Skip to content

[libLTO] add thinlto caching flags to libLTO #168567

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Nov 19, 2025
Merged

[libLTO] add thinlto caching flags to libLTO #168567

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
0eafb2b
[libLTO] add thinlto caching flags to libLTO
Oct 7, 2025
c3b7a83
address review comments
Nov 19, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
43 changes: 43 additions & 0 deletions llvm/tools/lto/lto.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
#include "llvm/LTO/legacy/LTOCodeGenerator.h"
#include "llvm/LTO/legacy/LTOModule.h"
#include "llvm/LTO/legacy/ThinLTOCodeGenerator.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetSelect.h"
Expand All @@ -44,6 +45,29 @@ static cl::opt<bool> EnableFreestanding(
"lto-freestanding", cl::init(false),
cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"));

static cl::opt<std::string> ThinLTOCacheDir(
"legacy-thinlto-cache-dir",
cl::desc("Experimental option, enable ThinLTO caching. Note: the cache "
"currently does not take the mcmodel setting into account, so you "
"might get false hits if different mcmodels are used in different "
"builds using the same cache directory."));

static cl::opt<int> ThinLTOCachePruningInterval(
"legacy-thinlto-cache-pruning-interval", cl::init(1200),
cl::desc("Set ThinLTO cache pruning interval (seconds)."));

static cl::opt<uint64_t> ThinLTOCacheMaxSizeBytes(
"legacy-thinlto-cache-max-size-bytes",
cl::desc("Set ThinLTO cache pruning directory maximum size in bytes."));

static cl::opt<int> ThinLTOCacheMaxSizeFiles(
"legacy-thinlto-cache-max-size-files", cl::init(1000000),
cl::desc("Set ThinLTO cache pruning directory maximum number of files."));

static cl::opt<unsigned> ThinLTOCacheEntryExpiration(
"legacy-thinlto-cache-entry-expiration", cl::init(604800) /* 1w */,
cl::desc("Set ThinLTO cache entry expiration time (seconds)."));

#ifdef NDEBUG
static bool VerifyByDefault = false;
#else
Expand Down Expand Up @@ -543,6 +567,25 @@ thinlto_code_gen_t thinlto_create_codegen(void) {
assert(CGOptLevelOrNone);
CodeGen->setCodeGenOptLevel(*CGOptLevelOrNone);
}
if (!ThinLTOCacheDir.empty()) {
auto Err = llvm::sys::fs::create_directories(ThinLTOCacheDir);
if (Err)
report_fatal_error(Twine("Unable to create thinLTO cache directory: ") +
Err.message());
bool result;
Err = llvm::sys::fs::is_directory(ThinLTOCacheDir, result);
if (Err || !result)
report_fatal_error(Twine("Unable to get status of thinLTO cache path or "
"path is not a directory: ") +
Err.message());
CodeGen->setCacheDir(ThinLTOCacheDir);

CodeGen->setCachePruningInterval(ThinLTOCachePruningInterval);
CodeGen->setCacheEntryExpiration(ThinLTOCacheEntryExpiration);
CodeGen->setCacheMaxSizeFiles(ThinLTOCacheMaxSizeFiles);
CodeGen->setCacheMaxSizeBytes(ThinLTOCacheMaxSizeBytes);
}

return wrap(CodeGen);
}

Expand Down