Implement the no_split_stack attribute.

This is a GNU attribute that allows split stacks to be turned off on a
per-function basis.

Differential Revision: http://reviews.llvm.org/D3817

llvm-svn: 209167
diff --git a/clang/test/CodeGenCXX/split-stacks.cpp b/clang/test/CodeGenCXX/split-stacks.cpp
new file mode 100644
index 0000000..3e12034
--- /dev/null
+++ b/clang/test/CodeGenCXX/split-stacks.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang -target x86_64-linux-gnu -fsplit-stack -S -std=c++11 %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-SEGSTK %s
+// RUN: %clang -target x86_64-linux-gnu -S -std=c++11 %s -emit-llvm -o - | FileCheck -check-prefix=CHECK-NOSEGSTK %s
+
+int foo() {
+  return 0;
+}
+
+template <typename T>
+[[gnu::no_split_stack]]
+int tnosplit() {
+  return 0;
+}
+
+[[gnu::no_split_stack]]
+int nosplit() {
+  return tnosplit<int>();
+}
+
+// CHECK-SEGSTK: define i32 @_Z3foov() [[SS:#[0-9]+]] {
+// CHECK-SEGSTK: define i32 @_Z7nosplitv() [[NSS1:#[0-9]+]] {
+// CHECK-SEGSTK: define linkonce_odr i32 @_Z8tnosplitIiEiv() [[NSS2:#[0-9]+]] {
+// CHECK-SEGSTK-NOT: [[NSS1]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-SEGSTK-NOT: [[NSS2]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-SEGSTK: [[SS]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-SEGSTK-NOT: [[NSS1]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-SEGSTK-NOT: [[NSS2]] = { {{.*}} "split-stack" {{.*}} }
+
+// CHECK-NOSEGSTK: define i32 @_Z3foov() [[NSS0:#[0-9]+]] {
+// CHECK-NOSEGSTK: define i32 @_Z7nosplitv() [[NSS1:#[0-9]+]] {
+// CHECK-NOSEGSTK: define linkonce_odr i32 @_Z8tnosplitIiEiv() [[NSS2:#[0-9]+]] {
+// CHECK-NOSEGSTK-NOT: [[NSS1]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-NOSEGSTK-NOT: [[NSS2]] = { {{.*}} "split-stack" {{.*}} }
+// CHECK-NOSEGSTK-NOT: [[NSS3]] = { {{.*}} "split-stack" {{.*}} }