CodeGen: ConstStructBuilder must verify packed constraints after padding

Before, ConstStructBuilder::AppendBytes would check packed constraints
prior to padding being added before the field's offset.  However, adding
this padding might force our struct to be packed.  Because we wouldn't
check *after* adding padding, ConstStructBuilder would be in an
inconsistent state leading to a crash.

This fixes PR21300.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@220153 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/test/CodeGen/const-init.c b/test/CodeGen/const-init.c
index 7d7ccae370..ccc6604c45 100644
--- a/test/CodeGen/const-init.c
+++ b/test/CodeGen/const-init.c
@@ -159,3 +159,14 @@ void g29() {
   static int b[1] = { "asdf" }; // expected-warning {{incompatible pointer to integer conversion initializing 'int' with an expression of type 'char [5]'}}
   static int c[1] = { L"a" };
 }
+
+// PR21300
+void g30() {
+#pragma pack(1)
+  static struct {
+    int : 1;
+    int x;
+  } a = {};
+  // CHECK: @g30.a = internal global %struct.anon.1 <{ i8 undef, i32 0 }>, align 1
+#pragma pack()
+}