Fix and enable generating general union initializers. Essentially, what

this does is reconstruct the type for structs and arrays if the type 
wouldn't be compatible otherwise.

The assertion about packing in the struct type reconstruction code 
sucks, but I don't see any obvious way to fix it.  Maybe we need a general
utility method to take a list of types and alignments and try to construct an
unpacked type if possible?

llvm-svn: 51785

1 files changed, 31 insertions, 0 deletions

diff --git a/clang/test/CodeGen/union-init.c b/clang/test/CodeGen/union-init.c
new file mode 100644
index 00000000000..9a515a72d92
--- /dev/null
+++ b/clang/test/CodeGen/union-init.c
@@ -0,0 +1,31 @@
+// RUN: clang -emit-llvm < %s -o -
+
+// A nice and complicated initialization example with unions from Python
+typedef int Py_ssize_t;
+
+typedef union _gc_head {
+	struct {
+		union _gc_head *gc_next;
+		union _gc_head *gc_prev;
+		Py_ssize_t gc_refs;
+	} gc;
+	long double dummy;  /* force worst-case alignment */
+} PyGC_Head;
+
+struct gc_generation {
+	PyGC_Head head;
+	int threshold; /* collection threshold */
+	int count; /* count of allocations or collections of younger
+		      generations */
+};
+
+#define NUM_GENERATIONS 3
+#define GEN_HEAD(n) (&generations[n].head)
+
+/* linked lists of container objects */
+struct gc_generation generations[NUM_GENERATIONS] = {
+	/* PyGC_Head,				threshold,	count */
+	{{{GEN_HEAD(0), GEN_HEAD(0), 0}},	700,		0},
+	{{{GEN_HEAD(1), GEN_HEAD(1), 0}},	10,		0},
+	{{{GEN_HEAD(2), GEN_HEAD(2), 0}},	10,		0},
+};