[ThinLTO] Support for specifying function index from pass manager

Summary:
Add a field on the PassManagerBuilder that clang or gold can use to pass
down a pointer to the function index in memory to use for importing when
the ThinLTO backend is triggered. Add support to supply this to the
function import pass.

Reviewers: joker.eph, dexonsmith

Subscribers: davidxl, llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D15024

llvm-svn: 254926

llvm/include/llvm/LinkAllPasses.h

@@ -86,6 +86,7 @@ namespace {
       (void) llvm::createDomViewerPass();
       (void) llvm::createGCOVProfilerPass();
       (void) llvm::createInstrProfilingPass();
+      (void) llvm::createFunctionImportPass();
       (void) llvm::createFunctionInliningPass();
       (void) llvm::createAlwaysInlinerPass();
       (void) llvm::createGlobalDCEPass();

llvm/include/llvm/Transforms/IPO.h

@@ -20,6 +20,7 @@
 
 namespace llvm {
 
+class FunctionInfoIndex;
 class ModulePass;
 class Pass;
 class Function;
@@ -85,6 +86,10 @@ ModulePass *createEliminateAvailableExternallyPass();
 ModulePass *createGVExtractionPass(std::vector<GlobalValue*>& GVs, bool
                                    deleteFn = false);
 
+//===----------------------------------------------------------------------===//
+/// This pass performs iterative function importing from other modules.
+ModulePass *createFunctionImportPass(FunctionInfoIndex *Index = nullptr);
+
 //===----------------------------------------------------------------------===//
 /// createFunctionInliningPass - Return a new pass object that uses a heuristic
 /// to inline direct function calls to small functions.

llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -15,9 +15,11 @@
 #ifndef LLVM_TRANSFORMS_IPO_PASSMANAGERBUILDER_H
 #define LLVM_TRANSFORMS_IPO_PASSMANAGERBUILDER_H
 
+#include <memory>
 #include <vector>
 
 namespace llvm {
+class FunctionInfoIndex;
 class Pass;
 class TargetLibraryInfoImpl;
 class TargetMachine;
@@ -114,6 +116,9 @@ public:
   /// added to the per-module passes.
   Pass *Inliner;
 
+  /// The function summary index to use for function importing.
+  FunctionInfoIndex *FunctionIndex;
+
   bool DisableTailCalls;
   bool DisableUnitAtATime;
   bool DisableUnrollLoops;

llvm/lib/Transforms/IPO/FunctionImport.cpp

@@ -256,23 +256,38 @@ getFunctionIndexForFile(StringRef Path, std::string &Error,
 
 /// Pass that performs cross-module function import provided a summary file.
 class FunctionImportPass : public ModulePass {
+  /// Optional function summary index to use for importing, otherwise
+  /// the summary-file option must be specified.
+  FunctionInfoIndex *Index;
 
 public:
   /// Pass identification, replacement for typeid
   static char ID;
 
-  explicit FunctionImportPass() : ModulePass(ID) {}
+  /// Specify pass name for debug output
+  const char *getPassName() const override {
+    return "Function Importing";
+  }
+
+  explicit FunctionImportPass(FunctionInfoIndex *Index = nullptr)
+      : ModulePass(ID), Index(Index) {}
 
   bool runOnModule(Module &M) override {
-    if (SummaryFile.empty()) {
-      report_fatal_error("error: -function-import requires -summary-file\n");
-    }
-    std::string Error;
-    std::unique_ptr<FunctionInfoIndex> Index =
-        getFunctionIndexForFile(SummaryFile, Error, diagnosticHandler);
-    if (!Index) {
-      errs() << "Error loading file '" << SummaryFile << "': " << Error << "\n";
-      return false;
+    if (SummaryFile.empty() && !Index)
+      report_fatal_error("error: -function-import requires -summary-file or "
+                         "file from frontend\n");
+    std::unique_ptr<FunctionInfoIndex> IndexPtr;
+    if (!SummaryFile.empty()) {
+      if (Index)
+        report_fatal_error("error: -summary-file and index from frontend\n");
+      std::string Error;
+      IndexPtr = getFunctionIndexForFile(SummaryFile, Error, diagnosticHandler);
+      if (!IndexPtr) {
+        errs() << "Error loading file '" << SummaryFile << "': " << Error
+               << "\n";
+        return false;
+      }
+      Index = IndexPtr.get();
     }
 
     // Perform the import now.
@@ -293,5 +308,7 @@ INITIALIZE_PASS_END(FunctionImportPass, "function-import",
                     "Summary Based Function Import", false, false)
 
 namespace llvm {
-Pass *createFunctionImportPass() { return new FunctionImportPass(); }
+Pass *createFunctionImportPass(FunctionInfoIndex *Index = nullptr) {
+  return new FunctionImportPass(Index);
+}
 }

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -18,6 +18,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/Passes.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/FunctionInfo.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Support/CommandLine.h"
@@ -108,6 +109,7 @@ PassManagerBuilder::PassManagerBuilder() {
     SizeLevel = 0;
     LibraryInfo = nullptr;
     Inliner = nullptr;
+    FunctionIndex = nullptr;
     DisableUnitAtATime = false;
     DisableUnrollLoops = false;
     BBVectorize = RunBBVectorization;
@@ -476,6 +478,9 @@ void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   // Provide AliasAnalysis services for optimizations.
   addInitialAliasAnalysisPasses(PM);
 
+  if (FunctionIndex)
+    PM.add(createFunctionImportPass(FunctionIndex));
+
   // Propagate constants at call sites into the functions they call.  This
   // opens opportunities for globalopt (and inlining) by substituting function
   // pointers passed as arguments to direct uses of functions.