re PR rtl-optimization/42889 ("-fcompare-debug failure (length)" with "-O1 -fgcse")

PR rtl-optimization/42889
	* df.h (df_set_bb_dirty_nonlr): New prototype.
	* df-core.c (df_set_bb_dirty_nonlr): New function.
	* df-scan.c (df_insn_rescan): Call it instead of
	df_set_bb_dirty for DEBUG_INSNs.

	* gcc.dg/pr42889.c: New test.

From-SVN: r156344

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2010-01-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/42889
+	* df.h (df_set_bb_dirty_nonlr): New prototype.
+	* df-core.c (df_set_bb_dirty_nonlr): New function.
+	* df-scan.c (df_insn_rescan): Call it instead of
+	df_set_bb_dirty for DEBUG_INSNs.
+
 2010-01-29  Richard Guenther  <rguenther@suse.de>
 
 	PR middle-end/37448

gcc/df-core.c

@@ -1354,6 +1354,30 @@ df_set_bb_dirty (basic_block bb)
 }
 
 
+/* Mark BB as needing it's transfer functions as being out of
+   date, except for LR problem.  Used when analyzing DEBUG_INSNs,
+   as LR problem can trigger DCE, and DEBUG_INSNs shouldn't ever
+   shorten or enlarge lifetime of regs.  */
+
+void
+df_set_bb_dirty_nonlr (basic_block bb)
+{
+  if (df)
+    {
+      int p;
+      for (p = 1; p < df->num_problems_defined; p++)
+	{
+	  struct dataflow *dflow = df->problems_in_order[p];
+	  if (dflow == df_lr)
+	    continue;
+	  if (dflow->out_of_date_transfer_functions)
+	    bitmap_set_bit (dflow->out_of_date_transfer_functions, bb->index);
+	  dflow->solutions_dirty = true;
+	}
+    }
+}
+
+
 /* Clear the dirty bits.  This is called from places that delete
    blocks.  */
 static void

gcc/df-scan.c

@@ -1301,7 +1301,10 @@ df_insn_rescan (rtx insn)
     }
 
   df_refs_add_to_chains (&collection_rec, bb, insn);
-  df_set_bb_dirty (bb);
+  if (DEBUG_INSN_P (insn))
+    df_set_bb_dirty_nonlr (bb);
+  else
+    df_set_bb_dirty (bb);
 
   VEC_free (df_ref, stack, collection_rec.def_vec);
   VEC_free (df_ref, stack, collection_rec.use_vec);

gcc/df.h

@@ -912,6 +912,7 @@ extern void df_simple_dataflow (enum df_flow_dir, df_init_function,
 extern void df_mark_solutions_dirty (void);
 extern bool df_get_bb_dirty (basic_block);
 extern void df_set_bb_dirty (basic_block);
+extern void df_set_bb_dirty_nonlr (basic_block);
 extern void df_compact_blocks (void);
 extern void df_bb_replace (int, basic_block);
 extern void df_bb_delete (int);

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2010-01-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/42889
+	* gcc.dg/pr42889.c: New test.
+
 2010-01-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* gcc.target/i386/pr42881.c: Use SSE2.

gcc/testsuite/gcc.dg/pr42889.c

@@ -0,0 +1,13 @@
+/* PR rtl-optimization/42889 */
+/* { dg-do compile } */
+/* { dg-options "-O -fgcse -fcompare-debug" } */
+
+extern int A[], B[];
+
+int
+foo (int x, int c, int i)
+{
+  if (A[i] && B[i])
+    x = x % ((c & 4) ? 8 : 4);
+  return x;
+}