From 4959d18a97c8b187db6fd0010546f46c3137e3c8 Mon Sep 17 00:00:00 2001 From: Paul Murphy Date: Thu, 28 Aug 2025 14:44:34 -0500 Subject: [PATCH] Rename -Zno-jump-tables to -Zjump-tables= Both gcc and llvm accept -fjump-tables as well as -fno-jump-tables. For consistency, allow rustc to accept -Zjump-tables=yes too. --- compiler/rustc_codegen_llvm/src/attributes.rs | 2 +- compiler/rustc_interface/src/tests.rs | 2 +- compiler/rustc_session/src/options.rs | 4 ++-- .../src/compiler-flags/jump-tables.md | 19 +++++++++++++++++++ .../src/compiler-flags/no-jump-tables.md | 19 ------------------- tests/assembly-llvm/x86_64-no-jump-tables.rs | 4 ++-- tests/codegen-llvm/no-jump-tables.rs | 10 ++++++---- 7 files changed, 31 insertions(+), 29 deletions(-) create mode 100644 src/doc/unstable-book/src/compiler-flags/jump-tables.md delete mode 100644 src/doc/unstable-book/src/compiler-flags/no-jump-tables.md diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs index 209b8efa2c3b..d22f40fd05a9 100644 --- a/compiler/rustc_codegen_llvm/src/attributes.rs +++ b/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.unstable_opts.jump_tables { return None; } diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs index be33db21d1df..384c38d3c395 100644 --- a/compiler/rustc_interface/src/tests.rs +++ b/compiler/rustc_interface/src/tests.rs @@ -814,6 +814,7 @@ fn test_unstable_options_tracking_hash() { tracked!(inline_mir_threshold, Some(123)); tracked!(instrument_mcount, true); tracked!(instrument_xray, Some(InstrumentXRay::default())); + tracked!(jump_tables, false); tracked!(link_directives, false); tracked!(link_only, true); tracked!(lint_llvm_ir, true); @@ -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); diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs index b89aec7d22a9..d10fd17677b7 100644 --- a/compiler/rustc_session/src/options.rs +++ b/compiler/rustc_session/src/options.rs @@ -2395,6 +2395,8 @@ options! { `=skip-entry` `=skip-exit` Multiple options can be combined with commas."), + jump_tables: bool = (true, parse_bool, [TRACKED], + "allow jump table and lookup table generation from switch case lowering (default: yes)"), layout_seed: Option = (None, parse_opt_number, [TRACKED], "seed layout randomization"), link_directives: bool = (true, parse_bool, [TRACKED], @@ -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], diff --git a/src/doc/unstable-book/src/compiler-flags/jump-tables.md b/src/doc/unstable-book/src/compiler-flags/jump-tables.md new file mode 100644 index 000000000000..3abf703cd361 --- /dev/null +++ b/src/doc/unstable-book/src/compiler-flags/jump-tables.md @@ -0,0 +1,19 @@ +# `jump-tables` + +The tracking issue for this feature is [#116592](https://github.com/rust-lang/rust/issues/116592) + +--- + +When set to no, this option enables the `-fno-jump-tables` flag for LLVM, which makes the +codegen backend avoid generating jump tables when lowering switches. + +When set to no, this option adds the LLVM `no-jump-tables=true` attribute to every function. + +Disabling jump tables can be used to help provide protection against +jump-oriented-programming (JOP) attacks, such as with the linux kernel's [IBT]. + +```sh +RUSTFLAGS="-Zjump-tables=no" cargo +nightly build -Z build-std +``` + +[IBT]: https://www.phoronix.com/news/Linux-IBT-By-Default-Tip diff --git a/src/doc/unstable-book/src/compiler-flags/no-jump-tables.md b/src/doc/unstable-book/src/compiler-flags/no-jump-tables.md deleted file mode 100644 index f096c20f4bd5..000000000000 --- a/src/doc/unstable-book/src/compiler-flags/no-jump-tables.md +++ /dev/null @@ -1,19 +0,0 @@ -# `no-jump-tables` - -The tracking issue for this feature is [#116592](https://github.com/rust-lang/rust/issues/116592) - ---- - -This option enables the `-fno-jump-tables` flag for LLVM, which makes the -codegen backend avoid generating jump tables when lowering switches. - -This option adds the LLVM `no-jump-tables=true` attribute to every function. - -The option can be used to help provide protection against -jump-oriented-programming (JOP) attacks, such as with the linux kernel's [IBT]. - -```sh -RUSTFLAGS="-Zno-jump-tables" cargo +nightly build -Z build-std -``` - -[IBT]: https://www.phoronix.com/news/Linux-IBT-By-Default-Tip diff --git a/tests/assembly-llvm/x86_64-no-jump-tables.rs b/tests/assembly-llvm/x86_64-no-jump-tables.rs index bb10042d8f62..0108c8817e35 100644 --- a/tests/assembly-llvm/x86_64-no-jump-tables.rs +++ b/tests/assembly-llvm/x86_64-no-jump-tables.rs @@ -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 `-Zjump-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: -Zjump-tables=no //@ only-x86_64 //@ ignore-sgx diff --git a/tests/codegen-llvm/no-jump-tables.rs b/tests/codegen-llvm/no-jump-tables.rs index 8f607e38350d..00609cff38d9 100644 --- a/tests/codegen-llvm/no-jump-tables.rs +++ b/tests/codegen-llvm/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 `-Zjump-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: -Zjump-tables=no +//@ [set_yes] compile-flags: -Zjump-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"{{.*}} } }