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Add support for -Cembed-bitcode=no
This commit is the Cargo half of support necessary for rust-lang/rust#70458. Today the compiler emits embedded bytecode in rlibs by default, but compresses it. This is both extraneous disk space and wasted build time for almost all builds, so the PR in question there is changing rustc to have a `-Cembed-bitcode` flag which, when enabled, places the bitcode in the object file rather than an auxiliary file (no extra compression), but also enables `-Cembed-bitcode=no` to disable bitcode emission entirely. This Cargo support changes Cargo to pass `-Cembed-bitcode=no` for almost all compilations. Cargo will keep `lto = true` and such working by not passing this flag (and thus allowing bitcode to get embedded), but by default `cargo build` and `cargo build --release` will no longer have any bitcode in rlibs which should result in speedier builds! Most of the changes here were around the test suite and various assertions about the `rustc` command lines we spit out. One test was hard-disabled until we can get `-Cembed-bitcode=no` into nightly, and then we can make it a nightly-only test. The test will then be stable again once `-Cembed-bitcode=no` hits stable. Note that this is intended to land before the upstream `-Cembed-bitcode` change. The thinking is that we'll land everything in rust-lang/rust all at once so there's no build time regressions for anyone. If we were to land the `-Cembed-bitcode` PR first then there would be a build time regression until we land Cargo changes because rustc would be emitting uncompressed bitcode by default and Cargo wouldn't be turning it off.
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16 files changed

+235
-168
lines changed

16 files changed

+235
-168
lines changed

‎crates/cargo-test-support/src/lib.rs

+8
Original file line numberDiff line numberDiff line change
@@ -1230,6 +1230,14 @@ impl Execs {
12301230
}
12311231
MatchKind::Unordered => {
12321232
let mut a = actual.lines().collect::<Vec<_>>();
1233+
// match more-constrained lines first, although in theory we'll
1234+
// need some sort of recursive match here. This handles the case
1235+
// that you expect "a\n[..]b" and two lines are printed out,
1236+
// "ab\n"a", where technically we do match unordered but a naive
1237+
// search fails to find this. This simple sort at least gets the
1238+
// test suite to pass for now, but we may need to get more fancy
1239+
// if tests start failing again.
1240+
a.sort_by_key(|s| s.len());
12331241
let e = out.lines();
12341242

12351243
for e_line in e {

‎src/cargo/core/compiler/build_context/target_info.rs

+10
Original file line numberDiff line numberDiff line change
@@ -41,6 +41,8 @@ pub struct TargetInfo {
4141
pub rustflags: Vec<String>,
4242
/// Extra flags to pass to `rustdoc`, see `env_args`.
4343
pub rustdocflags: Vec<String>,
44+
/// REmove this when it hits stable (1.44)
45+
pub supports_embed_bitcode: Option<bool>,
4446
}
4547

4648
/// Kind of each file generated by a Unit, part of `FileType`.
@@ -103,6 +105,13 @@ impl TargetInfo {
103105
.args(&rustflags)
104106
.env_remove("RUSTC_LOG");
105107

108+
let mut embed_bitcode_test = process.clone();
109+
embed_bitcode_test.arg("-Cembed-bitcode");
110+
let supports_embed_bitcode = match kind {
111+
CompileKind::Host => Some(rustc.cached_output(&embed_bitcode_test).is_ok()),
112+
_ => None,
113+
};
114+
106115
if let CompileKind::Target(target) = kind {
107116
process.arg("--target").arg(target.rustc_target());
108117
}
@@ -187,6 +196,7 @@ impl TargetInfo {
187196
"RUSTDOCFLAGS",
188197
)?,
189198
cfg,
199+
supports_embed_bitcode,
190200
})
191201
}
192202

‎src/cargo/core/compiler/mod.rs

+21-5
Original file line numberDiff line numberDiff line change
@@ -801,16 +801,32 @@ fn build_base_args<'a, 'cfg>(
801801

802802
// Disable LTO for host builds as prefer_dynamic and it are mutually
803803
// exclusive.
804-
if unit.target.can_lto() && !unit.target.for_host() {
805-
match *lto {
806-
Lto::Bool(false) => {}
807-
Lto::Bool(true) => {
804+
let lto_possible = unit.target.can_lto() && !unit.target.for_host();
805+
match lto {
806+
Lto::Bool(true) => {
807+
if lto_possible {
808808
cmd.args(&["-C", "lto"]);
809809
}
810-
Lto::Named(ref s) => {
810+
}
811+
Lto::Named(s) => {
812+
if lto_possible {
811813
cmd.arg("-C").arg(format!("lto={}", s));
812814
}
813815
}
816+
// If LTO isn't being enabled then there's no need for bitcode to be
817+
// present in the intermediate artifacts, so shave off some build time
818+
// by removing it.
819+
Lto::Bool(false) => {
820+
if cx
821+
.bcx
822+
.target_data
823+
.info(CompileKind::Host)
824+
.supports_embed_bitcode
825+
.unwrap()
826+
{
827+
cmd.arg("-Cembed-bitcode=no");
828+
}
829+
}
814830
}
815831

816832
if let Some(n) = codegen_units {

‎tests/testsuite/build.rs

+21-21
Original file line numberDiff line numberDiff line change
@@ -1149,13 +1149,13 @@ fn cargo_default_env_metadata_env_var() {
11491149
[COMPILING] bar v0.0.1 ([CWD]/bar)
11501150
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type dylib \
11511151
--emit=[..]link \
1152-
-C prefer-dynamic -C debuginfo=2 \
1152+
-C prefer-dynamic[..]-C debuginfo=2 \
11531153
-C metadata=[..] \
11541154
--out-dir [..] \
11551155
-L dependency=[CWD]/target/debug/deps`
11561156
[COMPILING] foo v0.0.1 ([CWD])
11571157
[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
1158-
--emit=[..]link -C debuginfo=2 \
1158+
--emit=[..]link[..]-C debuginfo=2 \
11591159
-C metadata=[..] \
11601160
-C extra-filename=[..] \
11611161
--out-dir [..] \
@@ -1177,13 +1177,13 @@ fn cargo_default_env_metadata_env_var() {
11771177
[COMPILING] bar v0.0.1 ([CWD]/bar)
11781178
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type dylib \
11791179
--emit=[..]link \
1180-
-C prefer-dynamic -C debuginfo=2 \
1180+
-C prefer-dynamic[..]-C debuginfo=2 \
11811181
-C metadata=[..] \
11821182
--out-dir [..] \
11831183
-L dependency=[CWD]/target/debug/deps`
11841184
[COMPILING] foo v0.0.1 ([CWD])
11851185
[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
1186-
--emit=[..]link -C debuginfo=2 \
1186+
--emit=[..]link[..]-C debuginfo=2 \
11871187
-C metadata=[..] \
11881188
-C extra-filename=[..] \
11891189
--out-dir [..] \
@@ -1581,7 +1581,7 @@ fn verbose_build() {
15811581
"\
15821582
[COMPILING] foo v0.0.1 ([CWD])
15831583
[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
1584-
--emit=[..]link -C debuginfo=2 \
1584+
--emit=[..]link[..]-C debuginfo=2 \
15851585
-C metadata=[..] \
15861586
--out-dir [..] \
15871587
-L dependency=[CWD]/target/debug/deps`
@@ -1599,8 +1599,8 @@ fn verbose_release_build() {
15991599
"\
16001600
[COMPILING] foo v0.0.1 ([CWD])
16011601
[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
1602-
--emit=[..]link \
1603-
-C opt-level=3 \
1602+
--emit=[..]link[..]\
1603+
-C opt-level=3[..]\
16041604
-C metadata=[..] \
16051605
--out-dir [..] \
16061606
-L dependency=[CWD]/target/release/deps`
@@ -1650,15 +1650,15 @@ fn verbose_release_build_deps() {
16501650
[RUNNING] `rustc --crate-name foo foo/src/lib.rs [..]\
16511651
--crate-type dylib --crate-type rlib \
16521652
--emit=[..]link \
1653-
-C prefer-dynamic \
1654-
-C opt-level=3 \
1653+
-C prefer-dynamic[..]\
1654+
-C opt-level=3[..]\
16551655
-C metadata=[..] \
16561656
--out-dir [..] \
16571657
-L dependency=[CWD]/target/release/deps`
16581658
[COMPILING] test v0.0.0 ([CWD])
16591659
[RUNNING] `rustc --crate-name test src/lib.rs [..]--crate-type lib \
1660-
--emit=[..]link \
1661-
-C opt-level=3 \
1660+
--emit=[..]link[..]\
1661+
-C opt-level=3[..]\
16621662
-C metadata=[..] \
16631663
--out-dir [..] \
16641664
-L dependency=[CWD]/target/release/deps \
@@ -4205,15 +4205,15 @@ fn build_filter_infer_profile() {
42054205
p.cargo("build -v --test=t1")
42064206
.with_stderr_contains(
42074207
"[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
4208-
--emit=[..]link -C debuginfo=2 [..]",
4208+
--emit=[..]link[..]-C debuginfo=2 [..]",
42094209
)
42104210
.with_stderr_contains(
4211-
"[RUNNING] `rustc --crate-name t1 tests/t1.rs [..]--emit=[..]link \
4211+
"[RUNNING] `rustc --crate-name t1 tests/t1.rs [..]--emit=[..]link[..]\
42124212
-C debuginfo=2 [..]",
42134213
)
42144214
.with_stderr_contains(
42154215
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--crate-type bin \
4216-
--emit=[..]link -C debuginfo=2 [..]",
4216+
--emit=[..]link[..]-C debuginfo=2 [..]",
42174217
)
42184218
.run();
42194219

@@ -4222,16 +4222,16 @@ fn build_filter_infer_profile() {
42224222
p.cargo("build -v --bench=b1")
42234223
.with_stderr_contains(
42244224
"[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
4225-
--emit=[..]link -C debuginfo=2 [..]",
4225+
--emit=[..]link[..]-C debuginfo=2 [..]",
42264226
)
42274227
.with_stderr_contains(
4228-
"[RUNNING] `rustc --crate-name b1 benches/b1.rs [..]--emit=[..]link \
4228+
"[RUNNING] `rustc --crate-name b1 benches/b1.rs [..]--emit=[..]link[..]\
42294229
-C debuginfo=2 [..]",
42304230
)
42314231
.with_stderr_does_not_contain("opt-level")
42324232
.with_stderr_contains(
42334233
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--crate-type bin \
4234-
--emit=[..]link -C debuginfo=2 [..]",
4234+
--emit=[..]link[..]-C debuginfo=2 [..]",
42354235
)
42364236
.run();
42374237
}
@@ -4252,7 +4252,7 @@ fn targets_selected_default() {
42524252
)
42534253
// Unit tests.
42544254
.with_stderr_does_not_contain(
4255-
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link \
4255+
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link[..]\
42564256
-C debuginfo=2 --test [..]",
42574257
)
42584258
.run();
@@ -4269,7 +4269,7 @@ fn targets_selected_all() {
42694269
)
42704270
// Unit tests.
42714271
.with_stderr_contains(
4272-
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link \
4272+
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link[..]\
42734273
-C debuginfo=2 --test [..]",
42744274
)
42754275
.run();
@@ -4286,7 +4286,7 @@ fn all_targets_no_lib() {
42864286
)
42874287
// Unit tests.
42884288
.with_stderr_contains(
4289-
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link \
4289+
"[RUNNING] `rustc --crate-name foo src/main.rs [..]--emit=[..]link[..]\
42904290
-C debuginfo=2 --test [..]",
42914291
)
42924292
.run();
@@ -4726,7 +4726,7 @@ fn build_lib_only() {
47264726
"\
47274727
[COMPILING] foo v0.0.1 ([CWD])
47284728
[RUNNING] `rustc --crate-name foo src/lib.rs [..]--crate-type lib \
4729-
--emit=[..]link -C debuginfo=2 \
4729+
--emit=[..]link[..]-C debuginfo=2 \
47304730
-C metadata=[..] \
47314731
--out-dir [..] \
47324732
-L dependency=[CWD]/target/debug/deps`

‎tests/testsuite/build_script.rs

+3-3
Original file line numberDiff line numberDiff line change
@@ -1139,19 +1139,19 @@ fn build_cmd_with_a_build_cmd() {
11391139
[RUNNING] `rustc [..] a/build.rs [..] --extern b=[..]`
11401140
[RUNNING] `[..]/a-[..]/build-script-build`
11411141
[RUNNING] `rustc --crate-name a [..]lib.rs [..]--crate-type lib \
1142-
--emit=[..]link -C debuginfo=2 \
1142+
--emit=[..]link[..]-C debuginfo=2 \
11431143
-C metadata=[..] \
11441144
--out-dir [..]target/debug/deps \
11451145
-L [..]target/debug/deps`
11461146
[COMPILING] foo v0.5.0 ([CWD])
11471147
[RUNNING] `rustc --crate-name build_script_build build.rs [..]--crate-type bin \
1148-
--emit=[..]link \
1148+
--emit=[..]link[..]\
11491149
-C debuginfo=2 -C metadata=[..] --out-dir [..] \
11501150
-L [..]target/debug/deps \
11511151
--extern a=[..]liba[..].rlib`
11521152
[RUNNING] `[..]/foo-[..]/build-script-build`
11531153
[RUNNING] `rustc --crate-name foo [..]lib.rs [..]--crate-type lib \
1154-
--emit=[..]link -C debuginfo=2 \
1154+
--emit=[..]link[..]-C debuginfo=2 \
11551155
-C metadata=[..] \
11561156
--out-dir [..] \
11571157
-L [..]target/debug/deps`

‎tests/testsuite/cross_compile.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -193,7 +193,7 @@ fn linker() {
193193
"\
194194
[COMPILING] foo v0.5.0 ([CWD])
195195
[RUNNING] `rustc --crate-name foo src/foo.rs [..]--crate-type bin \
196-
--emit=[..]link -C debuginfo=2 \
196+
--emit=[..]link[..]-C debuginfo=2 \
197197
-C metadata=[..] \
198198
--out-dir [CWD]/target/{target}/debug/deps \
199199
--target {target} \

‎tests/testsuite/freshness.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -1427,8 +1427,8 @@ fn reuse_panic_pm() {
14271427
.with_stderr_unordered(
14281428
"\
14291429
[COMPILING] bar [..]
1430-
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type lib --emit=[..]link -C debuginfo=2 [..]
1431-
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type lib --emit=[..]link -C panic=abort -C debuginfo=2 [..]
1430+
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type lib --emit=[..]link[..]-C debuginfo=2 [..]
1431+
[RUNNING] `rustc --crate-name bar bar/src/lib.rs [..]--crate-type lib --emit=[..]link -C panic=abort[..]-C debuginfo=2 [..]
14321432
[COMPILING] somepm [..]
14331433
[RUNNING] `rustc --crate-name somepm [..]
14341434
[COMPILING] foo [..]

‎tests/testsuite/lto.rs

+26
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
use cargo_test_support::project;
2+
use cargo_test_support::registry::Package;
3+
4+
#[cargo_test]
5+
fn with_deps() {
6+
Package::new("bar", "0.0.1").publish();
7+
8+
let p = project()
9+
.file(
10+
"Cargo.toml",
11+
r#"
12+
[package]
13+
name = "test"
14+
version = "0.0.0"
15+
16+
[dependencies]
17+
bar = "*"
18+
19+
[profile.release]
20+
lto = true
21+
"#,
22+
)
23+
.file("src/main.rs", "extern crate bar; fn main() {}")
24+
.build();
25+
p.cargo("build -v --release").run();
26+
}

‎tests/testsuite/main.rs

+1
Original file line numberDiff line numberDiff line change
@@ -61,6 +61,7 @@ mod local_registry;
6161
mod locate_project;
6262
mod lockfile_compat;
6363
mod login;
64+
mod lto;
6465
mod member_errors;
6566
mod message_format;
6667
mod metabuild;

‎tests/testsuite/profile_config.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -283,7 +283,7 @@ fn profile_config_override_precedence() {
283283
.with_stderr(
284284
"\
285285
[COMPILING] bar [..]
286-
[RUNNING] `rustc --crate-name bar [..] -C opt-level=2 -C codegen-units=2 [..]
286+
[RUNNING] `rustc --crate-name bar [..] -C opt-level=2[..]-C codegen-units=2 [..]
287287
[COMPILING] foo [..]
288288
[RUNNING] `rustc --crate-name foo [..]-C codegen-units=2 [..]
289289
[FINISHED] dev [unoptimized + debuginfo] target(s) in [..]",

‎tests/testsuite/profile_overrides.rs

+7-7
Original file line numberDiff line numberDiff line change
@@ -215,17 +215,17 @@ fn profile_override_hierarchy() {
215215
p.cargo("build -v").with_stderr_unordered("\
216216
[COMPILING] m3 [..]
217217
[COMPILING] dep [..]
218-
[RUNNING] `rustc --crate-name m3 m3/src/lib.rs [..] --crate-type lib --emit=[..]link -C codegen-units=4 [..]
219-
[RUNNING] `rustc --crate-name dep [..]dep/src/lib.rs [..] --crate-type lib --emit=[..]link -C codegen-units=3 [..]
220-
[RUNNING] `rustc --crate-name m3 m3/src/lib.rs [..] --crate-type lib --emit=[..]link -C codegen-units=1 [..]
221-
[RUNNING] `rustc --crate-name build_script_build m1/build.rs [..] --crate-type bin --emit=[..]link -C codegen-units=4 [..]
218+
[RUNNING] `rustc --crate-name m3 m3/src/lib.rs [..] --crate-type lib --emit=[..]link[..]-C codegen-units=4 [..]
219+
[RUNNING] `rustc --crate-name dep [..]dep/src/lib.rs [..] --crate-type lib --emit=[..]link[..]-C codegen-units=3 [..]
220+
[RUNNING] `rustc --crate-name m3 m3/src/lib.rs [..] --crate-type lib --emit=[..]link[..]-C codegen-units=1 [..]
221+
[RUNNING] `rustc --crate-name build_script_build m1/build.rs [..] --crate-type bin --emit=[..]link[..]-C codegen-units=4 [..]
222222
[COMPILING] m2 [..]
223-
[RUNNING] `rustc --crate-name build_script_build m2/build.rs [..] --crate-type bin --emit=[..]link -C codegen-units=2 [..]
223+
[RUNNING] `rustc --crate-name build_script_build m2/build.rs [..] --crate-type bin --emit=[..]link[..]-C codegen-units=2 [..]
224224
[RUNNING] `[..]/m1-[..]/build-script-build`
225225
[RUNNING] `[..]/m2-[..]/build-script-build`
226-
[RUNNING] `rustc --crate-name m2 m2/src/lib.rs [..] --crate-type lib --emit=[..]link -C codegen-units=2 [..]
226+
[RUNNING] `rustc --crate-name m2 m2/src/lib.rs [..] --crate-type lib --emit=[..]link[..]-C codegen-units=2 [..]
227227
[COMPILING] m1 [..]
228-
[RUNNING] `rustc --crate-name m1 m1/src/lib.rs [..] --crate-type lib --emit=[..]link -C codegen-units=1 [..]
228+
[RUNNING] `rustc --crate-name m1 m1/src/lib.rs [..] --crate-type lib --emit=[..]link[..]-C codegen-units=1 [..]
229229
[FINISHED] dev [unoptimized + debuginfo] [..]
230230
",
231231
)

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