Revert -Zbranch-protection

This reverts commit d331cb7, reversing
changes made to 78fd0f6.

This is a fix for #92885 as discussed on Zulip[1].

[1] https://zulip-archive.rust-lang.org/stream/238009-t-compiler/meetings/topic/.5Bweekly.5D.202022-01-27.20.2354818.html#269588396

Author: nagisa

compiler/rustc_codegen_llvm/src/context.rs

@@ -21,7 +21,7 @@ use rustc_middle::ty::layout::{
 };
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
-use rustc_session::config::{BranchProtection, CFGuard, CrateType, DebugInfo, PAuthKey, PacRet};
+use rustc_session::config::{CFGuard, CrateType, DebugInfo};
 use rustc_session::Session;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
@@ -242,34 +242,6 @@ pub unsafe fn create_module<'ll>(
         }
     }
 
-    if sess.target.arch == "aarch64" {
-        let BranchProtection { bti, pac_ret: pac } = sess.opts.debugging_opts.branch_protection;
-
-        llvm::LLVMRustAddModuleFlag(
-            llmod,
-            "branch-target-enforcement\0".as_ptr().cast(),
-            bti.into(),
-        );
-
-        llvm::LLVMRustAddModuleFlag(
-            llmod,
-            "sign-return-address\0".as_ptr().cast(),
-            pac.is_some().into(),
-        );
-        let pac_opts = pac.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
-        llvm::LLVMRustAddModuleFlag(
-            llmod,
-            "sign-return-address-all\0".as_ptr().cast(),
-            pac_opts.leaf.into(),
-        );
-        let is_bkey = if pac_opts.key == PAuthKey::A { false } else { true };
-        llvm::LLVMRustAddModuleFlag(
-            llmod,
-            "sign-return-address-with-bkey\0".as_ptr().cast(),
-            is_bkey.into(),
-        );
-    }
-
     llmod
 }
 

compiler/rustc_codegen_llvm/src/declare.rs

@@ -47,7 +47,6 @@ fn declare_raw_fn<'ll>(
 
     attributes::default_optimisation_attrs(cx.tcx.sess, llfn);
     attributes::non_lazy_bind(cx.sess(), llfn);
-
     llfn
 }
 

compiler/rustc_interface/src/tests.rs

@@ -8,11 +8,10 @@ use rustc_session::config::{build_configuration, build_session_options, to_crate
 use rustc_session::config::{
     rustc_optgroups, ErrorOutputType, ExternLocation, LocationDetail, Options, Passes,
 };
+use rustc_session::config::{CFGuard, ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
 use rustc_session::config::{
-    BranchProtection, Externs, OutputType, OutputTypes, PAuthKey, PacRet, SymbolManglingVersion,
-    WasiExecModel,
+    Externs, OutputType, OutputTypes, SymbolManglingVersion, WasiExecModel,
 };
-use rustc_session::config::{CFGuard, ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
@@ -719,10 +718,6 @@ fn test_debugging_options_tracking_hash() {
     tracked!(asm_comments, true);
     tracked!(assume_incomplete_release, true);
     tracked!(binary_dep_depinfo, true);
-    tracked!(
-        branch_protection,
-        BranchProtection { bti: true, pac_ret: Some(PacRet { leaf: true, key: PAuthKey::B }) }
-    );
     tracked!(chalk, true);
     tracked!(codegen_backend, Some("abc".to_string()));
     tracked!(crate_attr, vec!["abc".to_string()]);

compiler/rustc_session/src/config.rs

@@ -891,30 +891,6 @@ impl Passes {
     }
 }
 
-#[derive(Clone, Copy, Hash, Debug, PartialEq)]
-pub enum PAuthKey {
-    A,
-    B,
-}
-
-#[derive(Clone, Copy, Hash, Debug, PartialEq)]
-pub struct PacRet {
-    pub leaf: bool,
-    pub key: PAuthKey,
-}
-
-#[derive(Clone, Copy, Hash, Debug, PartialEq)]
-pub struct BranchProtection {
-    pub bti: bool,
-    pub pac_ret: Option<PacRet>,
-}
-
-impl Default for BranchProtection {
-    fn default() -> Self {
-        BranchProtection { bti: false, pac_ret: None }
-    }
-}
-
 pub const fn default_lib_output() -> CrateType {
     CrateType::Rlib
 }
@@ -2595,9 +2571,9 @@ impl PpMode {
 crate mod dep_tracking {
     use super::LdImpl;
     use super::{
-        BranchProtection, CFGuard, CrateType, DebugInfo, ErrorOutputType, InstrumentCoverage,
-        LinkerPluginLto, LocationDetail, LtoCli, OptLevel, OutputType, OutputTypes, Passes,
-        SourceFileHashAlgorithm, SwitchWithOptPath, SymbolManglingVersion, TrimmedDefPaths,
+        CFGuard, CrateType, DebugInfo, ErrorOutputType, InstrumentCoverage, LinkerPluginLto,
+        LocationDetail, LtoCli, OptLevel, OutputType, OutputTypes, Passes, SourceFileHashAlgorithm,
+        SwitchWithOptPath, SymbolManglingVersion, TrimmedDefPaths,
     };
     use crate::lint;
     use crate::options::WasiExecModel;
@@ -2691,7 +2667,6 @@ crate mod dep_tracking {
         OutputType,
         RealFileName,
         LocationDetail,
-        BranchProtection,
     );
 
     impl<T1, T2> DepTrackingHash for (T1, T2)

compiler/rustc_session/src/options.rs

@@ -417,8 +417,6 @@ mod desc {
     pub const parse_gcc_ld: &str = "one of: no value, `lld`";
     pub const parse_stack_protector: &str =
         "one of (`none` (default), `basic`, `strong`, or `all`)";
-    pub const parse_branch_protection: &str =
-        "a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
 }
 
 mod parse {
@@ -967,32 +965,6 @@ mod parse {
         }
         true
     }
-
-    crate fn parse_branch_protection(slot: &mut BranchProtection, v: Option<&str>) -> bool {
-        match v {
-            Some(s) => {
-                for opt in s.split(',') {
-                    match opt {
-                        "bti" => slot.bti = true,
-                        "pac-ret" if slot.pac_ret.is_none() => {
-                            slot.pac_ret = Some(PacRet { leaf: false, key: PAuthKey::A })
-                        }
-                        "leaf" => match slot.pac_ret.as_mut() {
-                            Some(pac) => pac.leaf = true,
-                            _ => return false,
-                        },
-                        "b-key" => match slot.pac_ret.as_mut() {
-                            Some(pac) => pac.key = PAuthKey::B,
-                            _ => return false,
-                        },
-                        _ => return false,
-                    };
-                }
-            }
-            _ => return false,
-        }
-        true
-    }
 }
 
 options! {
@@ -1137,8 +1109,6 @@ options! {
         (default: no)"),
     borrowck: String = ("migrate".to_string(), parse_string, [UNTRACKED],
         "select which borrowck is used (`mir` or `migrate`) (default: `migrate`)"),
-    branch_protection: BranchProtection = (BranchProtection::default(), parse_branch_protection, [TRACKED],
-        "set options for branch target identification and pointer authentication on AArch64"),
     cgu_partitioning_strategy: Option<String> = (None, parse_opt_string, [TRACKED],
         "the codegen unit partitioning strategy to use"),
     chalk: bool = (false, parse_bool, [TRACKED],