Auto merge of #68180 - ajpaverd:cfguard-rust, r=nagisa

Add support for Control Flow Guard on Windows.

LLVM now supports Windows Control Flow Guard (CFG): https://github.com/llvm/llvm-project/commit/d157a9bc8ba1085cc4808c6941412322a7fd884e
This patch adds support for rustc to emit the required LLVM module flags to enable CFG metadata (cfguard=1) or metadata and checks (cfguard=2). The LLVM module flags are ignored on unsupported targets and operating systems.

3 files changed, 30 insertions, 0 deletions

diff --git a/src/test/codegen/cfguard_checks.rs b/src/test/codegen/cfguard_checks.rs
new file mode 100644
index 00000000000..40a7353eac0
--- /dev/null
+++ b/src/test/codegen/cfguard_checks.rs
@@ -0,0 +1,10 @@
+// compile-flags: -Z control_flow_guard=checks
+
+#![crate_type = "lib"]
+
+// A basic test function.
+pub fn test() {
+}
+
+// Ensure the module flag cfguard=2 is present
+// CHECK: !"cfguard", i32 2
diff --git a/src/test/codegen/cfguard_disabled.rs b/src/test/codegen/cfguard_disabled.rs
new file mode 100644
index 00000000000..d1747931e15
--- /dev/null
+++ b/src/test/codegen/cfguard_disabled.rs
@@ -0,0 +1,10 @@
+// compile-flags: -Z control_flow_guard=disabled
+
+#![crate_type = "lib"]
+
+// A basic test function.
+pub fn test() {
+}
+
+// Ensure the module flag cfguard is not present
+// CHECK-NOT: !"cfguard"
diff --git a/src/test/codegen/cfguard_nochecks.rs b/src/test/codegen/cfguard_nochecks.rs
new file mode 100644
index 00000000000..c5d7afbae25
--- /dev/null
+++ b/src/test/codegen/cfguard_nochecks.rs
@@ -0,0 +1,10 @@
+// compile-flags: -Z control_flow_guard=nochecks
+
+#![crate_type = "lib"]
+
+// A basic test function.
+pub fn test() {
+}
+
+// Ensure the module flag cfguard=1 is present
+// CHECK: !"cfguard", i32 1