expmed.c (strict_volatile_bitfield_p): Fix off-by-one error.

* expmed.c (strict_volatile_bitfield_p): Fix off-by-one error.
* gcc.dg/20141029-1.c: New.

From-SVN: r216844

gcc/ChangeLog

+2014-10-29  DJ Delorie  <dj@redhat.com>
+
+	* expmed.c (strict_volatile_bitfield_p): Fix off-by-one error.
+
 2014-10-29  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/63587

gcc/expmed.c

@@ -457,7 +457,7 @@ strict_volatile_bitfield_p (rtx op0, unsigned HOST_WIDE_INT bitsize,
   /* Check for cases where the C++ memory model applies.  */
   if (bitregion_end != 0
       && (bitnum - bitnum % modesize < bitregion_start
-	  || bitnum - bitnum % modesize + modesize > bitregion_end))
+	  || bitnum - bitnum % modesize + modesize - 1 > bitregion_end))
     return false;
 
   return true;

gcc/testsuite/ChangeLog

+2014-10-29  DJ Delorie  <dj@redhat.com>
+
+	* gcc.dg/20141029-1.c: New.
+
 2014-10-29  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/63587

gcc/testsuite/gcc.dg/20141029-1.c

+/* { dg-do compile } */
+/* { dg-options "-fstrict-volatile-bitfields -fdump-rtl-final" } */
+
+#define PERIPH (*(volatile struct system_periph *)0x81234)
+
+struct system_periph {
+  union {
+    unsigned short WORD;
+    struct {
+      unsigned short a:1;
+      unsigned short b:1;
+      unsigned short  :5;
+      unsigned short c:1;
+      unsigned short  :8;
+    } BIT;
+  } ALL;
+};
+
+void
+foo()
+{
+  while (1)
+    {
+      PERIPH.ALL.BIT.a = 1;
+    }
+}
+/* { dg-final { scan-rtl-dump-times "mem/v(/.)*:HI" 4 "final" } } */
+/* { dg-final { cleanup-rtl-dump "final" } } */