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If an LLVM module's exports change, cannot reuse its post-LTO object file in

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incremental compilation.

This is symmetric to PR #67020, which handled the case where the LLVM module's
*imports* changed. This commit builds upon the infrastructure added there; the
export map is just the inverse of the import map, so we can build the export map
at the same time that we load the serialized import map.

Fix #69798
This commit is contained in:
Felix S. Klock II 2020-04-14 09:47:03 -04:00
parent 5179ebe206
commit e542f4fa59
1 changed files with 33 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

37
src/librustc_codegen_llvm/back/lto.rs
View file

@ -517,11 +517,20 @@ fn thin_lto(
let prev_imports = prev_import_map.modules_imported_by(module_name);
let curr_imports = curr_import_map.modules_imported_by(module_name);
let prev_exports = prev_import_map.modules_exported_by(module_name);
let curr_exports = curr_import_map.modules_exported_by(module_name);
let imports_all_green = curr_imports
.iter()
.all(|imported_module| green_modules.contains_key(imported_module));
let exports_all_green = curr_exports
.iter()
.all(|exported_module| green_modules.contains_key(exported_module));
if imports_all_green && equivalent_as_sets(prev_imports, curr_imports) {
if imports_all_green
&& equivalent_as_sets(prev_imports, curr_imports)
&& exports_all_green
&& equivalent_as_sets(prev_exports, curr_exports)
{
let work_product = green_modules[module_name].clone();
copy_jobs.push(work_product);
info!(" - {}: re-used", module_name);
@ -885,6 +894,8 @@ pub unsafe fn optimize_thin_module(
pub struct ThinLTOImports {
// key = llvm name of importing module, value = list of modules it imports from
imports: FxHashMap<String, Vec<String>>,
// key = llvm name of exporting module, value = list of modules it exports to
exports: FxHashMap<String, Vec<String>>,
}
impl ThinLTOImports {
@ -892,6 +903,10 @@ impl ThinLTOImports {
self.imports.get(llvm_module_name).map(|v| &v[..]).unwrap_or(&[])
}
fn modules_exported_by(&self, llvm_module_name: &str) -> &[String] {
self.exports.get(llvm_module_name).map(|v| &v[..]).unwrap_or(&[])
}
fn save_to_file(&self, path: &Path) -> io::Result<()> {
use std::io::Write;
let file = File::create(path)?;
@ -909,13 +924,17 @@ impl ThinLTOImports {
fn load_from_file(path: &Path) -> io::Result<ThinLTOImports> {
use std::io::BufRead;
let mut imports = FxHashMap::default();
let mut current_module = None;
let mut current_imports = vec![];
let mut exports: FxHashMap<_, Vec<_>> = FxHashMap::default();
let mut current_module: Option<String> = None;
let mut current_imports: Vec<String> = vec![];
let file = File::open(path)?;
for line in io::BufReader::new(file).lines() {
let line = line?;
if line.is_empty() {
let importing_module = current_module.take().expect("Importing module not set");
for imported in &current_imports {
exports.entry(imported.clone()).or_default().push(importing_module.clone());
}
imports.insert(importing_module, mem::replace(&mut current_imports, vec![]));
} else if line.starts_with(' ') {
// Space marks an imported module
@ -927,7 +946,7 @@ impl ThinLTOImports {
current_module = Some(line.trim().to_string());
}
}
Ok(ThinLTOImports { imports })
Ok(ThinLTOImports { imports, exports })
}
/// Loads the ThinLTO import map from ThinLTOData.
@ -951,7 +970,17 @@ impl ThinLTOImports {
.get_mut(importing_module_name)
.unwrap()
.push(imported_module_name.to_owned());
if !map.exports.contains_key(imported_module_name) {
map.exports.insert(imported_module_name.to_owned(), vec![]);
}
map.exports
.get_mut(imported_module_name)
.unwrap()
.push(importing_module_name.to_owned());
}
let mut map = ThinLTOImports::default();
llvm::LLVMRustGetThinLTOModuleImports(
data,