IR: Don't allow non-default visibility on local linkage

Visibilities of `hidden` and `protected` are meaningless for symbols
with local linkage.

  - Change the assembler to reject non-default visibility on symbols
    with local linkage.

  - Change the bitcode reader to auto-upgrade `hidden` and `protected`
    to `default` when the linkage is local.

  - Update LangRef.

<rdar://problem/16141113>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208263 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 79 insertions, 0 deletions

diff --git a/test/Bitcode/local-linkage-default-visibility.3.4.ll b/test/Bitcode/local-linkage-default-visibility.3.4.ll
new file mode 100644
index 0000000000..45a7b1213a
--- /dev/null
+++ b/test/Bitcode/local-linkage-default-visibility.3.4.ll
@@ -0,0 +1,79 @@
+; RUN: llvm-dis < %s.bc | FileCheck %s
+
+; local-linkage-default-visibility.3.4.ll.bc was generated by passing this file
+; to llvm-as-3.4.  The test checks that LLVM upgrades visibility of symbols
+; with local linkage to default visibility.
+
+@default.internal.var = internal global i32 0
+; CHECK: @default.internal.var = internal global i32 0
+
+@hidden.internal.var = internal hidden global i32 0
+; CHECK: @hidden.internal.var = internal global i32 0
+
+@protected.internal.var = internal protected global i32 0
+; CHECK: @protected.internal.var = internal global i32 0
+
+@default.private.var = private global i32 0
+; CHECK: @default.private.var = private global i32 0
+
+@hidden.private.var = private hidden global i32 0
+; CHECK: @hidden.private.var = private global i32 0
+
+@protected.private.var = private protected global i32 0
+; CHECK: @protected.private.var = private global i32 0
+
+@global = global i32 0
+
+@default.internal.alias = alias internal i32* @global
+; CHECK: @default.internal.alias = alias internal i32* @global
+
+@hidden.internal.alias = hidden alias internal i32* @global
+; CHECK: @hidden.internal.alias = alias internal i32* @global
+
+@protected.internal.alias = protected alias internal i32* @global
+; CHECK: @protected.internal.alias = alias internal i32* @global
+
+@default.private.alias = alias private i32* @global
+; CHECK: @default.private.alias = alias private i32* @global
+
+@hidden.private.alias = hidden alias private i32* @global
+; CHECK: @hidden.private.alias = alias private i32* @global
+
+@protected.private.alias = protected alias private i32* @global
+; CHECK: @protected.private.alias = alias private i32* @global
+
+define internal void @default.internal() {
+; CHECK: define internal void @default.internal
+entry:
+  ret void
+}
+
+define internal hidden void @hidden.internal() {
+; CHECK: define internal void @hidden.internal
+entry:
+  ret void
+}
+
+define internal protected void @protected.internal() {
+; CHECK: define internal void @protected.internal
+entry:
+  ret void
+}
+
+define private void @default.private() {
+; CHECK: define private void @default.private
+entry:
+  ret void
+}
+
+define private hidden void @hidden.private() {
+; CHECK: define private void @hidden.private
+entry:
+  ret void
+}
+
+define private protected void @protected.private() {
+; CHECK: define private void @protected.private
+entry:
+  ret void
+}
diff --git a/test/Bitcode/local-linkage-default-visibility.3.4.ll.bc b/test/Bitcode/local-linkage-default-visibility.3.4.ll.bc
new file mode 100644
index 0000000000..6e49f7e365
--- /dev/null
+++ b/test/Bitcode/local-linkage-default-visibility.3.4.ll.bc