Backport from trunk.

PR tree-optimization/86400 - set<string>::set<char (*)[2]) constructor does not
work with array argument.

gcc/ChangeLog:
	* gcc.dg/strlenopt-47.c: New test.
	* gcc.dg/strlenopt-48.c: New test.

gcc/testsuite/ChangeLog:
	* gcc.dg/strlenopt-47.c: New test.
	* gcc.dg/strlenopt-48.c: New test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-8-branch@262446 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 88 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 05892b482951..b75cb76afa24 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-07-05  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/86400
+	* tree-ssa-strlen.c (maybe_set_strlen_range): Use type size rather
+	than its domain to compute its the upper bound of a char array.
+
 2018-07-03  Carl Love  <cel@us.ibm.com>
 
 	Backport from trunk
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3f36dc0ee858..bc7d508d2cf8 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-07-05  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/86400
+	* gcc.dg/strlenopt-47.c: New test.
+	* gcc.dg/strlenopt-48.c: New test.
+
 2018-07-03  Carl Love  <cel@us.ibm.com>
 
 	Backport from trunk
diff --git a/gcc/testsuite/gcc.dg/strlenopt-47.c b/gcc/testsuite/gcc.dg/strlenopt-47.c
new file mode 100644
index 000000000000..68945c7c1a19
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/strlenopt-47.c
@@ -0,0 +1,36 @@
+/* PR tree-optimization/86400 - set<string>::set<char (*)[2]) constructor
+   does not work with array argument
+   Verify that strlen() calls with two-character array elements of
+   multidimensional arrays whose higher order dimension is 1 are not
+   folded.
+   { dg-do compile }
+   { dg-options "-O2 -Wall -fdump-tree-optimized" } */
+
+#include "strlenopt.h"
+
+void f (void)
+{
+  extern char a[1][2];
+  int n = strlen (*a);
+  if (n != 1)
+    abort();
+}
+
+void g (void)
+{
+  extern char b[1][2];
+  int n = strlen (b[0]);
+  if (n != 1)
+    abort();
+}
+
+void h (void)
+{
+  extern char c[1][2];
+  int n = strlen (&c[0][0]);
+  if (n != 1)
+    abort();
+}
+
+/* { dg-final { scan-tree-dump-times "= strlen" 3 "optimized" } }
+   { dg-final { scan-tree-dump-times "abort" 3 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-48.c b/gcc/testsuite/gcc.dg/strlenopt-48.c
new file mode 100644
index 000000000000..39bb32df6dd1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/strlenopt-48.c
@@ -0,0 +1,35 @@
+/* PR tree-optimization/86400 - set<string>::set<char (*)[2]) constructor
+   does not work with array argument
+   Verify that strlen() calls with one-character array elements of
+   multidimensional arrays are still folded.
+   { dg-do compile }
+   { dg-options "-O2 -Wall -fdump-tree-optimized" } */
+
+#include "strlenopt.h"
+
+void f (void)
+{
+  extern char a[2][1];
+  int n = strlen (a[1]);
+  if (n)
+    abort();
+}
+
+void g (void)
+{
+  extern char b[3][2][1];
+  int n = strlen (b[2][1]);
+  if (n)
+    abort();
+}
+
+void h (void)
+{
+  extern char c[4][3][2][1];
+  int n = strlen (c[3][2][1]);
+  if (n)
+    abort();
+}
+
+/* { dg-final { scan-tree-dump-times "strlen" 0 "optimized" } }
+   { dg-final { scan-tree-dump-times "abort" 0 "optimized" } } */
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c
index 87d3d0d043a6..ca42386d4454 100644
--- a/gcc/tree-ssa-strlen.c
+++ b/gcc/tree-ssa-strlen.c
@@ -1186,11 +1186,13 @@ maybe_set_strlen_range (tree lhs, tree src)
     return;
 
   tree type = TREE_TYPE (src);
-  if (tree dom = TYPE_DOMAIN (type))
-    if (tree maxval = TYPE_MAX_VALUE (dom))
+  if (tree size = TYPE_SIZE_UNIT (type))
+    if (size && TREE_CODE (size) == INTEGER_CST)
       {
-	wide_int max = wi::to_wide (maxval);
+	wide_int max = wi::to_wide (size);
 	wide_int min = wi::zero (max.get_precision ());
+	if (max != 0)
+	  --max;
 	set_range_info (lhs, VR_RANGE, min, max);
       }
 }