-fms-extensions: Implement half of #pragma init_seg

Summary:
This pragma is very rare.  We could *hypothetically* lower some uses of
it down to @llvm.global_ctors, but given that GlobalOpt isn't able to
optimize prioritized global ctors today, there's really no point.

If we wanted to do this in the future, I would check if the section used
in the pragma started with ".CRT$XC" and had up to two characters after
it.  Those two characters could form the 16-bit initialization priority
that we support in @llvm.global_ctors.  We would have to teach LLVM to
lower prioritized global ctors on COFF as well.

This should let us compile some silly uses of this pragma in WebKit /
Blink.

Reviewers: rsmith, majnemer

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D4549

llvm-svn: 213593

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/pragma-init_seg.cpp b/clang/test/SemaCXX/pragma-init_seg.cpp
new file mode 100644
index 00000000000..38520b0c2ef
--- /dev/null
+++ b/clang/test/SemaCXX/pragma-init_seg.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -fms-extensions %s -triple x86_64-pc-win32
+
+#pragma init_seg(L".my_seg") // expected-warning {{expected 'compiler', 'lib', 'user', or a string literal}}
+#pragma init_seg( // expected-warning {{expected 'compiler', 'lib', 'user', or a string literal}}
+#pragma init_seg asdf // expected-warning {{missing '('}}
+#pragma init_seg) // expected-warning {{missing '('}}
+#pragma init_seg("a" "b") // no warning
+#pragma init_seg("a", "b") // expected-warning {{missing ')'}}
+#pragma init_seg("a") asdf // expected-warning {{extra tokens at end of '#pragma init_seg'}}
+#pragma init_seg("\x") // expected-error {{\x used with no following hex digits}}
+#pragma init_seg("a" L"b") // expected-warning {{expected non-wide string literal in '#pragma init_seg'}}
+
+int f();
+#pragma init_seg(compiler)
+int __declspec(thread) x = f(); // expected-error {{initializer for thread-local variable must be a constant expression}}