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Auto merge of #50265 - japaric:sz, r=alexcrichton

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stabilize opt-level={s,z}

closes #35784
closes #47651

### Rationale

Since the lastest LLVM upgrade rustc / LLVM does more agressive loop unrolling. This results in increased binary size of embedded / no_std programs: a hundreds of bytes increase, or about a 7x increase, in the case of the smallest Cortex-M binary cf. #49260.

As we are shooting for embedded Rust on stable it would be great to also provide a way to optimize for size (which is pretty important for embedded applications that target resource constrained devices) on stable.

Also this has been baking in nightly for a long time.

r? @alexcrichton which team has to sign off this?
This commit is contained in:
bors 2018-05-21 12:33:19 +00:00
parent 21b5367045 2b09d7cc64
commit 6e6a4b1957
1 changed files with 9 additions and 21 deletions
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30
src/librustc/session/config.rs
View file

@ -2020,27 +2020,15 @@ pub fn build_session_options_and_crate_config(
}
OptLevel::Default
} else {
match (
cg.opt_level.as_ref().map(String::as_ref),
nightly_options::is_nightly_build(),
) {
(None, _) => OptLevel::No,
(Some("0"), _) => OptLevel::No,
(Some("1"), _) => OptLevel::Less,
(Some("2"), _) => OptLevel::Default,
(Some("3"), _) => OptLevel::Aggressive,
(Some("s"), true) => OptLevel::Size,
(Some("z"), true) => OptLevel::SizeMin,
(Some("s"), false) | (Some("z"), false) => {
early_error(
error_format,
&format!(
"the optimizations s or z are only \
accepted on the nightly compiler"
),
);
}
(Some(arg), _) => {
match cg.opt_level.as_ref().map(String::as_ref) {
None => OptLevel::No,
Some("0") => OptLevel::No,
Some("1") => OptLevel::Less,
Some("2") => OptLevel::Default,
Some("3") => OptLevel::Aggressive,
Some("s") => OptLevel::Size,
Some("z") => OptLevel::SizeMin,
Some(arg) => {
early_error(
error_format,
&format!(