From patchwork Wed Jun 23 18:53:59 2010
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Subject: 0003-Improve-VBEout-computation.patch
From: Maxim Kuvyrkov <maxim@codesourcery.com>
X-Patchwork-Id: 56702
Message-Id: <4C225847.1020900@codesourcery.com>
To: Jeff Law <law@redhat.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>
Date: Wed, 23 Jun 2010 22:53:59 +0400

On 6/22/10 4:02 PM, Maxim Kuvyrkov wrote:
...
> I'll post another version of the patch in a couple of days when I finish
> reworking other pieces of improvements to hoisting.

Updated version.  OK to check in?

Thanks,


diff --git a/gcc/gcse.c b/gcc/gcse.c
index 103f0e0..22576ca 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -4171,8 +4171,16 @@ compute_code_hoist_vbeinout (void)
       FOR_EACH_BB_REVERSE (bb)
 	{
 	  if (bb->next_bb != EXIT_BLOCK_PTR)
-	    sbitmap_intersection_of_succs (hoist_vbeout[bb->index],
-					   hoist_vbein, bb->index);
+	    {
+	      sbitmap_intersection_of_succs (hoist_vbeout[bb->index],
+					     hoist_vbein, bb->index);
+
+	      /* One of the quirks of code hoisting algorithm in Muchnick
+		 is that VBEout[BB] does not include expressions calculated
+		 in BB itself and available at its end.  Fix this.  */
+	      sbitmap_a_or_b (hoist_vbeout[bb->index],
+			      hoist_vbeout[bb->index], comp[bb->index]);
+	    }
 
 	  changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index],
 					      antloc[bb->index],
@@ -4184,7 +4192,17 @@ compute_code_hoist_vbeinout (void)
     }
 
   if (dump_file)
-    fprintf (dump_file, "hoisting vbeinout computation: %d passes\n", passes);
+    {
+      fprintf (dump_file, "hoisting vbeinout computation: %d passes\n", passes);
+
+      FOR_EACH_BB (bb)
+        {
+	  fprintf (dump_file, "vbein (%d): ", bb->index);
+	  dump_sbitmap_file (dump_file, hoist_vbein[bb->index]);
+	  fprintf (dump_file, "vbeout(%d): ", bb->index);
+	  dump_sbitmap_file (dump_file, hoist_vbeout[bb->index]);
+	}
+    }
 }
 
 /* Top level routine to do the dataflow analysis needed by code hoisting.  */
@@ -4298,6 +4316,11 @@ hoist_code (void)
 	  if (TEST_BIT (hoist_vbeout[bb->index], i)
 	      && TEST_BIT (transpout[bb->index], i))
 	    {
+	      /* If an expression is computed in BB and is available at end of
+		 BB, hoist all occurences dominated by BB to BB.  */
+	      if (TEST_BIT (comp[bb->index], i))
+		hoistable++;
+
 	      /* We've found a potentially hoistable expression, now
 		 we look at every block BB dominates to see if it
 		 computes the expression.  */