Rollup merge of rust-lang#73893 - ajpaverd:cfguard-stabilize, r=nikomatsakis

Stabilize control-flow-guard codegen option

This is the stabilization PR discussed in rust-lang#68793. It converts the `-Z control-flow-guard` debugging option into a codegen option (`-C control-flow-guard`), and changes the associated tests.

Author: Manishearth

src/bootstrap/builder.rs

@@ -1239,7 +1239,7 @@ impl<'a> Builder<'a> {
             && self.config.control_flow_guard
             && compiler.stage >= 1
         {
-            rustflags.arg("-Zcontrol-flow-guard");
+            rustflags.arg("-Ccontrol-flow-guard");
         }
 
         // For `cargo doc` invocations, make rustdoc print the Rust version into the docs

src/doc/rustc/src/codegen-options/index.md

@@ -42,6 +42,18 @@ generated code, but may be slower to compile.
 The default value, if not specified, is 16 for non-incremental builds. For
 incremental builds the default is 256 which allows caching to be more granular.
 
+## control-flow-guard
+
+This flag controls whether LLVM enables the Windows [Control Flow 
+Guard](https://docs.microsoft.com/en-us/windows/win32/secbp/control-flow-guard) 
+platform security feature. This flag is currently ignored for non-Windows targets. 
+It takes one of the following values:
+
+* `y`, `yes`, `on`, `checks`, or no value: enable Control Flow Guard.
+* `nochecks`: emit Control Flow Guard metadata without runtime enforcement checks (this 
+should only be used for testing purposes as it does not provide security enforcement).
+* `n`, `no`, `off`: do not enable Control Flow Guard (the default).
+
 ## debug-assertions
 
 This flag lets you turn `cfg(debug_assertions)` [conditional

src/librustc_codegen_llvm/context.rs

@@ -190,7 +190,7 @@ pub unsafe fn create_module(
 
     // Control Flow Guard is currently only supported by the MSVC linker on Windows.
     if sess.target.target.options.is_like_msvc {
-        match sess.opts.debugging_opts.control_flow_guard {
+        match sess.opts.cg.control_flow_guard {
             CFGuard::Disabled => {}
             CFGuard::NoChecks => {
                 // Set `cfguard=1` module flag to emit metadata only.

src/librustc_codegen_ssa/back/link.rs

@@ -1700,7 +1700,7 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
     }
 
     // OBJECT-FILES-NO, AUDIT-ORDER
-    if sess.opts.debugging_opts.control_flow_guard != CFGuard::Disabled {
+    if sess.opts.cg.control_flow_guard != CFGuard::Disabled {
         cmd.control_flow_guard();
     }
 

src/librustc_interface/tests.rs

@@ -420,6 +420,7 @@ fn test_codegen_options_tracking_hash() {
     // Make sure that changing a [TRACKED] option changes the hash.
     // This list is in alphabetical order.
     tracked!(code_model, Some(CodeModel::Large));
+    tracked!(control_flow_guard, CFGuard::Checks);
     tracked!(debug_assertions, Some(true));
     tracked!(debuginfo, 0xdeadbeef);
     tracked!(embed_bitcode, false);
@@ -537,7 +538,6 @@ fn test_debugging_options_tracking_hash() {
     tracked!(binary_dep_depinfo, true);
     tracked!(chalk, true);
     tracked!(codegen_backend, Some("abc".to_string()));
-    tracked!(control_flow_guard, CFGuard::Checks);
     tracked!(crate_attr, vec!["abc".to_string()]);
     tracked!(debug_macros, true);
     tracked!(dep_info_omit_d_target, true);

src/librustc_session/config.rs

@@ -103,7 +103,7 @@ pub enum Strip {
     Symbols,
 }
 
-/// The different settings that the `-Z control-flow-guard` flag can have.
+/// The different settings that the `-C control-flow-guard` flag can have.
 #[derive(Clone, Copy, PartialEq, Hash, Debug)]
 pub enum CFGuard {
     /// Do not emit Control Flow Guard metadata or checks.

src/librustc_session/options.rs

@@ -692,6 +692,8 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
         "choose the code model to use (`rustc --print code-models` for details)"),
     codegen_units: Option<usize> = (None, parse_opt_uint, [UNTRACKED],
         "divide crate into N units to optimize in parallel"),
+    control_flow_guard: CFGuard = (CFGuard::Disabled, parse_cfguard, [TRACKED],
+        "use Windows Control Flow Guard (default: no)"),
     debug_assertions: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "explicitly enable the `cfg(debug_assertions)` directive"),
     debuginfo: usize = (0, parse_uint, [TRACKED],
@@ -809,8 +811,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "enable the experimental Chalk-based trait solving engine"),
     codegen_backend: Option<String> = (None, parse_opt_string, [TRACKED],
         "the backend to use"),
-    control_flow_guard: CFGuard = (CFGuard::Disabled, parse_cfguard, [TRACKED],
-        "use Windows Control Flow Guard (default: no)"),
     crate_attr: Vec<String> = (Vec::new(), parse_string_push, [TRACKED],
         "inject the given attribute in the crate"),
     debug_macros: bool = (false, parse_bool, [TRACKED],

src/test/codegen/cfguard-checks.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z control-flow-guard=checks
+// compile-flags: -C control-flow-guard=checks
 // only-msvc
 
 #![crate_type = "lib"]

src/test/codegen/cfguard-disabled.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z control-flow-guard=no
+// compile-flags: -C control-flow-guard=no
 // only-msvc
 
 #![crate_type = "lib"]

src/test/codegen/cfguard-nochecks.rs

@@ -1,4 +1,4 @@
-// compile-flags: -Z control-flow-guard=nochecks
+// compile-flags: -C control-flow-guard=nochecks
 // only-msvc
 
 #![crate_type = "lib"]