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Don't trigger an LLVM build from check builds using the stage 0 compiler

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This commit is contained in:
Zalathar 2025-07-16 17:16:15 +10:00
parent 8388b31c5b
commit 7a217e1ba5
2 changed files with 19 additions and 18 deletions
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29
src/bootstrap/src/core/build_steps/compile.rs
View file

@ -1323,7 +1323,7 @@ pub fn rustc_cargo_env(
builder: &Builder<'_>,
cargo: &mut Cargo,
target: TargetSelection,
build_stage: u32,
_build_stage: u32,
) {
// Set some configuration variables picked up by build scripts and
// the compiler alike
@ -1379,18 +1379,24 @@ pub fn rustc_cargo_env(
cargo.rustflag("--cfg=llvm_enzyme");
}
// Note that this is disabled if LLVM itself is disabled or we're in a check
// build. If we are in a check build we still go ahead here presuming we've
// detected that LLVM is already built and good to go which helps prevent
// busting caches (e.g. like #71152).
// These conditionals represent a tension between three forces:
// - For non-check builds, we need to define some LLVM-related environment
// variables, requiring LLVM to have been built.
// - For check builds, we want to avoid building LLVM if possible.
// - Check builds and non-check builds should have the same environment if
// possible, to avoid unnecessary rebuilds due to cache-busting.
//
// Therefore we try to avoid building LLVM for check builds, but only if
// building LLVM would be expensive. If "building" LLVM is cheap
// (i.e. it's already built or is downloadable), we prefer to maintain a
// consistent environment between check and non-check builds.
if builder.config.llvm_enabled(target) {
let building_is_expensive =
let building_llvm_is_expensive =
crate::core::build_steps::llvm::prebuilt_llvm_config(builder, target, false)
.should_build();
// `top_stage == stage` might be false for `check --stage 1`, if we are building the stage 1 compiler
let can_skip_build = builder.kind == Kind::Check && builder.top_stage == build_stage;
let should_skip_build = building_is_expensive && can_skip_build;
if !should_skip_build {
let skip_llvm = (builder.kind == Kind::Check) && building_llvm_is_expensive;
if !skip_llvm {
rustc_llvm_env(builder, cargo, target)
}
}
@ -1407,6 +1413,9 @@ pub fn rustc_cargo_env(
/// Pass down configuration from the LLVM build into the build of
/// rustc_llvm and rustc_codegen_llvm.
///
/// Note that this has the side-effect of _building LLVM_, which is sometimes
/// unwanted (e.g. for check builds).
fn rustc_llvm_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelection) {
if builder.config.is_rust_llvm(target) {
cargo.env("LLVM_RUSTLLVM", "1");

8
src/bootstrap/src/core/builder/tests.rs
View file

@ -1298,7 +1298,6 @@ mod snapshot {
ctx.config("check")
.path("compiler")
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> cranelift 1 <host>
[check] rustc 0 <host> -> gcc 1 <host>
@ -1312,7 +1311,6 @@ mod snapshot {
ctx.config("check")
.path("rustc")
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
");
}
@ -1332,7 +1330,6 @@ mod snapshot {
.path("compiler")
.stage(1)
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> cranelift 1 <host>
[check] rustc 0 <host> -> gcc 1 <host>
@ -1464,7 +1461,6 @@ mod snapshot {
.paths(&["library", "compiler"])
.args(&args)
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> cranelift 1 <host>
[check] rustc 0 <host> -> gcc 1 <host>
@ -1478,7 +1474,6 @@ mod snapshot {
ctx.config("check")
.path("miri")
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> Miri 1 <host>
");
@ -1499,7 +1494,6 @@ mod snapshot {
.path("miri")
.stage(1)
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> Miri 1 <host>
");
@ -1552,7 +1546,6 @@ mod snapshot {
ctx.config("check")
.path("rustc_codegen_cranelift")
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> cranelift 1 <host>
[check] rustc 0 <host> -> gcc 1 <host>
@ -1566,7 +1559,6 @@ mod snapshot {
ctx.config("check")
.path("rust-analyzer")
.render_steps(), @r"
[build] llvm <host>
[check] rustc 0 <host> -> rustc 1 <host>
[check] rustc 0 <host> -> rust-analyzer 1 <host>
");