re PR tree-optimization/33723 (Inefficient code with compound literals)

	PR tree-optimization/33723
	* c-gimplify.c (c_gimplify_expr): Optimize INIT_EXPR or
	MODIFY_EXPR with non-addressable COMPOUND_LITERAL_EXPR as source.

	* gcc.c-torture/execute/20071029-1.c: New test.
	* gcc.dg/tree-ssa/pr33723.c: New test.

From-SVN: r129743

gcc/ChangeLog

+2007-10-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/33723
+	* c-gimplify.c (c_gimplify_expr): Optimize INIT_EXPR or
+	MODIFY_EXPR with non-addressable COMPOUND_LITERAL_EXPR as source.
+
 2007-10-29  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	PR tree-optimization/33614

gcc/c-gimplify.c

@@ -233,6 +233,29 @@ c_gimplify_expr (tree *expr_p, tree *pre_p, tree *post_p ATTRIBUTE_UNUSED)
     case COMPOUND_LITERAL_EXPR:
       return gimplify_compound_literal_expr (expr_p, pre_p);
 
+    case INIT_EXPR:
+    case MODIFY_EXPR:
+      if (TREE_CODE (TREE_OPERAND (*expr_p, 1)) == COMPOUND_LITERAL_EXPR)
+	{
+	  tree complit = TREE_OPERAND (*expr_p, 1);
+	  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_STMT (complit);
+	  tree decl = DECL_EXPR_DECL (decl_s);
+	  tree init = DECL_INITIAL (decl);
+
+	  /* struct T x = (struct T) { 0, 1, 2 } can be optimized
+	     into struct T x = { 0, 1, 2 } if the address of the
+	     compound literal has never been taken.  */
+	  if (!TREE_ADDRESSABLE (complit)
+	      && !TREE_ADDRESSABLE (decl)
+	      && init)
+	    {
+	      *expr_p = copy_node (*expr_p);
+	      TREE_OPERAND (*expr_p, 1) = init;
+	      return GS_OK;
+	    }
+	}
+      return GS_UNHANDLED;
+
     default:
       return GS_UNHANDLED;
     }

gcc/testsuite/ChangeLog

+2007-10-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/33723
+	* gcc.c-torture/execute/20071029-1.c: New test.
+	* gcc.dg/tree-ssa/pr33723.c: New test.
+
 2007-10-29  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	PR tree-optimization/33614

gcc/testsuite/gcc.c-torture/execute/20071029-1.c

+extern void exit (int);
+extern void abort (void);
+
+typedef union
+{
+  struct
+  {
+    int f1, f2, f3, f4, f5, f6, f7, f8;
+    long int f9, f10;
+    int f11;
+  } f;
+  char s[56];
+  long int a;
+} T;
+
+__attribute__((noinline))
+void
+test (T *t)
+{
+  static int i = 11;
+  if (t->f.f1 != i++)
+    abort ();
+  if (t->f.f2 || t->f.f3 || t->f.f4 || t->f.f5 || t->f.f6
+      || t->f.f7 || t->f.f8 || t->f.f9 || t->f.f10 || t->f.f11)
+    abort ();
+  if (i == 20)
+    exit (0);
+}
+
+__attribute__((noinline))
+void
+foo (int i)
+{
+  T t;
+again:
+  t = (T) { { ++i, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } };
+  test (&t);
+  goto again;
+}
+
+int
+main (void)
+{
+  T *t1, *t2;
+  int cnt = 0;
+  t1 = (T *) 0;
+loop:
+  t2 = t1;
+  t1 = & (T) { .f.f9 = cnt++ };
+  if (cnt < 3)
+    goto loop;
+  if (t1 != t2 || t1->f.f9 != 2)
+    abort ();
+  foo (10);
+  return 0;
+}

gcc/testsuite/gcc.dg/tree-ssa/pr33723.c

+/* PR tree-optimization/33723 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-gimple" } */
+
+typedef union
+{
+  struct
+  {
+    int f1, f2, f3, f4, f5, f6, f7, f8;
+    long int f9, f10;
+    int f11;
+  } f;
+  char s[56];
+  long int a;
+} T;
+
+void
+foo1 (void)
+{
+  T t;
+  t = (T) { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } };
+  test (&t);
+}
+
+void
+bar1 (void)
+{
+  T t = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } };
+  test (&t);
+}
+
+void
+baz1 (void)
+{
+  T t;
+  t = (const T) { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } };
+  test (&t);
+}
+
+void
+foo2 (void)
+{
+  T t;
+  t = (T) { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 } };
+  test (&t);
+}
+
+void
+bar2 (void)
+{
+  T t = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 } };
+  test (&t);
+}
+
+void
+baz2 (void)
+{
+  T t;
+  t = (const T) { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 } };
+  test (&t);
+}
+
+void
+baz3 (void)
+{
+  T t;
+  t = (const T) (T) { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 } };
+  test (&t);
+}
+
+/* { dg-final { scan-tree-dump-times "t = {}" 3 "gimple"} } */
+/* { dg-final { scan-tree-dump-times "t.f.f1 = 1" 4 "gimple"} } */
+/* { dg-final { scan-tree-dump-times "t.f.f8 = 8" 4 "gimple"} } */
+/* { dg-final { cleanup-tree-dump "gimple" } } */