From: Richard Biener <rguenther@suse.de>
Date: Mon, 26 Nov 2018 14:16:01 +0000 (+0000)
Subject: re PR tree-optimization/87645 (gcc hangs up on vr_values::vrp_visit_assignment_or_call)
X-Git-Tag: releases/gcc-7.4.0~19
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ed567c8b5d0696d434d01716af23673310d73db1;p=thirdparty%2Fgcc.git

re PR tree-optimization/87645 (gcc hangs up on vr_values::vrp_visit_assignment_or_call)

2018-10-19  Richard Biener  <rguenther@suse.de>

	PR middle-end/87645
	Backport from mainline
	2018-07-12  Richard Biener  <rguenther@suse.de>

	* gimple-match-head.c (gimple_resimplify1): Apply recursion
	limit.
	(gimple_resimplify2): Likewise.
	(gimple_resimplify3): Likewise.
	(gimple_resimplify4): Likewise.

	* gcc.dg/torture/pr87645.c: New testcase.

From-SVN: r266461
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 77d3a77c399b..68091e8c5848 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+2018-10-19  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/87645
+	Backport from mainline
+	2018-07-12  Richard Biener  <rguenther@suse.de>
+
+	* gimple-match-head.c (gimple_resimplify1): Apply recursion
+	limit.
+	(gimple_resimplify2): Likewise.
+	(gimple_resimplify3): Likewise.
+	(gimple_resimplify4): Likewise.
+
 2018-11-26  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/gimple-match-head.c b/gcc/gimple-match-head.c
index e7e9839a4b84..5a0d33174fbc 100644
--- a/gcc/gimple-match-head.c
+++ b/gcc/gimple-match-head.c
@@ -99,17 +99,34 @@ gimple_resimplify1 (gimple_seq *seq,
 	}
     }
 
+  /* Limit recursion, there are cases like PR80887 and others, for
+     example when value-numbering presents us with unfolded expressions
+     that we are really not prepared to handle without eventual
+     oscillation like ((_50 + 0) + 8) where _50 gets mapped to _50
+     itself as available expression.  */
+  static unsigned depth;
+  if (depth > 10)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Aborting expression simplification due to "
+		 "deep recursion\n");
+      return false;
+    }
+
+  ++depth;
   code_helper res_code2;
   tree res_ops2[3] = {};
   if (gimple_simplify (&res_code2, res_ops2, seq, valueize,
 		       *res_code, type, res_ops[0]))
     {
+      --depth;
       *res_code = res_code2;
       res_ops[0] = res_ops2[0];
       res_ops[1] = res_ops2[1];
       res_ops[2] = res_ops2[2];
       return true;
     }
+  --depth;
 
   return false;
 }
@@ -159,17 +176,30 @@ gimple_resimplify2 (gimple_seq *seq,
       canonicalized = true;
     }
 
+  /* Limit recursion, see gimple_resimplify1.  */
+  static unsigned depth;
+  if (depth > 10)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Aborting expression simplification due to "
+		 "deep recursion\n");
+      return false;
+    }
+
+  ++depth;
   code_helper res_code2;
   tree res_ops2[3] = {};
   if (gimple_simplify (&res_code2, res_ops2, seq, valueize,
 		       *res_code, type, res_ops[0], res_ops[1]))
     {
+      --depth;
       *res_code = res_code2;
       res_ops[0] = res_ops2[0];
       res_ops[1] = res_ops2[1];
       res_ops[2] = res_ops2[2];
       return true;
     }
+  --depth;
 
   return canonicalized;
 }
@@ -218,18 +248,31 @@ gimple_resimplify3 (gimple_seq *seq,
       canonicalized = true;
     }
 
+  /* Limit recursion, see gimple_resimplify1.  */
+  static unsigned depth;
+  if (depth > 10)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Aborting expression simplification due to "
+		 "deep recursion\n");
+      return false;
+    }
+
+  ++depth;
   code_helper res_code2;
   tree res_ops2[3] = {};
   if (gimple_simplify (&res_code2, res_ops2, seq, valueize,
 		       *res_code, type,
 		       res_ops[0], res_ops[1], res_ops[2]))
     {
+      --depth;
       *res_code = res_code2;
       res_ops[0] = res_ops2[0];
       res_ops[1] = res_ops2[1];
       res_ops[2] = res_ops2[2];
       return true;
     }
+  --depth;
 
   return canonicalized;
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c260750ffe4d..1c365d2fd7eb 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2018-10-19  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/87645
+	Backport from mainline
+	2018-07-12  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/torture/pr87645.c: New testcase.
+
 2018-11-26  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.dg/torture/pr87645.c b/gcc/testsuite/gcc.dg/torture/pr87645.c
new file mode 100644
index 000000000000..5360e3800800
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr87645.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+typedef unsigned a[8];
+a b, g;
+int c, d, e, f;
+int h() {
+    unsigned i = 2;
+    for (; i < 8; i++)
+      b[i] = 0;
+    for (; f;) {
+	d = 1;
+	for (; d < 14; d += 3) {
+	    e = 0;
+	    for (; e < 8; e++) {
+		i = 2;
+		for (; i < 8; i++)
+		  b[i] = 5 - (c - g[e] + b[i]);
+	    }
+	}
+    }
+}