[ThinLTO] Add an import cutoff for debugging/triaging
Summary:
Adds -import-cutoff=N which will stop importing during the thin link
after N imports. Default is -1 (no limit).
Reviewers: wmi
Subscribers: inglorion, llvm-commits
Differential Revision: https://reviews.llvm.org/D45127
llvm-svn: 328934
diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index d021b4a..26d7db1 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -71,6 +71,10 @@
"import-instr-limit", cl::init(100), cl::Hidden, cl::value_desc("N"),
cl::desc("Only import functions with less than N instructions"));
+static cl::opt<int> ImportCutoff(
+ "import-cutoff", cl::init(-1), cl::Hidden, cl::value_desc("N"),
+ cl::desc("Only import first N functions if N>=0 (default -1)"));
+
static cl::opt<float>
ImportInstrFactor("import-instr-evolution-factor", cl::init(0.7),
cl::Hidden, cl::value_desc("x"),
@@ -276,11 +280,18 @@
StringMap<FunctionImporter::ExportSetTy> *ExportLists = nullptr) {
computeImportForReferencedGlobals(Summary, DefinedGVSummaries, ImportList,
ExportLists);
+ static int ImportCount = 0;
for (auto &Edge : Summary.calls()) {
ValueInfo VI = Edge.first;
DEBUG(dbgs() << " edge -> " << VI.getGUID() << " Threshold:" << Threshold
<< "\n");
+ if (ImportCutoff >= 0 && ImportCount >= ImportCutoff) {
+ DEBUG(dbgs() << "ignored! import-cutoff value of " << ImportCutoff
+ << " reached.\n");
+ continue;
+ }
+
VI = updateValueInfoForIndirectCalls(Index, VI);
if (!VI)
continue;
@@ -343,6 +354,8 @@
// Mark this function as imported in this module, with the current Threshold
ProcessedThreshold = AdjThreshold;
+ ImportCount++;
+
// Make exports in the source module.
if (ExportLists) {
auto &ExportList = (*ExportLists)[ExportModulePath];