Add -Zno-jump-tables · rust-lang/rust@a65ec44 (original) (raw)

6 files changed

lines changed

Original file line number Diff line number Diff line change
@@ -137,6 +137,14 @@ fn instrument_function_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribu
137 137 }
138 138 }
139 139
140 +fn nojumptables_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
141 +if !cx.sess().opts.unstable_opts.no_jump_tables {
142 +return None;
143 +}
144 +
145 +Some(llvm::CreateAttrStringValue(cx.llcx, "no-jump-tables", "true"))
146 +}
147 +
140 148 fn probestack_attr<'ll>(cx: &CodegenCx<'ll, '_>) -> Option<&'ll Attribute> {
141 149 // Currently stack probes seem somewhat incompatible with the address
142 150 // sanitizer and thread sanitizer. With asan we're already protected from
@@ -293,6 +301,7 @@ pub fn from_fn_attrs<'ll, 'tcx>(
293 301 // FIXME: none of these three functions interact with source level attributes.
294 302 to_add.extend(frame_pointer_type_attr(cx));
295 303 to_add.extend(instrument_function_attr(cx));
304 + to_add.extend(nojumptables_attr(cx));
296 305 to_add.extend(probestack_attr(cx));
297 306 to_add.extend(stackprotector_attr(cx));
298 307
Original file line number Diff line number Diff line change
@@ -754,6 +754,7 @@ fn test_unstable_options_tracking_hash() {
754 754 tracked!(move_size_limit, Some(4096));
755 755 tracked!(mutable_noalias, Some(true));
756 756 tracked!(no_generate_arange_section, true);
757 +tracked!(no_jump_tables, true);
757 758 tracked!(no_link, true);
758 759 tracked!(no_profiler_runtime, true);
759 760 tracked!(no_unique_section_names, true);
Original file line number Diff line number Diff line change
@@ -1421,6 +1421,8 @@ options! {
1421 1421 "run all passes except codegen; no output"),
1422 1422 no_generate_arange_section: bool = (false, parse_no_flag, [TRACKED],
1423 1423 "omit DWARF address ranges that give faster lookups"),
1424 + no_jump_tables: bool = (false, parse_no_flag, [TRACKED],
1425 +"disable the jump tables and lookup tables that can be generated from a switch case lowering"),
1424 1426 no_leak_check: bool = (false, parse_no_flag, [UNTRACKED],
1425 1427 "disable the 'leak check' for subtyping; unsound, but useful for tests"),
1426 1428 no_link: bool = (false, parse_no_flag, [TRACKED],
Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
1 +// Test that jump tables are (not) emitted when the `-Zno-jump-tables`
2 +// flag is (not) set.
3 +
4 +// revisions: unset set
5 +// assembly-output: emit-asm
6 +// compile-flags: -O
7 +// [set] compile-flags: -Zno-jump-tables
8 +// only-x86_64
9 +
10 +#![crate_type = "lib"]
11 +
12 +extern "C" {
13 +fn bar1();
14 +fn bar2();
15 +fn bar3();
16 +fn bar4();
17 +fn bar5();
18 +fn bar6();
19 +}
20 +
21 +// CHECK-LABEL: foo:
22 +#[no_mangle]
23 +pub unsafe fn foo(x: i32) {
24 +// unset: LJTI0_0
25 +// set-NOT: LJTI0_0
26 +match x {
27 +1 => bar1(),
28 +2 => bar2(),
29 +3 => bar3(),
30 +4 => bar4(),
31 +5 => bar5(),
32 + _ => bar6(),
33 +}
34 +}
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
1 +// Test that the `no-jump-tables` function attribute are (not) emitted when
2 +// the `-Zno-jump-tables` flag is (not) set.
3 +
4 +// revisions: unset set
5 +// needs-llvm-components: x86
6 +// compile-flags: --target x86_64-unknown-linux-gnu
7 +// [set] compile-flags: -Zno-jump-tables
8 +
9 +#![crate_type = "lib"]
10 +#![feature(no_core, lang_items)]
11 +#![no_core]
12 +
13 +#[lang = "sized"]
14 +trait Sized {}
15 +
16 +#[no_mangle]
17 +pub fn foo() {
18 +// CHECK: @foo() unnamed_addr #0
19 +
20 +// unset-NOT: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
21 +// set: attributes #0 = { {{.*}}"no-jump-tables"="true"{{.*}} }
22 +}
Original file line number Diff line number Diff line change
@@ -92,6 +92,7 @@
92 92 -Z no-analysis=val -- parse and expand the source, but run no analysis
93 93 -Z no-codegen=val -- run all passes except codegen; no output
94 94 -Z no-generate-arange-section=val -- omit DWARF address ranges that give faster lookups
95 + -Z no-jump-tables=val -- disable the jump tables and lookup tables that can be generated from a switch case lowering
95 96 -Z no-leak-check=val -- disable the 'leak check' for subtyping; unsound, but useful for tests
96 97 -Z no-link=val -- compile without linking
97 98 -Z no-parallel-llvm=val -- run LLVM in non-parallel mode (while keeping codegen-units and ThinLTO)