re PR rtl-optimization/48141 (DSE compile time hog)

	PR rtl-optimization/48141
	* dse.c (record_store): If no positions are needed in an insn
	that cannot be deleted, at least unchain it from active_local_stores.

	* gcc.dg/pr48141.c: New test.

From-SVN: r171089

gcc/ChangeLog

+2011-03-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/48141
+	* dse.c (record_store): If no positions are needed in an insn
+	that cannot be deleted, at least unchain it from active_local_stores.
+
 2011-03-16  Dodji Seketeli  <dodji@redhat.com>
 
 	PR debug/47510

gcc/dse.c

 /* RTL dead store elimination.
-   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010
+   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
 
    Contributed by Richard Sandiford <rsandifor@codesourcery.com>
@@ -1530,8 +1530,7 @@ record_store (rtx body, bb_info_t bb_info)
 
       /* An insn can be deleted if every position of every one of
 	 its s_infos is zero.  */
-      if (any_positions_needed_p (s_info)
-	  || ptr->cannot_delete)
+      if (any_positions_needed_p (s_info))
 	del = false;
 
       if (del)
@@ -1543,7 +1542,8 @@ record_store (rtx body, bb_info_t bb_info)
 	  else
 	    active_local_stores = ptr->next_local_store;
 
-	  delete_dead_store_insn (insn_to_delete);
+	  if (!insn_to_delete->cannot_delete)
+	    delete_dead_store_insn (insn_to_delete);
 	}
       else
 	last = ptr;

gcc/testsuite/ChangeLog

+2011-03-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/48141
+	* gcc.dg/pr48141.c: New test.
+
 2011-03-16  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/cpp0x/constexpr-48089.C: New.

gcc/testsuite/gcc.dg/pr48141.c

+/* PR rtl-optimization/48141 */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+#define A i = 0;
+#define B A A A A A A A A A A
+#define C B B B B B B B B B B
+#define D C C C C C C C C C C
+#define E D D D D D D D D D D
+
+int
+foo (void)
+{
+  volatile int i = 0;
+  E E E E E E E E E E E
+  return 0;
+}