1 files changed, 29 insertions, 60 deletions

diff --git a/gcc/cse.c b/gcc/cse.c
index 557e8086d7f..7a05dad0307 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -37,6 +37,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "toplev.h"
 #include "output.h"
 #include "ggc.h"
+#include "timevar.h"
 
 /* The basic idea of common subexpression elimination is to go
    through the code, keeping a record of expressions that would
@@ -7605,81 +7606,42 @@ dead_libcall_p (insn)
    move dead invariants out of loops or make givs for dead quantities.  The
    remaining passes of the compilation are also sped up.  */
 
-void
-delete_trivially_dead_insns (insns, nreg, preserve_basic_blocks)
+int
+delete_trivially_dead_insns (insns, nreg)
      rtx insns;
      int nreg;
-     int preserve_basic_blocks;
 {
   int *counts;
   rtx insn, prev;
-  int i;
   int in_libcall = 0, dead_libcall = 0;
-  basic_block bb;
+  int ndead = 0, nlastdead, niterations = 0;
 
+  timevar_push (TV_DELETE_TRIVIALLY_DEAD);
   /* First count the number of times each register is used.  */
   counts = (int *) xcalloc (nreg, sizeof (int));
   for (insn = next_real_insn (insns); insn; insn = next_real_insn (insn))
     count_reg_usage (insn, counts, NULL_RTX, 1);
 
-  /* Go from the last insn to the first and delete insns that only set unused
-     registers or copy a register to itself.  As we delete an insn, remove
-     usage counts for registers it uses.
-
-     The first jump optimization pass may leave a real insn as the last
-     insn in the function.   We must not skip that insn or we may end
-     up deleting code that is not really dead.  */
-  insn = get_last_insn ();
-  if (! INSN_P (insn))
-    insn = prev_real_insn (insn);
-
-  if (!preserve_basic_blocks)
-    for (; insn; insn = prev)
-      {
-	int live_insn = 0;
-
-	prev = prev_real_insn (insn);
-
-	/* Don't delete any insns that are part of a libcall block unless
-	   we can delete the whole libcall block.
-
-	   Flow or loop might get confused if we did that.  Remember
-	   that we are scanning backwards.  */
-	if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
-	  {
-	    in_libcall = 1;
-	    live_insn = 1;
-	    dead_libcall = dead_libcall_p (insn);
-	  }
-	else if (in_libcall)
-	  live_insn = ! dead_libcall;
-	else
-	  live_insn = insn_live_p (insn, counts);
-
-	/* If this is a dead insn, delete it and show registers in it aren't
-	   being used.  */
-
-	if (! live_insn)
-	  {
-	    count_reg_usage (insn, counts, NULL_RTX, -1);
-	    delete_related_insns (insn);
-	  }
+  do
+    {
+      nlastdead = ndead;
+      niterations++;
+      /* Go from the last insn to the first and delete insns that only set unused
+	 registers or copy a register to itself.  As we delete an insn, remove
+	 usage counts for registers it uses.
+
+	 The first jump optimization pass may leave a real insn as the last
+	 insn in the function.   We must not skip that insn or we may end
+	 up deleting code that is not really dead.  */
+      insn = get_last_insn ();
+      if (! INSN_P (insn))
+	insn = prev_real_insn (insn);
 
-	if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
-	  {
-	    in_libcall = 0;
-	    dead_libcall = 0;
-	  }
-      }
-  else
-    for (i = 0; i < n_basic_blocks; i++)
-      for (bb = BASIC_BLOCK (i), insn = bb->end; insn != bb->head; insn = prev)
+      for (; insn; insn = prev)
 	{
 	  int live_insn = 0;
 
-	  prev = PREV_INSN (insn);
-	  if (!INSN_P (insn))
-	    continue;
+	  prev = prev_real_insn (insn);
 
 	  /* Don't delete any insns that are part of a libcall block unless
 	     we can delete the whole libcall block.
@@ -7703,7 +7665,8 @@ delete_trivially_dead_insns (insns, nreg, preserve_basic_blocks)
 	  if (! live_insn)
 	    {
 	      count_reg_usage (insn, counts, NULL_RTX, -1);
-	      delete_insn (insn);
+	      delete_insn_and_edges (insn);
+	      ndead++;
 	    }
 
 	  if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
@@ -7712,7 +7675,13 @@ delete_trivially_dead_insns (insns, nreg, preserve_basic_blocks)
 	      dead_libcall = 0;
 	    }
 	}
+    } while (ndead != nlastdead);
 
+  if (rtl_dump_file && ndead)
+    fprintf (rtl_dump_file, "Deleted %i trivially dead insns; %i iterations\n",
+	     ndead, niterations);
   /* Clean up.  */
   free (counts);
+  timevar_pop (TV_DELETE_TRIVIALLY_DEAD);
+  return ndead;
 }