From 5f37780372212a7245f0528e46dbeb741316bba1 Mon Sep 17 00:00:00 2001
From: Jan Hubicka <hubicka@ucw.cz>
Date: Fri, 5 Nov 2021 23:32:55 +0100
Subject: [PATCH] Fix ice in insert_access

gcc/ChangeLog:

	PR ipa/103073
	* ipa-modref-tree.h (modref_tree::insert): Do nothing for
	paradoxical and zero sized accesses.

gcc/testsuite/ChangeLog:

	PR ipa/103073
	* g++.dg/torture/pr103073.C: New test.
	* gcc.dg/tree-ssa/modref-11.c: New test.
---
 gcc/ipa-modref-tree.h                     | 30 ++++++++++++++++++++++++++++++
 gcc/testsuite/g++.dg/torture/pr103073.C   |  8 ++++++++
 gcc/testsuite/gcc.dg/tree-ssa/modref-11.c | 13 +++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/torture/pr103073.C
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/modref-11.c

diff --git a/gcc/ipa-modref-tree.h b/gcc/ipa-modref-tree.h
index bc428d1..54ae9e1 100644
--- a/gcc/ipa-modref-tree.h
+++ b/gcc/ipa-modref-tree.h
@@ -818,6 +818,36 @@ struct GTY((user)) modref_tree
 
     bool changed = false;
 
+    /* We may end up with max_size being less than size for accesses past the
+       end of array.  Those are undefined and safe to ignore.  */
+    if (a.range_info_useful_p ()
+	&& known_size_p (a.size) && known_size_p (a.max_size)
+	&& known_lt (a.max_size, a.size))
+      {
+	if (dump_file)
+	  fprintf (dump_file,
+		   "   - Paradoxical range. Ignoring\n");
+	return false;
+      }
+    if (known_size_p (a.size)
+	&& known_eq (a.size, 0))
+      {
+	if (dump_file)
+	  fprintf (dump_file,
+		   "   - Zero size. Ignoring\n");
+	return false;
+      }
+    if (known_size_p (a.max_size)
+	&& known_eq (a.max_size, 0))
+      {
+	if (dump_file)
+	  fprintf (dump_file,
+		   "   - Zero max_size. Ignoring\n");
+	return false;
+      }
+    gcc_checking_assert (!known_size_p (a.max_size)
+			 || !known_le (a.max_size, 0));
+
     /* No useful information tracked; collapse everything.  */
     if (!base && !ref && !a.useful_p ())
       {
diff --git a/gcc/testsuite/g++.dg/torture/pr103073.C b/gcc/testsuite/g++.dg/torture/pr103073.C
new file mode 100644
index 0000000..02b1eee
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr103073.C
@@ -0,0 +1,8 @@
+// { dg-do compile }
+int a;
+void b(bool c[], char d[], bool g[][55][21]) {
+  for (signed e = 0; e < 11; e += 3)
+    for (unsigned f = c[0] + 1; f < d[0]; f += 3)
+      a = g[0][e][f + 2];
+}
+
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-11.c b/gcc/testsuite/gcc.dg/tree-ssa/modref-11.c
new file mode 100644
index 0000000..de9ad16
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-11.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-modref1"  } */
+struct linkedlist {
+  struct linkedlist *next;
+};
+struct linkedlist *
+find_last (struct linkedlist *l)
+{
+  while (l->next)
+   l = l->next;
+  return l;
+}
+/* { dg-final { scan-tree-dump "noclobber noescape nodirectescape" "modref1"} } */
-- 
2.7.4