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Rollup merge of rust-lang#119556 - onur-ozkan:optimized-compiler-buil…
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…tins, r=onur-ozkan

Reland optimized-compiler-builtins config

Copy of rust-lang#102579 PR.

From rust-lang#102579:

> No concerns on my side. Currently, Jyn isn't actively working on the project. I will close this PR; open another one to cherry-pick the commits, resolve conflicts, and then r+ it.

> Fixes rust-lang#102560. Fixes rust-lang#101172. Helps with rust-lang#105065 (although there's some weirdness there - it's still broken when optimized-compiler-builtins is set to true).

Fixes rust-lang#102560. Fixes rust-lang#101172. Helps with rust-lang#105065

r? ghost
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matthiaskrgr authored Jan 4, 2024
2 parents edb2a1c + b5ccbcb commit b889dd5
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Showing 11 changed files with 101 additions and 31 deletions.
8 changes: 8 additions & 0 deletions config.example.toml
Original file line number Diff line number Diff line change
Expand Up @@ -339,6 +339,14 @@
# on this runtime, such as `-C profile-generate` or `-C instrument-coverage`).
#profiler = false

# Use the optimized LLVM C intrinsics for `compiler_builtins`, rather than Rust intrinsics.
# Requires the LLVM submodule to be managed by bootstrap (i.e. not external) so that `compiler-rt`
# sources are available.
#
# Setting this to `false` generates slower code, but removes the requirement for a C toolchain in
# order to run `x check`.
#optimized-compiler-builtins = if rust.channel == "dev" { false } else { true }

# Indicates whether the native libraries linked into Cargo will be statically
# linked or not.
#cargo-native-static = false
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21 changes: 16 additions & 5 deletions src/bootstrap/src/core/build_steps/compile.rs
Original file line number Diff line number Diff line change
Expand Up @@ -382,9 +382,7 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car

// Determine if we're going to compile in optimized C intrinsics to
// the `compiler-builtins` crate. These intrinsics live in LLVM's
// `compiler-rt` repository, but our `src/llvm-project` submodule isn't
// always checked out, so we need to conditionally look for this. (e.g. if
// an external LLVM is used we skip the LLVM submodule checkout).
// `compiler-rt` repository.
//
// Note that this shouldn't affect the correctness of `compiler-builtins`,
// but only its speed. Some intrinsics in C haven't been translated to Rust
Expand All @@ -395,8 +393,21 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
// If `compiler-rt` is available ensure that the `c` feature of the
// `compiler-builtins` crate is enabled and it's configured to learn where
// `compiler-rt` is located.
let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
let compiler_builtins_c_feature = if builder.config.optimized_compiler_builtins {
// NOTE: this interacts strangely with `llvm-has-rust-patches`. In that case, we enforce `submodules = false`, so this is a no-op.
// But, the user could still decide to manually use an in-tree submodule.
//
// NOTE: if we're using system llvm, we'll end up building a version of `compiler-rt` that doesn't match the LLVM we're linking to.
// That's probably ok? At least, the difference wasn't enforced before. There's a comment in
// the compiler_builtins build script that makes me nervous, though:
// https://github.com/rust-lang/compiler-builtins/blob/31ee4544dbe47903ce771270d6e3bea8654e9e50/build.rs#L575-L579
builder.update_submodule(&Path::new("src").join("llvm-project"));
let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
if !compiler_builtins_root.exists() {
panic!(
"need LLVM sources available to build `compiler-rt`, but they weren't present; consider enabling `build.submodules = true` or disabling `optimized-compiler-builtins`"
);
}
// Note that `libprofiler_builtins/build.rs` also computes this so if
// you're changing something here please also change that.
cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);
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35 changes: 18 additions & 17 deletions src/bootstrap/src/core/build_steps/dist.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2032,23 +2032,24 @@ fn install_llvm_file(builder: &Builder<'_>, source: &Path, destination: &Path) {
///
/// Returns whether the files were actually copied.
fn maybe_install_llvm(builder: &Builder<'_>, target: TargetSelection, dst_libdir: &Path) -> bool {
if let Some(config) = builder.config.target_config.get(&target) {
if config.llvm_config.is_some() && !builder.config.llvm_from_ci {
// If the LLVM was externally provided, then we don't currently copy
// artifacts into the sysroot. This is not necessarily the right
// choice (in particular, it will require the LLVM dylib to be in
// the linker's load path at runtime), but the common use case for
// external LLVMs is distribution provided LLVMs, and in that case
// they're usually in the standard search path (e.g., /usr/lib) and
// copying them here is going to cause problems as we may end up
// with the wrong files and isn't what distributions want.
//
// This behavior may be revisited in the future though.
//
// If the LLVM is coming from ourselves (just from CI) though, we
// still want to install it, as it otherwise won't be available.
return false;
}
// If the LLVM was externally provided, then we don't currently copy
// artifacts into the sysroot. This is not necessarily the right
// choice (in particular, it will require the LLVM dylib to be in
// the linker's load path at runtime), but the common use case for
// external LLVMs is distribution provided LLVMs, and in that case
// they're usually in the standard search path (e.g., /usr/lib) and
// copying them here is going to cause problems as we may end up
// with the wrong files and isn't what distributions want.
//
// This behavior may be revisited in the future though.
//
// NOTE: this intentionally doesn't use `is_rust_llvm`; whether this is patched or not doesn't matter,
// we only care if the shared object itself is managed by bootstrap.
//
// If the LLVM is coming from ourselves (just from CI) though, we
// still want to install it, as it otherwise won't be available.
if builder.is_system_llvm(target) {
return false;
}

// On macOS, rustc (and LLVM tools) link to an unversioned libLLVM.dylib
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2 changes: 2 additions & 0 deletions src/bootstrap/src/core/build_steps/test.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1845,6 +1845,8 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
llvm_components_passed = true;
}
if !builder.is_rust_llvm(target) {
// FIXME: missing Rust patches is not the same as being system llvm; we should rename the flag at some point.
// Inspecting the tests with `// no-system-llvm` in src/test *looks* like this is doing the right thing, though.
cmd.arg("--system-llvm");
}

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15 changes: 14 additions & 1 deletion src/bootstrap/src/core/config/config.rs
Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,8 @@ pub struct Config {
pub patch_binaries_for_nix: Option<bool>,
pub stage0_metadata: Stage0Metadata,
pub android_ndk: Option<PathBuf>,
/// Whether to use the `c` feature of the `compiler_builtins` crate.
pub optimized_compiler_builtins: bool,

pub stdout_is_tty: bool,
pub stderr_is_tty: bool,
Expand Down Expand Up @@ -848,6 +850,7 @@ define_config! {
// NOTE: only parsed by bootstrap.py, `--feature build-metrics` enables metrics unconditionally
metrics: Option<bool> = "metrics",
android_ndk: Option<PathBuf> = "android-ndk",
optimized_compiler_builtins: Option<bool> = "optimized-compiler-builtins",
}
}

Expand Down Expand Up @@ -1396,6 +1399,7 @@ impl Config {
// This field is only used by bootstrap.py
metrics: _,
android_ndk,
optimized_compiler_builtins,
} = toml.build.unwrap_or_default();

if let Some(file_build) = build {
Expand Down Expand Up @@ -1810,7 +1814,14 @@ impl Config {
}
target.llvm_config = Some(config.src.join(s));
}
target.llvm_has_rust_patches = cfg.llvm_has_rust_patches;
if let Some(patches) = cfg.llvm_has_rust_patches {
assert_eq!(
config.submodules,
Some(false),
"cannot set `llvm-has-rust-patches` for a managed submodule (set `build.submodules = false` if you want to apply patches)"
);
target.llvm_has_rust_patches = Some(patches);
}
if let Some(ref s) = cfg.llvm_filecheck {
target.llvm_filecheck = Some(config.src.join(s));
}
Expand Down Expand Up @@ -1909,6 +1920,8 @@ impl Config {
config.rust_debuginfo_level_std = with_defaults(debuginfo_level_std);
config.rust_debuginfo_level_tools = with_defaults(debuginfo_level_tools);
config.rust_debuginfo_level_tests = debuginfo_level_tests.unwrap_or(DebuginfoLevel::None);
config.optimized_compiler_builtins =
optimized_compiler_builtins.unwrap_or(config.channel != "dev");

let download_rustc = config.download_rustc_commit.is_some();
// See https://github.com/rust-lang/compiler-team/issues/326
Expand Down
32 changes: 24 additions & 8 deletions src/bootstrap/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -823,18 +823,34 @@ impl Build {
INTERNER.intern_path(self.out.join(&*target.triple).join("md-doc"))
}

/// Returns `true` if no custom `llvm-config` is set for the specified target.
/// Returns `true` if this is an external version of LLVM not managed by bootstrap.
/// In particular, we expect llvm sources to be available when this is false.
///
/// If no custom `llvm-config` was specified then Rust's llvm will be used.
/// NOTE: this is not the same as `!is_rust_llvm` when `llvm_has_patches` is set.
fn is_system_llvm(&self, target: TargetSelection) -> bool {
match self.config.target_config.get(&target) {
Some(Target { llvm_config: Some(_), .. }) => {
let ci_llvm = self.config.llvm_from_ci && target == self.config.build;
!ci_llvm
}
// We're building from the in-tree src/llvm-project sources.
Some(Target { llvm_config: None, .. }) => false,
None => false,
}
}

/// Returns `true` if this is our custom, patched, version of LLVM.
///
/// This does not necessarily imply that we're managing the `llvm-project` submodule.
fn is_rust_llvm(&self, target: TargetSelection) -> bool {
match self.config.target_config.get(&target) {
// We're using a user-controlled version of LLVM. The user has explicitly told us whether the version has our patches.
// (They might be wrong, but that's not a supported use-case.)
// In particular, this tries to support `submodules = false` and `patches = false`, for using a newer version of LLVM that's not through `rust-lang/llvm-project`.
Some(Target { llvm_has_rust_patches: Some(patched), .. }) => *patched,
Some(Target { llvm_config, .. }) => {
// If the user set llvm-config we assume Rust is not patched,
// but first check to see if it was configured by llvm-from-ci.
(self.config.llvm_from_ci && target == self.config.build) || llvm_config.is_none()
}
None => true,
// The user hasn't promised the patches match.
// This only has our patches if it's downloaded from CI or built from source.
_ => !self.is_system_llvm(target),
}
}

Expand Down
5 changes: 5 additions & 0 deletions src/bootstrap/src/utils/change_tracker.rs
Original file line number Diff line number Diff line change
Expand Up @@ -106,4 +106,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
severity: ChangeSeverity::Info,
summary: "The dist.missing-tools config option was deprecated, as it was unused. If you are using it, remove it from your config, it will be removed soon.",
},
ChangeInfo {
change_id: 102579,
severity: ChangeSeverity::Warning,
summary: "A new `optimized-compiler-builtins` option has been introduced. Whether to build llvm's `compiler-rt` from source is no longer implicitly controlled by git state. See the PR for more details.",
},
];
Original file line number Diff line number Diff line change
Expand Up @@ -47,4 +47,6 @@ ENV RUST_CONFIGURE_ARGS --disable-jemalloc \
--set=$TARGET.cc=x86_64-unknown-haiku-gcc \
--set=$TARGET.cxx=x86_64-unknown-haiku-g++ \
--set=$TARGET.llvm-config=/bin/llvm-config-haiku
ENV EXTERNAL_LLVM 1

ENV SCRIPT python3 ../x.py dist --host=$HOST --target=$HOST
2 changes: 2 additions & 0 deletions src/ci/docker/host-x86_64/dist-various-2/Dockerfile
Original file line number Diff line number Diff line change
Expand Up @@ -139,4 +139,6 @@ ENV RUST_CONFIGURE_ARGS --enable-extended --enable-lld --disable-docs \
--set target.wasm32-wasi-preview1-threads.wasi-root=/wasm32-wasi-preview1-threads \
--musl-root-armv7=/musl-armv7

ENV EXTERNAL_LLVM 1

ENV SCRIPT python3 ../x.py dist --host='' --target $TARGETS
1 change: 1 addition & 0 deletions src/ci/docker/host-x86_64/x86_64-gnu-llvm-17/Dockerfile
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ RUN sh /scripts/sccache.sh
# We are disabling CI LLVM since this builder is intentionally using a host
# LLVM, rather than the typical src/llvm-project LLVM.
ENV NO_DOWNLOAD_CI_LLVM 1
ENV EXTERNAL_LLVM 1

# Using llvm-link-shared due to libffi issues -- see #34486
ENV RUST_CONFIGURE_ARGS \
Expand Down
9 changes: 9 additions & 0 deletions src/ci/run.sh
Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,15 @@ fi
# space required for CI artifacts.
RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --dist-compression-formats=xz"

# Enable the `c` feature for compiler_builtins, but only when the `compiler-rt` source is available
# (to avoid spending a lot of time cloning llvm)
if [ "$EXTERNAL_LLVM" = "" ]; then
RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set build.optimized-compiler-builtins"
elif [ "$DEPLOY$DEPLOY_ALT" = "1" ]; then
echo "error: dist builds should always use optimized compiler-rt!" >&2
exit 1
fi

if [ "$DIST_SRC" = "" ]; then
RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-dist-src"
fi
Expand Down

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