From: Richard Biener <rguenther@suse.de>
Date: Mon, 17 Aug 2015 14:17:33 +0000 (+0000)
Subject: re PR tree-optimization/67221 (ICE at -Os and above on x86_64-linux-gnu: Segmentation... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=28251e2ce19fbbe5715ac33cf4a8c349d0c95faa;p=gcc.git

re PR tree-optimization/67221 (ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1))

2015-08-17  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/67221
	* tree-ssa-sccvn.c (visit_phi): Keep all-TOP args TOP.
	(sccvn_dom_walker::before_dom_children): Mark backedges of
	non-executable blocks as not executable.

	* gcc.dg/torture/pr67221.c: New testcase.

From-SVN: r226938
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 76d1d07043b..93ec58f4946 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2015-08-17  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67221
+	* tree-ssa-sccvn.c (visit_phi): Keep all-TOP args TOP.
+	(sccvn_dom_walker::before_dom_children): Mark backedges of
+	non-executable blocks as not executable.
+
 2015-08-17  David Sherwood  <david.sherwood@arm.com>
 
 	* config/arm/arm.c (neon_element_bits): Replace call to
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 394a42fafdd..93aed719457 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-08-17  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67221
+	* gcc.dg/torture/pr67221.c: New testcase.
+
 2015-08-17 Mike Stump  <mikestump@comcast.net>
            Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
diff --git a/gcc/testsuite/gcc.dg/torture/pr67221.c b/gcc/testsuite/gcc.dg/torture/pr67221.c
new file mode 100644
index 00000000000..d7d33c5826e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr67221.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+
+int a, b;
+
+int
+fn1 (int p)
+{
+  return 0 == 0 ? p : 0;
+}
+
+void
+fn2 ()
+{
+  int c = 1, d[1] = { 1 };
+lbl:
+  for (;;)
+    {
+      int e;
+      c ? 0 : 0 / c;
+      c = 0;
+      if (fn1 (d[0]))
+	break;
+      for (e = 0; e < 1; e++)
+	for (c = 1; b;)
+	  {
+	    if (a)
+	      break;
+	    goto lbl;
+	  }
+    }
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index a72a9208f07..aea6acc0451 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -3271,6 +3271,11 @@ visit_phi (gimple phi)
 	    break;
 	  }
       }
+  
+  /* If none of the edges was executable or all incoming values are
+     undefined keep the value-number at VN_TOP.  */
+  if (sameval == VN_TOP)
+    return set_ssa_val_to (PHI_RESULT (phi), VN_TOP);
 
   /* First see if it is equivalent to a phi node in this block.  We prefer
      this as it allows IV elimination - see PRs 66502 and 67167.  */
@@ -4463,7 +4468,7 @@ sccvn_dom_walker::before_dom_children (basic_block bb)
       reachable |= (e->flags & EDGE_EXECUTABLE);
 
   /* If the block is not reachable all outgoing edges are not
-     executable.  */
+     executable.  Neither are incoming edges with src dominated by us.  */
   if (!reachable)
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
@@ -4472,6 +4477,18 @@ sccvn_dom_walker::before_dom_children (basic_block bb)
 
       FOR_EACH_EDGE (e, ei, bb->succs)
 	e->flags &= ~EDGE_EXECUTABLE;
+
+      FOR_EACH_EDGE (e, ei, bb->preds)
+	{
+	  if (dominated_by_p (CDI_DOMINATORS, e->src, bb))
+	    {
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file, "Marking backedge from BB %d into "
+			 "unreachable BB %d as not executable\n",
+			 e->src->index, bb->index);
+	      e->flags &= ~EDGE_EXECUTABLE;
+	    }
+	}
       return;
     }