Fix bitfield accesses which straddle the boundary of the underlying

type.

 - This generates somewhat less optimal code than before but this is
   not hard to rectify once stable (at the cost of slightly more
   complex code).

 - This currently always uses little-endian ordering of the bitfield. 

 - This breaks the CodeGen/bitfield.c test because it was grepping for
   hard-coded assembly instructions. Will fix once a better test case
   is constructed (hard to do without execution).

 - This fixes SingleSource/UnitTests/2006-01-23-InitializedBitField.c
   and Regression/C/PR1386.c from the test suite.

 - <rdar://problem/6085090>, <rdar://problem/6094169>


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@54395 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/test/CodeGen/2008-07-22-packed-bitfield-access.c b/test/CodeGen/2008-07-22-packed-bitfield-access.c
new file mode 100644
index 0000000000..b41b5e0e40
--- /dev/null
+++ b/test/CodeGen/2008-07-22-packed-bitfield-access.c
@@ -0,0 +1,10 @@
+// RUN: clang %s -emit-llvm -o -
+
+int main () {
+  struct foo {
+    unsigned a:16;
+    unsigned b:32 __attribute__ ((packed));
+  } x;
+  x.b = 0x56789abcL;
+  return 0;
+}