Auto merge of #145974 - pmur:murp/stabilize-zno-jump-tables, r=<try>

Stabilize -Zno-jump-tables into -Cjump-tables=bool

try-job: x86_64-rust-for-linux

Author: rust-bors[bot]

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -229,7 +229,7 @@ fn instrument_function_attr<'ll>(
 }
 
 fn nojumptables_attr<'ll>(cx: &SimpleCx<'ll>, sess: &Session) -> Option<&'ll Attribute> {
-    if !sess.opts.unstable_opts.no_jump_tables {
+    if sess.opts.cg.jump_tables {
         return None;
     }
 

compiler/rustc_interface/src/tests.rs

@@ -620,6 +620,7 @@ fn test_codegen_options_tracking_hash() {
     tracked!(force_frame_pointers, FramePointer::Always);
     tracked!(force_unwind_tables, Some(true));
     tracked!(instrument_coverage, InstrumentCoverage::Yes);
+    tracked!(jump_tables, false);
     tracked!(link_dead_code, Some(true));
     tracked!(linker_plugin_lto, LinkerPluginLto::LinkerPluginAuto);
     tracked!(llvm_args, vec![String::from("1"), String::from("2")]);
@@ -831,7 +832,6 @@ fn test_unstable_options_tracking_hash() {
     tracked!(mutable_noalias, false);
     tracked!(next_solver, NextSolverConfig { coherence: true, globally: true });
     tracked!(no_generate_arange_section, true);
-    tracked!(no_jump_tables, true);
     tracked!(no_link, true);
     tracked!(no_profiler_runtime, true);
     tracked!(no_trait_vptr, true);

compiler/rustc_session/src/options.rs

@@ -2093,6 +2093,8 @@ options! {
         "instrument the generated code to support LLVM source-based code coverage reports \
         (note, the compiler build config must include `profiler = true`); \
         implies `-C symbol-mangling-version=v0`"),
+    jump_tables: bool = (true, parse_bool, [TRACKED],
+        "allow jump table and lookup table generation from switch case lowering (default: yes)"),
     link_arg: (/* redirected to link_args */) = ((), parse_string_push, [UNTRACKED],
         "a single extra argument to append to the linker invocation (can be used several times)"),
     link_args: Vec<String> = (Vec::new(), parse_list, [UNTRACKED],
@@ -2475,8 +2477,6 @@ options! {
         "omit DWARF address ranges that give faster lookups"),
     no_implied_bounds_compat: bool = (false, parse_bool, [TRACKED],
         "disable the compatibility version of the `implied_bounds_ty` query"),
-    no_jump_tables: bool = (false, parse_no_value, [TRACKED],
-        "disable the jump tables and lookup tables that can be generated from a switch case lowering"),
     no_leak_check: bool = (false, parse_no_value, [UNTRACKED],
         "disable the 'leak check' for subtyping; unsound, but useful for tests"),
     no_link: bool = (false, parse_no_value, [TRACKED],

src/ci/docker/scripts/rfl-build.sh

@@ -2,7 +2,8 @@
 
 set -euo pipefail
 
-LINUX_VERSION=v6.17-rc5
+# https://github.com/rust-lang/rust/pull/145974
+LINUX_VERSION=842cfd8e5aff3157cb25481b2900b49c188d628a
 
 # Build rustc, rustdoc, cargo, clippy-driver and rustfmt
 ../x.py build --stage 2 library rustdoc clippy rustfmt

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

@@ -209,6 +209,27 @@ Note that while the `-C instrument-coverage` option is stable, the profile data
 format produced by the resulting instrumentation may change, and may not work
 with coverage tools other than those built and shipped with the compiler.
 
+## jump-tables
+
+This option is used to allow or prevent the LLVM codegen backend from creating
+jump tables when lowering switches from Rust code.
+
+* `y`, `yes`, `on`, `true` or no value: allow jump tables (the default).
+* `n`, `no`, `off` or `false`: disable jump tables.
+
+To prevent jump tables being created from Rust code, a target must ensure
+all crates are compiled with jump tables disabled.
+
+Note, in many cases the Rust toolchain is distributed with precompiled
+crates, such as the core and std crates, which could possibly include
+jump tables. Furthermore, this option does not guarantee a target will
+be free of jump tables. They could arise from external dependencies,
+inline asm, or other complicated interactions when using crates which
+are compiled with jump table support.
+
+Disabling jump tables can be used to help provide protection against
+jump-oriented-programming (JOP) attacks.
+
 ## link-arg
 
 This flag lets you append a single extra argument to the linker invocation.

src/doc/unstable-book/src/compiler-flags/no-jump-tables.md

@@ -1,10 +1,10 @@
-// Test that jump tables are (not) emitted when the `-Zno-jump-tables`
+// Test that jump tables are (not) emitted when the `-Cjump-tables=no`
 // flag is (not) set.
 
 //@ revisions: unset set
 //@ assembly-output: emit-asm
 //@ compile-flags: -Copt-level=3
-//@ [set] compile-flags: -Zno-jump-tables
+//@ [set] compile-flags: -Cjump-tables=no
 //@ only-x86_64
 //@ ignore-sgx
 

tests/assembly-llvm/x86_64-no-jump-tables.rs

@@ -1,11 +1,12 @@
 // Test that the `no-jump-tables` function attribute are (not) emitted when
-// the `-Zno-jump-tables` flag is (not) set.
+// the `-Cjump-tables=no` flag is (not) set.
 
 //@ add-minicore
-//@ revisions: unset set
+//@ revisions: unset set_no set_yes
 //@ needs-llvm-components: x86
 //@ compile-flags: --target x86_64-unknown-linux-gnu
-//@ [set] compile-flags: -Zno-jump-tables
+//@ [set_no] compile-flags: -Cjump-tables=no
+//@ [set_yes] compile-flags: -Cjump-tables=yes
 
 #![crate_type = "lib"]
 #![feature(no_core, lang_items)]
@@ -19,5 +20,6 @@ pub fn foo() {
     // CHECK: @foo() unnamed_addr #0
 
     // unset-NOT: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
-    // set: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
+    // set_yes-NOT: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
+    // set_no: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
 }