re PR middle-end/32758 (ecj1 hangs)

	PR middle-end/32758
	* dce.c (dce_process_block): Don't delete setters of
	artificially used registers.

	* gcc.dg/cleanup-12.c: New test.

From-SVN: r127923

1 files changed, 12 insertions, 1 deletions

diff --git a/gcc/dce.c b/gcc/dce.c
index c9ff13f..c5af55e 100644
--- a/gcc/dce.c
+++ b/gcc/dce.c
@@ -527,6 +527,7 @@ static bool
 dce_process_block (basic_block bb, bool redo_out)
 {
   bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack);
+  bitmap au;
   rtx insn;
   bool block_changed;
   struct df_ref **def_rec, **use_rec;
@@ -569,6 +570,15 @@ dce_process_block (basic_block bb, bool redo_out)
 	bitmap_set_bit (local_live, DF_REF_REGNO (use));
     }
 
+  /* These regs are considered always live so if they end up dying
+     because of some def, we need to bring the back again.
+     Calling df_simulate_fixup_sets has the disadvantage of calling
+     df_has_eh_preds once per insn, so we cache the information here.  */
+  if (df_has_eh_preds (bb))
+    au = df->eh_block_artificial_uses;
+  else
+    au = df->regular_block_artificial_uses;
+
   FOR_BB_INSNS_REVERSE (bb, insn)
     if (INSN_P (insn))
       {
@@ -580,7 +590,8 @@ dce_process_block (basic_block bb, bool redo_out)
 
 	    /* The insn is needed if there is someone who uses the output.  */
 	    for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
-	      if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec)))
+	      if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec))
+		  || bitmap_bit_p (au, DF_REF_REGNO (*def_rec)))
 		{
 		  needed = true;
 		  break;