re PR tree-optimization/38884 (missed FRE with __real and __imag)

2011-10-06  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/38884
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle partial
	reads from aggregate SSA names.

	* gcc.dg/tree-ssa/ssa-fre-34.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-35.c: Likewise.

From-SVN: r179593

gcc/ChangeLog

+2011-10-06  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/38884
+	* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle partial
+	reads from aggregate SSA names.
+
 2011-10-05  Jakub Jelinek  <jakub@redhat.com>
 
 	* tree-vect-patterns.c (vect_pattern_recog_1): Add stmts_to_replace

gcc/testsuite/ChangeLog

+2011-10-06  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/38884
+	* gcc.dg/tree-ssa/ssa-fre-34.c: New testcase.
+	* gcc.dg/tree-ssa/ssa-fre-35.c: Likewise.
+
 2011-10-05  David S. Miller  <davem@davemloft.net>
 
 	* gcc.target/sparc/lzd.c: New test.

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-34.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1-details" } */
+
+#define vector __attribute__((vector_size(16) ))
+
+struct {
+    float i;
+    vector float global_res;
+} s;
+float foo(float f)
+{
+  vector float res = (vector float){0.0f,f,0.0f,1.0f};
+  s.global_res = res;
+  return *((float*)&s.global_res + 1);
+}
+
+/* { dg-final { scan-tree-dump "Replaced BIT_FIELD_REF.*with f" "fre1" } } */
+/* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-35.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1-details" } */
+
+struct s { _Complex float i; };
+void g(struct s *);
+
+float a1 (float dd)
+{
+  struct s sv;
+  sv.i = dd;
+  float d = __real__ sv.i;
+  g(&sv);
+  return d;
+}
+
+/* { dg-final { scan-tree-dump "Replaced REALPART_EXPR.*with dd" "fre1" } } */
+/* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/tree-ssa-sccvn.c

@@ -1489,7 +1489,66 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
 	}
     }
 
-  /* 4) For aggregate copies translate the reference through them if
+  /* 4) Assignment from an SSA name which definition we may be able
+     to access pieces from.  */
+  else if (ref->size == maxsize
+	   && is_gimple_reg_type (vr->type)
+	   && gimple_assign_single_p (def_stmt)
+	   && TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME)
+    {
+      tree rhs1 = gimple_assign_rhs1 (def_stmt);
+      gimple def_stmt2 = SSA_NAME_DEF_STMT (rhs1);
+      if (is_gimple_assign (def_stmt2)
+	  && (gimple_assign_rhs_code (def_stmt2) == COMPLEX_EXPR
+	      || gimple_assign_rhs_code (def_stmt2) == CONSTRUCTOR)
+	  && types_compatible_p (vr->type, TREE_TYPE (TREE_TYPE (rhs1))))
+	{
+	  tree base2;
+	  HOST_WIDE_INT offset2, size2, maxsize2, off;
+	  base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt),
+					   &offset2, &size2, &maxsize2);
+	  off = offset - offset2;
+	  if (maxsize2 != -1
+	      && maxsize2 == size2
+	      && operand_equal_p (base, base2, 0)
+	      && offset2 <= offset
+	      && offset2 + size2 >= offset + maxsize)
+	    {
+	      tree val = NULL_TREE;
+	      HOST_WIDE_INT elsz
+		= TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (TREE_TYPE (rhs1))));
+	      if (gimple_assign_rhs_code (def_stmt2) == COMPLEX_EXPR)
+		{
+		  if (off == 0)
+		    val = gimple_assign_rhs1 (def_stmt2);
+		  else if (off == elsz)
+		    val = gimple_assign_rhs2 (def_stmt2);
+		}
+	      else if (gimple_assign_rhs_code (def_stmt2) == CONSTRUCTOR
+		       && off % elsz == 0)
+		{
+		  tree ctor = gimple_assign_rhs1 (def_stmt2);
+		  unsigned i = off / elsz;
+		  if (i < CONSTRUCTOR_NELTS (ctor))
+		    {
+		      constructor_elt *elt = CONSTRUCTOR_ELT (ctor, i);
+		      if (compare_tree_int (elt->index, i) == 0)
+			val = elt->value;
+		    }
+		}
+	      if (val)
+		{
+		  unsigned int value_id = get_or_alloc_constant_value_id (val);
+		  return vn_reference_insert_pieces
+		           (vuse, vr->set, vr->type,
+			    VEC_copy (vn_reference_op_s, heap, vr->operands),
+			    val, value_id);
+		}
+	    }
+	}
+    }
+
+  /* 5) For aggregate copies translate the reference through them if
      the copy kills ref.  */
   else if (vn_walk_kind == VN_WALKREWRITE
 	   && gimple_assign_single_p (def_stmt)
@@ -1587,7 +1646,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
       return NULL;
     }
 
-  /* 5) For memcpy copies translate the reference through them if
+  /* 6) For memcpy copies translate the reference through them if
      the copy kills ref.  */
   else if (vn_walk_kind == VN_WALKREWRITE
 	   && is_gimple_reg_type (vr->type)