[PATCH] Allow vrp to thread across backedges using FSM threader

	* cfg-flags.def (IGNORE): New edge flag.
	* tree-vrp.c (identify_jump_threads): Mark and clear edges
	scheduled for removal with EDGE_IGNORE around call into
	jump threader.  Do no thread across edges with EDGE_IGNORE,
	but do allow threading across those with EDGE_DFS_BACK.

	* gcc.dg/tree-ssa/ssa-dom-thread-7.c: Adjust to look for
	realized jump threads.
	* gcc.dg/tree-ssa-pr66752-3.c: Look in vrp1 dump for jump
	threads rather than dom1 dump.

From-SVN: r229902

gcc/ChangeLog

+2015-11-06  Jeff Law <jeff@redhat.com>
+
+	* cfg-flags.def (IGNORE): New edge flag.
+	* tree-vrp.c (identify_jump_threads): Mark and clear edges
+	scheduled for removal with EDGE_IGNORE around call into
+	jump threader.  Do no thread across edges with EDGE_IGNORE,
+	but do allow threading across those with EDGE_DFS_BACK.
+
 2015-11-06  David Wohlferd  <dw@LimeGreenSocks.com>
 
 	* doc/md.texi (multi-alternative constraints): Don't document

gcc/cfg-flags.def

@@ -78,7 +78,7 @@ DEF_BASIC_BLOCK_FLAG(RTL, 9)
 DEF_BASIC_BLOCK_FLAG(FORWARDER_BLOCK, 10)
 
 /* Set on blocks that cannot be threaded through.
-   Only used in cfgcleanup.c.  */
+   Only used for jump threading.  */
 DEF_BASIC_BLOCK_FLAG(NONTHREADABLE_BLOCK, 11)
 
 /* Set on blocks that were modified in some way.  This bit is set in
@@ -177,6 +177,11 @@ DEF_EDGE_FLAG(TM_UNINSTRUMENTED, 15)
 /* Abort (over) edge out of a GIMPLE_TRANSACTION statement.  */
 DEF_EDGE_FLAG(TM_ABORT, 16)
 
+/* An edge we should ignore.  It should be entirely local to
+   passes.  ie, it is never set on any edge upon the completion
+   of any pass.  */
+DEF_EDGE_FLAG(IGNORE, 17)
+
 #endif
 
 /*

gcc/testsuite/ChangeLog

+2015-11-06  Jeff Law  <law@redhat.com>
+
+	* gcc.dg/tree-ssa/ssa-dom-thread-7.c: Adjust to look for
+	realized jump threads.
+	* gcc.dg/tree-ssa-pr66752-3.c: Look in vrp1 dump for jump
+	threads rather than dom1 dump.
+
 2015-11-06  Michael Collison  <michael.collison@linaro.org
 	    Ramana Radhakrishnan  <ramana.radhakrishnan@linaro.org>
 

gcc/testsuite/gcc.dg/tree-ssa/pr66752-3.c

 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-dom1-details -fdump-tree-optimized" } */
+/* { dg-options "-O2 -fdump-tree-vrp1-details -fdump-tree-optimized" } */
 
 extern int status, pt;
 extern int count;
@@ -33,7 +33,7 @@ foo (int N, int c, int b, int *a)
 }
 
 /* There are 3 FSM jump threading opportunities.  */
-/* { dg-final { scan-tree-dump-times "FSM" 3 "dom1"} } */
+/* { dg-final { scan-tree-dump-times "FSM" 3 "vrp1"} } */
 
 /* There should be no assignments or references to FLAG.  */
 /* { dg-final { scan-tree-dump-not "flag" "optimized"} } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c

 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-dom1-details" } */
-/* { dg-final { scan-tree-dump-times "FSM" 38 "dom1" } } */
+/* { dg-options "-O2 -fdump-tree-vrp1-stats -fdump-tree-dom1-stats -fdump-tree-dom2-stats" } */
+/* { dg-final { scan-tree-dump "Jumps threaded: 7"  "vrp1" } } */
+/* { dg-final { scan-tree-dump "Jumps threaded: 12" "dom1" } } */
+/* { dg-final { scan-tree-dump "Jumps threaded: 3"  "dom2" } } */
 
 enum STATE {
   S0=0,

gcc/tree-vrp.c

@@ -10076,9 +10076,9 @@ identify_jump_threads (void)
   mark_dfs_back_edges ();
 
   /* Do not thread across edges we are about to remove.  Just marking
-     them as EDGE_DFS_BACK will do.  */
+     them as EDGE_IGNORE will do.  */
   FOR_EACH_VEC_ELT (to_remove_edges, i, e)
-    e->flags |= EDGE_DFS_BACK;
+    e->flags |= EDGE_IGNORE;
 
   /* Allocate our unwinder stack to unwind any temporary equivalences
      that might be recorded.  */
@@ -10135,9 +10135,9 @@ identify_jump_threads (void)
 	     it to a specific successor.  */
 	  FOR_EACH_EDGE (e, ei, bb->preds)
 	    {
-	      /* Do not thread across back edges or abnormal edges
-		 in the CFG.  */
-	      if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
+	      /* Do not thread across edges marked to ignoreor abnormal
+		 edges in the CFG.  */
+	      if (e->flags & (EDGE_IGNORE | EDGE_COMPLEX))
 		continue;
 
 	      thread_across_edge (dummy, e, true, equiv_stack, NULL,
@@ -10146,6 +10146,10 @@ identify_jump_threads (void)
 	}
     }
 
+  /* Clear EDGE_IGNORE.  */
+  FOR_EACH_VEC_ELT (to_remove_edges, i, e)
+    e->flags &= ~EDGE_IGNORE;
+
   /* We do not actually update the CFG or SSA graphs at this point as
      ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
      handle ASSERT_EXPRs gracefully.  */