bjoernager/rust
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Move cgu_reuse a bit earlier

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There is no reason it needs to be lazily computed at the first iteration
of the cgu loop.
This commit is contained in:
bjorn3 2022-05-13 13:04:48 +00:00
parent 97d48bec2d
commit 1c1f16c3e3
1 changed files with 8 additions and 8 deletions
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16
compiler/rustc_codegen_ssa/src/base.rs
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@ -607,6 +607,11 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
second_half.iter().rev().interleave(first_half).copied().collect()
};
// Calculate the CGU reuse
let cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, &cgu)).collect::<Vec<_>>()
});
// The non-parallel compiler can only translate codegen units to LLVM IR
// on a single thread, leading to a staircase effect where the N LLVM
// threads have to wait on the single codegen threads to generate work
@ -618,7 +623,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
// non-parallel compiler anymore, we can compile CGUs end-to-end in
// parallel and get rid of the complicated scheduling logic.
#[cfg(parallel_compiler)]
let pre_compile_cgus = |cgu_reuse: &[CguReuse]| {
let pre_compile_cgus = || {
tcx.sess.time("compile_first_CGU_batch", || {
// Try to find one CGU to compile per thread.
let cgus: Vec<_> = cgu_reuse
@ -643,9 +648,8 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
};
#[cfg(not(parallel_compiler))]
let pre_compile_cgus = |_: &[CguReuse]| (FxHashMap::default(), Duration::new(0, 0));
let pre_compile_cgus = || (FxHashMap::default(), Duration::new(0, 0));
let mut cgu_reuse = Vec::new();
let mut pre_compiled_cgus: Option<FxHashMap<usize, _>> = None;
let mut total_codegen_time = Duration::new(0, 0);
let start_rss = tcx.sess.time_passes().then(|| get_resident_set_size());
@ -656,12 +660,8 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
// Do some setup work in the first iteration
if pre_compiled_cgus.is_none() {
// Calculate the CGU reuse
cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, &cgu)).collect()
});
// Pre compile some CGUs
let (compiled_cgus, codegen_time) = pre_compile_cgus(&cgu_reuse);
let (compiled_cgus, codegen_time) = pre_compile_cgus();
pre_compiled_cgus = Some(compiled_cgus);
total_codegen_time += codegen_time;
}