std: Improve downstream codegen in Command::env
#64186
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This commit rejiggers the generics used in the implementation of
`Command::env` with the purpose of reducing the amount of codegen that
needs to happen in consumer crates, instead preferring to generate code
into libstd.
This was found when profiling the compile times of the `cc` crate where
the binary rlib produced had a lot of `BTreeMap` code compiled into it
but the crate doesn't actually use `BTreeMap`. It turns out that
`Command::env` is generic enough to codegen the entire implementation in
calling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.
This change is done by removing the generic on the `CommandEnv` map
which is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a `use` statement defined
per-platform is used.
With this commit a debug build of `Command::new("foo").env("a", "b")`
drops from 21k lines of LLVM IR to 10k.
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r? @sfackler |
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Could this also be handled by a shim method at the |
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Yeah this could be handled either way, and that's how it works today where the generic |
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Yeah, it is a bit weird to use a generic with exactly one instantiation. @bors r+ |
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📌 Commit 0b7ba6e has been approved by |
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…=sfackler
std: Improve downstream codegen in `Command::env`
This commit rejiggers the generics used in the implementation of
`Command::env` with the purpose of reducing the amount of codegen that
needs to happen in consumer crates, instead preferring to generate code
into libstd.
This was found when profiling the compile times of the `cc` crate where
the binary rlib produced had a lot of `BTreeMap` code compiled into it
but the crate doesn't actually use `BTreeMap`. It turns out that
`Command::env` is generic enough to codegen the entire implementation in
calling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.
This change is done by removing the generic on the `CommandEnv` map
which is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a `use` statement defined
per-platform is used.
With this commit a debug build of `Command::new("foo").env("a", "b")`
drops from 21k lines of LLVM IR to 10k.
Centril
added a commit
to Centril/rust
that referenced
this pull request
Sep 6, 2019
…=sfackler
std: Improve downstream codegen in `Command::env`
This commit rejiggers the generics used in the implementation of
`Command::env` with the purpose of reducing the amount of codegen that
needs to happen in consumer crates, instead preferring to generate code
into libstd.
This was found when profiling the compile times of the `cc` crate where
the binary rlib produced had a lot of `BTreeMap` code compiled into it
but the crate doesn't actually use `BTreeMap`. It turns out that
`Command::env` is generic enough to codegen the entire implementation in
calling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.
This change is done by removing the generic on the `CommandEnv` map
which is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a `use` statement defined
per-platform is used.
With this commit a debug build of `Command::new("foo").env("a", "b")`
drops from 21k lines of LLVM IR to 10k.
bors
added a commit
that referenced
this pull request
Sep 6, 2019
Rollup of 10 pull requests Successful merges: - #63676 (Use wasi crate for Core API) - #64094 (Improve searching in rustdoc and add tests) - #64111 (or-patterns: Uniformly use `PatKind::Or` in AST & Fix/Cleanup resolve) - #64156 (Assume non-git LLVM is fresh if the stamp file exists) - #64161 (Point at variant on pattern field count mismatch) - #64174 (Add missing code examples on Iterator trait) - #64175 (Fix invalid span generation when it should be div) - #64186 (std: Improve downstream codegen in `Command::env`) - #64190 (fill metadata in rustc_lexer's Cargo.toml) - #64198 (Add Fuchsia to actually_monotonic) Failed merges: r? @ghost
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☔ The latest upstream changes (presumably #64209) made this pull request unmergeable. Please resolve the merge conflicts. |
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This commit rejiggers the generics used in the implementation of
Command::envwith the purpose of reducing the amount of codegen thatneeds to happen in consumer crates, instead preferring to generate code
into libstd.
This was found when profiling the compile times of the
cccrate wherethe binary rlib produced had a lot of
BTreeMapcode compiled into itbut the crate doesn't actually use
BTreeMap. It turns out thatCommand::envis generic enough to codegen the entire implementation incalling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.
This change is done by removing the generic on the
CommandEnvmapwhich is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a
usestatement definedper-platform is used.
With this commit a debug build of
Command::new("foo").env("a", "b")drops from 21k lines of LLVM IR to 10k.