)))
+	  if (DECL_P (*op1)
+	      || (REFERENCE_CLASS_P (*op1) && get_base_address (*op1)))
 	    {
 	      ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
-	      ref->pos = op0;
+	      ref->pos = op1;
 	      ref->is_read = true;
 	    }
 	}
     }
+  else
+    return clobbers_memory;
 
+  if (*op0
+      && (DECL_P (*op0)
+	  || (REFERENCE_CLASS_P (*op0) && get_base_address (*op0))))
+    {
+      ref = VEC_safe_push (data_ref_loc, heap, *references, NULL);
+      ref->pos = op0;
+      ref->is_read = false;
+    }
   return clobbers_memory;
 }