Roundtrip the inalloca bit on allocas through bitcode

This was an oversight in the original support.  As it is, I stuffed this
bit into the alignment.  The alignment is stored in log2 form, so it
doesn't need more than 5 bits, given that Value::MaximumAlignment is 1
<< 29.

Reviewers: nicholas

Differential Revision: http://reviews.llvm.org/D3943

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213118 91177308-0d34-0410-b5e6-96231b3b80d8

test/Bitcode/inalloca.ll

@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+; inalloca should roundtrip.
+
+define void @foo(i32* inalloca %args) {
+  ret void
+}
+; CHECK-LABEL: define void @foo(i32* inalloca %args)
+
+define void @bar() {
+  ; Use the maximum alignment, since we stuff our bit with alignment.
+  %args = alloca inalloca i32, align 536870912
+  call void @foo(i32* inalloca %args)
+  ret void
+}
+; CHECK-LABEL: define void @bar() {
+; CHECK: %args = alloca inalloca i32, align 536870912
+; CHECK: call void @foo(i32* inalloca %args)