From patchwork Thu Jul 15 15:50:26 2010
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Subject: [CFT,try,7] Emulated tls rewrite
From: Richard Henderson <rth@redhat.com>
X-Patchwork-Id: 58989
Message-Id: <4C3F2E42.4090605@redhat.com>
To: IainS <developer@sandoe-acoustics.co.uk>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
 Richard Guenther <richard.guenther@gmail.com>
Date: Thu, 15 Jul 2010 08:50:26 -0700

On 07/15/2010 12:59 AM, IainS wrote:
> unfortunately, although it applies cleanly, it doesn't bootstrap for me
> (against either 162180 or 162193).
> (fails in building libgomp/parallel.c with 'caller edge frequency 1000
> does not match BB frequency of 61')...
> ... I will look a little more - but this is uncharted territory for me ;)

Incremental patch follows.


r~


diff --git a/gcc/tree-emutls.c b/gcc/tree-emutls.c
index f7eb4cd..275e16b 100644
--- a/gcc/tree-emutls.c
+++ b/gcc/tree-emutls.c
@@ -580,6 +580,54 @@ lower_emutls_phi_arg (gimple phi, unsigned int i, struct lower_emutls_data *d)
     }
 }
 
+/* Mirror a portion of the logic from gimple_find_edge_insert_loc.
+   Determine if statements inserted on E will be insertted into the
+   predecessor block.  We *must* match gimple_find_edge_insert_loc
+   in order to pass verify_cgraph. 
+
+   If the destination has one predecessor and no PHI nodes, insert
+   there... Except that we *know* it has PHI nodes or else there's
+   nothing for us to do.  Skip this step.
+
+   If the source has one successor, the edge is not abnormal and the
+   last statement does not end a basic block, insert there.  */
+
+static bool
+will_insert_in_edge_src (edge e)
+{
+  basic_block src = e->src;
+
+  if ((e->flags & EDGE_ABNORMAL) == 0
+      && src != ENTRY_BLOCK_PTR
+      && single_succ_p (src))
+    {
+      gimple_stmt_iterator gsi;
+      gimple last;
+
+      /* If the block is empty, of course we use it.  */
+      gsi = gsi_last_bb (src);
+      if (gsi_end_p (gsi))
+	return true;
+
+      /* If the last stmt does not end the block, we insert after.  */
+      last = gsi_stmt (gsi);
+      if (!stmt_ends_bb_p (last))
+	return true;
+
+      /* If the last stmt is a trivial control, we insert before.  */
+      switch (gimple_code (last))
+	{
+	case GIMPLE_RETURN:
+	case GIMPLE_RESX:
+	  return true;
+	default:
+	  break;
+	}
+    }
+
+  return false;
+}
+
 /* Lower the entire function NODE.  */
 
 static void
@@ -605,34 +653,41 @@ lower_emutls_function_body (struct cgraph_node *node)
       gimple_stmt_iterator gsi;
       unsigned int i, nedge;
 
-      /* ??? This is the frequency of the new block that might be created by
-	 split_edge.  One might have thought EDGE_FREQUENCY.  However, this
-         *must* match split_edge, or we'll fail verify_cgraph.  */
-      d.bb_freq = CGRAPH_FREQ_BASE;
-
       /* Lower each of the PHI nodes of the block, as we may have 
 	 propagated &tlsvar into a PHI argument.  These loops are
 	 arranged so that we process each edge at once, and each
 	 PHI argument for that edge.  */
-
-      nedge = EDGE_COUNT (d.bb->preds);
-      for (i = 0; i < nedge; ++i)
+      if (!gimple_seq_empty_p (phi_nodes (d.bb)))
 	{
-	  edge e = EDGE_PRED (d.bb, i);
-
-          /* We can re-use any SSA_NAME created on this edge.  */
-          memset (VEC_address (tree, d.accessed), 0, n_tls * sizeof(tree));
-	  d.seq = NULL;
-
-	  for (gsi = gsi_start_phis (d.bb); !gsi_end_p (gsi); gsi_next (&gsi))
-	    lower_emutls_phi_arg (gsi_stmt (gsi), i, &d);
-
-	  /* Insert all statements generated by all phi nodes for this
-	     particular edge all at once.  */
-	  if (d.seq)
+	  nedge = EDGE_COUNT (d.bb->preds);
+	  for (i = 0; i < nedge; ++i)
 	    {
-	      gsi_insert_seq_on_edge (e, d.seq);
-	      any_edge_inserts = true;
+	      edge e = EDGE_PRED (d.bb, i);
+
+	      /* Choose the correct frequency for stmts to be
+		 insertted on this edge.  */
+	      if (will_insert_in_edge_src (e))
+		d.bb_freq = (compute_call_stmt_bb_frequency
+			     (current_function_decl, e->src));
+	      else
+		d.bb_freq = EDGE_FREQUENCY (e);
+
+	      /* We can re-use any SSA_NAME created on this edge.  */
+	      memset (VEC_address (tree, d.accessed), 0, n_tls * sizeof(tree));
+	      d.seq = NULL;
+
+	      for (gsi = gsi_start_phis (d.bb);
+		   !gsi_end_p (gsi);
+		   gsi_next (&gsi))
+		lower_emutls_phi_arg (gsi_stmt (gsi), i, &d);
+
+	      /* Insert all statements generated by all phi nodes for this
+		 particular edge all at once.  */
+	      if (d.seq)
+		{
+		  gsi_insert_seq_on_edge (e, d.seq);
+		  any_edge_inserts = true;
+		}
 	    }
 	}