From: Thomas Preud'homme <thomas.preudhomme@arm.com>
Date: Wed, 13 Aug 2014 09:37:41 +0000 (+0000)
Subject: backport: re PR middle-end/62103 (Incorrect folding of bitfield in a union on big... 
X-Git-Tag: releases/gcc-4.8.4~291
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6851753fdc2b2d4f1b3c3e7439714e7bd47f44e1;p=thirdparty%2Fgcc.git

backport: re PR middle-end/62103 (Incorrect folding of bitfield in a union on big endian targets)

2014-08-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    Backport from mainline
    2014-08-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    PR middle-end/62103
    * gimple-fold.c (fold_ctor_reference): Don't fold in presence of
    bitfields, that is when size doesn't match the size of type or the
    size of the constructor.

    gcc/testsuite/
    PR middle-end/62103
    * gcc.c-torture/execute/bitfld-6.c: New test.

From-SVN: r213899
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 25ac61f9356a..e7771545c208 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2014-08-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
+	2014-08-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR middle-end/62103
+	* gimple-fold.c (fold_ctor_reference): Don't fold in presence of
+	bitfields, that is when size doesn't match the size of type or the
+	size of the constructor.
+
 2014-08-12  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	Backport patch from mainline
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 5d08169b8b59..80020a99e08a 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -2955,8 +2955,8 @@ fold_ctor_reference (tree type, tree ctor, unsigned HOST_WIDE_INT offset,
      result.  */
   if (!AGGREGATE_TYPE_P (TREE_TYPE (ctor)) && !offset
       /* VIEW_CONVERT_EXPR is defined only for matching sizes.  */
-      && operand_equal_p (TYPE_SIZE (type),
-			  TYPE_SIZE (TREE_TYPE (ctor)), 0))
+      && !compare_tree_int (TYPE_SIZE (type), size)
+      && !compare_tree_int (TYPE_SIZE (TREE_TYPE (ctor)), size))
     {
       ret = canonicalize_constructor_val (unshare_expr (ctor), from_decl);
       ret = fold_unary (VIEW_CONVERT_EXPR, type, ret);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d55ac28b2dca..bcb2b66eff97 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2014-08-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	Backport from mainline
+	2014-08-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR middle-end/62103
+	* gcc.c-torture/execute/bitfld-6.c: New test.
+
 2014-08-10  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	Backport from trunk
diff --git a/gcc/testsuite/gcc.c-torture/execute/bitfld-6.c b/gcc/testsuite/gcc.c-torture/execute/bitfld-6.c
new file mode 100644
index 000000000000..50927dc1d53a
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/bitfld-6.c
@@ -0,0 +1,23 @@
+union U
+{
+  const int a;
+  unsigned b : 20;
+};
+
+static union U u = { 0x12345678 };
+
+/* Constant folding used to fail to account for endianness when folding a
+   union.  */
+
+int
+main (void)
+{
+#ifdef __BYTE_ORDER__
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  return u.b - 0x45678;
+#else
+  return u.b - 0x12345;
+#endif
+#endif
+  return 0;
+}