[ThinLTO] Enable iterative importing in FunctionImport pass

Analyze imported function bodies and add any new external calls to
the worklist for importing. Currently no controls on the importing
so this will end up importing everything possible in the call tree
below the importing module. Basic profitability checks coming next.

Update test to check for iteratively inlined functions.

llvm-svn: 254011

1 files changed, 36 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index c874e4f5da7..bd6eb8391dc 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -131,10 +131,24 @@ bool FunctionImporter::importFunctions(Module &M) {
 
     // The function that we will import!
     GlobalValue *SGV = Module.getNamedValue(CalledFunctionName);
+    StringRef ImportFunctionName = CalledFunctionName;
+    if (!SGV) {
+      // Might be local in source Module, promoted/renamed in dest Module M.
+      std::pair<StringRef, StringRef> Split =
+          CalledFunctionName.split(".llvm.");
+      SGV = Module.getNamedValue(Split.first);
+#ifndef NDEBUG
+      // Assert that Split.second is module id
+      uint64_t ModuleId;
+      assert(!Split.second.getAsInteger(10, ModuleId));
+      assert(ModuleId == Index.getModuleId(FileName));
+#endif
+    }
     Function *F = dyn_cast<Function>(SGV);
     if (!F && isa<GlobalAlias>(SGV)) {
       auto *SGA = dyn_cast<GlobalAlias>(SGV);
       F = dyn_cast<Function>(SGA->getBaseObject());
+      ImportFunctionName = F->getName();
     }
     if (!F) {
       errs() << "Can't load function '" << CalledFunctionName << "' in Module '"
@@ -156,8 +170,28 @@ bool FunctionImporter::importFunctions(Module &M) {
     if (L.linkInModule(&Module, Linker::Flags::None, &Index, F))
       report_fatal_error("Function Import: link error");
 
-    // TODO: Process the newly imported function and add callees to the
-    // worklist.
+    // Process the newly imported function and add callees to the worklist.
+    GlobalValue *NewGV = M.getNamedValue(ImportFunctionName);
+    assert(NewGV);
+    Function *NewF = dyn_cast<Function>(NewGV);
+    assert(NewF);
+
+    for (auto &BB : *NewF) {
+      for (auto &I : BB) {
+        if (isa<CallInst>(I)) {
+          DEBUG(dbgs() << "Found a call: '" << I << "'\n");
+          auto CalledFunction = cast<CallInst>(I).getCalledFunction();
+          // Insert any new external calls that have not already been
+          // added to set/worklist.
+          if (CalledFunction && CalledFunction->hasName() &&
+              CalledFunction->isDeclaration() &&
+              !CalledFunctions.count(CalledFunction->getName())) {
+            CalledFunctions.insert(CalledFunction->getName());
+            Worklist.push_back(CalledFunction->getName());
+          }
+        }
+      }
+    }
 
     Changed = true;
   }