From 7ecf840976dd8beb2538bab904ae844c33bf498e Mon Sep 17 00:00:00 2001
From: jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu, 15 Feb 2018 11:18:47 +0000
Subject: [PATCH] 	PR tree-optimization/84383 	* tree-ssa-strlen.c
 (maybe_diag_stxncpy_trunc): Don't look at 	dstoff nor call
 operand_equal_p if dstbase is NULL.

	* gcc.c-torture/compile/pr84383.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@257684 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog                                 |  4 ++++
 gcc/testsuite/ChangeLog                       |  3 +++
 gcc/testsuite/gcc.c-torture/compile/pr84383.c | 14 ++++++++++++++
 gcc/tree-ssa-strlen.c                         |  1 +
 4 files changed, 22 insertions(+)
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr84383.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 05b77100138..2768ada22b7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2018-02-15  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/84383
+	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Don't look at
+	dstoff nor call operand_equal_p if dstbase is NULL.
+
 	PR tree-optimization/84334
 	* match.pd ((A +- CST1) +- CST2 -> A + CST3): If A is
 	also a CONSTANT_CLASS_P, punt.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 2ac6e7b0dfa..c9f53d80b68 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2018-02-15  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/84383
+	* gcc.c-torture/compile/pr84383.c: New test.
+
 	PR tree-optimization/84334
 	* gcc.dg/pr84334.c: New test.
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr84383.c b/gcc/testsuite/gcc.c-torture/compile/pr84383.c
new file mode 100644
index 00000000000..b46f7819b74
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr84383.c
@@ -0,0 +1,14 @@
+/* PR tree-optimization/84383 */
+
+struct S { char *s; };
+void bar (struct S *);
+
+void
+foo (int a, char *b)
+{
+  struct S c[4];
+  bar (c);
+  __builtin_strncpy (c[a].s, b, 32);
+  c[a].s[31] = '\0';
+  bar (c);
+}
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 94ed2bedc03..09ffa154439 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -1878,6 +1878,7 @@ maybe_diag_stxncpy_trunc (gimple_stmt_iterator gsi, tree src, tree cnt)
       poly_int64 lhsoff;
       tree lhsbase = get_addr_base_and_unit_offset (lhs, &lhsoff);
       if (lhsbase
+	  && dstbase
 	  && known_eq (dstoff, lhsoff)
 	  && operand_equal_p (dstbase, lhsbase, 0))
 	return false;
-- 
2.11.4.GIT